Abstract

The discovery of Triassic missing links in the Panthalassan domain (Wallowa terrane, U.S.A.) substantiates a direct lineage between internally simple Triassic multichambered aragonitic foraminifers and internally partitioned Jurassic Robertinida. A new hierarchical subdivision is accordingly proposed for the order Robertinida, which is emended to encompass all known post-Paleozoic aragonitic multichambered foraminifers. At the highest taxonomic level, the suborder Robertinina is distinguished from the suborder Duostominina emended to encompass forms without internal structures attached to the aperture, including the planktonic family Favusellidae and the controversial form Pragsoconulus. Two new families (Robertonellidae, Trochosiphoniidae), four new subfamilies (Cassianopapillariinae, Praereinholdellinae, Pragsoconulinae, and Trochosiphoniinae), four new genera (Falsorheinoldella, Praerheinoldella, Robertonella, and Trochosiphonia), and seven new species (Falsorheinoldella ohmi, F. oregonica, Praerheinoldella galei, Robertonella rettorii, R. wallowensis, Trochosiphonia stanleyi, and T. josephi) are introduced. Phylogenetic links between Triassic robertinids, which experienced a rapid diversification during the Triassic, are clarified and their hypothetical long-term relationships with other foraminiferal groups are discussed.

INTRODUCTION

The order Robertinida groups multichambered aragonitic foraminifers that are assumed to possess internal partitions (Loeblich & Tappan, 1987). Considered as the direct descendant of a dark microgranular or agglutinated foraminifer and the common ancestor of the orders Buliminida, Globigerinida, and Rotaliida (Fuchs, 1973, 1975a; Tappan & Loeblich, 1988), it is a key group in foraminiferal evolution. Our understanding of the Robertinida lineage is yet limited. Internal structures in primitive forms have been overlooked, entailing taxonomic and phylogenetic inconsistencies.

Foraminifers assigned to the order Robertinida are recorded from the Early Triassic (Rettori et al., 1994) and have shown intense diversification periods in the Ladinian–Rhaetian (e.g., Kristan-Tollmann, 1960; Fuchs, 1967). Well-studied and well-calibrated in the Tethyan domain, they are abundant in Triassic Panthalassan deposits (Kristan-Tollmann & Tollmann, 1983; Kristan-Tollmann, 1988; Senff, 1992; Chablais et al., 2010) and represent potential tools for global biostratigraphic correlations (Kristan-Tollmann, 1988; Rigaud et al., 2010). Among Triassic “Robertinida,” Oberhauserellidae Fuchs, 1970, are regarded as the only group that survived the Triassic-Jurassic major extinction event, giving rise to the first planktonic foraminifers (Fuchs, 1973, 1975a; He, 1998). They are also considered as the direct ancestors of the Ceratobuliminoidea Cushman, 1927 (Fuchs, 1975a; von Hillebrandt, 2010, 2012), even though they display uncovered, dorsally inflated chambers and lack inner-chamber structures. The latter characteristic, besides, entails doubts in their taxonomic assignment to Robertinida.

Actually, contrary to previous views (Loeblich & Tappan, 1987; Kristan-Tollmann, 1988), most multichambered aragonitic Triassic foraminifers that have been positioned in the order Robertinida lack inner-chamber structures. Through a literature review and the study of new Early Mesozoic Robertinida, this paper intends to correct major inconsistencies existing in the classification and phylogeny of these multichambered aragonitic foraminifers. Up to now, the phylogeny of Robertinida has been mainly based on the studies of Fuchs (1973, 1975a) and their high-rank taxonomy, on the works of Loeblich & Tappan (1987, 1992). In the Triassic, the order Robertinida is thus believed to be only represented by the families Asymmetrinidae Brotzen, 1963, Duostominidae Brotzen, 1963, and Oberhauserellidae. Based on remarkably well-preserved material from the Wallowa terrane (Oregon, U.S.A.), we here document other, disregarded Triassic representatives of the order.

THE DEFINITION OF ROBERTINIDA

Until now, the uniqueness of Robertinida as an order including all internally partitioned and finely perforate benthic multichambered aragonitic foraminifers has been widely accepted. However, this definition proposed by Loeblich & Tappan (1987) is too restrictive to encompass all the genera that have been included in the group (Haynes, 1990). Most Cretaceous–Recent Robertinida possess internal partitions but older representatives do not necessarily display such structures.

In the Triassic, inner-chamber structures have been identified only in Duostomina biconvexaKristan-Tollmann, 1960, type species of the genus DuostominaKristan-Tollmann, 1960, and in D. altaKristan-Tollmann, 1960 (Kristan-Tollmann, 1966). These structures do not form internal plates as in the family Epistominidae Wedekind, 1937, are not attached to the aperture, and are limited to the chamber edges. They internally separate the double interiomarginal aperture of Duostomina and are probably features intrinsic to the family Duostominidae Brotzen, 1963. For instance, in Variostoma pralongenseKristan-Tollmann, 1960, a form also possessing two interiomarginal apertures, no internal structures are observed (e.g., see di Bari & Laghi, 1998, pl. 1, fig. 1). Likewise, the “arcus” or “vault” identified as an inner-chamber structure by Fuchs (1969) in PraegubkinellaFuchs, 1967, is a simple fold of the wall, giving to the chamber its kidney shape. It is not connected to the aperture and cannot be considered as an internal structure. Similarly, the wall projections possibly observed at the chamber roof of the genus Cassianopapillariadi Bari & Rettori, 1998 (nom. subst. for Papillariadi Bari & Rettori, 1996, preoccupied), are only inherited structures of the papillae formed on the umbilical side of the preceding whorl (see di Bari & Rettori, 1996, pl. 1, fig. 4b). All internally simple Triassic aragonitic foraminifers are yet assigned to the “internally partitioned” order Robertinida.

The presence or absence of internal partitions in multichambered aragonitic foraminifers should not be used at the highest taxonomic level as it would exclude early representatives of the group. As suggested by Haynes (1990), the Robertinida definition requires emendation.

TAXONOMIC POSITION OF ROBERTINIDA

Considered for a long time as an order or a class (Loeblich & Tappan, 1964, 1987, 1992), foraminifers are now regarded as a subphylum or phylum of protists (Cavalier-Smith, 2002, 2003; Adl et al., 2012; Pawlowski et al., 2013), and consequently, the order Robertinida might be elevated to the rank of subclass. Nevertheless, doubts persist on the foraminiferal high-rank taxonomy. According to molecular data, all calcareous and agglutinated multichambered foraminifers should be grouped together and separated from single-chambered and tubular forms sensu lato (e.g., class Globothalamea in Pawlowski et al., 2003, 2013; Bowser et al., 2006). Such grouping, based on basic morphological differences, would be consistent with the large-scale phylogenetic hypotheses proposed for Robertinida by Fuchs (1973, 1975a) and Tappan & Loeblich (1988). However, it would be less compatible with the traditional view of the foraminiferal taxonomy, which considers the wall mineralogy as a primary characteristic.

The wall of representatives of the order Robertinida is finely perforate and composed of thin laminae that are made up of aragonite needles showing a c-axis more or less perpendicular to the wall surface (Loeblich & Tappan, 1987; di Bari & Laghi, 1998). This wall structure and composition is close to that of the tubular Involutinida Hohenegger & Piller, 1977 (see Piller, 1978, 1983; di Bari & Laghi, 1994). At this time, molecular studies are too incomplete to allow any consistent phylogenetic hypothesis. Only two recent Robertinida have been sequenced (Jan Pawlowski, communication, 2014) and no molecular data on Involutinida exist. The Early Triassic foraminiferal record is very scarce, hindering large-scale phylogenetic reconstructions. The first Robertinida are believed to have originated from a Triassic descendant of Tetrataxidae Galloway, 1933 (Fuchs, 1973), or Trochamminidae Schwager, 1877 (Tappan & Loeblich, 1988). However, Triassic Tetrataxidae are only recovered from the Middle Triassic and Triassic Trochamminidae have only been cited from the uppermost Olenekian (Grădinaru et al., 2007). Conversely, primitive Involutinida are well-documented in the Olenekian (e.g., Rettori, 1995) but, except for their wall nature, share very few characteristics with the first Robertinida.

Pending the discovery of missing links or the contribution of new molecular data, it seems thus premature to elevate Robertinida to the rank of subclass or to group it with Involutinida or with another group of multichambered foraminifers. The high-rank taxonomic position of Robertinida in Globothalamea Pawlowski, Holzmann & Tyszka, 2013, remains an open question.

CLASSIFICATION OF ARAGONITIC FORAMINIFERS

In the subphylum Foraminifera d’Orbigny, 1826, the test mineralogical composition and the wall structure are traditionally regarded as primary criteria for classification and have been used to establish and separate suprafamiliar units (Loeblich & Tappan, 1987, 1992). Curiously, aragonitic foraminifers appear as an exception. The suborder Involutinina (sensu Loeblich & Tappan, 1987, 1992) includes all tubular aragonitic foraminifers, but has been assigned to the monocrystalline calcitic order Spirillinida Gorbatchik & Mantsurova, 1980 (see Loeblich & Tappan, 1992). Conversely, while robertinids have been elevated to the rank of order, they only include part of multichambered aragonitic foraminifers. According to Loeblich & Tappan (1992), other aragonitic multichambered forms would be included in the orders Buliminida Fursenko, 1958, Globigerinida Lankester, 1885, Rotaliida Lankester, 1885, and Spirillinida (including Involutinina); we can add the order Fusulinida Fursenko, 1958 (with Staffelloidea Miklukho-Maklay, 1949, nom. translat. Solovieva, 1978; see Wilde, 1975; Ross, 1982; Groves, 1991; Vachard et al., 2010; Hance et al., 2011), and the order Textulariida Lankester, 1885 (see Roberts & Murray, 1995), to their list. This peculiarity is mainly attributable to the unknown or poorly documented primary composition of the test of numerous foraminifers included in these groups.

In some cases, however, taxa have been excluded from Robertinida although their original aragonitic composition was established. Despite their aragonitic test (Gorbatchik & Kuznetsova, 1986), the multichambered Favuselloidea Longoria, 1974, have been included in Globigerinida, then supposed to encompass calcitic planktonic foraminifers only. This assignment has been widely accepted following BouDagher-Fadel et al. (1997), who have proposed to include both calcitic and aragonitic forms in Globigerinida. Nevertheless, molecular studies have now demonstrated that the order Globigerinida is polyphyletic and thus represents an artificial group (Darling et al., 1997, 2009; de Vargas et al., 1997; Ujiié et al., 2008). The adaptation to a planktonic lifestyle occurred several times in the foraminiferal evolution, implying that this mode of life has a lower taxonomic value than previously argued (Ujiié et al., 2008; Darling et al., 2009). As favuselloids only include extinct species, their potential phylogenetic link with other planktonic foraminifers cannot be verified by molecular studies. However, morphological and stratigraphic evidences strongly support that the families Oberhauserellidae and Globuligerinidae Loeblich & Tappan, 1984, are phylogenetically linked (Fuchs, 1973, 1975a; He, 1998; Wernli & Görög, 2007). The two groups only differ in their chamber morphology (entirely globular in Globuligerinidae). This characteristic is definitely insufficient to position these forms in two different orders. Therefore, with intent to obtain a more natural classification, we here assign favusellids to Robertinida rather than to Globigerinida (e.g., in Loeblich & Tappan, 1987; BouDagher-Fadel et al., 1997; Görög & Wernli, 2003).

Subsequent to the classification of Loeblich & Tappan (1987), the existence of new aragonitic taxa has been evidenced, even in the order Textulariida. According to both molecular and fossil data, Textulariida represent a paraphyletic to polyphyletic group (Pawlowski et al., 1997, 1999, 2013; Pawlowski, 2000; Bowser et al., 2006; Rigaud et al., in press). The agglutination process has arisen several times in the early evolution of foraminifers (Pawlowski et al., 2003; Vachard et al., 2010), and later, has been evidenced in the Miliolida, Rotaliida, and Fusulinida lineages (e.g., Rauzer-Chernousova, 1948; Reitlinger, 1950; Voloshinova & Reitlinger in Rauzer-Chernousova & Fursenko, 1959; Loeblich & Tappan, 1964; Brazhnikova & Vdovenko, 1973; Tappan & Loeblich, 1988; Bender, 1995; Fahrni et al., 1997; Vachard et al., 2010; Hance et al., 2011; Rigaud et al., in press). Hence, the presence of agglutinated grains cannot be confidently used as a criterion of high taxonomic value, and consequently, agglutinated multichambered foraminifers that use aragonite as a biomineralized cement such as “TextulariacrenataCheng & Zheng, 1978 (Roberts & Murray, 1995) might be true Robertinida (Bender, 1995). As yet no fossil data support a direct phyletic link between the two groups and it would be speculative to attempt such assignment. Nevertheless, in molecular phylogeny based on ribosomal SSU gene sequence data, the only sequenced Robertinida (i.e., Robertina arcticad’Orbigny, 1846) is found on a branch of multichambered Textulariida (see Bowser et al., 2006, fig. 5.3).

ROBERTINIDA TEST: PRESERVATION AND IDENTIFICATION

Aragonitic in composition, the Robertinida test is metastable and thus particularly susceptible to dissolution. As a result, fossil Robertinida are strongly subject to diagenetic alterations and commonly entirely recrystallized to calcisparite, if not previously micritized. This entails difficulties in their identification and leads to taxonomic confusions. Robertinida have been, for example, often mistaken with calcitic forms, entailing an underestimation of their diversity and, therefore, limiting our understanding of the lineage.

Very few Robertinida have shown a sufficient preservation to be analyzed using mineralogical determination methods (Wiewióra, 1964; Fuchs, 1969; Gorbatchik & Kuznetsova, 1986; di Bari & Rettori, 1996; BouDagher-Fadel et al., 1997; di Bari & Laghi, 1998; di Bari, 1999). When diagenetically altered, the original chemical composition and crystallography of the test of fossil Robertinida cannot be verified by instrumental means. Instead, the wall’s original aragonitic nature must be evidenced by indirect methods. All fossils do not respond equally to diagenetic processes. Due to their instability, aragonitic tests and shells are generally the first to be altered by diagenesis. In moderately diagenetically altered rocks, a thorough comparative study of the bioclasts’ structure and diagenetic texture may thus allow the recognition of aragonitic components. Such methods have already allowed the identification of fossil aragonitic tests prior to their analysis (e.g., see Wernli, 1987, for “protoglobigerinids”).

STUDIED SPECIMENS: WALL IMPREGNATION AND ORIGINAL COMPOSITION

The investigated material comes from the Black Marble Quarry (Oregon, U.S.A.) and the Mission Creek Quarry (Idaho, U.S.A.; Fig. 1). The two localities are both parts of the late Carnian–early late Norian Martin Bridge Formation (Rigaud, 2012), a major carbonate sequence of the Wallowa terrane (Whalen, 1988; Follo, 1994; Stanley et al., 2008), which originated in Panthalassa at calculated paleolatitudes of 18–24 ± 4° (Hillhouse et al., 1982; May & Butler, 1986). The sites, tectonically isolated from other carbonate occurrences, consist of fossiliferous limestone successions partly impregnated by hydrocarbons. Almost 250 thin sections have been made from the two quarries. Foraminifers are particularly abundant and diversified in the muddy lagoonal deposits of the lower part of the Black Marble Quarry (Rigaud et al., 2012, 2013a, b, in press) and the middle part of the Mission Creek Quarry.

Related to its long accretionary history, the Wallowa terrane has been particularly affected by both regional greenschist and pluton-related thermal metamorphism (Armstrong et al., 1977; Goldstrand, 1994; Avé Lallemant, 1995; Gray & Oldow, 2005). As a consequence, most limestone rocks of the Martin Bridge Formation are recrystallized to marble. In the few levels impregnated by hydrocarbons, however, the matrix and bioclasts look remarkably sheltered from diagenetic and metamorphic alterations. In these beds, comparative studies of the diagenetic textures (see Figs. 2.1–2.10) have evidenced significant differences between established aragonitic (e.g., dasycladaceans, gastropods, spherulites, Involutinida, Robertinida) and non-aragonitic elements that possess various calcitic compositions and microstructures (e.g., brachiopods, echinoderms, sponges, ostracods, and calcitic hyalino-radial, porcelaneous, or microgranular/agglutinated foraminifers).

All aragonitic grains are completely recrystallized and replaced by sparitic calcite crystals (Figs. 2–5), but their original structure is still recognizable. In aragonitic foraminifers, for example, the laminae and perforations outline are partially to wholly preserved (Figs. 2–5). This peculiar preservation is related to the pervasive hydrocarbon impregnation of the foraminiferal wall prior to its thermally controlled recrystallization. In thin section, hydrocarbon relics appear as a brownish lining in place of the original test and without any relationship to the sparitic calcite crystal limits (see grayish walls in the gray-scaled Figs. 2.10, 4.1, 5.1). This is characteristic of replacement growth during recrystallization. On a smaller scale, hydrocarbon relics appear as scattered inframicrometric, carbon-rich spherical elements (Figs. 2.10d, e, 4.1d), most probably located in place of the test primary microporosity. This configuration has allowed a fine, ghost preservation of the original microstructure of aragonitic components (Figs. 2.1–2.10, 3–5).

Conversely, the original tests or shells of non-aragonitic components are partially to well-preserved in these impregnated levels, whatever their original composition and microstructure (e.g., Figs. 2.5, 2.6). Possibly partly micritized or slightly recrystallized, they are never replaced by sparitic crystals and do not appear brownish in thin section. The test microporosity of microgranular and agglutinated foraminifers is also impregnated by hydrocarbon relics (mainly microcrystalline graphite) but, as the surrounding matrix, tests always appear black (Figs. 2.3, 2.5).

At the Black Marble Quarry, the state of preservation of bioclasts and grains is a remarkable example for comparative studies of the diagenetic results in carbonate rocks. Aragonitic components are generally too altered for paleontological investigations and their contribution to the sedimentary balance is largely underrated. We here evidence the aragonitic composition of various organisms (e.g., forms included in the families Robertonellidae and Trochosiphoniidae) that, under other states of preservation, would have most probably been considered as calcitic components.

SYSTEMATICS

In the order Robertinida, species diagnoses are generally based on the study of isolated specimens. The surface ornamentation and structure and the aperture position and morphology have thus been considered as key criteria for taxonomic subdivisions, entailing difficulties in their reliable determination in thin section (Wernli & Görög, 2000; Fugagnoli & Posenato, 2004; Gale et al., 2011) in such a way that Robertinida have been disregarded in limestone rocks. We here describe new Late Triassic Robertinida from thin sections. With the intention of obtaining a systematic classification, full attention has been given to the aperture morphology and the test surface. Nevertheless, as our specimens are randomly sectioned, we cannot exclude that the opening observed in the last sectioned chamber of a specimen represents a foramen. To limit such misinterpretation, the aperture has been defined on the observation of several specimens, except when otherwise indicated. Robertinids are major constituents of the Wallowa terrane shallow-water carbonate deposits. Thousands of specimens have been observed, allowing their accurate description.

The discovery of new Triassic Robertinida that lack internal partitions leads us to revise the whole group up to the superfamily level. Contrary to the taxonomy proposed by Loeblich & Tappan (1987, 1992), our revised classification encompasses the whole diversity of structures and morphologies existing in the group. The suborder is emended to include forms without internal structures. Higher classification is based on inner-chamber structures or umbilical region morphology. The main criteria used for the subdivision of Duostominina are presented in a determination key (Fig. 6). This new classification also provides an update of the robertinid stratigraphic distribution.

Subphylum FORAMINIFERA d’Orbigny, 1826

Class GLOBOTHALAMEA Pawlowski, Holzmann & Tyszka, 2013

Order ROBERTINIDA Mikhalevich, 1980, emend. herein

Ceratobuliminida Mikhalevich, 1980, p. 59.

Emended diagnosis

Test multichambered, conical to lenticular or subglobular, or ovate to elongate. Wall aragonitic, fibro-radial, primarily bilamellar but commonly thickened by additional laminae or lamellae, and finely perforate.

Stratigraphic distribution

Early Triassic–Holocene.

Comparison

Except for the perforation size (larger in Involutinida), the wall structure and composition of the multichambered Robertinida is identical to that of the undivided tubular Involutinida (Fig. 2.7). The presence of septa in robertinids easily allows their distinction. The two groups are known from the Olenekian (Early Triassic; Rettori, 1995).

The aragonitic order Robertinida shows high architectural similarities with some Buliminida, Globigerinida, and Rotaliida (all hyaline-calcitic), but a different wall crystallography. All mentioned calcitic taxa appeared later and possibly derived from a branch of Robertinida (Fuchs, 1973, 1975a; Tappan & Loeblich, 1988).

Remarks

Robertinids have been considered as foraminifers characterized by a complex apertural apparatus and inner-chamber partitions (e.g., Loeblich & Tappan, 1987). These are erroneous statements because Robertinida with a simple aperture and devoid of internal partitions have been documented up to the Cenomanian (within the family Favusellidae).

First considered as monolamellar (Reiss, 1958, 1963; Loeblich & Tappan, 1964; Hansen et al., 1969), the wall of Robertinida has been then regarded as bilamellar (McGowran, 1966a; di Bari, 1999). Actually, the wall of Robertinida is primarily bilamellar, but Mesozoic forms commonly show additional, more or less developed, laminae and lamellae. Cenozoic to Recent forms also locally display additional laminae, as discernible in the illustrations of McGowran (1966a, see laminae in pl. 1, figs. 3–6, pl. 2, figs. 1, 2, 6–8, pl. 3, figs. 3, 4, 6).

Although Robertinida are here emended to include all known post-Paleozoic multichambered aragonitic foraminifers, they are still one of the less diversified foraminiferal groups. As previously noted, on account of their poor preservation in the fossil record, it is likely that some Robertinida representatives have been erroneously included in the orders Buliminida, Globigerinida, Involutinida, Rotaliida, Spirillinida, and Textulariida. For example, Loeblich & Tappan (1987) have positioned aragonitic, possibly planktonic foraminifers (Globuligerinidae and Favusellidae) in Globigerinida and the genus PragsoconulusOberhauser, 1963 (aragonitic, multichambered), in Involutinida (Involutinina in Loeblich & Tappan, 1987, 1992). In order to avoid such taxonomic mix-up, X-ray analysis, SEM observations, chemical staining application, and, in the case of recrystallized tests, comparative studies of the diagenetic textures should be performed on any questionable calcareous foraminifer.

In addition to the poor definition and probable undervaluation of the order, there are significant inaccuracies in the description and subdivision of subordinate taxa. In Loeblich & Tappan (1987), the order Robertinida has been subdivided into four superfamilies: Duostominoidea Brotzen, 1963, Ceratobuliminoidea Cushman, 1927, Conorboidoidea Thalmann, 1952, and Robertinoidea Reuss, 1850. The superfamily Duostominoidea, for example, is defined as “nonlamellar, possibly originally aragonitic,” though the group is typified by the genus Duostomina that is incontestably lamellar and aragonitic (di Bari & Laghi, 1998; Gale et al., 2011). Furthermore, the defining characters that are used to separate families and subfamilies are non-systematic and often ambiguous or unreliable. For instance, details in the coiling mode such as a dextral or sinistral arrangement are either specified in superfamilies, families, or subfamilies diagnoses. Although sometimes predominant, these enrollment characteristics are known to be random in the group (Troelsen, 1954). The following high-rank subdivision for the order Robertinida uses clear and systematic criteria.

Suborder ROBERTININA Loeblich & Tappan, 1984, emend. herein

Emended diagnosis

Robertinida with inner-chamber structures attached or fused to the aperture.

Stratigraphic distribution

Early Jurassic (Hettangian)–Holocene.

Remarks

As Haynes (1990) noted in the classification of Loeblich & Tappan (1987), robertinins were inaccurately defined as planispiral to trochospiral. Although mostly trochospiral and sometimes planispiral, the robertinins may present other modes of coiling (e.g., uncoiled uniserial final stage in Colomia and Stedumia).

The internal plates observed in Robertinina representatives do not entirely divide the chambers. Chambers may be subdivided (e.g., in Robertina), but this subdivision is related to a wall infolding.

Superfamily CERATOBULIMINOIDEA Cushman, 1927, emend. herein

Emended diagnosis

Robertinina with a primarily trochospiral test and chambers partitioned by an internal plate attached to the inner margin of the aperture.

Stratigraphic distribution

Early Jurassic (Hettangian)–Holocene. Early Hettangian specimens of Reinholdella have been illustrated by von Hillebrandt (2010, 2012).

Comparison

Ceratobuliminoids show strong morphological similarities with some representatives of the calcitic Rotaliida superfamilies Asterigerinoidea d’Orbigny, 1839, Discorbinelloidea Sigal inPiveteau, 1952, Discorboidea Ehrenberg, 1838, and Siphoninoidea Cushman, 1927. All these calcitic groups differ from Ceratobuliminoidea in their wall composition, and Discorbinelloidea, Siphoninoidea, and most Discorboidea lack inner-chamber structures. Nevertheless, the wall composition and internal structures have been overlooked in numerous taxa that have been assigned to these five groups and their systematic assignment must be regarded with great caution.

Remarks

The internal plates that characterize Ceratobuliminoidea show a large range of size and morphology. More or less curved, they may occupy a horizontal, vertical, or oblique position according to the foramen location. They have been named “toothplates” but never form apertural protrusions (Grigelis, 1978). According to Revets (1989, 1993), true toothplates are limited to the buliminids. However, this definition must be revised as this group is now proved to be polyphyletic (Schweizer et al., 2008).

Ceratobuliminoids generally show important intraspecific morphological variations and their diversity in the fossil record has probably been overestimated (e.g., see Williamson & Stam, 1988). Genera that have been suitably included in the group comprise Ceratobulimina Toula, 1915, CeratocancrisFinlay, 1939, CeratolamarckinaTroelsen, 1954, EpistominaTerquem, 1883, EpistominataGrigelis, 1960, Garantella, Kaptarenko-Chernousova, 1956, HoeglundinaBrotzen, 1948, LamarckellaKaptarenko-Chernousova, 1956, LamarckinaBerthelin, 1881, MironovellaDain, 1970, PaulinaGrigelis, 1977, Pseudolamarckina Myatlyuk inRauzer-Chernousova & Fursenko, 1959, ReinholdellaBrotzen, 1948, SublamarckellaAntonova, 1958, VellaenaSrinivasan, 1966, and ZelamarckinaCollen, 1972. The wall composition and/or internal structure of the genera CancrisiellaDain, 1980, CeratobuliminoidesParr, 1950, Cerobertinella Myatlyuk inFursenko & Myatlyuk, 1980, EpistominoidesPlummer, 1934, Pseudoepistominella Kuznetsova inBykova et al., 1958, RectoepistominoidesGrigelis, 1960, Rogliciavan Bellen, 1941, RubratellaGrell, 1956, and SaintclairoidesMcCulloch, 1981, need clarification prior to their potential assignment to the group. According to McGowran (1966b), Ceratobuliminoides lacks inner-chamber plates, entailing doubts on its assignment to the Robertinina.

The genera ChalilovellaPoroshina, 1985 (probable Asterigerinoidea), and PseudosiphoninellaPoroshina, 1986 (probable Siphoninoidea), were assigned to the Ceratobuliminoidea. Their test shape and chamber morphology are different from those observed in this superfamily. As neither their wall composition nor their inner-chamber structures are known, it seems more reliable to exclude them from the group.

Superfamily CONORBOIDOIDEA Thalmann, 1952, emend. herein

Emended diagnosis

Robertinina with a trochospiral, biserial to uniserial test and chambers traversed by a hemicylindrical to cylindrical toothplate-like structure attached to the aperture edge.

Stratigraphic distribution

Late Jurassic (Oxfordian)–Late Cretaceous (Maastrichtian).

Comparison

The superfamily Conorboidoidea mainly differs from the superfamily Ceratobuliminoidea in the scroll- or pillar-like morphology of its inner-chamber structure. Conorboidoids mainly differ from “buliminoids” in the aragonitic nature of their wall. As described for “buliminoids” by Revets (1989, 1993), the toothplate-like structure in conorboidoids may fuse with the foraminal lip.

Remarks

The inner-chamber structures observed in Conorboidoidea are morphologically close to “buliminids toothplates.” It is still unknown whether this similarity is the result of a convergent adaptation to a comparable mode of life or the evidence of a direct phylogenetic link.

The superfamily includes the genera ColomiaCushman & Bermúdez, 1948, Conorboides Hofker inThalmann, 1952, and StedumiaBertram & Kemper, 1982. Subject to their aragonitic composition, the genera Paleopatellina Kasimova, Poroshina & Geodakchan in Geodakchan et al., 1973, PlacentulinaKasimova, 1978, and TrispirinaDanich, 1977, all finely perforate and provided with an internal cylindrical structure, and some species positioned in the genera PatellinellaCushman, 1928, and PseudopatellinellaTakayanagi, 1960, might be assigned to the group.

Superfamily ROBERTINOIDEA Reuss, 1850, emend. herein

Emended diagnosis

Robertinina with a trochospiral test, possibly becoming uncoiled, and chambers partitioned or subdivided by a wall infolding attached to the aperture margin.

Stratigraphic distribution

Paleocene–Holocene.

Comparison

Robertinoids are the only Robertinida showing chambers partitioned or subdivided by a wall infolding. In Robertinoidea, contrary to Ceratobuliminoidea, the foramen is homologous to the aperture and is not formed through resorption (Grigelis, 1978).

Remarks

In the literature, there is a significant divergence in the description of Robertinoidea internal structures. According to Höglund (1947), the wall infolding (diaphragm) is connected to the aperture via an arch. Conversely, Troelsen (1954) considered that the arch is part of the wall infolding which would be thus directly attached to the aperture.

The superfamily includes the genera AlliatinaTroelsen, 1954, AlliatinellaCarter, 1957, CerobertinaFinlay, 1939, GeminospiraMakiyama & Nakagawa, 1941, Robertinad’Orbigny, 1846, and RobertinoidesHöglund, 1947. The aragonitic composition of the genera CushmanellaPalmer & Bermúdez, 1936, and PseudobuliminaEarland, 1934, must be determined before their definitive assignment to the group. The genus SidebottominaSeiglie, 1964, tentatively positioned in the Robertinina by Loeblich & Tappan (1987) must be excluded from the group. Biserial, neither its wall composition nor its internal structure has been documented.

Suborder DUOSTOMININA Mikhalevich, 2013, emend.

Emended diagnosis

Robertinida with a simple or superficially partitioned chamber interior.

Composition

The suborder Duostominina includes the superfamilies Duostominoidea Brotzen, 1963, and Oberhauserelloidea Fuchs, 1975a.

Stratigraphic distribution

Early Triassic–Late Cretaceous (Cenomanian).

The species Krikoumbilica pileiformisHe, 1984, earliest known representative of the group, has been found in the Early Triassic (Olenekian) of Hydra, Greece (Rettori et al., 1994).

Comparison

Contrary to Robertinina, Duostominina may only display internal structures limited to the chamber edges.

Remarks

In the literature, representatives of Duostominina have been repeatedly described as “probably aragonitic.” The aragonitic nature of the wall of Cassianopapillaria, DiplotreminaKristan-Tollmann, 1960, Duostomina, FavusellaMichael, 1973, GlobuligerinaBignot & Guyader, 1971, KollmanitaFuchs, 1967, OberhauserellaFuchs, 1967, Pilleritadi Bari, 1999, Praegubkinella, Pragsoconulus, and VariostomaKristan-Tollmann, 1960, has been confirmed by X-ray analysis (Fuchs, 1969; Gorbatchik & Kuznetsova, 1986; di Bari & Rettori, 1996; BouDagher-Fadel et al., 1997; di Bari & Laghi, 1998; di Bari, 1999).

The suborder Duostominina is here considered to encompass both benthic and probable planktonic/tychopelagic forms (Favusellidae).

Superfamily DUOSTOMINOIDEA Brotzen, 1963, emend. herein

Emended diagnosis

Duostominina with a planispiral to trochospiral test and chambers partially or entirely covered by umbilical laminar deposits as successive chambers are added so that umbilical side sutures are not visible.

Stratigraphic distribution

Early Triassic (Olenekian)–Middle Jurassic (Bajocian). In Early Jurassic deposits, Duostominoidea are very rare but recent studies have demonstrated their presence in the early Hettangian (von Hillebrandt, 2010, 2012).

Comparison

Duostominoids are distinct from oberhauserelloids in their umbilical side, which is partially to entirely covered by laminar deposits. These laminar deposits may be very thin and/or laterally restricted, only slightly covering the umbilical sutures so that the suture area may appear slightly depressed.

Remarks

As stated by Kristan-Tollmann (1960) and demonstrated by di Bari & Laghi (1998) and Gale et al. (2011), duostominoids are plurilamellar. This lamellarity is, however, usually obliterated by diagenetic processes. This poor state of preservation possibly explains why Loeblich & Tappan (1987) defined the group as nonlamellar.

Family DUOSTOMINIDAE Brotzen, 1963, emend. Gale et al., 2011, emend. herein

Emended diagnosis

Trochospiral Duostominoidea with a convexo-plane, biconvex, or lenticular shape and chambers internally partitioned on their umbilical side by superficial wall thickenings, partially delimiting and individualizing the successive foramina and the aperture.

Composition

Up to now, inner-chamber thickenings around the edges and between the successive foramina and the aperture have only been identified in DuostominaKristan-Tollmann, 1960.

As Duostomina, Pillerita shows a double aperture separated by a tenon, which might be the evidence of a superficial internal partition. Accordingly, pending the observation of the chamber interior of Pillerita, we tentatively position this aragonitic form in Duostominidae. Previously, the genus Pillerita was positioned in the family Oberhauserellidae (di Bari, 1999) but this assignment is unsatisfactory as the genus lacks the arcus (sensu Fuchs, 1969) characteristic of the group.

Stratigraphic distribution

Middle Triassic (Anisian)–Late Triassic (Rhaetian).

Comparison

Duostominoids differ from other Robertinida in the nature of their inner-chamber structures, limited to the chamber edges (see Kristan-Tollmann, 1966, for details).

Remarks

Numerous dissimilarities have been observed between the families Duostominidae and Variostomatidae Kristan-Tollmann, 1963 (see Kristan-Tollmann, 1966; di Bari & Laghi, 1998). We here separate the two groups on account of the presence of superficial inner-chamber structures in Duostomina. According to Kristan-Tollmann (1966), these structures would evidence a phylogenetic link between Duostominidae and Ceratobuliminoidea representatives.

Before this work, all trochospiral Triassic Robertinida were either assigned to the families Duostominidae or Oberhauserellidae without consideration of their internal structure. A whole revision at the specific level of Triassic Robertinida, combining a study of isolated and sectioned specimens, is required in order to define the correct systematic position of each species and thus improve our knowledge of the phylogeny of the whole group.

Family ROBERTONELLIDAE, n. fam.

Diagnosis

Trochospiral, straight to flared conical Duostominoidea with an angular to carinate margin, internally simple chambers, and an umbilical region lined by thin laminar deposits, delimiting a deep and narrow umbilicus.

Stratigraphic distribution

Late Triassic (Carnian–Norian).

Comparison

Robertonellids differ from other Duostominoidea in their typical straight to flared conical shape and their deep and narrow umbilicus.

Remarks

The high-conical Carnian specimen illustrated in Brönnimann et al. (1974, pl. 1, fig. 24) most likely represents an intermediary form between variostomatids and robertonellids.

Genus Robertonella n. gen.

Type species: Robertonella rettorii n. gen., n. sp.

Derivatio nominis

The new genus is dedicated to Roberto Rettori (University of Perugia, Italy) for his contributions to foraminiferal studies.

Diagnosis

Test free, conical to flared conical, rounded in outline, with an angular to carinate margin. Evolute on the spiral side, involute on the umbilical side, it is formed by a globular proloculus with a simple, rounded opening, a short tubular chamber (in microspheric forms only, see Fig. 3.14), and trochospirally coiled ovoid to crescentiform chambers (in both microspheric and megalospheric forms). Each whorl is usually formed by three chambers. Each chamber, internally simple, develops a thin umbilical wall extension that lines the umbilical depression, delimiting a deep and narrow umbilicus (Figs. 3.1–3.3, 7–9). Wall originally fibro-radial and aragonitic, laminated and finely perforate. Aperture, single, a rounded opening in interiomarginal position.

Stratigraphic and geographic distribution

Late Triassic. Carnian–Norian of Tethys (Austria, ?Czech Republic, China) and late? Carnian–early Norian of the Panthalassan domain (Wallowa terrane, Oregon, U.S.A.).

Included species

The new genus comprises the species R. rettorii n. gen., n. sp. and R. wallowensis n. gen., n. sp.

Comparison

In the Triassic, diagenetically altered, sectioned specimens of Robertonella might be mistaken for representatives of the genus DuotaxisKristan, 1957. However, Duotaxis (finely agglutinated, non laminar) possesses lunate chambers, and its apertural slit is partly covered by a lobe, whereas Robertonella (aragonitic, laminar) shows crescentiform chambers with a simple, rounded interiomarginal aperture. Moreover, Robertonella displays a well-defined hollow umbilicus.

The tubular chamber of microspheric Robertonella might be compared with the tubular intermediary stage of calcitic, monocrystalline Patellinidae Rhumbler, 1906. However, in microspheric Robertonella, the tubular chamber is shorter, never forming a complete whorl.

Remarks

Robertonella shows similitude with foraminifers previously positioned in Placentulinidae Kasimova et al., 1980 (e.g., Paleopatellina, Patellinella, Placentulina, Pseudopatellinella, Trispirina). The wall composition of the oldest Placentulinidae is still uncertain. Morphologically, Robertonella is particularly close to Trispirina but possesses a less complex apertural system. On account of their high morphological similarities, it is most likely that these two forms are phyletically linked, whatever the test composition of the genus Trispirina (most likely aragonitic, hyaline-calcitic, or monocrystalline). In Loeblich & Tappan (1987), the genus Placentulina was synonymized under Trispirina. Placentulina, however, displays more chambers per whorls than Trispirina (triseriate) and, for that reason, must be considered as valid.

Robertonella rettorii n. gen., n. sp. Figs. 3.1–3.6, Fig. 4.15

Pragsoconulus? sp. inHe & Yue, 1987, p. 218, pl. V, figs. 6, 7.

Trocholina gracilis Blau inRoniewicz et al., 2007, p. 587, pl. 2, fig. 7.

Holotype

No. 2011-1-449b; Fig. 3.1.

Derivatio nominis

As for the genus, the species in named in honor of Roberto Rettori (University of Perugia, Italy).

Material

Thin sections stored in the Museum of Natural History, Geneva, Switzerland (collection MHNG 2011-1).

Type locality

Black Marble Quarry, Wallowa Mountains, Oregon, U.S.A.

Type level

Upper Triassic (upper? Carnian–lower Norian) of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Diagnosis

A medium to high conical Robertonella with numerous shallow chambers, an acute apical angle, and an angular margin.

Description

Test triseriate, medium to high conical, rounded in outline, with an acute apical angle and an angular margin. Microspheric forms (Figs. 3.4, 3.5) show a small globular proloculus followed by a short tubular chamber that never forms a complete whorl, and trochospirally coiled ovoid to crescent-shaped chambers, forming up to 10 whorls. Megalospheric forms (Fig. 3.3) display a large globular proloculus, possibly outside of the cone, and directly followed by 3–5 whorls of trochospirally coiled ovoid to crescent-shaped chambers. Chambers, internally simple, communicate by a single, rounded interiomarginal opening. First ovoid, slightly appressed, they rapidly become broad and low crescentiform but remain shallow. Their outer base is angular, possibly slightly prominent. Each chamber develops a thin umbilical wall extension that lines the umbilical depression, delimiting a deep and narrow rounded umbilicus. Sutures oblique, septa curved. Wall finely laminated and very finely perforate, originally fibro-radial and aragonitic but commonly recrystallized to calcisparite. Aperture, single, a rounded opening in interiomarginal position.

Dimensions

At the Black Marble Quarry, megalospheric specimens of R. rettorii reach 200 μm in height and 190 μm in width. The apical angle is between 40–50°. The globular proloculus shows a diameter ranging from 45–60 μm. The umbilicus is 15–25 μm in width. Microspheric specimens reach up to 310 μm in height and 200 μm in width. Their apical angle is between 35–50°. The globular proloculus shows a diameter ranging from 25–40 μm and the umbilicus is 10–20 μm in width.

In all specimens, chambers gradually increase in size, reaching a height of 25 μm and a width of 60 μm. Perforations, very fine, rarely discernible, are about 1 μm in diameter.

Microfacies and paleoecology

Muddy microfacies (mudstone/wackestone) typical of a quiet, periodically restricted, shallow-water lagoonal environment (Rigaud, 2012).

Fossil association

Abundant gastropods, ostracods, echinoderms, brachiopods, microproblematica, common algae (e.g., dasycladaceans, codiaceans), calcimicrobes, bivalves (megalodontids, wallowaconchids), bryozoans, sponges, and corals.

Foraminiferal association

Associated foraminifers are various Involutinidae (Aulosina, Aulotortus, Parvalamella), Mesoendothyridae (Wernlina), Oberhauserellidae (Praegubkinella, Oberhauserella, Schmidita), Trocholinidae (Frentzenella, Lamelliconus, Licispirella, Trocholina, Wallowaconus), and Variostomatidae (Cassianopapillaria, Variostoma), as well as indeterminate nodosariids, miliolids, ophtalmidiids, and polymorphinids.

Stratigraphic and geographic distribution

In Panthalassa, the species is only known from the late? Carnian–early Norian of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.). In Tethys, it occurs in the Carnian of China and in the early Norian of Austria.

Comparison

The new species is morphologically similar to Placentulina conicaKasimova, 1978, but possesses fewer chambers per whorl and a simpler apertural system, not related to an internal structure. It mainly differs from R. wallowensis in its shallower chambers, angular margin, generally higher number of whorls, and smaller apical angle. Additionally, in adult forms, the apical angle is always smaller and the test higher in R. rettorii.

Remarks

On account of its large rounded foramina and curved septa, in subaxial sections tangential to the septa, chambers may appear falsely partitioned (Figs. 3.1–3.5). A thorough observation of these structures with differing focus has attested that these partition-like or pillar-like features correspond to tangential sections of the septa.

Robertonella wallowensis n. gen., n. sp.

Figs. 3.7–3.14

?Tetrataxidae Galloway in Řehánek et al., 1996, p. 517, pl. 2, fig. 3.

Holotype

No. 2011-1-334; Fig. 3.7.

Derivatio nominis

From Wallowa, the name of the area where the type locality is situated (Wallowa Mountains, Wallowa County, Oregon, U.S.A.).

Material

Thin sections stored in the Museum of Natural History, Geneva, Switzerland (collection MHNG 2011-1).

Type locality

Black Marble Quarry, Wallowa Mountains, Oregon, U.S.A.

Type level

Upper Triassic (upper? Carnian–lower Norian) of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Diagnosis

A low to medium conical Robertonella with deep chambers, a highly variable, acute to obtuse apical angle, and a carinate margin.

Description

Test triseriate, low to medium conical, possibly flared conical and pagoda-shaped, rounded in outline, with a carinate margin, and either an acute, right, or obtuse apical angle. Microspheric forms (e.g., Figs. 3.8, 3.9) show a small globular proloculus followed by a short tubular chamber that never forms a complete whorl, and trochospirally coiled ovoid to crescent-shaped chambers, forming up to eight whorls. Megalospheric forms (e.g., Fig. 3.10) display a large globular proloculus, sometimes outside of the cone, directly followed by 3–5 whorls of trochospirally coiled ovoid to crescent-shaped chambers. Chambers, internally simple, communicate by a single, rounded interiomarginal opening. First ovoid, slightly appressed, they rapidly become broad, low crescentiform and deep, with an angular to carinate outer base, which, where well-defined, gives to the test a pagoda shape. Each chamber develops a thin umbilical wall extension that lines the umbilical depression, forming a continually deepening and widening umbilicus. Sutures oblique, septa curved. Wall finely laminated and very finely perforate, originally fibro-radial and aragonitic but commonly recrystallized in calcisparite. Aperture, single, a rounded opening in interiomarginal position.

Dimensions

At the Black Marble Quarry, megalospheric specimens of Robertonella wallowensis reach 150 μm in height and 230 μm in width. The apical angle is between 50–85°. The proloculus shows a diameter of 45–65 μm and the umbilicus is 15–20 μm in width. Microspheric specimens reach up to 180 μm in height and 350 μm in width, with an apical angle between 60–100°. The proloculus possesses a diameter ranging from 30–40 μm and the umbilicus is 15–30 μm in width.

In all specimens, the chambers gradually increase in size, reaching a height of 25 μm and a width of 120 μm. Perforations, very fine and rarely discernible, are about 1 μm in diameter.

Stratigraphic and geographic distribution

The species is known from the late? Carnia–nearly Norian of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.) and, uncertainly, in reworked Triassic, possibly Norian, material from the Czech Republic.

Comparison

Robertonella wallowensis is essentially homeomorphic with Trispirina but does not possess internal structures attached to the aperture. Additionally, the new species shows fewer chambers per whorl than representatives of Placentulina.

Remarks

The depositional environment and associated micro- and macrofossils are the same as described for R. rettorii.

Family TROCHOSIPHONIIDAE n. fam.

Diagnosis

Conical Duostominoidea with trochospirally coiled chambers delimiting a median siphon.

Composition

Trochosiphoniids include the new subfamilies Pragsoconulinae and Trochosiphoniinae.

Stratigraphic distribution

Middle Triassic (Ladinian)–Late Triassic (Norian); Early Jurassic (Hettangian–Sinemurian).

Comparison

Due to their characteristic siphon, Trochosiphoniidae are easily distinguishable from other Robertinida.

Remarks

The specimens illustrated by Rettori et al. (1998, “Piallina bronnimanni,” pl. 1, figs. 1, 2?, 3) most likely belong to this group.

Subfamily PRAGSOCONULINAE n. subfam.

Diagnosis

Trochosiphoniidae with a triangular outline and, at least in the adult stage, pipe-shaped, bifurcating chambers coiled from a twisted siphon, the end of which would correspond to the aperture (di Bari et al., 1997).

Composition

The subfamily only includes the genus PragsoconulusOberhauser, 1963.

Stratigraphic distribution

Middle Triassic (Ladinian)–Late Triassic (Carnian).

Comparison

Pragsoconulins are the only Robertinida possessing pipe-shaped chambers and a twisted siphon.

Remarks

The systematic position of the Ladinian–Carnian genus Pragsoconulus has long been a matter of debate (Oberhauser, 1963; Loeblich & Tappan, 1981, 1987; Piller, 1983; di Bari & Laghi, 1994; di Bari et al., 1997). Its architecture, wall composition, and chamber arrangement have been described in detail by di Bari et al. (1997). Multichambered, aragonitic, fibro-radial, laminated, and finely perforate, it is undoubtedly a Robertinida. On account of its distinctive median siphon and simple, undivided earliest ovoid chambers, we here assign the genus Pragsoconulus to the family Trochosiphoniidae. Owing to wall folds, chambers become pipe-shaped, bifurcating during ontogeny. This is a unique feature. According to di Bari et al. (1997), the aperture would correspond to the open end of the median siphon and not to the opening observed at the end of the last pipe-shaped chamber.

Subfamily TROCHOSIPHONIINAE n. subfam.

Diagnosis

Trochosiphoniidae with ovoid chambers only, a straight siphon and a single, interiomarginal aperture.

Composition

Only includes the genus Trochosiphonia n. gen.

Stratigraphic distribution

Late Triassic (Carnian–Norian); Early Jurassic (Hettangian–Sinemurian). Trochosiphoniinae (unpublished data) have been recently found in the Early Jurassic of Adnet (northern Calcareous Alps, Austria).

Comparison

Due to their characteristic straight siphon, trochosiphoniins are easily distinguishable from other Robertinida. From the family Robertonellidae, they also differ in their chamber morphology (ovoid and not crescentiform in Trochosiphoniinae) and the rounded shape of their margin (angular to carinate in Robertonellidae).

Genus Trochosiphonia n. gen.

Type species: Trochosiphonia stanleyi n. gen., n. sp.

Derivatio nominis

From its trochospiral coiling and characteristic siphon.

Diagnosis

Test free, elongate to drop-like, rounded conical. It is formed by a globular proloculus with a rounded opening usually followed by triserially arranged, internally simple ovoid chambers. Trochospirally coiled, chambers delimit a straight, axial siphon, which is lined by thin laminar umbilical extensions of the wall of successive chambers (Figs. 4.2–4.5, 4.11, 4.13). Spiral suture covered by laminar dorsal extensions of the wall of successive chambers (Figs. 4.1, 4.4, 4.7, 4.8, 4.10, 4.11). Wall aragonitic, fibro-radial, laminated, and finely perforate. Aperture, single, a rounded opening in interiomarginal position.

Included species

The new genus comprises the species T. stanleyi n. gen., n. sp. and T. josephi n. gen., n. sp.

Stratigraphic and geographic distribution

Norian of Austria, late? Carnian–early Norian of Oregon (U.S.A.).

Comparison

Trochosiphonia shows similarities with the genus SiphovalvulinaSeptfontaine, 1988, from which it differs in its wall composition, straight siphon (twisted in Siphovalvulina), and rounded, interiomarginal aperture (basal aperture connected to the siphon in primitive Siphovalvulina). Isolated specimens of Trochosiphonia show superficial similarities with specimens of the genus VerneuilinoidesLoeblich & Tappan, 1949. The aperture of Verneuilinoides, however, is an interiomarginal arch and its wall is clearly agglutinated (e.g., see Verneuilinoides mauritii inHaig & McCartain, 2010, figs. 6:21–6:25).

In tangential sections, on account of its aragonitic, laminated wall, Trochosiphonia might be confused with microgastropods. The presence of perforations in Trochosiphonia allows its unambiguous distinction.

Remarks

Specimens of Trochosiphonia found at the Black Marble Quarry are generally triseriate throughout. However, some transverse sections of Trochosiphonia stanleyi display up to 3.5–4 chambers/whorl. As no criterion allows proving that these sections are slightly oblique, we prefer to describe the genus as usually having three chambers per whorl.

Trochosiphonia stanleyi n. gen., n. sp.

Figs. 4.1–4.7

Holotype

No. 2011-1-449f; Fig. 4.1.

Derivatio nominis

Named in honor of George D. Stanley, Jr. (University of Montana, U.S.A.) for his contribution to the study of the Wallowa terrane.

Material

Thin sections stored in the Museum of Natural History, Geneva, Switzerland (collection MHNG 2011-1).

Type locality

Black Marble Quarry, Wallowa Mountains, Oregon, U.S.A.

Type level

Upper Triassic (upper? Carnian–lower Norian) of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Diagnosis

A Trochosiphonia with moderately enlarging chambers, steadily twisted around a straight siphon.

Description

Test free, conical-elongate to drop-like, rounded in outline and margin, with an acute apical angle. Trochospiral, it is formed by a globular proloculus with a simple, rounded opening usually followed by three slightly appressed, ovoid chambers per whorl, delimiting a straight siphon on up to 6–7 whorls. Chambers, moderately enlarging during ontogeny and internally simple, are steadily twisted whorl by whorl. Separated by oblique septa, they communicate by a single, rounded interiomarginal opening. The siphon, in median position, is oval to rounded in transverse section and lined by thin laminar umbilical extensions developed from the walls of successive chambers. Test surface smooth, spiral suture slightly covered by the dorsal wall extensions of successive chambers (Figs. 4.1, 4.4, 4.7). Wall finely laminated and very finely perforate, originally fibro-radial and aragonitic but commonly recrystallized to calcisparite. Aperture, single, a rounded opening in interiomarginal position.

Dimensions

In the Black Marble Quarry, specimens of T. stanleyi reach 230 μm in height and 150 μm in width. The apical angle is generally between 40–50°. The proloculus is globular with a diameter ranging from 20–30 μm, and chambers, which gradually increase in size, reach a height of 45 μm and delimit a 10–20-μm wide siphon. Wall perforations, very fine and rarely discernible, are about 1 μm in diameter. Foramina are 5–15 μm in diameter.

Stratigraphic and geographic distribution

The species is only known from the late? Carnian–early Norian of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Comparison

Trochosiphonia stanleyi is a homeomorph of “SiphovalvulinacolomiBouDagher-Fadel, Rose, Bosence & Lord, 2001. However, in T. stanleyi chambers are not directly connected to the siphon. It has to be noted that “S.colomi does not show the characteristic twisted siphon of the genus Siphovalvulina. Besides, the reported microgranular/agglutinated composition of the wall of “S.colomi” has not been proved yet. In the type-material, its test appears dark microgranular, slightly recrystallized but possibly finely perforate (see BouDagher-Fadel et al., 2001, pl. 1, figs. 1–4). In the same material, aragonitic components (e.g., dasycladaceans) display a similar appearance (see BouDagher-Fadel et al., 2001, text-figs. 3 a, c, d).

Remarks

The depositional environment and associated micro- and macrofossils are the same as described for R. rettorii.

Trochosiphonia josephi n. gen., n. sp.

Figs. 4.8–4.15

Holotype

No. 2011-1-449h, Fig. 4.8.

Derivatio nominis

From the type locality near the town of Joseph (Wallowa County, Oregon, U.S.A.), named in honor of the Native American Nez Percé, Chief Joseph.

Material

Thin sections stored in the Museum of Natural History, Geneva, Switzerland (collection MHNG 2011-1).

Type locality

Black Marble Quarry, Wallowa Mountains, Oregon, U.S.A.

Type level

Upper Triassic (upper? Carnian–lower Norian) of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Diagnosis

A Trochosiphonia with slightly enlarging chambers, almost arranged in tiers around a straight siphon.

Description

Test free, conical elongate, rounded in outline and margin, with an acute apical angle. Triseriate throughout, it is formed by a globular proloculus with a simple, rounded opening followed by 7–8 whorls of ovoid, internally simple chambers, delimiting a straight siphon. Separated by oblique septa, chambers slightly enlarged during ontogeny and communicate by a single, rounded interiomarginal opening. Chambers of successive whorls are almost aligned. The siphon, in median position, is oval to rounded in section and lined by thin laminar umbilical extensions of the wall of successive chambers. Test surface smooth, spiral sutures slightly covered by the wall dorsal extensions of successive chambers (Figs. 4.8, 4.10, 4.11). Wall finely laminated and very finely perforate, originally fibro-radial and aragonitic but commonly recrystallized to calcisparite. Aperture, single, a rounded opening in interiomarginal position.

Dimensions

In the Black Marble Quarry, specimens of T. josephi reach 190 μm in height and 80 μm in width. The apical angle is generally between 25–40°. The globular proloculus has a diameter ranging from 15–30 μm. Chambers delimit a 15–20 μm-wide siphon and gradually increase in size, reaching a height of 35 μm. Perforations, very fine, rarely discernible, are about 1 μm in diameter. Foramina are 5–15 μm in diameter.

Stratigraphic and geographic distribution

The species is known from the late? Carnian–early Norian of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.) and from the Norian of the Dachstein Formation (Austria; unpublished data).

Comparison

Trochosiphonia josephi differs from T. stanleyi in its more obtuse apical angle and almost aligned chambers that only slightly enlarge during ontogeny.

Remarks

The depositional environment and associated micro- and macrofossils are the same as described for R. rettorii.

Family VARIOSTOMATIDAE Kristan-Tollmann, 1963, emend. herein

Asymmetrinidae Brotzen, 1963, p. 76.

Emended diagnosis

Lenticular, convexo-plane, to elongate Duostominoidea with a rounded to acute margin, internally simple chambers, and an umbilical region filled or partially filled by laminar deposits.

Composition

The family Variostomatidae comprises the subfamilies Asymmetrininae Brotzen, 1963, Cassianopapillariinae n. subfam., Praereinholdellinae n. subfam., and Variostomatinae Kristan-Tollmann, 1963.

Stratigraphic distribution

Early Triassic (Olenekian)–Late Triassic; ?Middle Jurassic (Aalenian–Bajocian).

Comparison

The absence of superficial inner-chamber structures in the family Variostomatidae allows their distinction from Duostominidae and the absence of wall folds, from Oberhauserellidae.

Remarks

Oberhauserellidae are predominantly dextral whereas Variostomatidae and Duostominidae are mostly sinistral.

Subfamily ASYMMETRININAE Brotzen, 1963, nomen translat. and emend. herein

Emended diagnosis

Predominantly planispiral, lenticular, and possibly subacute Duostominoidea with internally simple, arched to subtriangular chambers and an umbilical region either completely smooth or with a superficial umbilicus.

Composition

The subfamily Asymmetrininae includes the genera AsymmetrinaKristan-Tollmann, 1960, InvolvinaKristan-Tollmann, 1960, and PlagiostomellaKristan-Tollmann, 1960.

Stratigraphic distribution

Late Triassic.

Remarks

Representatives of this group have been described from isolated material and no inner structure has been documented. In view of their simple morphology and aperture (without tenon), we tentatively assign them to the family Variostomatidae.

Subfamily CASSIANOPAPILLARIINAE n. subfam.

Diagnosis

Trochospiral, low convexo-plane to conical Variostomatidae with numerous subrhomboid to oblong, dorsally inflated chambers per whorl, an umbilical region partly or entirely covered by papillose lamellae, and a double, interiomarginal aperture.

Composition

The subfamily Cassianopapillariinae includes the genera Cassianopapillaria and Diplotremina. The umbilical surface of Cassianopapillaria is entirely covered by papillae whereas in Diplotremina, which shows radial grooves along the sutures, papillae are limited to the umbilicus (see Kristan-Tollmann 1960, pl. 14, figs. 1b, c, 2b, 3b, c, 4b, pl. 15, figs. 1b, c, 2b, 3b, 4, pl. 16, figs. 1a, 3c, 4b, c, 5, 6b, c).

Stratigraphic distribution

Late Triassic (Carnian–Norian).

Comparison

The subfamily Cassianopapillariinae differs from the subfamily Variostomatinae in its papillose umbilical region.

Remarks

We here illustrate for the first time Cassianopapillariinae from the late Carnian–early/middle Norian of North America (Figs. 2.8, 2.9). Up to now, the genus Cassianopapillaria was reported only from the Carnian of Italy.

Subfamily PRAEREINHOLDELLINAE n. subfam.

Diagnosis

Trochospiral, biconvex to convexo-plane Variostomatidae with numerous ovoid to rhomboid chambers per whorl, an umbilical region filled or partially filled by straight laminar deposits, and a single, interiomarginal aperture.

Composition

The subfamily Praereinholdellinae includes the genera Falsoreinholdella n. gen., KrikoumbilicaHe, 1984, Praereinholdella n. gen., and possibly PraelamarckinaKaptarenko-Chernousova, 1956.

Stratigraphic distribution

Early Triassic (Olenekian)–Late Triassic; ?Middle Jurassic (Aalenian–Bajocian).

Comparison

From Epistomininae, Praereinholdellinae differ in lacking inner-chamber plates.

Remarks

On account of their morphological similarities with the earliest known epistominids, Praereinholdellinae are here regarded as their direct ancestors. The specimens illustrated by von Hillebrandt (2012, pl. 4, figs. 1, 4, 5, pl. 6, fig. 3) provide a solid link between the two groups.

In the family Epistominidae, the presence or absence of additional material on the spiral side has not been regarded as an important taxonomic criterion. This is, however, a key characteristic as it controls the test shape and the type of ornamentation, both used in Epistominidae classification.

Genus Falsoreinholdella n. gen.

Type species: Falsoreinholdella ohmi n. gen., n. sp.

Derivatio nominis

From the Latin “falsus” (5 false, wrong) and the genus name Reinholdella, for the false resemblance existing between the two taxa.

Diagnosis

Test free, convexo-plane to subconical, circular in outline, with a subrounded margin. It is formed by a globular proloculus followed by numerous ovoid to subrhomboid, internally simple, trochospirally coiled chambers. Each chamber develops a dorsal wall extension that covers the spiral suture and an umbilical wall extension that incompletely fills the umbilical depression, forming a median umbilicus. Wall aragonitic, fibro-radial, laminated, and finely perforate. Aperture, single, a rounded opening in interiomarginal position.

Stratigraphic and geographic distribution

late? Carnian–early Norian of Oregon (U.S.A.).

Included species

The new genus comprises the species F. ohmi n. gen., n. sp. and F. oregonica n. gen., n. sp.

Comparison

Falsoreinholdella is homeomorphous of various Epistominidae but does not possess inner-chamber structures. The new genus mainly differs from Krikoumbilica in the subrhomboid morphology of its chambers. It differs from Praelamarckina in its foramen position and aperture morphology. The latter possesses areal intercameral foramina and an interiomarginal slit-like aperture.

Falsoreinholdella ohmi n. gen., n. sp.

Figs. 5.5–5.9

Duostominidae inBrönnimann et al., 1974, p. 35, pl. 1, fig. 25.

Holotype

No. 2011-1-489d; Fig. 5.5.

Derivatio nominis

Named in honor of Uwe Ohm for his outstanding contribution to the study of epistominids.

Type locality

Black Marble Quarry, Wallowa Mountains, Oregon, U.S.A.

Type level

Upper Triassic (upper? Carnian–lower Norian) of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Diagnosis

A Falsoreinholdella with a narrow umbilical region, subrounded chambers, and a medium convexo-plane to subconical test.

Description

Test free, medium convexo-plane to subconical, circular in outline, with a subrounded margin. It is formed by a globular proloculus followed by 6–7 trochospirally coiled subrounded chambers per whorl, forming up to 3.5 whorls. Chambers, internally simple, first ovoid, slightly appressed, increase moderately in size and progressively become subrhomboid. Separated by curved septa, they communicate by a single, rounded interiomarginal opening. Each chamber develops an umbilical wall extension that incompletely fills the umbilical depression, forming a temporary median umbilicus which is completely filled at the end of each whorl. Test surface smooth; spiral sutures slightly covered by dorsal extensions of the wall of successive chambers. Wall laminated and finely perforate, originally fibro-radial and aragonitic but commonly recrystallized to calcisparite. Aperture, single, a rounded opening in interiomarginal position.

Dimensions

In the Black Marble Quarry, specimens of F. ohmi reach 170 μm in height and 220 μm in width. The proloculus shows a diameter ranging from 20–25 μm and chambers may attain 45 μm in height. Perforations, very fine, rarely discernible in our material, are about 1 μm in diameter.

Stratigraphic and geographic distribution

The species is known from the late? Carnian–early Norian of the Martin Bridge Formation at the Black Marble Quarry (Wallowa terrane, Oregon, U.S.A.) and the Carnian of Iran (Brönnimann et al., 1974).

Comparison

The new species shows morphological similarities with Duostomina altaKristan-Tollmann, 1960, from which it differs in lacking superficial inner-chamber structures and a double aperture.

Remarks

The depositional environment and associated micro- and macrofossils are the same as described for R. rettorii.

Falsoreinholdella oregonica n. gen., n. sp.

Figs. 2.10, 5.1–5.4

Holotype

No. 2011-1-349d; Fig. 5.1.

Derivatio nominis

From the type locality state name, Oregon, U.S.A.

Material

Thin sections stored in the Museum of Natural History, Geneva, Switzerland (collection MHNG 2011-1).

Type locality

Black Marble Quarry, Wallowa Mountains, Oregon, U.S.A.

Type level

Upper Triassic (upper? Carnian–lower Norian) of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Diagnosis

A Falsoreinholdella with a wide umbilical region, rounded chambers, and a low convexo-plane test.

Description

Test free, low convexo-plane, circular in outline, with a rounded margin. It is formed by a globular proloculus followed by 6–8 trochospirally coiled rounded chambers per whorl, forming up to 4 whorls. Chambers, internally simple, first ovoid, slightly appressed, slowly increase in size and progressively become subrhomboid. Separated by curved septa, they communicate by a single, rounded interiomarginal opening. Each chamber develops an umbilical wall extension that incompletely fills the umbilical depression, forming a temporary small median umbilicus, which is completely filled at the end of each whorl. Test surface smooth, spiral sutures slightly covered by the dorsal extensions developed from the wall of successive chambers. Wall laminated and finely perforate, originally fibro-radial and aragonitic, but commonly recrystallized to calcisparite. Aperture, single, a rounded opening in interiomarginal position.

Dimensions

In the Black Marble Quarry, specimens of F. oregonica reach 140 μm in height and 200 μm in width. The proloculus shows a diameter ranging from 15–25 μm. Chambers may attain 45 μm in height. Perforations, very fine, rarely discernible, are about 1 μm in diameter.

Stratigraphic and geographic distribution

The species is only known from the late? Carnian–early Norian of the Martin Bridge Formation, at the Black Marble Quarry (Wallowa terrane, Oregon, U.S.A.).

Comparison

Falsoreinholdella oregonica mainly differs from F. ohmi in its lower trochospiral test, more rounded spiral side, more rounded chambers, and wider umbilical region. Additionally, as chambers of F. oregonica only slightly enlarge with ontogeny, the species is generally smaller than F. ohmi for the same number of whorls.

Remarks

The depositional environment and associated micro- and macrofossils are the same as described for R. rettorii.

Genus Praereinholdella n. gen.

Type species: Praereinholdella galei n. gen., n. sp.

Derivatio nominis

From the Latin “prae” (5 before) and the genus name Reinholdella, for its primitive morphology with regard to Reinholdella.

Diagnosis

Test free, trochospirally coiled, formed by a globular proloculus and numerous ovoid to rhomboid, internally simple chambers. Each chamber develops a dorsal wall extension that partially covers the spiral side and an umbilical wall extension that fills the umbilicus. Wall aragonitic, fibro-radial, laminated, and finely perforate. Aperture, single, a rounded opening in interiomarginal position.

Included species

The new genus comprises the species P. argolicaSkourtsis-Coroneou, Trifonova & Tselepidis, 1992, and P. galei n. gen., n. sp.

Stratigraphic and geographic distribution

Anisian of Greece, late? Carnian–middle late? Norian of Idaho (U.S.A.).

Comparison

Praereinholdella differs from Falsoreinholdella in its more involute test (filled umbilical depression and thick lamellar apex), from Variostoma in its single aperture, subrhomboid chambers, and fewer whorls, and from Duostomina in its lack of internal structure and single aperture. From Epistomina, Garantella, and Reinholdella the new genus notably differs in lacking an inner-chamber plate.

Praereinholdella galei n. gen., n. sp.

Figs. 5.10–5.14

Holotype

No. 2011-1-220a; Fig. 5.10.

Derivatio nominis

Named in honor of Luka Gale (Geological Survey of Slovenia) for his contribution to the study of Triassic foraminifers.

Material

Thin sections stored in the Museum of Natural History, Geneva, Switzerland (collection MHNG 2011-1).

Type locality

Mission Creek Quarry, Idaho County, Idaho, U.S.A.

Type level

Upper Triassic (upper? Carnian–lower/middle upper? Norian) of the Martin Bridge Formation (Wallowa terrane, Oregon, U.S.A.).

Diagnosis

A low convexo-plane to biconvex Praereinholdella with gradually enlarging subrhomboid chambers and a subangular margin.

Description

Test free, low convexo-plane to biconvex, circular in outline, with a subrounded to subangular margin. It is formed by a globular proloculus followed by 6–9 trochospirally coiled chambers per whorl, forming up to 2.5 whorls. Chambers, internally simple, first ovoid, slightly appressed, gradually increase in size, becoming subrhomboid. Separated by curved, oblique septa, they communicate by a single, rounded to oval interiomarginal opening. Each chamber develops a dorsal wall extension that partially covers the spiral side and an umbilical wall extension that fills the umbilicus (Figs. 5.10, 5.14). Test surface not ornamented. Wall laminated and finely perforate, originally fibro-radial and aragonitic but commonly recrystallized to calcisparite. The last opening, a probable aperture, is generally barely visible (e.g., partially preserved in Figs. 5.10 and 5.14), but always appears single, rounded and in interiomarginal position.

Dimensions

In the Mission Creek Quarry, specimens of P. galei reach 110 μm in height and 230 μm in width. The proloculus shows a diameter ranging from 15–25 μm and chambers may attain 50 μm in height. Perforations, very fine, rarely discernible in our material, are about 1 μm in diameter.

Microfacies and paleoecology

Muddy microfacies (mud-stone/wackestone) typical of a protected shallow-water, lagoonal environment (Rigaud, 2012).

Fossil association

Abundant and large dasycladaceans (Diplopora oregonensis) and common porostromates, echinoids, gastropods, bivalves, and brachiopods.

Foraminiferal association

Dominant, the new species is only associated with a few foraminifers of the families Involutinidae (Parvalamella), Oberhauserellidae (Schmidita), Variostomatidae (Cassianopapillaria), and Ophthalmidiidae (?Gsollbergella).

Stratigraphic and geographic distribution

The species is only known from the late? Carnian–early/middle late? Norian of the Martin Bridge Formation, at the Mission Creek Quarry (Wallowa terrane, Idaho, U.S.A.).

Comparison

Praereinholdella galei differs from P. argolica in its more angular margin and less rapidly widening chambers.

Subfamily VARIOSTOMATINAE Kristan-Tollmann, 1963, nomen translat. and emend. herein

Emended diagnosis

Trochospiral, convexo-plane to conical elongate Variostomatidae with numerous subrhomboid to oblong, dorsally inflated chambers per whorl, an umbilical region filled or partially filled by straight laminar deposits, and a double, interiomarginal aperture.

Composition

The subfamily Variostomatinae only includes the genus Variostoma.

Stratigraphic distribution

Middle Triassic (Anisian)–Late Triassic (Rhaetian).

Comparison

The subfamily Variostomatinae differs from the subfamily Robertonellinae in a higher number of chambers per whorl, a less angular margin, and, when present, a shallower umbilicus.

Remarks

The initial assignment of Variostoma to Duostominidae has been considered as doubtful (di Bari & Laghi, 1998; Gale et al., 2011). Basically, the genus would possess an “alveolar” wall (di Bari & Laghi, 1998). Then, according to Fuchs (1975b), the two apertures of the genus are rounded to elliptical, the complex lobate structure observed by Kristan-Tollmann (1960) being the result of a partial dissolution of the test. This interpretation has been confirmed by di Bari & Laghi (1998). Finally, the absence of any internal structures in Variostoma (see di Bari & Laghi, 1998, pl. 1, fig. 1) definitively excludes it from Duostominidae.

Superfamily OBERHAUSERELLOIDEA Fuchs, 1975a, emend. herein

Emended diagnosis

Duostominina with a trochospiral test and depressed, uncovered umbilical sutures.

Stratigraphic distribution

Middle Triassic (Anisian)–Late Cretaceous (Cenomanian).

Family FAVUSELLIDAE Longoria, 1974, emend. Banner & Desai, 1988, emend. herein

Globuligerinidae Loeblich & Tappan, 1984, p. 38.

Conoglobigerinidae Simmons et al., 1997, p. 20.

Emended diagnosis

Convexo-plane, conical, to subglobular Oberhauserelloidea with internally simple and entirely inflated chambers, giving to the test a bulging shape.

Composition

The family Favusellidae here emended includes the Aalenian–Valanginian subfamily Globuligerininae Loeblich & Tappan, 1984, and the Kimmeridgian–Cenomanian subfamily Favusellinae Longoria, 1974.

Remarks

Favusellids are here classified in Robertinida. This assignment is proposed on account of the high morphological similarities existing between the families Oberhauserellidae and Favusellidae and in accordance with their stratigraphic distribution. As postulated by Fuchs (1973, 1975a) and substantiated by Wernli & Görög (2007), the latter would have originated from the former. The presence of a reticulate ornamentation in Oberhauserella (see di Bari, 1999, pl. 6, fig. 4) supports this hypothesis.

On account of their inflated chambers, Favusellidae have been regarded as planktonic foraminifers (e.g., BouDagher-Fadel et al., 1997). From the Bajocian, in slope to basinal environments, the occurrence of characteristic bloom-like Favusellidae deposits would tend to confirm this hypothesis. However, it is premature to generalize this assumption to all Favusellidae as all representatives of the family are not found in as rich and highly diversified thanatocoenoses. In the Callovian, for example, the same species may be found as a minor constituent of epicontinental, shallow-marine deposits or as a major constituent of basinal deposits (Görög & Wernli, 2003). Favusellids occupied both neritic and pelagic domains, and according to our current knowledge, they might be represented by either benthic, planktonic, and/or tychopelagic forms (see Darling et al., 2009, for definition).

All Globuligerininae (CompactogerinaSimmons, Bou-Dagher-Fadel, Banner & Whittaker, 1997, Conoglobigerina Morozova inMorozova & Moskalenko, 1961, Globuligerina, and HaeuslerinaSimmons, BouDagher-Fadel, Banner & Whittaker, 1997) show a test surface with pseudomuricae whereas all Favusellinae (Favusella and AscoliellaBanner & Desai, 1988) show a test surface with a favose reticulation.

Stratigraphic distribution

Middle Jurassic (Aalenian)–Late Cretaceous (Cenomanian). The earliest Favusellidae have been documented in a supposed Late Triassic olistolith from Crimea, Ukraine (Korchagin et al., 2003). This olistolith would occur within Early Jurassic sediments, together with other olistoliths of Carboniferous to Early Jurassic age. Pending other descriptions of Triassic Favusellidae, on account of this particular tectono-sedimentary context, we consider a Late Triassic age suspect.

Görög (1994) described a Favusellidae (Globuligerina geczyiGörög, 1994) in the Hettangian-Sinemurian of Hungary. This form, of “modern” aspect (Wernli, 1995), would be a contaminant (BouDagher-Fadel et al., 1997).

Family OBERHAUSERELLIDAE Fuchs, 1970

Diagnosis

Low convexo-plane to almost conical Oberhauserelloidea with a chamber wall folded on its umbilical side, forming at least one arcus (sensu Fuchs, 1969).

Composition

The family Oberhauserellidae includes the genera Kollmannita, Oberhauserella, PraegubkinellaFuchs, 1967, and SchmiditaFuchs, 1967. The validity of these genera is still under discussion (see di Bari, 1999).

Comparison

Oberhauserellidae differ from Favusellidae in their less bulging shape and folded chamber wall. In the family Oberhauserellidae, the chamber wall is folded whereas in the family Duostominidae, the chamber wall is internally thickened, forming internal structures related to the successive foramina and the aperture.

Representatives of Diplotremina show radial grooves along the sutures that, on account of their sutural position, cannot be confused with the arcus observed in oberhauserellids.

Remarks

The “arcus” or “vault” identified in the family Oberhauserellidae is merely a wall infolding (see Fuchs, 1969, pl. 2, fig. a, pl. 3). Contrary to that of Robertinoidea, this wall infolding is never attached to the aperture. The protrusion pointed out by Fuchs (1969, pl. 1, figs. a, b) is a section of the foramen margin and not an internal structure or an arcus.

According to Fuchs (1975a), the wall folds observed on the umbilical side of the oberhauserellids are ancestral features of epistominid “toothplates” and allow distinguishing genera. Detailed investigations of holotypes and well-preserved Ladinian–Carnian specimens by di Bari (1999) have revealed only one arcus in the genera Kollmannita and Oberhauserella and, thus, refute Fuchs’ statement. During evolution, these folds have actually been reduced in the lineage, up to the origination of the family Favusellidae, which possesses inflated chambers.

Stratigraphic distribution

Middle Triassic (Anisian)–Late Jurassic (Oxfordian).

REMARKS ON THE USE OF INNER-CHAMBER STRUCTURES IN TAXONOMY

In Robertinida, all inner-chamber structures are closely related to the aperture. The function of these structures remains unknown, but on account of their position, their probable significant biological role leads us to regard them as features of high taxonomic value. This interpretation is consistent with previous works on the group, but traditional foraminiferal taxonomic concepts have been deeply challenged by molecular studies (see review in Schweizer et al., 2011). In hyaline-calcitic foraminifers, comparable internal structures (toothplates) have proved to be unreliable for high taxonomic subdivisions. According to molecular data, “Buliminida” and Rotaliida, which were taxonomically separated on account of their internal structures, would form a unique group (see Schweizer et al., 2008). In a same lineage, toothplates might even be lost through evolution (Ujiié et al., 2008).

As a consequence of these molecular findings, the Robertinida subdivision proposed in this study might appear questionable. Nevertheless, this subdivision is structurally, ontogenetically, morphologically, and stratigraphically supported. The complexity of Robertinida does not attain that of Rotaliida. A coherent morphological evolution, with transitional forms, can be retraced from the Triassic (see next section). Holocene representatives show similar wall characteristics as their Late Triassic ancestors, with fine laminae and perforations (see McGowran, 1966a). Except in microspheric Robertonella n. gen., first chambers are ovoid and slightly appressed in all representatives of the group. From the acquisition of internal plates in the order Robertinida, only two Ceratobuliminoidea-like, possibly aragonitic foraminifers that would be devoid of internal structures have been described (Ceratobuliminoides and Praelamarckina). These forms are poorly documented and it would be useless to discuss whether they constitute the last known Variostomatidae or a Robertinina which has lost its internal plate, pending a better knowledge of their structure, wall composition, and stratigraphic range.

TRIASSIC AND POST-TRIASSIC ROBERTINIDA PHYLOGENY

The Triassic period is characterized by the appearance and explosion of multichambered aragonitic foraminifers. Triassic robertinids are generally separated in two major lineages, namely the Duostominoidea and Oberhauserelloidea lineages. So far, these two lineages have been studied separately and their taxonomic differences and phyletic relationships overlooked. The oldest Duostominoidea are known from the Olenekian, with the species Krikoumbilica pileiformisHe, 1984. This species possesses subrhomboid dorsally inflated chambers, a broad circular laminar umbilicus, and a single interiomarginal aperture. In view of its stratigraphic position and simple morphology, it is the most probable common ancestor of all known Triassic Robertinida, including oberhauserelloids that display an uncovered, non-lamellar umbilicus. Foraminifers of the superfamily Duostominoidea have showed a rapid diversification during the Triassic, giving rise to a large range of morphotypes. Their evolution is, for example, marked by the appearance of planispiral coiling (Asymmetrina, Involvina, Plagiostomella), a siphon (Pragsoconulus, Trochosiphonia), papillose lamellae (Cassianopapillaria, Diplotremina), and a double aperture (Variostoma) possibly separated by a tenon (Cassianopapillaria, Diplotremina, Pillerita) and internally partitioned by superficial wall thickenings (at least Duostomina). On the other hand, the Oberhauserelloidea lineage is comparatively simpler and less diversified in the Triassic. In spite of their apparent lower evolutionary rate, Oberhauserellidae have been regarded as the common ancestor of all post-Triassic Robertinida. The origination of Favusellidae from Oberhauserellidae (Fuchs, 1973, 1975a; Wernli & Görög, 2007) is both morphologically and stratigraphically supported but a direct phyletic link between Oberhauserellidae and Ceratobuliminoidea (Fuchs, 1973, 1975a; Tappan & Loeblich, 1988; He, 1998; von Hillebrandt, 2010, 2012) is dubious. The discovery of new Triassic Robertinida in the Panthalassan domain (Wallowa terrane, U.S.A.), missing links of the Robertinida lineage, refutes the latter phyletic hypothesis (Fig. 7). With the exception of the inner-chamber structures, the new genera Falsoreinholdella and Praereinholdella show all morphological characteristics of epistominids (Ceratobuliminoidea) and are better candidates for their origination than Duostomina (as proposed by Kristan-Tollmann, 1966), Oberhauserella (by He, 1998, and von Hillebrandt, 2010), Praegubkinella (by von Hillebrandt, 2010, 2012), or Schlagerina (by Fuchs, 1975a). The existence of transitional forms between Praereinholdellinae and Reinholdellinae in Early Jurassic rocks of Austria (see “cf. Reinholdella n. sp.” invon Hillebrandt, 2012, pl. 4, figs. 1, 4, 5, pl. 6, fig. 3) confirms this new phyletic hypothesis. Therefore, the new subfamily Falsoreinholdellinae documents a solid, direct phyletic link between the families Variostomatidae and Epistominidae.

Representatives of the order Robertinida are particularly well documented in the Carnian and, probably for that reason, show their greater diversity during this stage (15 genera). In other Triassic stages, their record is incomplete and a part of their early evolution is probably undisclosed. Pending the discovery of additional missing links relating the different Robertinida taxa, we here propose a new phyletic tree based on the increasing complexity of the architecture of Triassic Robertinida and taking into account their stratigraphic distribution (Fig. 7). An alternative phyletic option would be to consider the Trochosiphoniidae as descendants of a Triassic “VerneuilinoidesLoeblich & Tappan, 1949, and the Robertonellidae as descendants of a Triassic “Tetrataxidae,” but this polyphyletic hypothesis must be rejected as only founded on superficial morphological similarities. In view of the inframicrometric perforations characterizing the group, a polyphyletic origination or an origination of the Robertinida from a coeval trochospiral undivided tubular Involutinina seems also unlikely. The presence of a short tubular chamber in the early stage of microspheric Robertonella thus remains enigmatic, as according to Pawlowski et al. (2013) this feature would be characteristic of the class Tubothalamea.

LARGE-SCALE EVOLUTION

In foraminiferal evolution, the aragonitic order Robertinida is regarded as the transitional group between microgranular/agglutinated and hyaline-calcitic foraminifers (Fuchs, 1973, 1975a; Tappan & Loeblich, 1988).

The derivation of Robertinida from a multichambered trochospiral agglutinated (Trochamminidae according to Tappan & Loeblich, 1988) or microgranular (Tetrataxidae according to Fuchs, 1975a) ancestor is partly founded on the apparent evolution of their wall structure and composition during the Triassic (Fuchs, 1967, 1975c; Koehn-Zaninetti, 1969; Premoli Silva, 1971; Zaninetti, 1976). The earliest Robertinida are believed to have possessed a pseudochitinous inner layer (Kristan-Tollmann, 1963; Koehn-Zaninetti, 1969) and a microgranular or agglutinated outer layer (Kristan-Tollmann, 1963, 1966, 1988; Koehn-Zaninetti, 1969; Fuchs, 1975c), whereas their wall would be merely aragonitic and lamellar from the Late Triassic (Fuchs, 1967, 1969, 1975c; Zaninetti, 1976). This wall evolution is possibly a misinterpretation related to a diagenetic alteration of the observed specimens as suggested by Gale et al. (2011), but no solid proof has been published to incontestably refute this wall evolution theory. The study of well-preserved Norian–Rhaetian Robertinida has clearly demonstrated the fibrous aragonitic nature of their wall (Fuchs, 1975c; Hohenegger & Piller, 1975; di Bari & Rettori, 1996; di Bari & Laghi, 1998), but relatively well-preserved Ladinian–Carnian robertinids have shown either a fibrous aragonitic (di Bari, 1999) or a microgranular wall (Fuchs, 1975b, c; Hohenegger & Piller, 1975). The transitional evolution from a microgranular to an aragonitic wall has been documented prior to the Triassic in the superfamily Staffelloidea of the Fusulinida lineage (Vachard, 1990; Vachard et al., 2003) and should not be considered as aberrant. This type of aragonitic wall is particularly developed in the genera Staffella Ozawa, 1925, NankinellaLee, 1934, and SphaerulinaLee, 1934 (Figs. 2.11, 2.12). The superfamily Staffelloidea, however, was extinct prior to the Triassic and on account of the complex structure and morphology of its representatives, cannot be regarded as a potential ancestor for Robertinida.

The hypothesis that some hyaline-calcitic foraminifers originated from Robertinida (Fuchs, 1973, 1975a; oldest ancestor of the hyaline-calcitic subfamily Ashbrookiinae Loeblich & Tappan, 1984), and trochosiphoniins, also found in Early Jurassic rocks of Austria (in study), resemble more the turrilinids and the guembelitriids than the oberhauserellids do. Our record of Robertinida in Early Jurassic rocks, however, is very limited, especially in the Panthalassan domain, and therefore, numerous phyletic and taxonomic problems remain unsolved. Extensive research on the group and its potential relationships with calcitic and microgranular to agglutinated foraminifers are required. The discovery of new localities and refuge areas should allow substantiating or refuting the here suggested polyphyletic origin for the order Rotaliida sensu lato (including representatives of the former orders “Globigerinida” and “Buliminida” and the family Placentulinidae).

CONCLUSIONS

The Triassic period is marked by the appearance and radiation of the order Robertinida, which attained their greatest diversity during the Late Triassic (18 genera) and not during the Pliocene as proposed by Tappan & Loeblich (1988). The understanding of the origin and early diversification of these aragonitic forms is of primary importance to comprehend the large-scale foraminiferal evolution, as they represent a probable transitional group between microgranular and hyaline-calcitic foraminifers.

In the Robertinida lineage, the appearance of internal partitions related to the aperture is a major evolutionary acquisition. Former representatives possessed simple chambers (Variostomatidae). The first internal structures were limited to the chamber margins (Duostominidae) and true inner-chamber plates are only known from the earliest Hettangian (Ceratobuliminoidea). In more advanced Robertinida, these plates are either distorted, forming toothplate-like structures (Conorboidoidea) or possibly attached or fused to a wall infolding (Robertinoidea).

Unlike previous thinking, at least three to four major groups of Robertinida survived the Triassic-Jurassic major extinction event and might be at the origin of several distinct new foraminiferal lineages, questioning the supposed monophyly of calcitic, hyalino-radial Globothalamea.

ACKNOWLEDGMENTS

The authors wish to thank Joachim Blau (University of Frankfurt) for early discussions that helped to the development of this paper and Roland Wernli (University of Geneva) for his constructive comments on a draft version of this manuscript. David Haig, K. Ueno, P. Brenckle, and an anonymous reviewer are thanked for their critical comments. The present report is part of an international project funded by the National Swiss Science Foundation (grants 200021-113816 and 200020-124402 to R.M. and PBGEP2-145580 to S.R.).