Abstract We examined the palaeogeographical distribution of selected Cambrian trace fossils. Astropolichnus hispanicus , Climactichnites , Syringomorpha nilssoni and early examples of Paleodictyon all have a restricted palaeogeographical distribution, probably representing that of their producers. A cosmopolitan distribution is seen in Didymaulichnus miettensis and in early examples of Rusophycus and Dactyloidites . Oldhamia shows a wide distribution in Lower Cambrian deep-sea sediments although that of Oldhamia geniculata is restricted.

Abstract Organism–matground interactions reflect two somewhat interrelated aspects: (1) the environmental restriction of microbial mats through geologic time and (2) the evolutionary changes in benthic faunas. The history of such interactions may be subdivided into six phases: (1) Ediacaran, (2) Cambrian, (3) Ordovician, (4) Silurian to Permian, (5) Early Triassic, and (6) Middle Triassic to Holocene. Widespread matgrounds in both shallow- and deep-marine deposits during the Ediacaran provided substrates that were available for benthic colonization and the development of various interactions. The most abundant ichnofossils in Ediacaran rocks are very simple grazing trails ( Helminthopsis ichnoguild), representing grazing of organic matter concentrated within microbial mats below a thin veneer of sediment. In shallow-marine environments, interactions were also evidenced by the mollusk-like Kimberella and associated scratch marks ( Radulichnus ) preserved on microbial mats. Interactions are also indicated for vendozoans, as reflected by serially repeated resting traces of Dickinsonia and the related genus Yorgia preserved on biomats. By the latest Ediacaran, simple burrow systems (treptinids) also occur in association with matgrounds. The replacement of matgrounds by mixgrounds was arguably the most significant change at the ecosystem scale in the history of marine life. By the Early Cambrian, branched burrow systems became more complex and common, resulting in increasing disruption of matgrounds in nearshore and offshore settings. While matgrounds were widespread in supratidal and upper- to middle-intertidal environments during most of the early Paleozoic, lower-intertidal deposits were already intensely bioturbated by the late Early Cambrian. The diachronic nature of the Agronomic Revolution is evident in the deep sea, where microbial matground ecosystems persisted during most, if not all, of the Cambrian. In addition to the Helminthopsis ichnoguild, Cambrian deep-marine ichnofaunas also consist of arthropod trackways and sophisticated feeding strategies represented by different Oldhamia ichnospecies, revealing complex architectural designs by undermat miners. In contrast, in deep-marine Lower Ordovician deposits, microbial textures are rare and patchy and typically not associated with trace fossils. Biomats persisted into the late Paleozoic in the innermost, freshwater region of estuarine systems, as well as in fluvio-lacustrine deposits, glacial lakes, and fjords. Ichnofaunas dominated by very shallow tier structures, such as arthropod trackways and grazing trails, locally associated with matgrounds, were common in these deposits. The widespread development of matgrounds after the end-Permian mass extinction sets the stage for the reappearance of feeding strategies linked to the exploitation of biomats. However, subsequent faunal recovery and deep and pervasive bioturbation resulting from the establishment of the Modern evolutionary fauna led to increased restriction of microbial mats. Analysis of ichnofaunas in matgrounds provides evidence of the temporal and environmental restriction of biomats and allows a better understanding of animal–matground interactions, as well as of preservational biases in the trace-fossil record.

The Gondwanan Icehouse Period spanned between the mid-Carboniferous and Early Permian waning by the early Late Permian. Early postglacial sea-level rise related to the final stage of the Late Paleozoic Ice Age favored creation of accommodation space with preservation potential for productive anoxia events in the newly inundated shelves and peat-forming conditions favored by rapid water table rise in updip positions in the basin. The combined effect of fast glacioeustatic sea-level rise and subsidence along basin margins led to a drastic landward facies shift; the newly created space was sufficient to accommodate a transgressive systems tract (TST) that, irrespective of the age of the glacial episode, exhibits common characteristics across Gondwana. High fresh-water discharges related to the retreat of glaciers resulted in associated reduction in coastal salinity. Therefore, fjord-like settings as part of early postglacial inland seas seem to be a valid analogue for many of these TSTs. The examples of glacial-postglacial transitions analyzed in this contribution are present in a variety of basin types, namely, those ranging from backarc foreland basins to rifts. In all of them a clear retrogradational stacking pattern is detectable in the transition from glacially dominated settings to glacially influenced early postglacial environments. Examples from South America (Calingasta-Uspallata and Paganzo Basins), South Africa (Karoo Basin), Peninsular India (several Gondwana basins), and eastern Australia (Tasmania Basin) help define two basic types of TSTs: (1) complete TSTs, with a basal part of clast-poor, massive to poorly stratified diamictites, thinly bedded diamictites, shales with ice-rafted debris (IRD) and IRD-free shales, and an upper part dominated by open-marine shales representing the maximum flooding of the shelf; and (2) base-cut TSTs in which the basal transgressive portion is mostly omitted, and the TST is exclusively represented by open-marine shales generally devoid of IRD. Whereas the complete TSTs are common in cases in which high sediment supply rates via rain-out, ice rafting, and settling of fines prevail during the early phase of deglaciation, the base-cut TSTs, on the other end, reflect the dominance of drastic sealevel rises related to fast glacier retreats.

The late Paleozoic (Carboniferous–Permian) Gondwanan glaciation is represented in the subsurface of eastern and central Saudi Arabia by the Hercynian (or pre-Unayzah) unconformity and the lower part of the overlying Unayzah Formation. The subsequent postglacial transgression is manifest in the upper members of the Unayzah Formation as well as the lowermost clastic deposits of the overlying Khuff Formation. Its component sediments result from ongoing climatic amelioration following the demise of the ice age, as well as tectonic influences related to the creation of the Neotethys Ocean. The Unayzah Formation is subdivided into four stratigraphic members. Thus, directly overlying the Hercynian unconformity in many places are sandstones and minor conglomerates of the Unayzah C member. These were laid down within a widespread, braided glaciofluvial depositional system. They represent glacial outwash produced during times of glacial retreat throughout the duration of the late Paleozoic glaciation. An unknown number of glacial readvances occurred that significantly deformed these retreat-phase outwash sands and gravels, creating major glacially tectonized push moraine nappes. Those are interpreted from a number of distinctive and discrete shear zones that are uniquely associated with the Unayzah C member. The upper surface of the Unayzah C member is an unconformity that marks the final subglacial surface at the time of maximum advance of the ice. The terminal melt-out phase of the Gondwanan glaciation is represented by the Unayzah B member. Paleomagnetic evidence suggests that this member was deposited at high latitudes, ~75° S. This member comprises a large number of depositional facies that are essentially glaciolacustrine in character. Those facies include (1) small-scale ice-contact push moraines indicative of minor glacial readvance, (2) ice-proximal sublacustrine debris flows (massive diamictites) and associated gravity flow deposits, and (3) ice-distal, sublacustrine stratified diamictites, ripple cross-laminated sandstones, and laminated mudrocks. Facies associations within the Unayzah B member consistently show evidence of sustained glacial retreat and flooding of the landscape by filling and spilling over of numerous glacial lakes. This flooding sequence probably represents the maximum climatically related postglacial transgressive event in Saudi Arabia. In the western part of the study area there is evidence that the ice remained longer, and it is tentatively interpreted as a local center for high altitude (“alpine”) glaciation. Deposition of the Unayzah B member was terminated abruptly by a drainage event that is marked by a widespread sharp contact with the overlying unnamed middle Unayzah member. The latter member displays no unequivocally glacially related depositional facies, and paleomagnetic data suggest that it was deposited at ~55° S. It is dominated by red floodplain siltstones and very fine–grained sandstones that contain relatively isolated bodies of coarser fluvial and eolian sandstones. These eolianites display possible cold-climate characteristics. This is particularly true in the western part of the study area, which is consistent with a relatively sustained, high altitude ice cap in that area. The unnamed middle Unayzah member is capped in many places by a paleosol horizon. This represents a hiatus of unknown but probably prolonged duration and thus suggests a disconformable contact between the unnamed middle Unayzah member and the overlying Unayzah A member. The Unayzah A member is dominated by sediments that are strongly characteristic of terrestrial deposition in a semiarid to arid environment (including ephemeral lakes and streams as well as eolian deposits). Paleomagnetic data suggest paleolatitudes ~28° S. The continental eolian clastic deposits of this member in places display a cyclicity in their stratal architecture that is related to fluctuations in the paleo–water table. These fluctuations are possibly related to distant marine transgression, which is supported by the occurrence of a distinctive bioturbated sandstone very close to the top of the Unayzah A member. That marine-influenced sandstone is observed in widely separated localities at either end of the study area and may represent the final breakthrough of transgressive marine waters close to the end of Unayzah A time. In several places the uppermost deposits of the Unayzah A member are characterized by thick paleosols. These represent a prolonged period of nondeposition, interpreted to be directly related to thermal doming of the Arabian plate prior to rifting and opening of the Neotethys Ocean, and the consequent formation of the pre-Khuff unconformity, which terminated Unayzah deposition. Overlying the pre-Khuff unconformity are various siliciclastic facies of the eponymous Basal Khuff Clastics member of the Khuff Formation. The depositional facies of the lowermost Basal Khuff Clastics range from shallow marine in the southeastern part of the study area to predominantly fluvial in the west. This reflects the westward-directed transgression of the Khuff Formation following thermal collapse in the wake of the rifting that created the Neotethys Ocean. That tectonically related transgression reached its fullest expression with deposition of the carbonates and evaporites that dominate the upper members of the Khuff Formation. This stratigraphic evolution of the late Paleozoic in Saudi Arabia can confidently be correlated in sequence stratigraphic terms with coeval sediments laid down across the Arabian Peninsula.

Popular reconstructions of late Paleozoic glaciation depict a single massive ice sheet centered over Victoria Land and extending outward over much of Gondwana. This view is untenable, as interpretations presented here indicate that glaciogenic strata in southern Victoria Land were deposited in a glaciomarine setting, and that ice entered the area from at least two different ice centers on opposite sides of the depositional basin. Reports from other areas also reveal that multiple ice sheets, ice caps, and alpine glaciers diachronously waxed and waned across Gondwana during the Carboniferous and Permian. Glaciogenic rocks of the Lower Permian Metschel Tillite contain glaciotectonic structures and glaciogenic deposits that include (1) sheared diamictites, (2) thrust sheets, (3) massive and stratified diamictites, and (4) sheet sandstones. These features formed as subglacial deforming beds, thrust moraines at glacial termini, and as glaciomarine deposits associated with temperate glaciers. A glaciomarine setting, rather than a glaciolacustrine setting, is suggested, owing to the abundance of meltwater plume deposits. A wedge-shaped sandstone body at the base of the overlying Weller Coal Measures was deposited as a grounding-line fan. Results of this study imply deposition in ice-marginal glaciomarine settings from ice radiating out of multiple glacial centers. These findings are significant because multiple glaciers, covering a given area, contain considerably less ice volume than a single massive ice sheet. Therefore, the waxing and waning of multiple ice masses during the late Paleozoic would have influenced global climate and eustatic sea level much differently than would have a single massive Gondwanan ice sheet.

The continental glaciation of Gondwanaland in the Late Carboniferous–Early Permian left traces in many places in southern and eastern Africa. This paper focuses on the last glacial advance and consecutive deglaciation leading to the formation of large euxinic lakes with high concentrations of organic matter. The Idusi Formation in the Tanzanian Ruhuhu Basin (initiating the Karoo cycle, which extends into the Triassic) provides the type section for this depositional sequence. It is subdivided into a lower Lisimba Member, the basal unit of glacial origin, and an upper Lilangu Member, characterized by postglacial black shale and rhythmites as evidence of a climatic amelioration on a large regional scale in Africa. Thickness and facies variations are attributed to a pronounced paleotopography as the result of scouring glaciers and local tectonic events. There is a gradual change between the members, reflecting a continuous climatic amelioration and change of sediment supply. The lacustrine environment was terminated by the onset of braided stream deposition (Mpera Sandstone Member); an erosional unconformity between the units marks the start of initial rifting in the Early Permian. This is followed by the development of extensive coal swamps in a temperate climate, where organic matter predominated over clastic supply. Periglacial deposits with tillites and rhythmites, containing dropstones, are overlain by glaciolacustrine laminites intercalated with glaciofluvial marginal deltaic sediments. Deglaciation provided water and accommodation space for the evolution of extensive anaerobic stratified lakes, which were the focus of prolific deposition of organic matter. This black shale may contain up to 11% TOC (total organic carbon) content. Eventually, the lake became shallower and was succeeded by alluvial fan deposition. The duration of the glaciation and deglaciation was ~20–25 m.y., and the lacustrine phase lasted ~4–5 m.y. These ages have been verified by palynology ( Granulatisporites confluens Oppel zone). The hydrocarbon potential of the black shale was estimated by Rock-Eval pyrolyses. Hydrogen index, maximum temperature (T max ), and vitrinite reflection were used to determine kerogen type, maturity stage, and subsidence history. A promising potential with respect to gaseous hydrocarbon generation was detected from both the euxinic black shale and the overlying coals. A comparison with other Tanzanian Karoo basins reveals similar conditions in TOC values and temperature history. The wide regional extent of the anaerobic lacustrine black shale of the deglaciation event in several eastern and southern African basins evinces a similar climatic and regional tectonic framework in the pre-breakup phase of Gondwanaland during the Early Permian. This period of time may be of some importance in the future when the economic potential with respect to hydrocarbon generation of the Permian basins is scrutinized in more detail.

A correlation between plant zones and palynozones within a sequence-stratigraphic framework for the upper Paleozoic rocks of the Paraná Basin, Brazil, is attempted for the first time. Our study indicates that (1) the stratigraphic boundaries (lithostratigraphic boundaries and sequence boundaries) are not coincident with most of the biostratigraphic horizons; (2) the boundaries between palynozones and plant zones are also not coincident with each other; and (3) the boundaries of palynozones lie near the maximum flooding surfaces through the interval analyzed. The emerging pattern suggests that plant zones are mostly controlled by depositional processes and palynozones by climate-driven changes. Therefore, the plant zones correspond to distinct ecofacies, and are better regarded as ecozones rather than as biozones. On the other hand, the climatic changes that affected the palynofloras were related directly to the most significant transgressive events, suggesting a link with eustatic oscillations caused by Early Permian Glacial-Interglacial Phases. Aims of further work may include (a) evaluation of taphonomic controls in plant-bearing beds, (b) better understanding of the relation between the plant-bearing strata and their equivalent palynologic zones, (c) correlation between palynologic and paleobotanic data and the sequence-stratigraphic framework already established in other areas, and (d) improvement of the chronostratigraphic chart of the basin through the discovery of layers suitable for radiometric dating.

The Levipustula Fauna (included in the Levipustula levis Zone) is a relatively diversified fossil assemblage composed of brachiopods, bivalves, bryozoans, gastropods, and crinoids. This fauna usually is associated with glaciomarine sequences related to the Carboniferous glacial event that affected the southwestern Gondwanan margin. The Levipustula Fauna has been identified in different units (e.g., Hoyada Verde, La Capilla, Leoncito, and Yalguaraz Formations) exposed in the Calingasta-Uspallata Basin. The Hoyada Verde Formation, herein proposed as a key section, contains the most complete record of the Levipustula Fauna. A detailed compositional, taphonomic, and paleoecological study of this section allows us to propose two associations within the so-called Levipustula Zone: the “Intraglacial Levipustula Fauna,” present in the diamictite-dominated lower part, and the “Postglacial Levipustula Fauna,” dominant in the upper part of section. The fossils of the “Intraglacial Levipustula Fauna” are scarce and poorly diversified. These two features suggest environmentally stressed conditions, probably related to low temperatures in areas close to glaciers. In comparison, the “Postglacial Levipustula Fauna,” relatively more abundant and diverse, exhibits compositional variations that could be explained by paleoenvironmental changes associated with fluctuations in substratum and food supply, such as those identified in modern ecosystems. The identification of the “Intraglacial Levipustula Fauna” and the “Postglacial Levipustula Fauna” may constitute a new tool for understanding the particular relationship between faunal assemblages and climatic variations linked to the Gondwanan glaciation in the Calingasta-Uspallata Basin. Also, the new “Intraglacial Levipustula Fauna” identified in the Hoyada Verde Formation would have biostratigraphical and paleogeographical implications in intra- and inter-basinal correlations.

Late Paleozoic ichnofaunas from eight different Gondwanic basins (Paganzo, San Rafael, Tarija, Paraná, Karoo, Falkland, Transantarctic, and Sydney) provide valuable evidence for reconstructing the environmental conditions of postglacial transgressions. The depositional environment of most of these transgressive fine-grained deposits historically has been controversial, with interpretations ranging from freshwater lacustrine to brackish-water estuarine, and even normal-salinity, open-marine platforms. Although the various units differ in the degree of marine connection, the common theme in all is the presence of freshwater ichnofaunas in direct association with glacially influenced coasts affected by strong discharges of meltwater. Ichnofaunas are typically dominated by nonspecialized grazing trails ( Mermia , Helminthopsis , Helminthoidichnites ), simple feeding traces ( Treptichnus ), arthropod trackways ( Diplichnites , Umfolozia ), and fish trails ( Undichna ), representing examples of the Mermia and, to a lesser extent, the Scoyenia ichnofacies. A complex paleogeography of fjords and deep, large coastal lakes is suggested. Freshwater conditions were prevalent during most of the time because these areas were affected by a strong discharge of fresh water due to melting of the ice masses during deglaciation. The simple dichotomy between marine and nonmarine settings is misleading because these peculiar assemblages should first be understood in terms of their paleoecologic significance, and subsequently placed within a larger paleoenvironmental context. Laterally persistent, albeit diachronous, peri-Gondwanan ichnofaunas characterize melting of the late Paleozoic ice caps. Temporal recurrence of these ichnofaunas through the Late Carboniferous–Middle Permian indicates a common response of benthic faunas under similar ecological conditions during deglaciation events.

The late Paleozoic climatic evolution of Gondwana can be traced by analyzing the benthic ecology of its coastal environments as revealed by their ichnologic content. Latest Carboniferous–earliest Permian transgressive deposits occur in the lower member of the Tupe Formation, Paganzo Group, western Argentina. Three different trace-fossil assemblages are present as part of two complete depositional sequences. Trace-Fossil Assemblage 1 consists of Treptichnus pollardi and Helminthopsis abeli , which occur in fine-grained heterolithic facies. This assemblage characterizes a subaqueous freshwater substrate in a flood-plain environment. Trace-Fossil Assemblage 2, consisting of Halopoa isp., Palaeophycus crenulatus and Planolites montanus , occurs in thin-bedded, tabular sandstone. The tracemakers inhabited a low-energy distal-bay environment dominated by background sedimentation with sporadic storm episodes. The trace fossils represent the activity of post-storm colonizers. Trace-Fossil Assemblage 3 is monospecific, comprising only Rhizocorallium commune preserved at the interface between a sandstone bed and the overlying mudstone. The tracemakers inhabited the overlying muddy substrate in a low-energy distal-bay environment and burrowed down into the sediment, expanding laterally at the top of the underlying sandstone layer. Trace-Fossil Assemblages 2 and 3 do not resemble typical marine ichnocoenoses and can be considered a depauperate Cruziana ichnofacies, suggesting brackish-water conditions in a restricted marine embayment. The ichnofauna associated with the latest Carboniferous–earliest Permian transgression of the Tupe Formation is compared with that in the older (early Late Carboniferous) postglacial transgression recorded in the underlying Guandacol Formation. The latter reflects freshwater conditions related to an extreme meltwater influx coming from retreating glaciers in fjord environments. In contrast, the latest Carboniferous–earliest Permian transgression in the Paganzo Basin occurred in a confined, brackish-water embayment, but away from the direct influence of meltwater discharges.

The Lower Permian Mackellar Formation is well exposed in a 10,000 km 2 outcrop belt in the Nimrod, Beardmore, and Shackleton Glacier areas of the Transantarctic Mountains. This formation directly overlies glacial deposits and provides a unique glimpse of high paleolatitude conditions during the last icehouse to greenhouse transition. The unit records deposition in the Mackellar Lake or Inland Sea (MLIS), a fresh-water body at ~80° S paleolatitude that was broadly analogous to Glacial Lake Agassiz and was filled by fine-grained turbidites. Low total organic carbon (TOC) content and predominant vitrinite and inertinite are consistent with a low influx of organic matter from a sparsely vegetated, recently deglaciated terrain. A widespread but low-diversity ichnofauna and variable (although low overall) levels of bioturbation suggest oxic conditions and a bottom fauna restricted to areas of low sedimentation. Integration of sedimentologic, organic geochemical, and paleobiologic information with results of climate models and characteristics of modern lakes enhances reconstruction of parameters that controlled the functioning of the lake as an ecosystem. Regression equations relating mean annual temperature and mean depth of modern lakes to the number of ice-free days applied to the MLIS indicate ice cover from two to five months a year. Estimates of the depth of mixing and depth to the thermocline, based on maximum length, maximum width, and area, suggest a mixing depth of ~50 m and a thermocline of ~20 m. The MLIS probably was stratified during the summer and was dimictic, with overturns occurring after fall cooling and after ice melt; mixing was enhanced by turbidity currents. Productivity was low, as recorded by the low TOC, but organic matter fixed in the surface water of the lake may have been degraded and not recorded in the sediments. In spite of its high paleolatitude, the MLIS as reconstructed was dynamic and biologically active; the same probably was true of other Permian postglacial lakes.

Abstract The Lower Permian Rio Bonito and Palermo Formations represent part of the infill of the Paraná Basin, southern Brazil. Integrated analysis of cores, outcrops and well logs from coal fields in Rio Grande do Sul allows sedimentologic, ichnologic, and sequence-stratigraphic characterization of these successions. The Río Bonito Formation has been typically interpreted as fluvio-deltaic. However, the transgressive nature of the succession, the vertical increase in ichnodiversity and bioturbation intensity, and the vertical passage from brackish-water ichnofaunas to fully marine assemblages argue against a prograding delta and suggest deposition in fluvio-estuarine settings. The lowstand fluvial deposits are unbioturbated. Estuarine deposits of the transgressive systems tract comprise tidal channel, point bar, coal-bearing marsh, and estuary mouth deposits. Estuarine ichnofaunas are characterized by simple tiering structures, low degrees of bioturbation, low diversity, and dominance of simple burrows produced by inferred trophic generalists. The top of the Rio Bonito Formation is represented by a shoreface unit consisting of high-energy, storm-dominated, lower to middle shoreface sandstones, laterally grading into moderate-energy shoreface deposits. High-energy shoreface deposits typically lack bioturbation, but deep burrows may be present locally. Moderate-energy shoreface deposits show alternations of opportunistic and climax suites. The transitional interval between the Rio Bonito and Palermo formations displays features indicative of deposition in a restricted, brackish-water lagoon. The Palermo Formation mostly represents transgressive deposition in open marine environments. A wave ravinement surface separates the underlying marginal-marine deposits from the overlying open marine interval. Open marine strata form regional parasequences. Offshore transition to upper and lower offshore deposits are punctuated by transgressive surfaces of erosion, demarcated by suites attributable to the Glossifungites Ichnofacies. Upper offshore to offshore-transition softground trace fossil assemblages are the most diverse. Degrees of bioturbation are high and tiering structures are relatively complex. Lower offshore deposits are highly variable in their degrees of bioturbation. Shelf deposits are unbioturbated, probably reflecting oxygen-depleted conditions, and delineate maximum flooding of the basin. Comparison with other ichnofaunas suggests that Permian brackish-water assemblages are more similar to Mesozoic ichnofaunas than to earlier Paleozoic ones. However, Permian brackish-water deposits are less pervasively bioturbated and contain less diverse trace fossil suites than their Cretaceous equivalents.

Abstract The field of Ichnology bridges the gap between the areas of paleontology and sedimentology, but has connections to many subdisciplines within these areas. Biogenic structures record the behavior of their tracemakers and provide valuable information in paleoecologic and paleoenvironmental analysis. As in situ ethologic structures, trace fossils or ichnofossils yield valuable insights into the paleoecology of ancient benthic communities and the environmental dynamics of depositional systems. Ichnology is truly a multifaceted field, and a broad selection of its facets is represented in the 28 papers of this volume. The papers are the product of Ichnia 2004, the First International Congress on Ichnology, convened by Jorge F. Genise and held from 19 to 23 April 2004 at the Museo Paleontológico Egidio Feruglio in Trelew, Patagonia, Argentina. Seven papers connected with the congress, containing ichnotaxonomy, were published separately, in Ichnos, volume 13, issue 4, edited by J.F. Genise, R.N. Melchor, R.G. Netto, and A.K. Rindsberg. Several symposium volumes, books, and short-course notes have been published in recent years ( Pemberton et al., 2001 ; Buatois et al., 2002 ; Kowalewski and Kelley, 2002 ; Hasiotis, 2002 ; Kelley et al., 2003 ; Buatois and Mángano, 2003 ; McIlroy, 2004 ; Webby et al., 2004 ; Miller, 2007 ; Seilacher, 2007 ), and ichnology can be considered a particularly active research area in steady growth. The 28 papers herein are arranged in five groups that reveal the broad scope of ichnology. One of the

Abstract: Two basic approaches are used to assess the paleobiology of continental associations between insect herbivores and their host plants. First is a biological approach that emphasizes phylogeny of extant representatives of lineages with fossil records. Second is a paleobiological approach that provides intrinsic evaluation of fossil associational evidence, of which there are several types of studies. One type of study is intensive examination of single insect-herbivore associations that involve a continuum from generalists to specialists requiring detailed autecological deductions about life habits. Another tack is assessment of herbivore damage patterns from selected plant hosts through slices of time for understanding the ecological evolution of a component community. Alternatively, comprehensive analyses can be made of the feeding patterns within a single or a series of regional floras. The record of plant-insect associations has five advantages. Associational data (1) are typically present in deposits that lack insect body fossils; (2) often surpass in abundance and usefulness insect body fossils in the same deposit; (3) frequently antedate their respective insect body fossils; (4) provide invaluable behavioral data that are unavailable from body fossils; and (5) supply crucial data for testing hypotheses in paleobiology and evolutionary biology that otherwise are unachievable. Disadvantages involve difficulties in circumscribing insect culprits, absence of extant ecological data to which fossil data can be compared, and lack of attention by paleobotanists and botanists in collecting damaged specimens. An associational view of fossil land plants and insects provides a dynamic, process-oriented view of ecosystem evolution that is needed in paleobiology.

Abstract: Organisms are homeostatic organic wholes. Their organization is understandable, and fractally repeated, from the level of the cell to whole individual organisms, through higher taxonomie groups up to the level of the biosphere. This is not fully appreciated by most biologists and paleontologists owing to emphasis on investigation of the parts (individual organs) that constitute static anatomy, rather than the dynamic morphological interrelationships. The morphodynamic approach, which is largely synonymous with a holistic heterochronic approach, also allows us to view organisms as complex systems: i.e., as manifestations of iterative or recursive fractal organization. Using the Schadian paradigm, already successfully applied to an understanding of modern mammals, and the relationships between morphology (form), physiology, and behavior, it is possible to gain insight into reiterating, recursive, or fractal patterns of organization in dinosaurs, pterosaurs, and other extinct archosaurs. Once these whole-body morphodynamic relationships are understood, as inherent, intrinsic, or “formal” aspects of vertebrate development, all natural groups of organisms can be seen in a new light: i.e., recurrent patterns of morphological organization (convergence) are seen as necessary correlates of physiological organization and behavior. In turn, all these organic attributes help us understand dynamic evolutionary development of any natural taxonomic group (clade). Thus, ontogeny reiterates and creates phylogeny (and vice versa) in a series of fractal, recursive manifestations of form, physiology, and behavior. Appreciation of the intricacy of this complex fractal organization is an exercise in pattern recognition, with surprising implications, especially for paleontology. First, it confirms the interrelatedness of all organisms, one of the central tenets of modern evolutionary theory. Second, it supports the view that higher natural taxonomic groups, already recognized by biology and paleontology, are in reality superorganisms, with inherently similar organizational structure, modified only by spatial and temporal scaling (heterochrony). Thus, all have their own inherent spatio-temporal developmental trajectories (form, life span, and relative emphasis of proximal and distal—or inner and outer/peripheral organs). Third, convergence and iterative evolution can be understood as an inherent quality of a reiterating or recursive fractal system and not merely as an adaptation to external pressures of the environment. This inference is strongly supported by evo-devo studies. Fourth, the modification of the natural organic system, in part or wholly, will lead to a compensation or ripple effect throughout the whole system. Moreover, the phylogeny of a particular group may not be controlled by external environmental pressures to the degree often supposed. Rather, such phylogenies may be natural heterochronic cycles of repeated growth at levels of organization corresponding to higher taxonomic groups (= superorganisms). Such intricate, inherent (or formal) organic organization reveals lawful patterns of morphological relationships that extend beyond isolated and/or shared character recognition. Thus, it may be possible to predict the general form and physiology of the whole animal from an analysis or understanding of the parts (a process akin to modeling). This is particularly useful in paleontology. The morphodynamic approach does more than revive Cuvier’s principle of the correlation of “some” parts. It impels us to recast our previously static understanding of morphology in the light of the inherently dynamic nature of complex systems, showing us how “all” parts are ultimately related.