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Intraspecific variability, biostratigraphy and paleobiological significance of the southern Gondwana ammonoid genus Lytohoplites Spath

Veronica V. Vennari and Beatriz Aguirre-Urreta
Intraspecific variability, biostratigraphy and paleobiological significance of the southern Gondwana ammonoid genus Lytohoplites Spath
Journal of Paleontology (July 2019) 93 (4): 702-726

Abstract

Lytohoplites Spath, 1925 is a late Tithonian-?early Berriasian ammonoid genus with a southern perigondwanean distribution. Two Lytohoplites species, L. burckhardti (Mayer-Eymar in Burckhardt, 1900) (type species) and L. vetustoides (Burckhardt, 1903), were originally described from carbonate successions of the Vaca Muerta Formation, Neuquen Basin, Argentina. Nevertheless, the holotype of L. burckhardti consisted of a single incomplete specimen that is currently missing. This situation compelled the search for new Lytohoplites specimens in Argentina and the selection of a neotype for L. burckardti. New Lytohoplites representatives were obtained through bed-by-bed collections performed at five localities in the Neuquen Basin. In addition to the taxonomic revision of the Lytohoplites species occurring in the basin, a paleobiological approach was preferred to conduct a paleontological analysis of L. burckhardti, including a description of its ontogeny, probable sexual dimorphism, and spectrum of intraspecific variability. Results of the qualitative and quantitative analyses supported the homogeneity of L. burckhardti as a taxonomic unit, thus implying that L. vetustoides should be considered its synonym. Lytohoplites in the Neuquen Basin is restricted to beds assigned to the Andean Substeueroceras koeneni Assemblage Zone (upper Tithonian-lower Berriasian), and not to the Andean Corongoceras alternans Assemblage Zone (upper Tithonian). Furthermore, the paleobiogeographic distribution of Lytohoplites around southern Gondwana and the herein reported occurrence of L. subcylindricus Collignon, 1962, otherwise only known from Madagascar, lend support to the existence of a functional trans-Gondawana seaway at least since the upper Tithonian.


ISSN: 0022-3360
EISSN: 1937-2337
Coden: JPALAZ
Serial Title: Journal of Paleontology
Serial Volume: 93
Serial Issue: 4
Title: Intraspecific variability, biostratigraphy and paleobiological significance of the southern Gondwana ammonoid genus Lytohoplites Spath
Affiliation: Museo de Historia Natural de San Rafael, San Rafael, Argentina
Pages: 702-726
Published: 201907
Text Language: English
Publisher: Paleontological Society, Lawrence, KS, United States
References: 122
Accession Number: 2019-063782
Categories: Invertebrate paleontologyStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes 2 appendices
Illustration Description: illus. incl. strat. cols., 2 plates, 2 tables, sketch maps
S36°06'00" - S34°36'00", W70°09'00" - W69°45'00"
Secondary Affiliation: Universidad de Buenos Aires, ARG, Argentina
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, The Paleontological Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201933
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