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Jambura PL, Solonin SV, Cooper SL, Mychko EV, Arkhangelsky MS, Türtscher J, Amadori M, Stumpf S, Vodorezov AV, Kriwet J. Fossil marine vertebrates (Chondrichthyes, Actinopterygii, Reptilia) from the Upper Cretaceous of Akkermanovka (Orenburg Oblast, Southern Urals, Russia). CRETACEOUS RESEARCH 2024; 155:105779. [PMID: 38799703 PMCID: PMC7615991 DOI: 10.1016/j.cretres.2023.105779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Upper Cretaceous coastal marine deposits are widespread in the Southern Urals with a number of marine vertebrates previously reported from this region. However, previous studies on the vertebrate faunas in this region often lack detailed taxonomic descriptions and illustrations, rendering comparisons to other faunal assemblages difficult. A new diverse vertebrate assemblage comprising cartilaginous and bony fishes, as well as marine reptiles, is described here from the Orenburg region near Akkermanovka (Southern Urals, Russia). Thirty five taxa are identified, including three holocephalans (Elasmodus sp., Ischyodus yanschini, Chimaeroid indet.), two hybodontiform sharks (Meristodonoides sp., cf. Polyacrodus sp.), 17 neoselachians (Paraorthacodus cf. andersoni, Paraorthacodus sp., Synechodus sp., Cederstroemia nilsi, Acrolamna acuminata, Archaeolamna ex gr. kopingensis, Cretalamna sarcoportheta, Cretoxyrhina mantelli, Eostriatolamia segedini, E. venusta, Hispidaspis horridus, H. cf. gigas, Pseudocorax laevis, Pseudoscapanorhynchus compressidens, Scapanorhynchus rhaphiodon, Squalicorax kaupi, Ptychodus rugosus), a holostean (Lepisosteidae indet.), nine teleosts (Protosphyraena sp., Saurodontidae indet., cf. Pachyrhizodus sp., Pachyrhizodontidae indet., Enchodus petrosus, E. ferox, E. cf. gladiolus, E. spp., Alepisauroidei indet.), two plesiosaurs (Polycotylidae indet., Plesiosauria indet.), and one mosasaurid (Tylosaurinae indet.). Based on the faunal assemblage, a Santonian-?early Campanian age is proposed. Lamniform sharks are the best represented group in terms of taxic diversity and relative abundance, probably reflecting the peak in diversity this group experienced following the Cenomanian radiation in the Late Cretaceous. The faunal assemblage of Akkermanovka exhibits significant taxonomic overlaps with assemblages reported from Asia and North America, but not from Southern Hemisphere continents, indicating east-west dispersal of several marine taxa during the Late Cretaceous.
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Affiliation(s)
- Patrick L. Jambura
- Department of Palaeontology, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
- Vienna Doctoral School of Ecology and Evolution (VDSEE), University of Vienna, Djerassiplatz 1, 1030 Vienna, Austria
| | - Sergey V. Solonin
- Department of Geography, Ecology and Natural Management, Ryazan State University named for S. Yesenin, 390000 Ryazan, Russia
| | - Samuel L.A. Cooper
- Museum am Löwentor, Staatliches Museum für Naturkunde Stuttgart, 70191 Stuttgart, Germany
- Department of Paleontology, Hohenheim University, 70599 Stuttgart, Germany
| | - Eduard V. Mychko
- Shirshov Institute of Oceanology, Russian Academy of Sciences, 117997 Moscow, Russia
- Museum of the World Ocean, 236006 Kaliningrad, Russia
- Institute of Living Systems, Immanuel Kant Baltic Federal University, 236016 Kaliningrad, Russia
- Borissiak Paleontological Institute, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Maxim S. Arkhangelsky
- Department of General Geology and Minerals, Saratov State University, 410012 Saratov, Russia
- Department of Oil and Gas, Saratov State Technical University, 410054 Saratov, Russia
| | - Julia Türtscher
- Department of Palaeontology, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
- Vienna Doctoral School of Ecology and Evolution (VDSEE), University of Vienna, Djerassiplatz 1, 1030 Vienna, Austria
| | - Manuel Amadori
- Department of Palaeontology, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
| | - Sebastian Stumpf
- Department of Palaeontology, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
| | - Alexey V. Vodorezov
- Department of Geography, Ecology and Natural Management, Ryazan State University named for S. Yesenin, 390000 Ryazan, Russia
| | - Jürgen Kriwet
- Department of Palaeontology, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
- Vienna Doctoral School of Ecology and Evolution (VDSEE), University of Vienna, Djerassiplatz 1, 1030 Vienna, Austria
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A New Large †Pachycormiform (Teleosteomorpha: †Pachycormiformes) from the Lower Jurassic of Germany, with Affinities to the Suspension-Feeding Clade, and Comments on the Gastrointestinal Anatomy of Pachycormid Fishes. DIVERSITY 2022. [DOI: 10.3390/d14121026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pachycormiformes is a diverse clade of stem-teleost actinopterygian fishes with a stratigraphic range from the Lower Jurassic (Toarcian) to Upper Cretaceous (Maastrichtian). The Toarcian Posidonienschiefer Formation in SW Germany records the earliest occurrence of †Pachycormiformes in the fossil record, offering unique and crucial insight into the clade’s origins and early adaptive radiation in the Early Jurassic. However, Early Jurassic taxa remain poorly studied with the taxonomic diversity and stratigraphic/geographic distributions insufficiently defined, thus masking the early part of this evolutionary radiation. Here, we report a new genus and species of pachycormid fish from the Posidonienschiefer Formation identified by phylogenetic analysis as falling in an intermediate position between Saurostomus and Ohmdenia at the base of the suspension-feeding clade. The new taxon shows a unique suite of cranial and postcranial characters. Several synapomorphies of the suspension-feeding clade, notably, the morphology of the hyomandibula, elongation of the skull, and reduced squamation are shared with the new taxon. The intestinal tract is exceptionally preserved, providing one of the most complete examples of pachycormid gastric anatomy. A comparison of the gastrointestinal anatomy of the new genus with other pachycormiforms indicates extensive taxonomic variation within the clade, in the configuration of both the midgut and spiral valve, potentially related to trophic divergence. The results highlight an underestimated high diversity and the rapid acquisition of trophic specializations in Pachycormiformes much earlier in the clade’s evolution than previously considered.
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