Wang, W., Li, C., Scheyer, T. M., and Zhao, L. 2019. A new species of Cyamodus (Placodontia, Sauropterygia) from the early Late Triassic of south-west China. Journal of Systematic Palaeontology. Link.
Abstract - The Triassic eastern Tethyan faunas have continued to yield numerous specimens of marine reptile taxa in recent years. Nevertheless, compared with other sauropterygian clades, the diversity of placodonts in these faunas is low, and remains of this group are relatively rare in the fossil assemblages. Here, we report a new cyamodontoid specimen (ZMNH M8820) from the early Late Triassic of Guizhou, south-west China. This specimen is a nearly complete skeleton lacking only the forelimbs. It is distinct from other known Chinese placodonts as it features a large skull with remarkably enlarged supratemporal fenestrae and a small and less regularly arranged carapace. Interestingly, this new specimen resembles the European Cyamodus more than any Chinese cyamodontoid genera, particularly when considering the dentition and other cranial morphology. However, it differs from known Cyamodus species in some cranial features (e.g. epipterygoid fully ossified, posttemporal fenestra large, dentition derived) and the absence of a separate pelvic shield. Furthermore, based on an updated data matrix of placodonts, our phylogenetic results support the affinity of this new Chinese specimen with European Cyamodus species, and a new species, Cyamodus orientalis sp. nov., is erected here. This new material represents the first reported Cyamodus specimen in the world that preserves a three-dimensional skull with an associated postcranial skeleton and it extends the distribution of this genus into the early Carnian of the eastern Tethys. The existence of Cyamodus, a nearshore taxon, in south-west China at this time reveals greater similarity and more rapid intercommunication than previously known between western and eastern Tethyan vertebrate faunas, although the palaeobiogeographical origin and migration history of Cyamodontidae – and of other clades of placodont reptiles – are still obscure due to the scarcity of material from the northern and southern margins of the Palaeotethys.
Showing posts with label placodont. Show all posts
Showing posts with label placodont. Show all posts
Palaeontology Online: Fossil Focus: Placodonts
This link is to a new article at Palaeontology Online providing an overview of Triassic marine placodonts. Palaeontology Online is a website sponsored by the Palaeontological Association (who publish the journal Palaeontology) featuring regular articles written by subject experts on all aspects of paleontology.
Two New Triassic Content Papers
I don't think that I have mentioned these previously [if I have please don't comment :)]
This paper came out earlier this year in Zootaxa.
Kammerer, C.F., and K.D. Angielczyk. 2009. A proposed higher taxonomy of anomodont therapsids. Zootaxa 2018:1-24.
Abstract- A higher-level taxonomic framework for the Permo-Triassic anomodont therapsids (dicynodonts and their relatives) is presented in order to bring concordance between reconstructions of anomodont phylogeny and nomenclature. Taxonomic histories, remarks on current usage, and phylogenetic definitions are provided for twenty-two higher level (i.e., suprageneric) anomodont taxa: Anomodontia, Bidentalia, Chainosauria, Cistecephalidae, Cryptodontia, Dicynodontia, Dicynodontoidea, Emydopidae, Emydopoidea, Endothiodontia, Eumantelliidae, Geikiidae, Geikiinae, Kingoriidae, Kistecephalia, Lystrosauridae, Myosauridae, Oudenodontidae, Pylaecephalidae, Rhachiocephalidae, Therochelonia, and Venyukovioidea. Additionally, lists of diagnostic characters supporting each of these higher taxa are given, utilizing the results of several recent phylogenetic analyses of anomodont relationships.
This recent paper is free in Palaeo3:
Diedrich, C. 2009. The vertebrates of the Anisian/Ladinian boundary (Middle Triassic) from Bissendorf (NW Germany) and their contribution to the anatomy, palaeoecology, and palaeobiogeography of the Germanic Basin reptiles.
Palaeogeography, Palaeoclimatology, Palaeoecology 273:1-16.
doi:10.1016/j.palaeo.2008.10.026
Abstract - Systematically excavated bones are described from Bissendorf (Osnabrücker Bergland, north-western Germany). The bone bed in the compressus zone of the Ceratitenschichten (Meißner Fm, Upper Muschelkalk, Anisian/Ladinian boundary, Middle Triassic) was dated by ceratites. Sedimentologically, it is a bioclastic rudstone built mainly from Coenothyris vulgaris brachiopods, which were heavily compressed into a 3 mm thin layer. Parts of the bone bed and the following 15 cm of autochthonous mud were partially eroded synsedimentary by the compressus storm event. The material of the not-rich bone bed in the Germanic Upper Muschelkalk consists of isolated teeth or fin spines from five well-known shark species: Hybodus longiconus Agassiz, 1843, Acrodus lateralis Agassiz, 1837, Acrodus gaillardoti Agassiz, 1837, Palaeobates angustissimus Agassiz, 1838 and Polyacrodus polycyphus Agassiz, 1837. Teeth and scales from the teleosteans Gyrolepis sp, Dollopterus sp., Colobodus maximus, Quenstedt, 1835, C. frequens, Dames [Dames, W., 1888. Die Ganoiden des Deutschen Muschelkalkes. Palaeontologische Abhandlungen 4, 133–180] and Saurichthys sp. have been proved. Found were mostly vertebra centra and ribs, but also teeth and some other postcranial bones from the small pachypleurosaurs Anarosaurus sp. as well as mostly Neusticosaurus sp. These originated from adult and juvenile animals which indicates the primary habitat and populations of this region. Large marine nothosaur reptiles found include Nothosaurus cf. mirabilis Münster, 1834, and N. giganteus Münster, 1834. Proof of two placodonts is given thanks to Placodus gigas Agassiz, 1833 and Cyamodus sp. Finally, a tooth from the terrestrial lepidosaur Tanystrophaeus longibardicus (Bassani, 1866) is the northerly most sample found. The recorded fauna is well-known with complete skeletons of the described species from the northern Tethys (Mte. San Giorgio, Switzerland). The reptile skeletons are presented here in reconstruction. The bone bed composition in Bissendorf shows differences in the younger and more terrestrial mixed as well as the age difference in bone beds of northern (enodis/posseckeri zone) and southern Germany (dorsoplanus zone). At Bissendorf, only nearly complete marine vertebrates occur within the maximum high stand. High marine ichthyosaurs seem to be absent, indicating a shallow marine position in the western Germanic Basin.
This paper came out earlier this year in Zootaxa.
Kammerer, C.F., and K.D. Angielczyk. 2009. A proposed higher taxonomy of anomodont therapsids. Zootaxa 2018:1-24.
Abstract- A higher-level taxonomic framework for the Permo-Triassic anomodont therapsids (dicynodonts and their relatives) is presented in order to bring concordance between reconstructions of anomodont phylogeny and nomenclature. Taxonomic histories, remarks on current usage, and phylogenetic definitions are provided for twenty-two higher level (i.e., suprageneric) anomodont taxa: Anomodontia, Bidentalia, Chainosauria, Cistecephalidae, Cryptodontia, Dicynodontia, Dicynodontoidea, Emydopidae, Emydopoidea, Endothiodontia, Eumantelliidae, Geikiidae, Geikiinae, Kingoriidae, Kistecephalia, Lystrosauridae, Myosauridae, Oudenodontidae, Pylaecephalidae, Rhachiocephalidae, Therochelonia, and Venyukovioidea. Additionally, lists of diagnostic characters supporting each of these higher taxa are given, utilizing the results of several recent phylogenetic analyses of anomodont relationships.
This recent paper is free in Palaeo3:
Diedrich, C. 2009. The vertebrates of the Anisian/Ladinian boundary (Middle Triassic) from Bissendorf (NW Germany) and their contribution to the anatomy, palaeoecology, and palaeobiogeography of the Germanic Basin reptiles.
Palaeogeography, Palaeoclimatology, Palaeoecology 273:1-16.
doi:10.1016/j.palaeo.2008.10.026
Abstract - Systematically excavated bones are described from Bissendorf (Osnabrücker Bergland, north-western Germany). The bone bed in the compressus zone of the Ceratitenschichten (Meißner Fm, Upper Muschelkalk, Anisian/Ladinian boundary, Middle Triassic) was dated by ceratites. Sedimentologically, it is a bioclastic rudstone built mainly from Coenothyris vulgaris brachiopods, which were heavily compressed into a 3 mm thin layer. Parts of the bone bed and the following 15 cm of autochthonous mud were partially eroded synsedimentary by the compressus storm event. The material of the not-rich bone bed in the Germanic Upper Muschelkalk consists of isolated teeth or fin spines from five well-known shark species: Hybodus longiconus Agassiz, 1843, Acrodus lateralis Agassiz, 1837, Acrodus gaillardoti Agassiz, 1837, Palaeobates angustissimus Agassiz, 1838 and Polyacrodus polycyphus Agassiz, 1837. Teeth and scales from the teleosteans Gyrolepis sp, Dollopterus sp., Colobodus maximus, Quenstedt, 1835, C. frequens, Dames [Dames, W., 1888. Die Ganoiden des Deutschen Muschelkalkes. Palaeontologische Abhandlungen 4, 133–180] and Saurichthys sp. have been proved. Found were mostly vertebra centra and ribs, but also teeth and some other postcranial bones from the small pachypleurosaurs Anarosaurus sp. as well as mostly Neusticosaurus sp. These originated from adult and juvenile animals which indicates the primary habitat and populations of this region. Large marine nothosaur reptiles found include Nothosaurus cf. mirabilis Münster, 1834, and N. giganteus Münster, 1834. Proof of two placodonts is given thanks to Placodus gigas Agassiz, 1833 and Cyamodus sp. Finally, a tooth from the terrestrial lepidosaur Tanystrophaeus longibardicus (Bassani, 1866) is the northerly most sample found. The recorded fauna is well-known with complete skeletons of the described species from the northern Tethys (Mte. San Giorgio, Switzerland). The reptile skeletons are presented here in reconstruction. The bone bed composition in Bissendorf shows differences in the younger and more terrestrial mixed as well as the age difference in bone beds of northern (enodis/posseckeri zone) and southern Germany (dorsoplanus zone). At Bissendorf, only nearly complete marine vertebrates occur within the maximum high stand. High marine ichthyosaurs seem to be absent, indicating a shallow marine position in the western Germanic Basin.
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