Palacrodon
| Palacrodon Temporal range: Triassic,
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Diapsida |
| Clade: | Neodiapsida |
| Genus: | †Palacrodon Broom, 1906 |
| Species | |
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| Synonyms | |
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Palacrodon is an extinct genus of Triassic reptile with a widespread distribution. It was initially described from teeth collected in Early Triassic deposits in South Africa, and later reported from the Early Triassic of Antarctica[1] and the Late Triassic of Arizona.[2] Although previously considered an early rhynchocephalian, it is currently considered to be a non-saurian neodiapsid.[3]
History
The type specimen of Palacrodon browni was described from the Early Triassic Cynognathus Assemblage Zone of South Africa by Robert Broom, who classified it in Rhynchocephalia.[4] Malan (1963) questioned the rhynchocephalian placement of Palacrodon, viewing it as either a lizard or procolophonid.[5] A skull collected from the lower part of Fremouw Formation of Antarctica was named Fremouwsaurus geludens by Gow (1992),[6] but that taxon was synonymized with Palacrodon by Gow (1999).[1] Gow also described new material of the genus from South Africa and concluded that Palacrodon itself was not a member of Rhynchocephalia due to its lack of a quadratojugal and the presence of a lacrimal.[6][1]
In 2018, new tooth and jaw material was described from the Adamanian-age Blue Mesa Member of the Chinle Formation in Arizona. This extends the stratigraphic range of the form into the Norian stage of the Late Triassic.[2] A 2022 paper re-evaluating the Fremouw specimen found it to be closely related to Sauria within the Neodiapsida, and suggested that it may have been arboreal based on the elongated phalanges of the hands.[3]
References
- ^ a b c Gow, C. (1999). "The Triassic reptile Palacrodon browni Broom, synonymy and a new specimen". Palaeontologia Africana. 35: 21–23.
- ^ a b Kligman, Ben T.; Marsh, Adam D.; Parker, William G. (2018). "First records of diapsid Palacrodon from the Norian, Late Triassic Chinle Formation of Arizona, and their biogeographic implications". Acta Palaeontologica Polonica. 63 (1): 117–127. doi:10.4202/app.00426.2017.
- ^ a b Jenkins, Kelsey M.; Meyer, Dalton L.; Lewis, Patrick J.; Choiniere, Jonah N.; Bhullar, Bhart-Anjan S. (2022). "Re-description of the early Triassic diapsid Palacrodon from the lower Fremouw formation of Antarctica". Journal of Anatomy. doi:10.1111/joa.13770.
- ^ Broom, R. (1905). "On a new South African Triassic rhynchocephalian". Transactions of the South African Philosophical Society. 16: 379–380. doi:10.1080/21560382.1905.9526075.
- ^ Malan, M. E. (1963-05-01). "The dentitions of the South African rhynchocephalia and their bearing on the origin of the Rhynosaurs". South African Journal of Science. 59 (5): 214–220. doi:10.10520/AJA00382353_2356.
- ^ a b Gow, C. (1992). "An enigmatic new reptile from the Lower Triassic Fremouw Formation of Antarctica" (PDF). Palaeontologia Africana. 29: 21–23.
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