Biology:Paraptychodus
Paraptychodus is a genus of extinct, durophagous shark that lived in North America during the Albian of the Early Cretaceous (ca. 100-105 Ma). It is notable for being the likely immediate evolutionary ancestor of the shark genus, Ptychodus. It is represented in the fossil record by one species, Pt. washitaensis.[1][2]
Phylogeny and evolution
Paraptychodus is the earliest known ptychodontid and likely immediate ancestor to Ptychodus.[1] Based on complete body fossils from Mexico, Ptychodus has recently been classified as a lamniform, making Paraptychodus a lamniform as well.[3]
The Albian record of Paraptychodus and early occurrences of Ptychodus in the Cenomanian suggest a North American origin for Ptychodus.[1]
Dentition
Like Ptychodus, Paraptychodus possessed a durophagous dentition. Its teeth have a convex crown surface crossed by transverse ridges. Although it differed from Ptychodus in having the labial protuberance and lingual sulcus featured in the tooth root and not the crown.[1][2] And, Paraptychodus posterior teeth have a raised, pointed crown not observed in any Ptychodus species.[1]
Paleobiology
Paraptychodus inhabited the early Western Interior Seaway alongside a number of other shark genera such as Leptostyrax, Cretalamna, and Squalicorax.[1] Given the size of their teeth, the largest being < 1 cm in size, it was likely a small shark (< 2 m).[3][2] The depositional environment it was found in has been interpreted to be a shallow, near-shore shelf populated with numerous hard-bodied invertebrates. Researcher Shawn Hamm hypothesized Paraptychodus could have preyed upon small ammonoids.[2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Hamm, Shawn A. (2015-05-01). "Paraptychodus washitaensis n. gen. et n. sp., of Ptychodontid shark from the Albian of Texas, USA". Cretaceous Research 54: 60–67. doi:10.1016/j.cretres.2014.10.015. ISSN 0195-6671. https://linkinghub.elsevier.com/retrieve/pii/S0195667114001906.
- ↑ 2.0 2.1 2.2 2.3 Hamm, S.A. (2020) Stratigraphic, Geographic, and Paleoecological Distribution of the Late Cretaceous Shark Genus Ptychodus within the Western Interior Seaway, North America. New Mexico Museum of Natural History and Science, Bulletin, 81, 1–94. https://nmdigital.unm.edu/digital/collection/bulletins/id/7316/
- ↑ 3.0 3.1 Vullo, Romain; Villalobos-Segura, Eduardo; Amadori, Manuel; Kriwet, Jürgen; Frey, Eberhard; González González, Margarito A.; Padilla Gutiérrez, José M.; Ifrim, Christina et al. (2024-04-30). "Exceptionally preserved shark fossils from Mexico elucidate the long-standing enigma of the Cretaceous elasmobranch Ptychodus" (in en). Proceedings of the Royal Society B: Biological Sciences 291 (2021). doi:10.1098/rspb.2024.0262. ISSN 0962-8452. PMID 38654646. PMC 11040243. https://royalsocietypublishing.org/doi/10.1098/rspb.2024.0262.
Wikidata ☰ Q21345680 entry
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