Ophidiomorpha is a proposed clade composed of snakes and a number of extinct squamate groups. The clade was defined by Placi and Caldwell (2007) as a node-based clade containing the most recent common ancestor of dolichosaurs, adriosaurs, Aphanizocnemus, and fossil and extant Ophidia and all of its descendants.[1]

Ophidimorphs
Temporal range: Middle Jurassic - Holocene, 170–0 Ma
Fossils of Adriosaurus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Pythonomorpha
Clade: Ophidiomorpha
Palci and Caldwell, 2007
Subgroups

The existence of Ophidiomorpha as a clade may become problematic as it is placed within the Pythonomorpha, a clade that itself is not universally agreed upon containing mosasaurs and snakes, their most recent common ancestor and all of its descendants. Indeed, most 20th-century herpetologists and paleontologists rejected this idea and sought instead to demonstrate a close relationship between mosasaurs and varanid lizards.

Pythonomorpha was later resurrected by a number of paleontologists (Lee, 1997; Caldwell et Lee, 1997) who had conducted cladistic analyses that seemed to show that snakes and mosasaurs may have been more closely related to one another than either were to the varanid lizards, and that snakes more likely arose from aquatic ancestors.[2]

Other authors have rejected the Ophidiomorpha hypothesis, finding that Mosasauria (including dolichosaurs) are unrelated to snakes.[3]

References edit

  1. ^ Palci, A., & Caldwell, M. W. (2007). Vestigial forelimbs and axial elongation in a 95 million-year-old non-snake squamate. Journal of Vertebrate Paleontology, 27(1), 1-7.
  2. ^ Lee, M. S. Y. 1997. The phylogeny of varanoid lizards and the affinities of snakes. Philosophical Transactions of the Royal Society of London B 352:53-91.
  3. ^ Augusta, Bruno G.; Zaher, Hussam; Polcyn, Michael J.; Fiorillo, Anthony R.; Jacobs, Louis L. (2022-08-11), Gower, David J.; Zaher, Hussam (eds.), "A Review of Non-Mosasaurid (Dolichosaur and Aigialosaur) Mosasaurians and Their Relationships to Snakes", The Origin and Early Evolutionary History of Snakes (1 ed.), Cambridge University Press, pp. 157–179, doi:10.1017/9781108938891.011, ISBN 978-1-108-93889-1, retrieved 2024-01-30