SVP abstracts 21: Vancleavea: ~3x larger than we thought

Price 2020 presents
new larger specimens of Vancleavea campi (Fig. 1; Parker and Barton 2008; Nesbitt et al. 2009), a derived thalattosaur close to Helveticosaurus in the large reptile tree (LRT, 1751 taxa).

Figure 2. The Thalattosauria and outgroups (Wumengosaurus and Stereosternum) to scale.

Figure 1. The Thalattosauria and outgroups (Wumengosaurus and Stereosternum) to scale.

From the Price 2020 abstract:”
“The basal archosauriform Vancleavea campi has long been thought to represent a relatively small, semi-aquatic, predator from the Late Triassic ecosystems found in the entire Upper Triassic strata of western North America.”

Orginally Vancleavea was considered an archosauriform, but it resembles no other archosauriformes. Adding taxa shifts Vancleavea to the Thalattosauria. This has been online since 2011. So, Price should add taxa to clear up this decade-old problem.

“Here, I describe four partial dentaries recovered from the Duke Ranch Member of the Redonda Formation of eastern New Mexico. All specimens are referred to Vancleavea campi on the basis of a number of characters of the dentary shared with a complete individual of the taxon, here postulated to represent autapomorphies of Vancleavea campi.”

“These dentaries show that Vancleavea was a much larger animal than previously thought, and an estimate of the total minimum length is presented using isometric scaling. The total length of the largest individual is estimated close to four meters.”

That would make Vancleavea the largest thalalattosaur (Fig. 1).

“This size may have allowed Vancleavea to hunt larger prey within its environment and therefore shifts its role in the ecosystem to that of a semi-aquatic apex predator. I interpret the size increase as a growth series within the taxon, but acknowledge that further evidence is needed in support of this hypothesis.”

Nesbitt SJ, Stocker MR, Small BJ and Downs A 2009. The osteology and relationships of Vancleavea campi (Reptilia: Archosauriformes). Zoological Journal of the Linnean Society 157 (4): 814–864. doi:10.1111/j.1096-3642.2009.00530.x.
Parker WG and Barton B 2008. New information on the Upper Triassic archosauriform Vancleavea campi based on new material from the Chinle Formation of Arizona. Palaeontologia Electronica 11 (3): 20p.
Price R 2020. New specimens of the Archosauriform Vancleavea campi from the Upper Triassic (Rhaetian) Redonta Formation of Eastern New Mexico indicates Vancleavea campi was an apex predator. SVP abstracts 2020.


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