Two new species of polycotylid plesiosaurs

The second paper in the two-part report on by Albright et al. on plesiosaurs from the Upper Cretaceous Tropic Shale of southern Utah (Journal of Vertebrate Palaeontology, Volume 27(1) p. 41-58), introduces two new genera and species of polycotylid plesiosaur and contributes to the systematics of polycotylid plesiosaurs. The first new genus and species, Palmula quadratus possesses a unique combination of characters amongst polycotylid plesiosaurs – distinctly polygonal epipodials combined with small overall adult size. Palmula is also the only named representative of a new subfamily proposed by Albright et al, the Palmulainae, a clade diagnosed by polygonal epipodials.

The other new plesiosaur, Eopolycotylus rankini, is an almost complete specimen named after David O. Rankin who discovered the fossil in 2001. “I’ve been fossil hunting since I was 9 years old” explains Rankin, who made his first large pliosaur find at the age of 14. So what is it like to have a plesiosaur named after you? “I’m very excited about it” says Rankin, “Its like having your own little piece of history, and science.” Rankin also assisted the excavation team who excavated Eopolycotylus rankini in 2003. The team from the Museum of Northern Arizona in Flagstaff was headed by Dr David Gillette who is a coauthor of the paper.

E. rankini is a representative of a second new subfamily, the Polycotylinae, which also includes the majority of known polycotylids. As in all other polycotylines the epipodials of Eopolycotylus are broader than long, contrasting with the condition in Palmulines.

More photographs of the Eopolycotylus excavation are available on David Rankin’s website. A Palmula and Eopolycotylus ‘genus page’ will be added to the Plesiosaur Directory in the near future.

N.B. I have this article, and the other JVP plesiosaur articles discussed here, as PDFs which I would be happy to share.

eopolycotylus excavation
The pectoral and pelvic girdles of Eopolycotylus, in situ, being excavated by a team from the Museum of Northern Arizona (photograph by D.O. Rankin, used with kind permission).

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