A short story of three Tylosaurus.

There are many genera of mosasaurs, those often giant sea-going lizards of the Late Cretaceous. Among the largest is Tylosaurus (Fig. 1). Distinct from other mosasaurs, Tylosaurus had a long, cylindrical snout which may have been used to ram and stun prey and mating rivals.

I ran across an extraordinary mount of T. kansasensis with what appeared to be giant flippers both fore and aft (Fig. 1, top). The specimen is part of a traveling exhibit of the Burpee Museum called ‘Savage Ancient Seas. T. kansasensis was described recently by Mike Everhart, famous for his OceansofKansas.com website.

T. kansasensis (Everhart 2005, FHSM VP-2295)- “Among the key differences separating this species from other tylosaurines are a shortened, more rounded pre-dental process of the premaxilla, a distinctive quadrate lacking an infrastapedial process, and a parietal foramen located adjacent to the frontal-parietal suture.” Since Mike’s paper did not mention the giant flippers, I dropped him a line.

Figure 1. Tylosaurus represented by three species. T. kansasensis, T. proriger and T. dyspelor. Note the differences in flipper size.

Figure 1. Tylosaurus represented by three specimens: T. kansasensis, T. proriger and T. dyspelor. Note the differences in flipper size. This T. dyspelor (Osborn 1899) may be T. proriger. I don’t know the details of tylosaur systematics. Click to enlarge. Note: M. Everhart of OceansofKansas.com thought the fingers and toes were much too long on the T. kansasensis mounted specimen above.

Mike thought the flippers of the T. kansasensis mount were too large and wondered if the distortion was possibly caused by a wide-angle lens. I don’t think the camera was the problem here. If anyone has more data on this mount, please share it.

When you set three specimens next to one another, the similarities and differences are easier to see.

Earlier we looked at Jurassic World’s version of a super-sized mosasaur. Here the scale is actually set in stone! ~

Everhart MJ 2005. Tylosaurus kansasensis, a new species of tylosaurine (Squamata: Mosasauridae) from the Niobrara Chalk of western Kansas, U.S.A. Netherlands Journal of Geosciences / Geologie en Mijnbouw, 84(3), p. 231-240.
Marsh OC. 1872. Note on RhinosaurusAmerican Journal of Science 4 (20): 147.
Takuya K; Caldwell MW 2011. Two new plioplatecarpine (Squamata, Mosasauridae) genera from the Upper Cretaceous of North America, and a global phylogenetic analysis of plioplatecarpines. Journal of Vertebrate Paleontology 31 (4): 754–783.



1 thought on “A short story of three Tylosaurus.

  1. NOT photo distortion on the kansasensis pic. Otherwise, the far flippers with look way smaller. Cool post, David! Very informative!

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