The Tylosaurus Collection
A virtual collection of Tylosaurus specimens from Kansas and elsewhere
Copyright © 2001-2008 by Mike Everhart
LEFT: A right side, ventral view of the skull and cervical vertebrae of a large Tylosaurus proriger in the field (scale = 1 meter).
Tylosaurs were a very successful group of large mosasaurs, living in the late Cretaceous from the Coniacian to the middle of the Campanian age (about 88 to 78 million years ago). Tylosaurs grew to be quite large, with some individuals reaching lengths of 15 meters or more. They were apparently distributed worldwide since their fossils (including Hainosaurus) are found in North America, Europe, New Zealand and most recently from as far south as Antarctica. One of the first specimens from Kansas to be exhibited (see Osborn, 1900) is still on display at the American Museum of Natural History. Tylosaurs had a heavy rostrum (premaxilla) that extended beyond their front teeth, leading some paleontologists to believe that the structure may have been used for ramming their prey, or in fights with other mosasaurs. Preserved stomach contents indicate that tylosaurs preyed on many varieties of smaller animals, including other mosasaurs and plesiosaurs. See Williston's (1898) drawings of a Tylosaurus proriger skull HERE.
|One of the last places that I expected to see a Kansas tylosaur was during my 2002 visit to Japan. This picture shows the left side of a Tylosaurus proriger (HMG-1288) skull from western Kansas on exhibit in the Hobetsu Museum in Hobetsu, (northern island of Hokkaido), Japan. The skull was purchased for exhibit in the museum. My host, Dr. Usami, and the museum director, Mr. Sakurai are standing in the background. The museum features many late Cretaceous fossils from the island of Hokkaido, including other mosasaurs, a large and nearly complete elasmosaur, marine turtles and ammonites. I wish to thank Mr. Sakurai and the staff of the museum for their kindness and assistance during my visit. (Hobetsu Museum, Japan - in Japanese)|
Click on the Thumbnail
Specimen Number / I.D.
|This string of vertebrae was collected in 1967 from the Fort Hays Limestone in Ellis County, KS by M.V. Walker and was identified as Tylosaurus sp. by Everhart (2005). It is the oldest example of Tylosaurus known (Lower Coniacian) from Kansas and the only mosasaur remains ever collected from the Fort Hays Limestone.||FHSM VP-2297 - Fort Hays State University, Sternberg Museum of Natural History.|
|The most interesting thing about this Tylosaurus skull (HMG-1288) from Logan County is the pathology shown on the right side. A large area of damaged bone was visible on the right side of premaxilla and a fracture was evident in the suture between the premaxilla and right maxilla. The unusual 'humped' silhouette of the skull may indicate additional fractures.||Hobetsu Museum, Japan|
|This picture shows the extent of the damage to the skull (HMG-1288), including the rearward displacement of the first tooth in the right maxilla.||Hobetsu Museum, Japan|
|The damage on the premaxilla (and the fractures) appears to have been caused by an impact with something very hard and solid, like a rock(?). This picture shows that some healing had taken place before the mosasaur died.||(HMG-1288) - Hobetsu Museum, Japan|
|Tylosaurus proriger as exhibited on the south wall of the Sternberg Memorial Museum in 1992. This specimen is about 10 meters (30 feet) in length. See the same display at the new Sternberg Museum here. (LARGE FILE)||Sternberg Museum VP-3|
|Tylosaurus proriger, dorsal and left lateral view of skull. NEW 2/2000 - For close-ups of the skull, click on the following: Premaxilla, anterior upper and lower jaws, left post orbital frontal, left jugal, and left quadrate. A new picture of the skull is located HERE.||Sternberg Museum VP-3|
|Tylosaurus proriger, dorsal and left lateral view of skull, different angle. In 1930, George F. Sternberg wrote regarding this specimen, "Recently I mounted a skeleton, now on the walls of the Kansas State Teachers College [Fort Hays State University] at Hays, which is thirty and one-half feet long. It has a skull four feet long. Four paddles helped propel his powerful body through the water. It was carnivorous, living on the flesh of many animals which inhabited these same waters. This is not the largest mosasaur known, nor is it the smallest."||Sternberg Museum VP-3|
|Tylosaurus proriger, dorsal and left lateral view of muzzle and lower jaws. The extended premaxilla shows up well in this picture.||Sternberg Museum VP-3|
|Tylosaurus proriger, dorsal and left lateral view of the back half of the skull||Sternberg Museum VP-3|
|This picture shows the same specimen about 1926, relatively soon after it was found. It is still in the plaster and burlap jacket that had been placed on it in the field. George F. Sternberg provided the photograph when he offered the specimen to Charles Gilmore at the Smithsonian Institution (USNM). Gilmore declined, citing another specimen obtained earlier from Charles Sternberg.||Photo collection of the USNM.|
|The left quadrate of VP-3, in position between the squamosal (top) and the lower jaw (lower).||Sternberg Museum VP-3|
|Tylosaurus proriger; view of ribs and left front paddle. Mosasaur limbs were greatly shortened and modified into paddles.||Sternberg Museum VP-3|
|The tip of the tail (caudal vertebrae) of the VP-3 Tylosaurus proriger.||Sternberg Museum VP-3|
|Tylosaurus nepaeolicus, dorsal view of muzzle unit. NEW 2/2000 - For close-ups of the skull, click on the following: frontal; pterygoids; maxillas; right maxilla; premaxilla (1), (2), (3) and (4); quadrate; and teeth.||Sternberg Museum VP-7262|
|A Tylosaurus nepaeolicus partial skull w/quadrate from a very large and fairly complete specimen. Note the extension of the premaxilla over the front teeth. It was originally collected in 1984 by the Sternberg Museum and I found additional pieces of the skull in 1990. Click here for a recent (2002) publication on this specimen.||Sternberg Museum VP-7262|
|Tylosaurus nepaeolicus lower jaws. NEW 2/2000 - For a close-up of the frontal and parietal, Click HERE.||Sternberg Museum VP-2209|
|A picture of a Tylosaurus specimen in the Tübingen Museum in Germany. Collected by Charles Sternberg from the Smoky Hill Chalk Formation.||Natural History Museum, University of Tübingen. From von Huene, 1919.|
|Tylosaurus proriger, lateral view of left side of skull (approximately six feet in length), (Bunker Mosasaur, Pierre Shale, Kansas). This specimen is featured on the Bunker Mosasaur webpage.||KUVP 5033, The University of Kansas, Museum of Natural History|
|Tylosaurus proriger, lateral view of left side of skull and upper body, (Bunker Mosasaur, Pierre Shale, Kansas). This specimen is featured on the Bunker Mosasaur webpage, and is one of the largest tylosaurs ever found (KUVP 5033).||The University of Kansas, Museum of Natural History|
|Tylosaurus proriger, partial dentarys and a vertebra. NEW 2/2000 - For close-ups of this specimen, click on the following: Dentarys, teeth (1) and teeth (2). Click here for the vertebrae of another large Tylosaurus (VP-642)||Sternberg Museum VP-2496|
|Tylosaurus proriger, root of 6th tooth of right dentary compared to man's fist. This jaw came from a very large mosasaur, similar in size to the Bunker Mosasaur shown above (Pierre Shale; Campanian).||Sternberg Museum VP-2496|
|Tylosaurus proriger, dorsal and left lateral view of skull. This specimen represents the earliest documented record of this species (early Santonian). This specimen is featured on the Tylosaurus webpage. The skull is 1.2 meters (4 feet) long.||Fick Fossil and History Museum, Oakley, KS|
|Tylosaurus proriger, sclerotic ring from left eye. This specimen is featured on the Tylosaurus webpage||Fick Fossil and History Museum, Oakley, KS|
|Tylosaurus proriger, close up of left side of skull and lower jaw. This specimen is featured on the Tylosaurus webpage||Fick Fossil and History Museum, Oakley, KS|
|Tylosaurus proriger, muzzle and anterior portion of left lower jaw. This specimen is featured on the Tylosaurus webpage||Fick Fossil and History Museum, Oakley, KS|
|Tylosaurus proriger, dorsal view of frontal /parietal suture. This specimen is featured on the Tylosaurus webpage||Fick Fossil and History Museum, Oakley, KS|
|Tylosaurus proriger, lateral view of left quadrate with preserved soft tissue. This specimen is featured on the Tylosaurus webpage||Fick Fossil and History Museum, Oakley, KS|
|The snout (premaxilla and both maxillas of a large (10 meter) Tylosaurus proriger from the Cody formation of eastern Wyoming (late Campanian?). This formation is comparable to the Pierre Shale of western Kansas.||Exhibited in the Tate Geological Museum, Casper, WY|
|Tylosaurus proriger, dorsal and left lateral view of skull||The University of Kansas, Museum of Natural History|
|A very large Tylosaur proriger specimen from the upper Smoky Hill Chalk of Logan County, collected by Judge E.P. West. Originally this specimen was identified as Tylosaurus dyspelor.||The University of Kansas, Museum of Natural History, KUVP 1032.|
|Tylosaurus sp., rostrum, partial denatures and maxillaries||Sternberg Museum VP-6907|
|Tylosaurus kansasensis., dorsal and right lateral view of skull||Sternberg Museum VP-78|
|Tylosaurus sp., Note: The left quadrate is displayed on right side of skull in this mounted specimen.||Sternberg Museum VP-78|
|Tylosaurus kansasensis., dorsal and right lateral view of
skull (different lighting)
|Sternberg Museum VP-78|
|The holotype specimen of Tylosaurus kansasensis Everhart 2005, dorsal and left lateral view. For another view of the skull, click HERE. The shorter premaxilla is a characteristic that seperartes T. kansasensis from T. nepaeolica and T. proriger. Here is a view of the skull as found with the cervical vertebrae at an odd angle to the skull. This may indicate a broken neck or other injury that occurred at the time of death.||Sternberg Museum VP-2295|
|Tylosaurus kansasensis., ventral and right lateral view. The lack of an infrastapedial process on the quadrates of T. kansasensis is another feature that distinguishes them from the other Tylosaurus species. For a view of the right quadrate, go HERE. The skull is about 70 cm in length and came from an animal that was about 5.6 m in length (18 feet long).||Sternberg Museum VP-2295|
|Tylosaurus kansasensis; Note the two deep bite marks on frontal. The bites are probably from another, larger Tylosaurus.||Sternberg Museum VP-2295|
|Tylosaurus kansasensis; note the large bite marks on right dentary (marked with blue triangles). It is likely that this mosasaur died from a bite that crushed the skull.||Sternberg Museum VP-2295|
|Tylosaurus sp., muzzle unit, dentarys and right quadrate||Sternberg Museum VP-3366|
|Tylosaurus sp., right quadrate and rostrum||Sternberg Museum VP-3366|
|The cast of a skull of Tylosaurus n. sp. in a private collection. Part of a very complete set of remains, included preserved cartilage from the Smoky Hill Chalk of Kansas. (UCB 138626). Collected by H. T. Martin in 1927.||The University of California Museum of Paleontology at Berkeley|
|Tylosaurus sp., dorsal view of disarticulated skull. This specimen is featured on the new species of Tylosaur page.||Private Collection|
|Part of a huge Tylosaurus skull recovered from the Pierre Shale of South Dakota. This specimen may, in fact, be a later and related species called Hainosaurus.||The Museum of Geology at the South Dakota School of Mines and Technology|
|This is a scan of a photograph of preserved scales associated with a Tylosaurus proriger specimen. It was published by S.W. Williston in Volume IV of the University Geological Survey of Kansas (1898).||The University of Kansas, Museum of Natural History|
Bell, G. L. Jr. 1997. Part IV: Mosasauridae - Introduction. pp. 281-292 In Callaway J. M. and E. L Nicholls, (eds.), Ancient Marine Reptiles, Academic Press, 501 pages.
Bell, G. L. Jr. 1997. A phylogenetic revision of North American and Adriatic Mosasauroidea. pp. 293-332 In Callaway J. M. and E. L Nicholls, (eds.), Ancient Marine Reptiles, Academic Press, 501 pages.
Everhart, M. J. 2000. Mosasaurs: Last of the great marine reptiles. Prehistoric Times. 44:29-31.
Everhart, M. J. 2001. Revisions to the Biostratigraphy of the Mosasauridae (Squamata) in the Smoky Hill Chalk Member of the Niobrara Chalk (Late Cretaceous) of Kansas. Kansas Academy Science Trans 104(1-2):56-75.
Everhart, M. J. 2002. New data on cranial measurements and body length of the mosasaur, Tylosaurus nepaeolicus (Squamata; Mosasauridae), from the Niobrara Formation of western Kansas. Kansas Academy of Science, Transactions 105(1-2):33-43.Everhart, M. J. 2002. Remains of immature mosasaurs (Squamata; Mosasauridae) from the Niobrara Chalk (Late Cretaceous) argue against nearshore nurseries. (Abstract) Journal of Vertebrate Paleontology 22(suppl. to 3):52A.
Everhart, M. J. 2004. Late Cretaceous interaction between predators and prey. Evidence of feeding by two species of shark on a mosasaur. PalArch, vertebrate palaeontology series 1(1):1-7.
Everhart, M. J. 2004. Tylosaurus novum sp. An update on an unnamed species of basal tylosaurine. Abstract book and field guide of the First Mosasaur Meeting, Schulp, A. S. and John W. M. Jagt (eds.), Natuurhistorisch Museum Maastricht, the Netherlands, pp. 35-39.
Everhart, M. J. 2004. Plesiosaurs as the food of mosasaurs; new data on the stomach contents of a Tylosaurus proriger (Squamata; Mosasauridae) from the Niobrara Formation of western Kansas. The Mosasaur 7:41-46.
Everhart, M. J. 2005. Rapid evolution, diversification and distribution of mosasaurs (Reptilia; Squamata) prior to the K-T Boundary. Tate 2005 11th Annual Symposium in Paleontology and Geology, Casper, WY, p. 16-27 (not peer-reviewed).
Everhart, Michael J. 2005. Oceans of Kansas - A Natural History of the Western Interior Sea. Indiana University Press, 320 pp.
M.J. 2005. Probable plesiosaur gastroliths from the basal Kiowa Shale (Early Cretaceous)
of Kiowa County, Kansas. Kansas Academy of Science, Transactions 108 (3/4): 109-115.
Everhart, M.J. 2005. Earliest record of the genus Tylosaurus (Squamata; Mosasauridae) from the Fort Hays Limestone (Lower Coniacian) of western Kansas. Transactions 108 (3/4): 149-155.
Everhart, M.J. 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.
Kiernan, C. R. 2002. Stratigraphic distribution and habitat segregation of mosasaurs in the Upper Cretaceous of western and central Alabama, with an historical review of Alabama mosasaur discoveries. Journal of Vertebrate Paleontology 22(1):91-103.
Russell, D. A. 1967. Systematics and morphology of American mosasaurs. Peabody Museum of Natural History, Yale University, Bulletin 23.
Schumacher, B. A. 1993. Biostratigraphy of Mosasauridae (Squamata, Varanoidea) from the Smoky Hill Chalk Member, Niobrara Chalk (Upper Cretaceous) of Western Kansas, Unpub. Masters Thesis, Fort Hays State University, 68 pp.
Stewart, J. D., 1990. Niobrara Formation vertebrate stratigraphy, pages 19-30, In Bennett, S. C. (ed.), Niobrara Chalk Excursion Guidebook, The University of Kansas Museum of Natural History and the Kansas Geological Survey.
Williston, S. W. 1898. Mosasaurs. The University Geological Survey of Kansas, Part V. 4:81-347, pls. 10-72.