- Tylosaurinae
Taxobox
name = Tylosaurines
fossil_range =Late Cretaceous
image_width = 200px
image_caption = "Tylosaurus"
regnum =Animal ia
phylum = Chordata
classis = Sauropsida
ordo =Squamata
familia =Mosasauridae
subfamilia = Tylosaurinae
subfamilia_authority = Williston, 1895Williston, S. W. 1895. New or little-known extinct vertebrates. "Kansas University Quarterly" 6:95-98.]
subdivision_ranks = Genera
subdivision =
*"Hainosaurus "
*"Taniwhasaurus "
*"Tylosaurus "Tylosaurinae Williston, S. W. 1897. Range and distribution of the mosasaurs with remarks on synonymy. "Kansas University Quarterly" 4(4):177-185.] is a
subfamily ofmosasaur s, a diverse group of LateCretaceous marinelizard s.Russell (1967, pp. 170 Russell DA, 1967. Systematics and morphology of American mosasaurs. Peabody Museum of Natural History, Yale University, Bulletin 23.] ) defined the Tylosaurinae as follows: "Large
rostrum present anterior topremaxilla ry teeth. Twelve or more teeth indentary andmaxilla . Cranial nerves X, XI, and XII leave lateral wall ofopisthotic through a singleforamen . No canal in basioccipital or basispehnoid for basilar artery. Suprastapedial process ofquadrate moderately large, distally pointed. Dorsal edge of surangular rounded and longitudinally horizontal...Twenty nine presacralvertebrae present. Length of presacral series less than that of postsacral series in "Tylosaurus ",neural spine s of posteriorcaudal vertebrae at most only slightly elongated, do not form an appreciable fin.Haemal arch es unfused to caudal centra. Appendicular elements lack smoothly finished articular surfaces."Genera referrable to the Tylosaurinae (informally and collectively known as "tylosaurines" or "tylosaurs") have been found on all continents except Australia and South America. The
etymology for the subfamily is derived from thegenus of thetype species , "Tylosaurus". In general, tylosaurs were large-bodied marine lizards armed with sturdy, conical teeth and an elongated premaxilla and extensions of the dentaries that do not bear teeth to the very end such as is found in other genera of mosasaurs. Cope's original concept of a "battering ram" snout is not supported by fossil evidence. Stomach contents from a tylosaur recovered inSouth Dakota Martin JE, Bjork PR. 1987. Gastric residues associated with a mosasaur from the late Cretaceous (Campanian) Pierre Shale in South Dakota. "Dakoterra" 3:68-72.] included remains of another mosasaur,a bony fish , the large, flightlessseabird "Hesperornis ", and possibly ashark , indicating that tylosaurs were generalists. Another specimen collected by Charles Sternberg Sternberg CH. 1922. Explorations of the Permian of Texas and the chalk of Kansas, 1918. Kansas Academy of Science, Transactions 30(1):119-120. (Papers - Fifty-first annual meeting, 1919), State Printer, Topeka.] included the bones of a small plesiosaur (see also Everhart MJ. 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.] ).Lingham-Soliar Lingham-Soliar T. 1992. The tylosaurine mosasaurs (Reptilia, Mosasauridae) from the upper Cretaceous of Europe and Africa. "Bulletin de L’Institut Royal des Sciences Naturelles de Belgique. Sciences de la Terre" 62:171-194.] suggested that tylosaurines were not among the fastest swimming nor the strongest mosasaurids. However, they are lightly built, having greatly reduced the weight of their bodies and possessing relatively small
pectoral andpelvic girdles, fore- and hindlimbs. Their bone is highly cancellous and may have been impregated withfat cells during life, adding buoyancy. These traits suggest that tylosaurs may have been ambushpredator s. Tylosaurs were among the largest mosasaurs, with some species of "Tylosaurus" and "Hainosaurus" reaching lengths of 9-15+ meters, making them among the largest of all marine reptiles. A smallspecies of "Tylosaurus" reported by Russell , "T. "zangerli" has since proven to be a juvenile individual of "T. proriger" Kiernan CR, 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.] . Everhart Everhart MJ. 2005a. "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): 231-240.] erected a third species ("T. kansasensis") from the Smoky Hill Chalk.Tylosaurs first appear in the fossil record in the
early Coniacian Everhart MJ. 2005b. Earliest record of the genus "Tylosaurus" (Squamata; Mosasauridae) from the Fort Hays Limestone (Lower Coniacian) of western Kansas. "Transactions" 108 (3/4): 149-155.] and persist well into theMaastrichtian , a period of approximately twenty million years.Species and Taxonomy
*Tylosaurinae
**"Tylosaurus " (?paraphyletic )
***"T. proriger"
***"T. nepaeolicus"
***"T. kansasensis"
***"T. pembinensis"
***"T. saskatchewanensis"
***"T. ivoensis" (Possibly a species of "Taniwhasaurus" Caldwell MW, Konishi T, Obata I, Muramoto K. 2008. New species of "Taniwhasaurus" (Mosasauridae, Tylosaurinae) from the upper Santonian-lower Campanian (Upper Cretaceous) of Hokkaido, Japan. "Journal of Vertebrate Paleontology" 28 (2): 339-348.] )
**"Hainosaurus "
***"H. bernardi"
***"H. gaudryi"
**"Taniwhasaurus "
***"T. oweni" (="Tylosaurus haumuriensis")
***"T. mikasaensis"
***"T. antarcticus"References
Further reading
*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 pp.
*Lindgren, J. et. Siverson, M. 2002."Tylosaurus ivoensis": a giant mosasaur from the early Campanian of Sweden. Royal Society of Edinburgh "Transactions: Earth Sciences" Vol. 93(1):73-93.
*Russell, D. A. 1970. The vertebrate fauna of the Selma Formation of Alabama, Part VII, The mosasaurs, "Fieldiana, Geology Memoirs" 3(7):369-380.
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