Hostname: page-component-76fb5796d-zzh7m Total loading time: 0 Render date: 2024-04-25T12:23:05.871Z Has data issue: false hasContentIssue false
  • English
  • Français

Russellosaurus coheni n. gen., n. sp., a 92 million-year-old mosasaur from Texas (USA), and the definition of the parafamily Russellosaurina

Published online by Cambridge University Press:  01 April 2016

M.J. Polcyn  and
G.L. Bell Jr.
M.J. Polcyn*
Affiliation:
Shuler Museum of Paleontology, Southern Methodist University, Dallas, Texas 75275, USA
G.L. Bell Jr.
Affiliation:
Guadalupe Mountains National Park, Salt Flat, Texas 79847, USA
*
* Corresponding author. Email: mpolcyn@mail.smu.edu
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

A new mosasaur, Russellosaurus coheni, is described from the Collignoniceras woollgari Zone (lower Middle Turonian) at Cedar Hill, Dallas County, Texas. At approximately 92 Ma, it is the oldest well-preserved mosasaur skull from North America. It possesses characters diagnostic of Plioplatecarpinae but retains numerous plesiomorphies as well. Phylogenetic analysis indicates a close relationship with Yaguarasaurus columbianus, and these two, together with Tethysaurus nopcsai, form a clade that occupies a position basal to the divergence of the subfamilies Tylosaurinae and Plioplatecarpinae. Russellosaurus coheni is proposed as the nominal taxon of a new mosasaur clade, parafamily taxon novum Russellosaurina, which includes Plioplatecarpinae, Tylosaurinae, their common ancestor and all descendants. Tethysaurus retains a plesiopedal limb and girdle morphology, and along with Russellosaurus and Yaguarasaurus, cranial plesiomorphies. Dallasaurus turneri, a temporally and geographically sympatric plesiopedal mosasaur, occupies a basal position within Mosasaurinae. This phyletic arrangement confirms that marine adaptations, such as development of paddle-like limbs, occurred independently in at least two lineages of mosasaurs, once within Mosasaurinae and once within Russellosaurina.

Keywords

MosasaurPlioplatecarpinaeTethysaurusTuronianYaguarasaurus
Type
Research Article
Information
Netherlands Journal of Geosciences , Volume 84 , Special Issue 3: Proceedings of the First Mosasaur Meeting , September 2005 , pp. 321 - 333
Copyright
Copyright © Stichting Netherlands Journal of Geosciences 2005

References

Antunes, M.T., 1964. O Neocretácico e o Cenozoico do Litoral de Angola. Junta de Investigações do Ultramar (Lisbon): 255 pp.Google Scholar
Bardet, N., Suberbiola, X.P. & Jalil, N.-E., 2003. A new mosasauroid (Squamata) from the Late Cretaceous (Turonian) of Morocco. Comptes Rendus Palevol 2(8): 607–616.Google Scholar
Bell, G.L. Jr., 1993. A phylogenetic analysis of mosasauroidea (Squamata). University of Texas, Austin, Texas, 293 pp. (unpublished Ph.D. dissertation).Google Scholar
Bell, G.L. Jr., 1997. A phylogenetic revision of North American and Adriatic Mosasauroidea. In: Callaway, J.M. & Nicholls, E.L. (eds): Ancient Marine Reptiles. Academic Press (San Diego): 293–332.Google Scholar
Bell, G.L. Jr. & Polcyn, M.J., 2005. Dallasaurus turneri, a new primitive mosasauroid from the Middle Turonian of Texas and comments on the phylogeny of Mosasauridae (Squamata). In: Schulp, A.S. & Jagt, J.W.M. (eds): Proceedings of the First Mosasaur Meeting. Netherlands Journal of Geosciences 84: 177–194.Google Scholar
Bell, G.L. Jr. & Sheldon, H.A., 1986. Description of a very young mosasaur from Greene County, Alabama, Journal of the Alabama Academy of Science 57: 76–82.Google Scholar
Caldwell, M.W., 1995. The pectoral girdle and forelimb of Carsosaurus marchesetti (Aigialosauridae), with a preliminary phylogenetic analysis of mosasauroids and varanoids. Journal of Vertebrate Paleontology 15: 516–531.Google Scholar
Caldwell, M.W., 1996. Ontogeny and phylogeny of the mesopodial skeleton in mosasauroids reptiles. Zoological Journal of the Linnean Society 116: 407–436.Google Scholar
Caldwell, M.W., 2000. On the aquatic squamate Dolìchosaurus longicollìs Owen, 1850 (Cenomanian, Upper Cretaceous), and the evolution of elongate necks in squamates. Journal of Vertebrate Paleontology 20: 720–735.Google Scholar
Carroll, R.L. & DeBraga, M., 1992. Aigialosaurs: mid-Cretaceous varanoid lizards. Journal of Vertebrate Paleontology 12: 66–86.Google Scholar
DeBraga, M., 1990, Anatomical and Functional Changes between Terrestrial Varanoid Lizards and Aquatic Mosasaurs, McGill University, Montreal (unpublished Masters thesis).Google Scholar
DeBraga, M. & Carroll, R.L., 1993. The origin of mosasaurs as a model of macroevolutionary patterns and processes. Evolutionary Biology 27: 245–322.Google Scholar
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. Transactions of the Kansas Acadademy of Sciences 105: 33–43.Google Scholar
Jacobs, L.L., Ferguson, K., Polcyn, M.J. & Rennison, C., 2005. Cretaceous δ13C stratigraphy and the age of dolichosaurs and early mosasaurs. In; Schulp, A.S. & Jagt, J.W.M., (eds): Proceedings of the First Mosasaur Meeting. Netherlands Journal of Geosciences 84: 257–268.Google Scholar
Jacobs, L.L., Polcyn, M.J., Taylor, L.H. & Ferguson, K., 2005. Sea surface temperatures and palaeoenvironmerits of dolichosaurs and early mosasaurs. In: Schulp, A.S. & Jagt, J.W.M., (eds): Proceedings of the First Mosasaur Meeting. Netherlands Journal of Geosciences 84: 269–281.Google Scholar
Lingham-Soliar, T., 1988. The mosasaur, Goronyosaurus, from the Upper Cretaceous of Sokoto State, Nigeria. Palaeontology 31: 747–762.Google Scholar
Lingham-Soliar, T., 1994. The mosasaur ‘Angolasaurus’ bocagei (Reptilia: Mosasauridae) from the Turonian of Angola re-interpreted as the earliest member of the genus Platecarpus. Paläontologische Zeitschrift 68: 267–282.Google Scholar
Páramo, M.E., 1994. Posición sistematica de un reptil marino con base en los restos fósiles encontrados en capas del Cretacico superior en Yaguara (Huila). Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales 19(72): 63–80.Google Scholar
Páramo, M.E., 2000. Yaguarasaurus columbianus (Reptila, Mosasauridae), a primitive mosasaur from the Turonian (Upper Cretaceous) of Columbia. Historical Biology 14: 121–131.Google Scholar
Polcyn, M.J., Tchernov, E. & Jacobs, L.L., 1999. The Cretaceous biogeography of the eastern Mediterranean with a description of a new basal mosasauroid from ‘Ein Yabrud, Israel. In: Tomida, Y. & Vickers-Rich, P. (eds): Proceedings of the 2nd Gondwanan Dinosaur Symposium. National Science Museum Monographs 15: 259–290.Google Scholar
Polcyn, M.J., Tchernov, E. & Jacobs, L.L., 2003. Haasiasaurus gen. nov., a new generic name for the basal mosasauroid Haasia Polcyn et al., 1999. Journal of Vertebrate Paleontology 23: 476.Google Scholar
Russell, D.A., 1967. Systematics and morphology of American mosasaurs (Reptilia, Sauria). Peabody Museum of Natural History, Yale University, Bulletin 23: 1–241.Google Scholar
Swofford, D.L., 2002. PAUP*. Phylogenetic Analysis Using Parsimony (*and Other Methods). Sinauer Associates, Sunderland, Massachusetts.Google Scholar