Russellosaurus
 | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (March 2015) |
| Russellosaurus Temporal range: Late Cretaceous,
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| Skull drawing | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Clade: | †Mosasauria |
| Family: | †Mosasauridae |
| Clade: | †Russellosaurina |
| Subfamily: | †Yaguarasaurinae |
| Genus: | †Russellosaurus Polcyn & Bell, 2005 |
| Type species | |
| †Russellosaurus coheni Polcyn & Bell, 2005
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Russellosaurus is an
mosasauroid from the Late Cretaceous of North America. The genus was described from a skull discovered in an exposure of the Arcadia Park Shale (lower Middle Turonian) at Cedar Hill, Dallas County in the south-central part of the DFW Metroplex in Texas, United States. The skull (SMU 73056, Shuler Museum of Paleontology, Southern Methodist University) was found in 1992 by a member of the Dallas Paleontological Society, who then donated to the museum. Other fragmentary specimens of Russellosaurus have been recovered from the slightly older Kamp Ranch Limestone at two other localities in the Dallas
area.
Etymology
The
paleontologist Dale A. Russell for his extensive work on mosasaurs ("Russell's lizard"). This is the second species of mosasaur to have been named for Russell, the first being Selmasaurus
russelli (Wright and Shannon, 1988). The type specimen of Russellosaurus is notable as being the oldest well-preserved mosasaur yet found in North America.
Description
Polcyn et. Bell (2005, p. 323) diagnose Russellosaurus as follows: "Small, lightly built mosasaur,
cartilaginous
contact with parietal. Median cleft in posterior parietal margin in dorsoventral aspect."
Species
Polcyn et Bell (2005, p. 322) designated Russellosaurus the type genus of a new parafamily of mosasaurs, the Russellosaurina (= subfamily Russellosaurinae of Bell, 1997). This
are believed to constitute a clade "basal to the divergence" of the subfamilies Plioplatecarpinae and Tylosaurinae.Based on the lack of fusion between elements of the basicarnium and a high degree of vascularization of the bone surface, which suggests the animal was undergoing a rapid growth stage when it died, the
Dallasaurus turneri
, was recovered from the same Cedar Hill locality as this specimen.
Sources
- 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.
- Polcyn, M. J. and Bell, G. L., Jr. 2005. Russellosaurus coheni n. gen., n. sp., a 92 million-year-old mosasaur from Texas (USA), and the definition of the parafamily Russellosaurina. Netherlands Journal of Geosciences 84(3):321–333.
- Wright, K. R. and S. W. Shannon. 1988. Selmasaurus russelli, a new plioplatecarpine mosasaur (Squamata, Mosasauridae) from Alabama. Journal of Vertebrate Paleontology 8(1):102–107.