| Rugosuchus | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Archosauria |
| Clade: | Pseudosuchia |
| Clade: | Crocodylomorpha |
| Family: | †Paralligatoridae |
| Genus: | †Rugosuchus Wu et al., 2001 |
| Type species | |
| †Rugosuchus nonganensis Wu et al., 2001 | |
Rugosuchus (meaning "uneven or wrinkledcrocodile", in reference to texturing on itsupper jaw bones) is anextinctgenus ofneosuchiancrocodyliform[1] from theCretaceous ofChina. It is known from most of a skull, a partialpostcranial skeleton, and a second partial skeleton including part of thehips. It was described by Xiao-Chun Wu and colleagues in 2001, withR. nonganensis as the type species. At the time of its description, it was the most complete crocodyliform from northeastern China, and only the second known.
Rugosuchus isbased onIGV 33, most of a skull. Wu et al. assigned two other specimens to this genus: IGV 31, much of a skeleton lacking a skull and most of the limbs; and IGV 32, threevertebrae, a partial hip, and a fragment ofthigh bone. These three specimens had been collected in 1958 by the Petroleum Geological Survey of theSong-Liao Basin, and remained unstudied for many years. The locality is near Fulongquan,Nong'an County,Jilin, in the Song-Liao Basin. Theformation is not known for certain, but is probably theNenjiang Formation. The age of the Nenjiang Formation has been debated, but as of the description ofRugosuchus was thought to be latest Early Cretaceous, based onostracode,bivalve, and fish fossils.[2] However, most of later studies consider it as late Cretaceous instead.[3]
Skull IGV 33 is thought to have come from an adult, based on the fusion of bones. It is somewhat elongate, being about 28 centimeters (11 in) long but only an estimated 13 centimeters (5 in) at its widest. Themaxillae, the main tooth-bearing bones of the upper jaw, had unusual elongate depressions on their sides, nine or ten per maxilla. Other skull bones had heavily textured surfaces, as is seen on other crocodyliforms. Thepremaxillae at the tip of the snout had five teeth each, and the maxillae 16 or 17, with wide spacing; because the jaws are closed, the teeth of the lower jaw cannot be observed.[2]
Wu et al. noted that their new genus was not aneusuchian because of the form of the palatal bones, but it was probably more closely related to the eusuchians than other extinct crocodyliforms likeGoniopholis by having more than two rows ofbony armor running its length, and by the form of the armor. They interpretedRugosuchus as similar toBernissartia,Shamosuchus and the unnamed "Glen Rose Form", but not asderived.[2] However, a more recentphylogenetic analysis by Turner and Buckley (2008) places it with the "Glen Rose Form" in aclade with Eusuchia, more derived thanBernissartia.[4]
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