Genusaurus Temporal range:
Early Cretaceous,
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | † Neoceratosauria |
Superfamily: | † Abelisauroidea |
Genus: | †
Genusaurus Accarie et al., 1995 |
Species: | †G. sisteronis
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Binomial name | |
†Genusaurus sisteronis Accarie et al., 1995
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Genusaurus ( /ˌdʒɛnjʊˈsɔːrəs/ JEN-yuu-SOR-əs; [1] meaning "knee lizard") is a genus of abelisauroid dinosaur from the Early Cretaceous. Its fossils were found in France. Genusaurus is believed to have lived during the Albian stage, around 112-100 million years ago. [2] [3]
Genusaurus possesses several distinguishing traits. The dorsal vertebrae are elongated. The elements of the pelvis are strongly fused. The thighbone shows a low bone plateau below the major trochanter; to the front an accessory trochanter is present. The epicondyle of the inner femoral condyle is well-developed. The cnemial crest strongly extends to the front and is curved upwards. The fibula has a distinctive boss serving as an attachment for the Musculus iliofibularis. The upper inner side of the fibula is strongly hollowed out. [4]
Genusaurus was originally estimated to have been 3.16 metres (10.4 ft) long. From the 38 centimetres (15 in) thighbone, a weight of 129.6 kilograms (286 lb) was extrapolated. [4] Later estimates, while confirming the length of 3 metres (9.8 ft), [2] have reduced the weight to 50 kilograms (110 lb), [5] or even 35 kilograms (77 lb). [6] In 2016, its length was estimated at 3.6 metres (12 ft), making it the smallest abelisaurid. [7]
The type species, Genusaurus sisteronis, is the only named species. It is based on a partial skeleton found in 1984-1986 in the Albian Bevons Beds, holotype MNHN Bev.1. The holotype contains seven partial dorsal vertebrae, a piece of a sacral, a piece of an ilium, the top of a pubic bone, a thighbone, the top of a shinbone, the top of a fibula and a metatarsal. It was named and described by Hugues Accarie, Bernard Beaudoin, Jean Dejax, Gérard Friès, Jean-Guy Michard and Philippe Taquet in 1995. [4] The genus name is derived from the Latin word genu (knee) and refers to the cnemial crest in front of the proximal end of the tibia. [4] The specific name refers to Sisteron, the town near which the specimen was found. [4]
Accarie et al. assigned Genusaurus to the ceratosaur group of theropods, more precisely to the Coelophysoidea. [4] A 2008 cladistic analysis by Carrano and Sampson placed Genusaurus in the Noasauridae along with Laevisuchus, Masiakasaurus, Noasaurus, and Velocisaurus; in turn, noasaurids are part of the Abelisauroidea group, which is part of the ceratosaur group. [3] Subsequent phylogenetic analyses found Genusaurus to be a member of the Abelisauridae, specifically the Majungasaurinae. [8]