Genusaurus

Genusaurus; Temporal range: Early Cretaceous, 106 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Superfamily:	†Abelisauroidea
Family:	†Abelisauridae
Genus:	†Genusaurus; Accarie et al., 1995
Species:	†G. sisteronis
Binomial name
	†Genusaurus sisteronis; Accarie et al., 1995

Genusaurus (/ˌdʒɛnjʊˈsɔːrəs/ JEN-yuu-SOR-əs;^[1] meaning "knee lizard") is a genus of abelisaurid theropod 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]

Description

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]

Size

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]

Discovery and naming

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]

Classification

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 either a member of the Noasauridae or Abelisauridae.^[8]^[9]^[10]

References

^ Creisler, Ben (July 7, 2003). "Dinosauria Translation and Pronunciation Guide G". Archived from the original on December 25, 2010. Retrieved December 7, 2012.
^ ^a ^b Holtz, Thomas R. Jr. (2007). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. New York: Random House. Genus list "last updated August 1, 2008". ISBN 978-0-375-82419-7.
^ ^a ^b Carrano, Matthew T.; Sampson, Scott D. (2007). "The Phylogeny of Ceratosauria (Dinosauria: Theropoda)" (PDF). Journal of Systematic Palaeontology. 6 (2): 183–236. doi:10.1017/S1477201907002246. S2CID 30068953.
^ ^a ^b ^c ^d ^e ^f Accarie, H., B. Beaudoin, J. Dejax, G. Fries, J.C. Michard, and P. Taquet (1995). "Découverte d'un Dinosaure théropode nouveau (Genusaurus sisteronis n. g., n. sp.) dans l'Albien marin de Sisteron (Alpes de Haute-Provence, France) et extension au Crétacé inférieur de la lignée cératosaurienne". Compte rendu hebdomadaire des scéances de l'Académie des Sciences à Paris. 320 (2): 327-334 Translation into English.
^ Montague, J. R. (2006). "Estimates of body size and geological time of origin for 612 dinosaur genera (Saurischia, Ornithischia)". Florida Scientist. 69 (4): 243–257.
^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 78
^ Grillo, O. N.; Delcourt, R. (2016). "Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king". Cretaceous Research. 69: 71–89. Bibcode:2017CrRes..69...71G. doi:10.1016/j.cretres.2016.09.001.
^ Wang, S.; Stiegler, J.; Amiot, R.; Wang, X.; Du, G.-H.; Clark, J.M.; Xu, X. (2017). "Extreme Ontogenetic Changes in a Ceratosaurian Theropod" (PDF). Current Biology. 27 (1): 144–148. Bibcode:2017CBio...27..144W. doi:10.1016/j.cub.2016.10.043. PMID 28017609.
^ Leonardo S. Filippi; Ariel H. Méndez; Rubén D. Juárez Valieri; Alberto C. Garrido (2016). "A new brachyrostran with hypertrophied axial structures reveals an unexpected radiation of latest Cretaceous abelisaurids". Cretaceous Research. 61: 209–219. Bibcode:2016CrRes..61..209F. doi:10.1016/j.cretres.2015.12.018. hdl:11336/149906.
^ Baiano, M. A.; Coria, R.; Chiappe, L. M.; Zurriaguz, V.; Coria, L. (2023). "Osteology of the axial skeleton of Aucasaurus garridoi: phylogenetic and paleobiological inferences". PeerJ. 11. e16236. doi:10.7717/peerj.16236. PMC 10655716. PMID 38025666.