Spinostropheus

Spinostropheus
Temporal range: Middle Jurassic
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Clade:Dinosauria
Order:Saurischia
Suborder:Theropoda
Clade:†Ceratosauria
Genus:†Spinostropheus
Sereno et al. 2004
Type species
Spinostropheus gautieri
Lapparent, 1960 [originally Elaphrosaurus gautieri]

Spinostropheus is a genus of small carnivorous ceratosaurian theropod dinosaur that lived in the Middle Jurassic period of Niger. The type and only species is S. gautieri.

Description

Spinostropheus was a relatively small theropod. In 2010, Gregory S. Paul estimated its length at four metres, and its weight at two hundred kilogrammes.[1]

History of discovery

In 1959, Albert-Félix de Lapparent excavated fossils near Oued Timmersöi, west of In Tedreft in the Agadez desert. Among the finds were the remains of a theropod. In 1960, de Lapparent, based on these, named a second species of the genus Elaphrosaurus, E. gautieri. The specific name honours François Gautier, the discoverer of the type locality.[2]

In 2004, Paul Sereno, John Wilson and John Conrad named a separate genus: Spinostropheus. The generic name is derived from Latin spina, "spine", and Greek στροφεύς, stropheus, "vertebra", and refers to the epipophyseal processes of the cervical vertebrae, which are prominent and dorso-ventrally flattened.[3]

The holotype, MNHN 1961-28, was found in a layer of the Tiouraren Formation dating from the Bathonian-Oxfordian.[4] De Lapparent had presumed that the strata dated from the Early Cretaceous. It consists of a cervical vertebra, seven pieces of the dorsals, three pieces of the sacrum, five tail vertebrae, a humerus, the lower end of a pubic bone, the lower end of a thighbone, a piece of a shinbone, a piece of a fibula, a metatarsal, four additional pieces of the metatarsus and a phalanx of a toe. The paratypes were an ulna, a metatarsal and a second partial skeleton consisting of vertebrae and limb elements. In 2004, Sereno e.a. referred a third skeleton, specimen MNN TIG6 consisting of a series of cervical and dorsal vertebrae together with some ribs.[3]

Phylogeny

In 2002, a cladistic analysis by Sereno et al found Spinostropheus to be the sister taxon of the Abelisauria. In this study only the data from specimen MNN TIG6 were considered.[5] Subsequent studies have confirmed the original interpretation as a basal ceratosaur, outside of Neoceratosauria, more closely in the evolutionary tree to Elaphrosaurus.[6]

See also

References

  1. ↑ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 78
  2. ↑ A-F. de Lapparent, 1960, "Les Dinosauriens du "Continental intercalaire" du Saharal central", Mémoires de la Société géologique de France, nouvelle série 39(88A): 1-57
  3. 1 2 Sereno, P. C.; Wilson, J. A.; Conrad, J. L. (2004). "New dinosaurs link southern landmasses in the Mid-Cretaceous". Proceedings of the Royal Society B: Biological Sciences. 271 (1546): 1325–1330. doi:10.1098/rspb.2004.2692. PMC 1691741. PMID 15306329.
  4. ↑ Rauhut, O.W.M.; Lopez-Arbarello, A. (2009). "Considerations on the age of the Tiouaren Formation (Iullemmeden Basin, Niger, Africa): Implications for Gondwanan Mesozoic terrestrial vertebrate faunas". Palaeogeography, Palaeoclimatology, Palaeoecology. 271: 259–267. doi:10.1016/j.palaeo.2008.10.019.
  5. ↑ Sereno, P.C.; Conrad, J.L.; Wilson, J.A. (2002). "Abelisaurid theropods from Africa: Phylogenetic and biogeographic implications". Journal of Vertebrate Paleontology. 22 (3): 106A.
  6. ↑ Carrano, M.; Sampson, S. (2008). "Phylogeny of Ceratosauria (Dinosauria: Theropoda)". Journal of Systematic Palaeontology. 6: 183–236. doi:10.1017/s1477201907002246.
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