Dracovenator Regenti

''Dracovenator'' () is a genus of neotheropod dinosaur that lived approximately 201 to 199 million years ago during the early part of the Jurassic period in what is now South Africa. ''Dracovenator'' was a medium-sized, moderately built, ground-dwelling, bipedal carnivore, that could grow up to an estimated in length and in body mass. Its type specimen was based on only a partial skull that was recovered.

Discovery

The type material BP/1/5243 for ''Dracovenator'' was discovered at the "Upper Drumbo Farm" locality in the upper Elliot Formation which is part of the Stormberg Group in Eastern Cape Province, South Africa. It was collected by James Kitching and Regent "Lucas" Huma in sandstone that was deposited during the Hettangian stage of the Jurassic period, approximately 201 to 199 million years ago. The paratype material BP/1/5278 (originally assigned to ''Syntarsus rhodesiensis'') was discovered in 1981, also at the Elliot Formation in pinkish-maroon silty mudstone that was deposited in Hettangian sediments. Both the holotype and paratype specimen were housed in the fossil collection of the Evolutionary Studies Institute, part of the School of Geosciences of the University of the Witwatersrand, in Johannesburg, South Africa. Unfortunately the cranial material house at the Evolutionary Studies Institute was lost and no new fossils of ''Dracovenator'' have currently been found.

The genus name is a contraction of the Latin words ''draco'' meaning "dragon", and ''venator'' meaning "hunter"; thus, "dragon hunter". "Draco" refers to its discovery in the foothills of Drakensberg, which is "Dragon's Mountain" in the Dutch language. The specific name, ''regenti'', was named in the honor of the late Regent 'Lucas' Huma, who was Professor Kitching's field assistant. ''Dracovenator'' was described and named by Adam M. Yates in 2005 and the type species is ''Dracovenator regenti''.

Description

''Dracovenator'' is estimated to have measured between in length and in body mass.Smith, N.D., Makovicky, P.J., Pol, D., Hammer, W.R., and Currie, P.J. (2007).
The Dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: Phylogenetic Review and Synthesis
. ''U.S. Geological Survey and The National Academies'' The holotype specimen, BP/1/5243, consists of both premaxillae, a fragment of the maxilla, two dentary fragments, a partial surangular bone, a partial angular bone, a partial prearticular bone, an articular bone, and several teeth. ''Dracovenator'' has a kink in its upper jaws, between the maxilla and the premaxilla. The back end of the lower jaw features an array of lumps and bumps, a condition seen in ''Dilophosaurus'', but to a much smaller extent. Munyikwa and Raath (1999) reassigned paratype BP/1/5278, which was originally assigned to '' Syntarsus rhodesiensis'', to ''Dracovenator'', a juvenile specimen which consists of bones from the front of the skull, teeth, and jaw bones.Munyikwa and Raath, 1999. Further material of the ceratosaurian dinosaur ''Syntarsus'' from the Elliot Formation (Early Jurassic) of South Africa. ''Palaeontologia Africana''. 35:55–59.

A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism. According to Yates (2005) ''Dracovenator'' can be distinguished based on the following characteristics: the presence of a large bilobed fossa surrounding a large lateral premaxillary foramen that is connected to the alveolar margin by a deep narrow channel; a deep, oblique notch on the lateral surface of the articular bone, separating the retroarticular process from the posterior margin of the glenoid, a particularly well-developed dorsal, tab-like processes on the articular bone—the first on the medial side, just posterior to the opening of the chorda tympanic foramen and the second on the lateral side on the anterolateral margin of the fossa for the m. depressor mandibulae.

Classification

Yates (2005) assigned ''Dracovenator'' to the clade Neotheropoda.A. M. Yates. 2005. A new theropod dinosaur from the Early Jurassic of South Africa and its implications for the early evolution of theropods. Palaeontologia Africana 41:105–122 The first cladistic analysis found that this genus formed a clade with the basal theropods ''Dilophosaurus'' and ''Zupaysaurus''. The skull of the type specimen, exhibits a mosaic of both ancestral and derived theropod characteristics. The following cladogram, based on the phylogenetic analysis conducted by Smith, Makovicky, Pol, Hammer, and Currie in 2007, outlines the relationships of ''Dracovenator'' and its close relatives:Smith, N.D., Makovicky, P.J., Pol, D., Hammer, W.R., and Currie, P.J. (2007). "The dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: Phylogenetic review and synthesis." In Cooper, A.K. and Raymond, C.R. et al. (eds.), Antarctica: A Keystone in a Changing World––Online Proceedings of the 10th ISAES, USGS Open-File Report 2007-1047, Short Research Paper 003, 5 p.

Paleoecology

The Upper Elliot Formation is thought to have been an ancient floodplain. Fossils of the prosauropod dinosaur ''Massospondylus'' and ''Plateosaurus'' have been recovered from the Upper Elliot Formation, which boasts the world's most diverse fauna of early Jurassic ornithischian dinosaurs, including ''Abrictosaurus'', ''Fabrosaurus'', ''Heterodontosaurus'', and ''Lesothosaurus'', among others. The Forest Sandstone Formation was the paleoenvironment of protosuchid crocodiles, sphenodonts, the dinosaur ''Massospondylus'' and indeterminate remains of a prosauropod. ''Dracovenator'' is thought to have preyed on the prosauropod dinosaurs in its paleoenvironment.

References

External links

Dinosaur Mailing List announcing discovery (includes full abstract)

{{Taxonbar, from=Q60778

Theropoda
Dinosaur genera
Hettangian dinosaurs
Elliot Formation
Fossil taxa described in 2005
Dinosaurs of South Africa