Australovenator

Australovenator (meaning "southern hunter") is a genus of megaraptoran theropod dinosaur that lived during the Late Cretaceous period in what is now Australia. The holotype (name-bearing) specimen consists of a partial skeleton that was discovered in rocks of the Winton Formation in near Elderslie Station in 2006. Its remains, including elements of the forelimbs, hindlimbs, pelvis, and lower jaws, were found intermingled with those of the sauropod dinosaur Diamantinasaurus. These rock layers derive from the Cenomanian stage of the Cretaceous period, about 95 million years ago. Australovenator was described by Australian paleontologist Scott Hocknull and colleagues in 2009. The genus contains a single species, A. wintonensis, though fragmentary remains from the Eumeralla and Wonthaggi Formations may belong to Australovenator as well. Australovenator was around 6 metres (20 ft) long and weighed 310–500 kilograms (680–1,100 lb). This makes it smaller than most South American megaraptorans, but among the largest carnivorous dinosaurs known from Australia. Although a skull is not known, it likely had an elongated, slender head like other megaraptorans. Its dentaries (lower jaws) are lightly-built and have 19 teeth each. The forelimbs are massive, with bowed, S-shaped humeri (upper arm bones) and terminate in giant, sharp claws. Its hindlimbs are relatively gracile, with a thin metatarsus in contrast to the robust metatarsi of theropods like Chilantaisaurus. Most phylogenetic analyses recover Australovenator as a basal member of Megaraptoridae, a family of long-armed, carnivorous tetanurans that occupied Australia, South America, Asia and possibly Africa and North America during the Cretaceous period. However, the higher relationships of Megaraptora are uncertain. The Winton Formation is dominated by sandstone, indicating an oxbow lake or similar lacustrine environment. Other dinosaurs known from this site include the sauropods Diamantinasaurus and Wintonotitan, an unnamed ankylosaur, and a larger, possibly distinct, megaraptoran.