Australovenator

Australovenator is a megaraptorid dinosaur from the Late Cretaceous of Australia. It was named in 2009 by Scott A. Hocknull and his associates. It was a bizzare dinosaur due to its flexible limbs, which have been the subject of many studies.

## Physiology

Australovenator was a theropod with a stout body, moderately long legs, a long tail, a moderately long neck, and a moderately long, conical head with large jaws. Perhaps the most defining trait of Australovenator was its long arms, which had 3 fingers on each hand, the first two of which bore large, sickle-shaped claws. Most of its body (excluding its head, legs, and underside) may have been covered in short, fuzz-like feathers, while its underside, head, and legs would have been covered in scaly skin.

## Diet

Australovenator was a predator, preying on small ornithischians and smaller theropods. Its teeth had knife-like serrations from back to back, and its sickle claw was used to help grab prey as the dinosaur bit down on them.

## Ecology

In addition to being long, Australovenator's arms were extremely flexible; its forearms formed a 144° angle with its humeri at their maximum extension (with the maximum angle to which they could flex being 66°), its radius could twist around its ulna so that its hands faced each other when its arms were flexed, and its fingers had varying angles of extension and flexion, all of which were greater than 30°. The former two traits are shared in common with birds (with the latter trait in particular being convergently evolved, since more taxonomically-derived non-avian dinosaurs such as Velociraptor were incapable of doing this), and all three were indicative of a predator that relied on its arms for prey capture. [1] Due to its proportionally long lower legs, it would have been capable of outrunning prey items (usually smaller ornithopods), and thus likely chased them down over small distances; once it got close, it would outstretch its arms to grab its prey before pulling it towards its chest so that it could finish it off with a killing bite. Along with this, its feet were analyzed in detail, using computer-generated scans of an emu foot for reference; while the take-home message of this analysis was that soft tissues such as muscle and fat may impact a bone's range of motion, it noted that the claw on its second toe was splayed outwards, and hypothesized that this injury was caused by heavy impact, meaning that Australovenator may have kicked at foes similarly to modern birds (especially since said claw was the largest out of all of its foot claws, similarly to them). [2]

## In popular culture

In the fifth episode of the 1999 documentary *Walking with Dinosaurs*, a "polar allosaur" stalks the Leaellynasaura clan in an attempt to prey on them, eventually managing to kill the matriarch thanks to some stray Muttaburrasaurus drowning out quieter sounds with their calls for the rest of the herd. Seeing as the real-life theropod was later discovered to be a megaraptorid, many people assume that the predator was an outdated Australovenator reconstruction. While this is unlikely because Australovenator's anatomy was well-known even back when it was discovered, an interesting thing to note is that it may have been present in the same geological formation as Leaellynasaura (being present at similar elevations within the crust), meaning that the two may have encountered each other in life. [3]

## References

1. White, M. A., Bell, P. R., Cook, A. G., Barnes, D. G., Tischler, T. R., Bassam, B. J., & Elliott, D. A. (2015). Forearm range of motion in Australovenator wintonensis (Theropoda, Megaraptoridae). PLoS ONE, 10(9). https://doi.org/10.1371/journal.pone.0137709
2. White, M. A., Cook, A. G., Klinkhamer, A. J., & Elliott, D. A. (2016). The pes of Australovenator wintonensis (Theropoda: Megaraptoridae): Analysis of the pedal range of motion and biological restoration. PeerJ, 4. https://doi.org/10.7717/peerj.2312
3. Poropat, S. F., White, M. A., Vickers-Rich, P., & Rich, T. H. (2019). New megaraptorid (Dinosauria: Theropoda) remains from the Lower Cretaceous Eumeralla Formation of Cape Otway, Victoria, Australia. Journal of Vertebrate Paleontology, 39(4). https://doi.org/10.1080/02724634.2019.1666273