MEANING: Southern thief
PERIOD: Late Cretaceous
CONTINENT: South America
Austroraptor is a the largest dromaeosaur to be discovered in the Southern Hemisphere, estimated at around 5-6 m in length, and weighing about 300 kg. An unenlagiine, it had a low and elongated skull with relatively small teeth, and proportionally long legs. These adaptations suggest a piscivorous, or fish-eating diet.
Austroraptor is from the Late Cretaceous. The Cretaceous is the third and final geological period of the Mesozoic Era, with the Late Cretaceous making up roughly the second half of it, lasting from about 100 to 66 million years ago. It was a time of significant evolutionary change, with dinosaurs reaching their greatest diversity before the mass extinction at the end of the Cretaceous.
The Cretaceous was a period with a relatively warm climate, though the Late Cretaceous experienced a global cooling trend, caused by falling levels of carbon dioxide in the atmosphere. The continents were nearing their present positions, but high sea levels flooded low-lying regions, turning Europe into an archipelago, and forming the Western Interior Seaway in North America. These seas were home to a variety of marine reptiles, including mosasaurs and plesiosaurs, while pterosaurs and birds shared the skies.
On land, dinosaurs continued to thrive and diversify during the Late Cretaceous, producing many of the most well-known goups, including tyrannosaurs, hadrosaurs, and pachycephalosaurs. Established Cretaceous dinosaur clades like the ceratopsians, ankylosaurs, and dromaeosaurs continued to flourish. Sauropod species consisted almost exclusively of titanosaurs, which seemed to be confined to the Southern Hemisphere for much of the Late Cretaceous. Flowering plants and grasses diversified and spread, becoming the dominant flora similar to what we see today.
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene (K–Pg) extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. This event, likely triggered by an asteroid impact, is marked by the abrupt K–Pg boundary, a distinct geologic layer separating the Mesozoic and Cenozoic Eras. In its aftermath, mammals and avian dinosaurs rapidly diversified, becoming the dominant land animals of the Cenozoic Era.
Austroraptor is a dromaeosaur. Dromaeosauridae is a family of feathered theropod dinosaurs that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards'. Dromaeosaurids were small to medium-sized carnivores, ranging from about 0.5 to 6 meters in length. Smaller species included Microraptor and Velociraptor, while larger examples included species such as Utahraptor, Dakotaraptor and Achillobator.
The dromaeosaurid body plan includes a relatively large skull, serrated teeth, narrow snout, and forward-facing eyes which indicate some degree of binocular vision. The distinctive dromaeosaurid body plan helped to rekindle theories that dinosaurs may have been active, fast, and closely related to birds. Dromaeosaurids, like most other theropods, had a moderately long S-curved neck, and their trunk was relatively short and deep. They had long arms that could be folded against the body in some species, and relatively large hands with three long fingers ending in large claws. Their tails were long and slender, which helped them balance and quickly maneuver during locomotion.
Dromaeosaurid feet had an enlarged second toe, bearing an unusually large, curved, sickle-shaped claw, which was held off the ground or 'retracted' when walking. This distinctive claw is thought to have been used in capturing prey and climbing trees. It was especially blade-like in the large-bodied predatory eudromaeosaurs.