2009 – Hesperonychus described
On this day in dinosaurs, a little predator stepped out of the shadows. The small dromeosaurid is known from a single, incomplete pelvic girdle discovered by Dr. Elizabeth Nicholls in 1982 in Alberta’s Dinosaur Provincial Park. Phil Currie and Nick Longrich described the animal in a 2009 paper, and it is thought that some miniature toe claws in the Royal Tyrrell Museum of Paleontology may belong to the diminutive creature as well.
Hesperonychus–whose name means ‘western claw’–lived 76.5 million years ago. It weighed about 4 pounds and was less than 3 feet in length. Not exactly a terror to something human-sized. But Hesperonychus filled an important ecologic niche–a small microraptorine taking on pint-size prey, alongside some very big neighbors.
Until Hesperonychus was discovered, microraptorines were thought to be a group isolated to the early Cretaceous in Asia. But Hesperonychus proves otherwise, with a late Cretaceous member of the group in North America.