March 16th

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 / Dinopedia

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.

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