The Western Claw

Discovered in Alberta's Dinosaur Park Formation's Cretaceous strata representing the Campanian stage of 76.5 MYA, Hesperonychus elizabethae is a small dromaeosaur known from a pelvic girdle discovered by Dr. Elizabeth Nicholls of the Royal Tyrrell Museum in 1982. The skeletal element remained in storage until 2009 when it was described by Longrich and Currie (A microraptorine (Dinosauria–Dromaeosauridae) from the Late Cretaceous of North America). A number of claws that appear to be allometrically and anatomically related to Hesperonychus, but these have not been described or officially attributed to the small dinosaur. Measuring in at an estimated length of 1 m (3.3 ft) and weight of 1.9 kg (2.2 lbs), Hesperonychus appears to have been a fully adult but one of the smallest carnivores of North America. Despite the small amount of material, the description relied on comparison between this pelvis and the pelves of other dromaeosaurs.

©Nobu Tamura CC BY 3.0