The Smallest Known (Extinct) North American Dinosaur

I haven't done a paleo' post here in a while. I've taken to posting that sort of thing via Twitter. However, here's one so cool I have to take time to note it. A new genus and species of heterodontosaurid dinosaur has been described from the Late Jurassic Morrison Formation (Brushy Basin Member) of Colorado, from fossils discovered back in 1979 (it's often a long road, from collection to description). Several individuals are represented, and the largest, though fully adult, would have been only 65 to 75 cm (26 to 30 inches) long and probably weighed no more than 0.5 to 0.75 kg (1.1 to 1.7 pounds). Named Fruitadens haagarorum, this tiny ornithischian was likely an omnivore, like other heterodontosaurids.

It unseats the diminutive Cretaceous theropod Albertonykus borealis (described in 2008) as the smallest-known nonavian dinosaur from North America.




A partial jaw of Fruitadens haagarorum.



An artist's life restoration scale model of Fruitadens haagarorum (note the tyrannosaurid skull in the background).