On a fateful day 210 million years ago, two crocodile cousins about the size of jackals stood side-by-side amid the low ferns of a humid riverbank that would one day become northern New Mexico. One of the crocs, Hesperosuchus agilis, had a long snout, large back legs, and smaller, thinner arms. A land dweller, Hesperosuchus was speedy and liked to hunt for food near rivers and streams.