The skeleton including femora, tibiae, fibulae and incomplete parts of a scapula, humerus, ulna, left and right ischium, vertebrae, ribs, partial armor over the pelvic girdle plus at least 60 detached armor plates and 8 teeth was found in the Late Cretaceous (Upper Campanian) marine Point Loma Formation, near Carlsbad, California.
Its coxae and trochanters are black; its femora is black except becoming brownish to orange on its apical 1/4, and shiny except for the mesofemur, which is sparsely gray on its apical 2/3; tibiae are orange; tarsi are orange.
They have several unusual features, for example, the posterior femora are greatly enlarged, being strongly adapted for leaping; in some species those hind femora actually are larger than the abdomen.