Gnathostomata
Available for editorial, museum & print licensing — inquiries & rates →
Postosuchus was a Late Triassic rauisuchid that lived in southern North America. Rauisuchids were a group of crocodile-line archosaurs, not dinosaurs, although their apparently bipedal (two-legged) locomotion made Postosuchus superficially resemble theropod dinosaurs. Living at a time when dinosaurs were still ascending, it would have been an apex predator, with a deep skull and powerful bite.
The adult (TTUP 9000) and a subadult (TTUP 9002), drawn to scale.
Postosuchus isn't known from hatchlings, and in the adult and subadult the large head ("all the better to eat you with...") doesn't change much, but surprisingly the forelimb does. Comparing the humerus (upper arm bone) to the femur (thigh bone), we can see that the forelimb is getting proportionately smaller in the adult. To be sure, the arm keeps growing, but not as fast as the leg. If we assume this trend projects back to hatchling Postosuchus, it probably reflects a shift from an animal more comfortable on all fours as a juvenile, to one that is more bipedal (two-legged) with age.
| Stage | Length m | Skull m | Femur m | Humerus m | Skull ÷ femur | Humerus ÷ femur |
|---|---|---|---|---|---|---|
| AdultTTUP 9000 | 5m | 0.56m | 0.52m | 0.26m | 1.08 | 0.50 |
| SubadultTTUP 9002 | 3.8m | 0.42m | 0.40m | 0.24m | 1.05 | 0.60 |
Subadult (TTUP 9002)
