Wannanosaurus (Greek for "Wannan lizard"); pronounced wah-NON-oh-SORE-us
Woodlands of Asia
Late Cretaceous (80-70 million years ago)
Size and Weight:
About 2 feet long and 10 pounds
Small size; thick skull
We may never know for sure, but it seems likely that Wannanosaurus (or a dinosaur very much like it) was the ancestor of all the pachycephalosaurs, or bone-headed dinosaurs. Like most ancestral genera, this herbivore was very small, and probably scurried beneath the feet of the larger hadrosaurs and titanosaurs of the late Cretaceous period. The question, of course, is why Wannanosaurus had such a thick skull: some paleontologists believe pachycephalosaur males head-butted each other for dominance, but for a creature the size of Wannanosaurus, it seems more likely that its bony head would have served as a primitive form of defense.