← Rex's Notes
Ankylosaurus
Living tank with a club for a tail.
Said: ang-KIE-loh-SOR-us
Era: Cretaceous · 68 to 66 million years ago
Diet: Herbivore
Habitat: Coastal forests of western North America
Size: about the length of a pickup truck with trailer.
What it was like
Ankylosaurus was covered head to toe in armor plates, even on its eyelids. The club at the end of its tail could swing hard enough to break a T. rex's leg bone.
What we know now
Finite element analysis of the tail club suggests impact forces sufficient to fracture the metatarsals of large theropods. The osteoderms are not solid bone; they have a complex internal fiber structure that absorbs and redistributes impact, similar to modern composite armor. It walked on all fours with a slow, deliberate gait.
Notes
- Belly was the only unarmored area, the obvious target.
- Recent CT scans show a complex, twisty nasal passage, possibly used to cool blood or resonate calls.
- Babies were born without their tail clubs; the bones fused with age.