Dinosaurs / Cretaceous / Anodontosaurus
Anodontosaurus
Cretaceous an-oh-DON-toe-SAWR-us, “toothless lizard”
Anodontosaurus was a late-surviving ankylosaurine that roamed western Canada during the latest Cretaceous period. First collected from the Horseshoe Canyon Formation in Alberta, it measured around five to six metres in length and weighed roughly two tonnes. Described in 1929 by Charles Mortram Sternberg, it was given the name toothless lizard because the original skull specimen had suffered taphonomic damage that stripped its dentition, though living individuals possessed normal rows of leaf-shaped teeth. Previously subsumed within Euoplocephalus, Anodontosaurus was recognized as distinct due to its pointed cranial ornamentation, specific caputegulae arrangements, and a distinctly shaped tail club knob with pointed lateral margins. It was among the last flourishing ankylosaurs of North America before the end-Cretaceous extinction event.
It was named 'toothless' because the holotype skull had lost all its teeth during post-mortem fossilisation.
Where and when
Anodontosaurus lived in the Late Cretaceous, from 72.8 to 66.8 million years ago (Campanian-Maastrichtian age). Its remains come from Canada, in the Horseshoe Canyon Formation.
The numbers
Length 5.5 m (estimates run from 5 to 6 m). Mass about 2.1 t. Hip height about 1.5 m. That is 3.2 human-lengths, or 0.49 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.