Although the name Dinosauria means "terrible lizards", the dinosaurs are not lizards at all, but instead are their own separate group of reptiles (the "terrible" part depends on whom you ask). Even so, there were actual big lizards living alongside the dinosaurs during the Cretaceous Period. This is a dorsal (back) vertebra of Palaeosaniwa, a large lizard that lived at the end of the age of dinosaurs, about 67 million years ago. This vertebra, shown here from the front, was collected in the Hell Creek Formation of Montana by the late Harley Garbani and donated to the Western Science Center by his wife, Mary.Palaeosaniwa was a carnivorous lizard related to the living monitor lizards, such as the giant Komodo dragon and the goanna shown below; as such, its prey probably included small dinosaurs from time to time. Of the nearly 30 species of lizards known from North America around 67 million years ago, Palaeosaniwa is the largest, and in fact is also the biggest land-dwelling lizard from the entire Cretaceous Period. The only larger lizards around at this time were the immense mosasaurs, giant marine lizards that could reach up to 40 feet in length. Palaeosaniwa was probably around five feet long and weighed about 13 lbs, still an impressive creature even alongside titans like Tyrannosaurus and Triceratops with which it shared its habitat.
By Andrew McDonald