Bonitasaura (Greek for "La Bonita lizard"); pronounced bo-NEAT-ah-SORE-ah
Woodlands of South America
Late Cretaceous (70-65 million years ago)
Size and Weight:
About 30 feet long and 10 tons
Square jaw with blade-shaped teeth
Generally, paleontologists have a frustrating time locating the skulls of titanosaurs, an offshoot of sauropods that flourished in the late Cretaceous period (this is because of a quirk in sauropod anatomy, whereby the skulls of dead individuals are easily detached from the rest of their skeletons). Bonitasaura is one of the rare titanosaurs to be represented by the fossil of a lower jaw, which shows an unusually square, blunt head and, more strikingly, blade-shaped structures in the back designed to shear off vegetation.
As for the rest of Bonitasaura, this titanosaur appears to have looked like your average four-legged plant eater, with its long neck and tail, thick, pillar-like legs, and bulky trunk. Paleontologists have noted a strong resemblance to Diplodocus, which implies that Bonitasaura rushed to occupy the niche left vacant by Diplodocus (and related sauropods) when that genus went extinct millions of years earlier.