Dinosaurs existed during the Mesozoic Era, first appearing around 230 million years ago and dying out about 65 million years ago. However, scientists largely agree that birds are the direct descendants of dinosaurs. If s... More »

As of 2014, most palaeontologists believe that the Argentinosaurus was the largest dinosaur to have ever lived. It may have been the largest land animal to have ever existed. More »

www.reference.com Pets & Animals Dinosaurs

One of the smartest dinosaurs was the Troodon, which was 6.5 feet long but had a brain-to-body ratio similar to that of a modern bird or mammal. The dumbest dinosaur was the stegosaurus, its brain was the size of a walnu... More »

www.reference.com Pets & Animals Dinosaurs

The purported mass dinosaur die off known as the K-Pg extinction event took place during the end of the Cretaceous Period (K) during the Mesozoic Era some 65 million years ago. This scientific theory is based on the stud... More »

Dinosaurs come from the evolution of early primitive organisms approximately 230 million years ago and it is unknown why these organisms evolved into dinosaurs. Scientists have been able to trace dinosaurs back 228 milli... More »

The ankylosaurus became extinct with the other great dinosaurs during the Cretaceous-Paleogene extinction event that occurred about 66 million years ago. While some questions remain about what caused this extinction, geo... More »

The earliest conclusive evidence of the evolution of dinosaurs dates their origins to 230 million years ago. They are believed to have evolved from other reptilian species and developed certain defining characteristics, ... More »