Long before giant sauropod dinosaurs left their tracks along muddy tidal flats in Texas, the ancestors of Sarahsaurus moved northward from the Southern Hemisphere into what is now North America. These dinosaur dispersals occurred multiple times once the supercontinent Pangaea began to split apart 200 million years ago. Mass extinctions resulted from the effects of volcanic activity associated with the break-up of Pangaea. These extinctions emptied many land-based ecological niches, setting the stage for the evolution of Sarahsaurus and other early dinosaurs.
Sarahsaurus was discovered by Dr. Timothy Rowe and his field team from TMM’s Vertebrate Paleontology Laboratory. The fossilized skeleton was preserved in 190 million year old rocks of the Kayenta Formation in northeastern Arizona and was collected under a permit granted by the Navajo Nation. The scientific name of this new dinosaur, Sarahsaurus aurifontanalis, was given in honor of Mrs. Sarah Butler, Austin philanthropist and supporter of the arts and sciences, and also references Gold Spring (aurum, Latin for gold and fontanalis, Latin for “of the spring”), the locality where the dinosaur was found.
After years of painstaking preparation of the skeleton of Sarahsaurus, Dr. Rowe and colleagues have learned much about this intriguing new dinosaur. Sarahsaurus was 14 feet (4.3 meters) long and estimated to weigh 250 lbs (113 kg). Its long neck supported a small head. Sarahsaurus had large hind limbs with column-like thigh bones, a characteristic that would be an advantageous adaptation inherited by its descendants, the gigantic sauropod dinosaurs. But unlike its massive relatives, Sarahsaurus did not always support its body on all four limbs. Sarahsaurus may have utilized its clawed powerful hands to tear into downed trees or other places to find small animal prey. The elongated leaf-shaped teeth of Sarahsaurus were serrated, which also suggests this dinosaur was an omnivore.