An extinct species of large wild cattle that inhabited Asia, Europe, and North Africa. It is the ancestor of domestic cattle. The species survived in Europe until 1627, when the last recorded aurochs died in the Jaktorów Forest, Poland.
Like most small dinosaurs, Hypsilophodon was bipedal: it ran on two legs. Its entire body was built for running. A light-weight, minimized skeleton, low, aerodynamic posture, long legs and stiff tail, immobilised by ossified tendons, for balance: all would have allowed it to travel remarkably fast for its size.
It is thought that without a club on its tail, Nodosaurus would have been left without much in terms of active defenses. When threatened, it probably dropped to the ground so that only its armored back and sides were exposed, much like modern-day hedgehogs.
Its most unusual feature was the skull, which is both large and strongly built, but simultaneously flat and concave: this feature is rare and, apart from some brontotheres, not regularly characteristic of any other known mammal.
It was an early relative of Lambeosaurus, and shows a number of iguanodont-like features, including three stacked teeth for each visible tooth, small maxillary teeth, and an unusually powerful build for a hadrosaur.
Macrauchenia had a somewhat camel-like body, with sturdy legs, a long neck and a relatively small head. Its feet, however, more closely resembled those of a modern rhinoceros, with one central toe and two side toes on each foot.
There were more than sixty spoon shaped teeth in the jaws of Yunnanosaurus, and were unique among prosauropods in that its teeth were self-sharpening because they “[wore] against each other as the animal fed.”
Some paleontologists have postulated that this dinosaur may have actually had a sail that grew out of its back. If it did, then it would have been used to make the dinosaur look better, for regulation of body temperature or maybe even used for mating rituals.
Elasmotherium is thought to have had a keratinous horn, indicated by a circular dome on the forehead. There was likely a large hump of muscle on the back, which is generally thought to have supported a heavy horn.