Here is the oldest dinosaur from the dome head: the most complete fossil of a pachicefalosauro

For pachicefalosauri, the “thick head lizards” of the Cretaceous, the armored skull was an indispensable weapon in the clashes with rival males. Now the discovery of the oldest and most complete fossil ever found of this dinosaur from the dome head confirms that the bone vault thickened the boss was a biological feature so important, that it was already present in a very early phase of its evolution.

The remains of the oldest pachicefalosaur ever found emerged in a excavation in the Gobi desert, in Mongolia, and have now been described in an article on Nature.

The new species has been renamed Zavacephale Rinpochefrom two words in Tibetan who mean “root” and “jewel”. The first term has to deal with the ancient origins of the animal, lived between 115 and 108 million years ago, 14 million years before when paleontologists had previously placed the evolution of the dome skull. The second word refers to the value of the animal and the fact that the fossil was set in the rock, like a gem in the frame of a ring.

To raise the value of the fossil even more, studied in detail by the scientists of North Carolina State University, there is the fact that it is the most complete ever found, with an almost intact skull, the bones of the limbs, most of the vertebrae and hips. The authors of the study have even managed to reconstruct the front limbs and the content of the animal stomach, and to trace at his age at the time of death. The result is a new cross -section on the evolutionary history of these dinosaurs and their everyday life.

The analysis of a bone champion of the animal, of which the growth rings were studied as it is done with the trunks of the trees, revealed that the dinosaur was a teenager still in full growth at the time of death: it was about one meter long and weighed less than 6 kg (some adult pachicefalosauri were more than 4 meters long, for 400 kg of weight). Despite the young age of the dinosaur, the bone vault of the skull already appears perfectly formed, as proof of the importance that it was supposed to have in the fighting fights with the other specimens. Moreover, it is covered with dimples, perhaps residual of other bone structures that we do not know.

The fossil made it possible to study another anatomical trait that remained long mysterious, the appearance of the front legs: once reconstructed, they proved unexpectedly minute, almost disproportionate to the rest of the body, not so dissimilar, in size, from those of the T. Rex.

The Zavacephalehowever, he didn’t use them to hunt, because he was a herbivorous.

Speaking of the dinosaur diet, where once there was the animal’s stomach, gastrolytes were found, stones ingested by some animals – even modern, such as hens and crocodiles – to help shredding food and grinding hard plants in the stomach. They were also used by other dinosaurs, such as the stegosaurus, but it is the first time that they are found in a pachicefalosauro.