“I can’t express in words just how exciting and what a privilege this is to announce to the world a brand new dinosaur – one that’s a transitional, that tells us in some ways how we moved from smaller biped animals to bigger, heavier quadruped animals,” said Dr Matthew Bonnan, associate professor of biology at Western Illinois University, who has been working with South African colleagues at two Early Jurassic (about 195 million years ago) quarry sites in the Free State.

Bonnan’s co-researchers include palaeontologist Dr Adam Yates of the Bernard Price Institute for Palaeontological Research at the University of the Witwatersrand (primary investigator); Dr Johann Neveling (geologist) of the Council for Geoscience in Pretoria; Marc Blackbeard, a master’s degree student at the University of the Witwatersrand (who discovered the first bones of Aardonyx and helped excavate and map the site); and Dr Anusuya Chinsamy (palaeontologist) of the University of Cape Town, who specialises in histology – examining thin sections of bone in living and fossil vertebrates for clues to their growth.

Their discovery has been accepted for publication in the Proceedings of the Royal Society B, a significant journal of biological research and reviews. An analysis of the bone microstructure of the 7 m-long herbivore indicates that it was young and still growing. Its skeletal anatomy shares a number of key features with sauropods, and its limb proportions show that Aardonyx was a biped, although its interlocking forearm bones suggest that it could occasionally walk on all fours.

The skull and jaws show signs that this dinosaur had a wide gape and could bulk-browse, taking in huge mouthfuls of vegetation in each bite, an adaptation amplified later in sauropod dinosaurs. Despite its relatively small size, sauropod-like vertebral joints had developed to brace its back bone, and the thigh bone (femur) was straightened for weight-support, Bonnan said.

Source: Western Illinois University