Dinosaurs and their precursors lived side by side in the earliest stages of dinosaur evolution.
Max Langer at the University of São Paulo in Brazil and his colleagues explored some of the oldest-known rocks that contain dinosaur fossils, aged between 237 million and 228 million years old. The team unearthed a new species of an early 'lizard-hipped' dinosaur (Buriolestes schultzi; pictured right), which co-existed with a non-dinosaur relative, Ixalerpeton polesinensis (left). The non-dinosaur had skull and bone characteristics that resemble those of later dinosaurs, showing where key parts of dinosaur anatomy came from. The dinosaur's teeth suggested that it ate small animals, unlike later species in its class that fed only on plants.
The findings suggest that dinosaurs did not rapidly replace their predecessors during their early evolution.
Curr. Biol. http://doi.org/bsww (2016)