Oldest-Ever Footprints Scrambles Dinosaur Origin Theory

Walking through mud in what is now Poland, a dinosaur thought to be about the size of a domestic cat left behind footprints that paleontologists believe constitute the oldest footprints on Earth.

The footprints, preserved in fossilized form, date back 250 million years. If the findings hold up, that would mean dinosaurs existed about 9 million years earlier than previously believed.

The researchers who made the discovery in the Holy Cross Mountains of central Poland - Grzegorz Nied?wiedzki, Stephen Brusatte, and Richard Butler - detailed their findings online Oct. 6 in the Proceedings of the Royal Society B.

"The oldest dinosaurs and their immediate relatives were small and rare," said Brusatte.

The dinosaur in question was a relative pipsqueak who walked on all fours. What's especially intriguing is the time line in which it apparently lived. The footprints left behind approximate a period in the Earth's history in which most life had been wiped out during the so-called Permian-Triassic extinction event. it was generally believed that dinosaurs made their appearance on the world's stage some 15 million years after that tumultuous event. But the footprints date to only a couple of million years after that mass extinction.

"The biggest crisis in the history of life also created one of the greatest opportunities in the history of life by emptying the landscape and making it possible for dinosaurs to evolve," said Brusatte.