North America's oldest frog has been discovered preserved in rocks in Arizona.

Bizarre on Female First

Bizarre on Female First

Minuscule remains of the unnamed species - which lived around 216 million years ago and shared the landscape with dinosaurs - could provide evidence of the tiny creatures moving beneath larger animals' feet.

As revealed in Biology Letters, scientists found tiny shards of hip bone - smaller than a fingernail - in fragments of rock from Arizona, alongside remains of huge, crocodile-like phytosaurs, and other early dinosaur species.

While the specimen found by palaeontologist Dr. Michelle Stocker has similarities to modern day frogs, it's not thought to be a direct ancestor of the amphibians we see around the world today.