A forgotten rock in the courtyard of an Australian school has been found to feature 66 dinosaur footprints dating back 200 million years.

A treasure in plain sight. Dozens of dinosaur footprints were discovered on the surface of a rock that had been sitting in the yard of a school in Australia for over twenty years, reports BFM TV.

The rock had been extracted from the Callide mine near Biloela. "It's incredible to think that such a rich piece of history has been resting in a schoolyard all this time," said Anthony Romilio.

This is one of the highest concentrations of dinosaur footprints per square meter ever observed in Australia.

47 Different Dinosaurs

"Fossils as significant as this one can go unnoticed for years, even when they are in plain sight," said University of Queensland paleontologist Anthony Romilio.

He identified 66 footprints, made by 47 different dinosaurs, from the early Jurassic period, around 200 million years ago. According to the researcher, these footprints were left by dinosaurs crossing "a patch of white, wet clay, possibly walking along or crossing a watercourse."

These dinosaurs were relatively small, "with legs ranging from 15 to 50 cm long," described Anthony Romilio, adding that "dinosaurs with such feet were plant-eaters with long legs, stocky bodies, short arms, and a small head equipped with a beak."

The results of his research were published in the scientific journal Historical Biology.