The earliest known fossils associated with dinosaurs have been identified in 250-million-year-old rocks from Poland.
The fossils -- footprints made by dinosaur relatives known as dinosauromorphs -- suggest that dinosaurs evolved from small, four-legged animals that lived during the Early Triassic just a few million years after the "Great Dying," Earth's most severe extinction event to date.
"For some reason, the major dinosaur lineages survived this extinction -- we don't know exactly why, and it may have been little more than random fortune -- and they probably then had the freedom to flower in a post-apocalyptic world," lead author Stephen Brusatte told Discovery News.
"(Dinosauromorphs) are the very closest relatives to dinosaurs, animals that were right on the cusp of becoming dinosaurs, shared many features with dinosaurs, probably looked and behaved like dinosaurs, but are not bona fide dinosaurs by definition," Brusatte, a paleontologist at the American Museum of Natural History, explained.
The finding was published in the Proceedings of the Royal Society B
Brusatte and colleagues Grzegorz Niedzwiedzki and Richard Butler analyzed multiple fossilized animal tracks dating from the Early and Middle Triassic at the Holy Cross Mountains in southern Poland, an exciting new frontier for early dinosaur research.
The oldest tracks from this site are only about a half an inch in length, so the scientists conclude they belonged to an animal that was approximately the same size as a modern housecat, weighing at most around four pounds. Its hind legs were also longer than its forelimbs, since the footprints overstep the handprints.
Read more at Discovery News
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