250mn-year-old footprints discovered push back dino evolution by 9mn yrs

WASHINGTON - Scientists have discovered 250-million-year-old footprints in rocks from Poland that suggest dinosaurs evolved up to nine million years earlier than previously thought.

The fossils of 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,” Discovery News quoted Stephen Brusatte as saying.

“(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 added.

The tracks are only about a half an inch in length, indicating a size similar to that of a house cat weighing at most around four pounds. Its hind legs were also longer than its forelimbs, since the footprints overstep the handprints.

Three primary attributes of the dinosauromorph tracks allowed the research team to connect the fossils to this group of animals.

First, he said the three central digits of the track-maker are dominant and the outer ‘toes’ are reduced - a feature unique to dinosaurs. Second, the digits are essentially parallel, and this reflects the unique condition of dinosaurs and close relatives in which the foot is a tightly bunched structure. And third is the unique ankle development of the dinosaurs.

“(It’s) a simple hinge and not a more complex rotary joint like the ankles of crocodile-line archosaurs, lizards and even humans,” he said.

“The Earth had been devastated by massive climactic changes at the end of the Permian, and pulses of flash warming continued through the Early Triassic, some five million years, continually destabilizing the environment and delaying full recovery of ecosystems,” Michael Benton, professor of vertebrate palaeontology at the University of Bristol said.

The study is published in Proceedings of the Royal Society B paper. (ANI)