Big meat-eating dinosaurs like the infamous Tyrannosaurus rex sprang from a much smaller carnivorous dinosaur that ate pretty much anything it could get into its tooth-festooned mouth, had skin covered by a wispy plume of feathers and roamed the planet when Utah was beachfront property and Earth had a single gigantic continent.
Tawa hallae, whose discovery was announced Thursday by University of Utah scientist Randall Irmis, a paleontologist, geologist and curator at the Utah Museum of Natural History who helped unearth the new species, may only have been about as big as a St. Bernard but is a huge step toward understanding what in the world was going on about 213 million years ago when Tawa was busy working its way up the primordial food chain.
Fossil bones of Tawa, named after the Hopi word for the Puebloan sun god, were recovered from a dig site in northern New Mexico known as Hayden Quarry. The quarry is located on Ghost Ranch, where the late painter Georgia O'Keeffe once lived.
Any glimpse into the Triassic Period (248 million to 206 million years ago) is important because science knows a lot more about how dinosaurs went extinct than how they came to be in the first place, particularly carnivores.
Their cataclysmic demise was probably to do to a killer meteor shower about 65 million years ago. Or they were done in by a climate-changing series of volcanoes. One of the most scientifically arcane but most exciting aspects of the study findings, which were published Thursday in the journal Science, is that the Tawa discovery "changes our understanding of the relationships of early dinosaurs and provides fantastic insight into the evolution of the skeleton of the first carnivorous dinosaurs," Irmis said.
The find is a big deal because it offers real evidence — entire skeleton fossils in Tawa's case — of the previously unknown dinosaur, he said.
The specimens are also remarkably well preserved, he said, noting that because dinosaur bones are hollow, they are usually broken and crushed, "but those of Tawa are nearly pristine."
In its day, Tawa wasn't at the top of the food chain, but near it. It isn't the direct ancestor of but is in the same family of Tyrannosaurus rex, which came some 15 million years later and, despite the huge lizard's limited protein-only diet, quickly rose to and stayed on top of the heap.
There were bigger dinosaurs around at Tawa's time, but it was well suited to survival, Irmis said. It adapted to equatorial climates it encountered as it migrated north from what is now South America. At that time, the part of the Earth that is now Utah was balmy all year and was located on the shore of the now Pacific Ocean shoreline.
The dinosaur apparently moved south to north as it traversed the landscape, which at the time was a huge single continent called Pangea. Earth was probably mostly flat with no large mountain ranges or oceans of water in between that would form as Pangea later split into separate continents, Irmis said.
The study represents the clearest glimpse yet of the carnivorous dinosaurs' genealogy, he noted. The discovery also provides more evidence of genetic links between dinosaurs and birds of today.
The brain case and neck of Tawa has the same bone pattern as birds have and was surrounded by air sacs, giving the dinosaur a bone structure that is almost a mirror image of the neck of a modern-day turkey.
Irmis and the team of researchers, led by Sterling Nesbit of the University of Texas, Austin, said they expect many more pieces to be added to the early carnivore puzzle from bones waiting to be found at the Hayden Quarry, where thousands of fossils have been discovered since a group of volunteer bone hunters tripped over the first Tawa fossils in 2004.