Illustration by Jeffrey Martz
Published April 13, 2011
A newly discovered dinosaur species bridges the gap between the earliest known group of predators and more advanced beasts such as Tyrannosaurus rex, according to a new study.
Found at New Mexico's Ghost Ranch fossil site, the primitive dinosaur lived about 205 million years ago. (Related pictures: "'Nasty' Little Predator From Dinosaur Dawn Found.")
The dinosaur, which stood as tall as a large dog, boasts a very unusual skull, said study co-author Hans-Dieter Sues, a vertebrate paleontologist at the National Museum of Natural History in Washington, D.C.
"It has a deep, short snout and these monstrous front teeth. That's a kind of skull structure for a predatory dinosaur that's really unexpected for this early point in time," Sues said.
These features helped earn the new dinosaur the name Daemonosaurus chauliodus, or "buck-toothed evil spirit" in Greek.
(Also see "'Weird' Buck-toothed Dino Found in China.")
Earliest Dinosaurs Were Survivors
The oldest known dinosaurs lived in what's now South America during the late Triassic Period, some 230 million years ago. This group included early versions of two-legged predators known as theropods.
But a big gap in the fossil record just after this time led many experts to suggest that these early dinosaurs had simply died out.
"The idea," Sues said, "was that there was this early diversification of dinosaurs ... but then they went extinct, and more advanced predators took over during the late Triassic and diversified later at the Triassic-Jurassic boundary, when we know that dinosaur predators greatly diversified and increased a lot in size."
Now the Daemonosaurus find links the two dinosaur groups.
"Our new dinosaur, along with another one that was found a few years ago ... at the same site, indicates that those basal dinosaurs already included a number of early theropods, and that they survived all the way through the Triassic to nearly the beginning of the Jurassic Period."
Bucktooth Dino Bridges Evolutionary Gap
For now Daemonosaurus is known only by its fossilized skull and neck vertebrae.
But the fossils show that the dinosaur has several features—including cavities in its vertebrae linked to the respiratory system—that bridge the evolutionary gap between the earliest dinosaurs and the neotheropods, the next group of predatory dinosaurs to evolve.
Finding the dino in New Mexico adds another interesting aspect to the discovery, Sues said.
"We had some inkling that the earliest dinosaurs had made it into the Northern Hemisphere when the supercontinent Pangaea was still in existence and animals could walk around on dry land. But the fossil record was limited to South America," he said.
"The new find gives further evidence that the earliest radiation of dinosaurs did have a wider distribution, and it is due to the incompleteness of the fossil record that we'd found them only in Argentina and Brazil."
The new dinosaur is described in the April 13 issue of the journal Proceedings of the Royal Society B.
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