Meet the dog-sized dinosaur that could be the oldest ever found

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Jan 14, 2013, 2:52 PM EST

Though we know much, much more about dinosaurs now than we did even a few decades ago, scientists still haven't pinned down exactly when the creatures first emerged on our planet. Now, thanks to new analysis of an old find, archaeologists have evidence of a dinosaur at least 10 million years older than any other species. Is this the first dinosaur?

Known as Nyasasaurus parringtoni, the dinosaur likely weighed between 45 and 135 pounds and was about as tall as a Labrador (3 feet or so, from the hip, anyway), but was 7 to 10 feet long thanks to a long neck and a long tail.

Using fossilized bones found in Tanzania in the 1930s believed to be from a Nyasasaurus, researchers dated the creature to between 240 and 245 million years ago, which would place it in the Middle Triassic period (245 to 228 million years ago), making it an estimated 10 to 15 million years older than any other dinosaur species we know about.

"If the newly named Nyasasaurus parringtoni is not the earliest dinosaur, then it is the closest relative found so far," said Sterling Nesbitt, a postdoctoral biology researcher at the University of Washington who was the lead researcher on the project.

Using only one upper arm bone and six vertebrae from Nyasasaurus, the researchers dated the animal back to the Middle Triassic through analyzing the soil layer it was found in and comparing that with similar layers throughout the world. Though they didn't have many bones to work with, the researchers pointed out that the bone tissue growth in the fossils they did have strongly suggests that they had the right creature.

"We can tell from the bone tissues that Nyasasaurus had a lot of bone cells and blood vessels," said Sarah Werning of the University of California, Berkeley, who did the bone analysis. "In living animals, we only see this many bone cells and blood vessels in animals that grow quickly, like some mammals or birds."

Archaeologists have theorized for more than a century that dinosaurs lived in the Middle Triassic period, but until now there was no real evidence of it. According to Nesbitt, Nyasasaurus is the best proof yet that those theories were right.

"Previous to this find, all the oldest dinosaurs were all equally old from the same place in Argentina, and those sediments are about 230 million years [old]. So this pushes the dinosaur lineage or the closest relative to dinosaurs all the way back to the Middle Triassic," Nesbitt said. "This is our best evidence of a Middle Triassic dinosaur."

The find also changes perceptions of how dinosaurs emerged. Though we often think of dinosaurs as creatures that burst on the scene, ruled the Earth for a while and then blinked out, finds like Nyasasaurus suggest the emergence of these beasts was more gradual.

"They were a unique group, but they didn't evolve and take over terrestrial ecosystems immediately," Nesbitt said. "Most of what we see in museums are from the Jurassic and Cretaceous when they did dominate -- at their origins they were just a part of the radiation of Archosaurs."

So, if Nesbitt and his team are right, dinosaurs are older than we thought. Now we wait and see what other Middle Triassic dinos we might find out there.

(Via Huffington Post)