Dinosaur Lost World Found in Texas City
for National Geographic News
|March 18, 2009|
Just down the road from the local Starbucks, a rich trove of 95-million-year-old dinosaurs, sharks, and other prehistoric beasts—and their feces—have been unearthed in Arlington, one of Texas's biggest cities (map), researchers said this week.
Together the fossils help flesh out the very different Texas of the Cretaceous period, which lasted from 146 to 66 million years ago (prehistoric time line).
The discoveries include a new, unnamed, mid-size species of theropod, part of the two-legged, predatory dinosaur group that included Tyrannosaurus rex. The site also contains the most complete skeleton to date of a Protohadros, one of the earliest known duck-billed dinosaurs.
Crocodiles, turtles, fish, and parts of ancient plants and trees—including a 6-foot (183-centimeter) log—were also found.
The Arlington Archosaur Site (Archosaur means "ruling reptiles") was first discovered in 2003, but excavations began only in spring 2008. Paleontologists detailed their find on Tuesday at a meeting of the Geological Society of America's South-Central Section in Dallas.
Texas: 95 Million B.C.
Today the fossil site "is about as urban as you can get," said paleontologist Derek Main of the University of Texas in Arlington. "It's surrounded by several highways, and there's a Starbucks down the street. You can get coffee if you want."
But the remains hark back to a time when much of Texas was underwater, covered by an enormous inland sea that bisected North America and joined the Gulf of Mexico and the Arctic Ocean.
At the time, Arlington would have been on a low-lying coastal plain. Here, swampy bogs transitioned gradually into shallow seas—a place not unlike the Mississippi River Delta today (map).
In addition to bones, the Texas dinosaur site is host to one of North America's most varied assortments of coprolites, or petrified feces.
(See "Dino Dung: Paleontology's Next Frontier?")
"Almost any animal we found the fossil for, we also found their poo," Main said.
Inside the coprolites, the team has found everything from bits of chewed bone, plants, shells, and even bits of coral," Main said—clues to the prehistoric animals' behaviors and diets.
Paleontologists are eagerly awaiting further details from the unusual site.
"Early Cretaceous dinosaur fossils are rare in general," according to Aaron Pan, science curator at the Fort Worth Museum of Science and History, who was not involved in the excavations.
The preponderance of fossils at the Arlington site is due to the area's formerly boggy condition, which is particularly good at preserving remains.
Another rarity in Arlington is the presence of both land and sea animals, due to the city's past life as a stretch of coastal plain. Most Texas fossil sites from the early Cretaceous are limited to marine creatures, since most of the state was underwater.
"It's very unusual to get a mixture of so many different animals together," Pan said.
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