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Acrocanthosaurus
atokensis image used by permission of NC State Museum of Natural
Sciences
Not only is the "Terror of the South" is coming home to North Carolina, but a new "terror lizard" has just been discovered within a few miles of the Research Triangle. On August 16, 1999, UNC paleontologist Joseph Carter held a news conference to introduce the bones of a rauisuchian--a one-ton, ten-foot-long creature, a forerunner of the true dinosaurs, who lived in our area some 221 million years ago.
The rauisuchian (raw-ih-SOO-kee-un) was found in a Triangle Brick Company quarry. The company has several quarries in the long basin that stretches from Durham through Sanford and beyond. Scientists want to keep the exact location secret to protect it from fossil collectors who might rip fossils out of the ground before they can be identified and studied.
The Durham-Sanford Basin is one of a series of similar basins stretching through the Piedmont of states from New Jersey to South Carolina. These "Triassic basins" are ancient cracks in the earth that formed as Africa began to separate from America, forming the Atlatic Ocean. Stream sediments washed down into the basins, sometimes covering the remains of animals and plants. Today these sediments appear as deep beds of sandstone and siltstone. These beds weather to form dense clay deposits mined for brick.
Remains of small dinosaurs and other early reptiles have been found in these Triassic areas before, but never anything the size of this animal. Rauisuchians were the top predators of their days, like antique versions of the much-later tyrannosaurs. They walked on all fours, like giant lizards.
The new animal hasn't been named yet. Its bones will eventually be displayed at the North Carolina State Museum of Natural Sciences.
Which reminds us.....
On December 1, 1998, the Museum of Natural Sciences announced plans for a spectacular display of a flesh-eating dinosaur that roamed our state more than 100 million years ago. The dinosaur fossil will occupy the tall, domed tower of the new museum, scheduled to open in downtown Raleigh in April 2000.
These plans were released a little less than a year after the Museum revealed that it has purchased the best of the world's four known skeletons of Acrocanthosaurus atokensis, aka "Terror of the South," which roamed what is now the southeastern United States 45 million years before the time of Tyrannosaurus rex.
Before we all learn how to spell "Acrocanthosaurus", let's raise a few questions. What sort of animal was this? Was it really as big and fearsome as T. rex? When and how did it live? Are its bones found in North Carolina? What other dinosaurs lived in our state? All these questions and more are likely to arise when school classes begin touring the Museum's new building.
Like T. rex, Acrocanthosaurus was a meat-eating dinosaur that preyed mostly on plant-eating dinosaurs even bigger than itself. "Acro," as scientists tend to call Acrocanthosaurus for short, lived 112 million years ago, in the early part of the Cretaceous period; T. rex lived near the end of the Cretaceous, 45 million years later. Acro was not quite as big as T. rex; an adult acrocanthosaur stood about 4 meters (13 feet) tall, just a little less than T. rex. Acro was also somewhat lighter in build than T. rex, and its head, although certainly fearsome enough, was not as large as T. rex's.
Acrocanthosaurs lived on the coastal plain of the southeastern United States, ranging from Texas to Maryland, at least. Therefore it must have lived in North Carolina, although no fossils of acrocanthosaurs are known from our state. The land was higher then, because North America had only recently separated from Africa and the Atlantic was much narrower. As a result, many of the places we might expect to find acrocanthosaur bones in North Carolina now lie underwater along or near our coast. The fossil the Museum purchased was found in Oklahoma.
In Texas, paleontologists have found fossilized tracks which appear to record an attack by an acrocanthosaur on a larger, plant-eating dinosaur. (There's an article on this dinosaur trackway in the December 1997 issue of Scientific American, but the article is not available online.) The acrocanthosaur approached from the rear and matched strides with its prey, much as modern predators such as lions do today. It then lunged at the other dinosaur, probably attempting to rip open a wound using its razor-sharp teeth. Acro appears to have hunted with a strategy different from that of T. rex. Acro's teeth are designed for ripping flesh from bone; it could wound its prey repeatedly and then wait for the prey to bleed to death. T. rex had heavier teeth; it could kill more directly, crushing the prey's bones in its more powerful jaws.
Although acrocanthosaurs haven't been found in North Carolina, scientists have found fossils of other Cretaceous dinosaurs in the Tar Heel state. A site in Bladen County produced bones of three dinosaurs, all smaller than Acro: the duck-billed plant-eater Hypsibema, the ostrich-like coelurosaur Ornithomimus, and the medium size predator Dryptosaurus. These fossils were all found in what geologists call the Black Creek Formation, which is 25 to 30 million years younger than Acro. (For an account of these dinosaurs, look for Fred Beyer's book, "North Carolina: The Years Before Man," published by Carolina Academic Press.)
Internet Sources
Posted January 2, 1998. Revised, with new links, December 1, 1998. Features remain online as long as they remain current; they may be updated if new information becomes available.
Copyright © 1998, Center for Mathematics and Science Education. Teachers have permission to duplicate this page for use in teaching their own classes. All other rights reserved. You are welcome to link to this page, but do not copy its contents.
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