The partial skeleton of a massive sauropod dinosaur, unearthed at an Egyptian site that its discoverers call "dinosaur heaven," makes its debut in the 1 June issue of the international journal Science. Dubbed Paralititan stromeri, the dinosaur is one of the largest ever discovered from the Cretaceous period (about 146 to 65 million years ago) in Africa, and may be the second most massive dinosaur ever found.
The discovery of Paralititan, whose name means "tidal giant," also marks the revival of Egypt's Bahariya Oasis as a paleontological treasure trove. In the early 20th century, teams led by German geologist Ernst Stromer uncovered a wealth of Late Cretaceous fossils at the site, including four dinosaur species, but the fossils were destroyed during an Allied attack on Munich in World War II. Paralititan is the first dinosaur discovery reported from the site since 1935.
The Science authors, led by Joshua B. Smith of the University of Pennsylvania, hope that Paralititan and other discoveries at Bahariya will help answer some questions about a relatively mysterious time and place in vertebrate history. Scientists have found groups of vertebrates that were common to South America and Madagascar during the Late Cretaceous, but these same groups appear to be missing from Africa. Some paleontologists think this pattern exists because the South American and Malagasy land masses were somehow connected at the time, to the exclusion of Africa.
The Science researchers suggest, however, that this puzzling absence may be simply a matter of fewer researchers working at African sites, making fewer discoveries to fill in the gap.
"The fact that there isn't a lot of information about Late Cretaceous vertebrates in Africa might be a function of the lack of people looking for them," says Smith.
An analysis of Paralititan 's skeletal features convinced the researchers that the fossil was a new species of titanosaurid, a group of long-necked, long-tailed, plant-eating dinosaurs that includes some of the largest land animals ever. Paralititan certainly holds its own in the weight category. Its humerus, or upper arm bone, measures 1.69 meters in length, and is about 14 percent longer than the next largest Cretaceous sauropod humerus. Estimates of Paralititan 's' overall body size suggest that it may have been one of the heaviest terrestrial vertebrates yet discovered, with the largest specimens stretching 90 to 100 feet in length and weighing 75-80 tons.
Smith and colleagues discovered the partial skeleton preserved in fine-grained sediments full of plant remains and root casts. The overall geology of the site suggests that Bahariya may have once resembled the tropical mangrove coasts of Florida, a low-energy, shallow water area of tidal flats and tidal channels, say the authors.
Paralititan 's skeleton appears to lie where it first fell, since the parts of the skeleton are associated, and the bones of carcass couldn't have been carried by the low velocity currents or floated to their final resting place in the shallow waters. But that doesn't mean that this final rest was undisturbed. Smith and colleagues also uncovered evidence that the skeleton was scavenged by another dinosaur.
"The skeleton was spread around in sort of an odd way, and the bones weren't separated at the bone sutures. In fact, the pelvis was ripped apart, just torn to bits," says Smith. The researchers also uncovered the probable scavenger's calling card-a tooth, too big to have been transported to the site, possibly from the carnivorous dinosaur Carcharodontosaurus.
Along with Paralititan, the Science researchers uncovered other fossils that they believe may belong to some of Stromer's lost dinosaur species, as well as fossils from fish, crab, coelacanth, and crocodile-like species. Many of these fossils are giants in their own right, causing Smith and colleagues to speculate on the special nature of the Egyptian site.
"It's really weird, because along with Paralititan and other big sauropods, we also have three carnivores in this system that are the size of T. rex. The amount of biomass in this area had to be enormous to support all that," says Smith.
Noting the abundant plant remains at the site, the researchers suggest that the area in the Late Cretaceous may have been one of the most productive systems on earth, much like a modern rainforest.
"We may have stumbled on dinosaur heaven at Bahariya," says Smith.
The research team plans to return to the site at the end of this year, continuing work that they hope will give them a better picture of Paralititan 's place within the entire ecosystem.
The other members of the research team include Matthew C. Lamanna, Peter Dodson, Jennifer R. Smith, and Robert F. Giegengack at the University of Pennsylvania, Philadelphia, Kenneth J. Lacovara at Drexel University, Philadelphia, Jason C. Poole at the Academy of Natural Sciences, Philadelphia, and Yousry Attia at the Egyptian Geological Survey and Mining Authority, Cairo, Egypt. This research was supported in part by Cosmos Studios, MPH Entertainment, the University of Pennsylvania, the Andrew K. Mellon Foundation, E. de Hellebranth, and the Delaware Valley Paleontological Society.
Materials provided by American Association For The Advancement Of Science. Note: Content may be edited for style and length.
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