PHILADELPHIA -- A curious piece of bone spotted by a University of Pennsylvania professor during a horseback ride in southern Montana led to the discovery of a new dinosaur with a long neck, a whiplike tail and a mysterious extra hole in its skull.
The new find is a sauropod, a classification of plant-eating dinosaurs with long necks and tails, small heads, and four elephantlike legs. At 50 feet long, it's a smaller cousin of better-known sauropods, Diplodocus and Apatosaurus.
The 150-million-year-old creature is described by Penn scientists in the current issue of the paleontology journal, Acta Paleontologica Polonica.
"It has a number of distinguishing features, but the most striking is this second hole in its skull, a feature we have never seen before in a North American dinosaur," said Peter Dodson, senior author of the research study and anatomy professor at Penn's veterinary school.
The Jurassic-age find was first spotted by William Donawick, emeritus professor of surgery at Penn's School of Veterinary Medicine, while on a horseback ride in fall 1998 in far southern Montana, not far from the Wyoming ranch owned by his daughter and son-in-law. He returned to Philadelphia with a piece of bone for his colleague, Dodson, who found it tantalizing enough that an expedition got underway the following summer.
Researchers have named the dinosaur Suuwassea emilieae (SOO-oo-WAH-see-uh eh-MEE-LEE-aye), after a Crow Indian word meaning "ancient thunder," and for late Philadelphia socialite Emilie deHellebrath, who funded the digs that unearthed more than 50 bones, from a 43-inch shoulder blade and a 53-inch rib to the two-holed skull that has scientists stumped.
"The extra hole in the skull is still a mystery," said Jerry Harris, study coauthor and a Penn graduate student researcher. "It has only been seen before in two dinosaurs from Africa and one from South America." While its Diplodocus relatives have a single hole on the top of the skull for the nasal cavity, Suuwassea second hole's purpose is unknown, he said.
The bones were unearthed in 1999 and 2000, but had to be coaxed from their rocky enclosures, cleaned up, and subjected to a lengthy process of measurements, comparative studies, published papers and peer review before passing muster as a new dinosaur, Dodson said.
Suuwassea emilieae's new home is the Academy of Natural Sciences in Philadelphia, where it will be available for teachers, researchers and students to study. It may even be assembled and displayed one day, said academy paleontologist Ted Daeschler.
Suuwassea was found on what once was waterfront property that looked onto a body of water called the Sundance Sea. The location of the find is unusual, researchers said, because most of the dinosaur bones have been found in drier parts of the so-called Morrison Formation farther south.
"It's from a time period and a place that makes it relatively unique," Daeschler said.
Suuwassea emilieae is the first new sauropod in more than a century from the fossil-rich area that paleontologists call the Morrison Formation, which stretches from Montana to New Mexico, Dodson said. Many more are likely to be derived as archeological research continues to intensify in the United States, China and Argentina, he said.
"We're living now in a golden age of dinosaur paleontology," Dodson said. "They're being found at a startling rate all over the world."