WASHINGTON -- A primitive, long-necked dinosaur that weighed an estimated 20 tons and grew to a length of 70 feet is the newest species to be plucked from the African Sahara by a team led by paleontologist Paul Sereno of the University of Chicago.
To be unveiled at a news conference at the National Geographic Society, a sponsor of the project, the species was discovered in the Republic of Niger and is described in the Nov. 12 issue of the journal Science. Full-size cast skeletons of a 60-foot-long adult, rearing to a height of more than 30 feet, and a juvenile posed in mid stride have been constructed.
Toiling in temperatures exceeding 120, Sereno's team excavated tons of bone and rock on a 1997 expedition and then spent two years cleaning and studying the bones. "With 95 percent of its skeleton preserved, the new species stands as the most complete long-necked dinosaur ever discovered from the Cretaceous period," said Sereno.
The new dinosaur, named Jobaria tiguidensis, lived about 135 million years ago in the Cretaceous, when open forests and broad rivers characterized the region that is desert today. Jobaria refers to "Jobar," a creature in the legends of the local Tuareg nomads that is linked to the exposed bones; tiguidensis refers to a cliff near the excavation sites.
The main graveyard contained bones of several adults and juveniles, suggesting that Jobaria once roamed in herds of mixed age, Sereno said. Although an ancient flash flood quickly buried the animals, some may have died at the hands of the chief meat-eating dinosaur of the time, Afrovenator, a 27-foot-long predator previously discovered in the same area by Sereno's team. Tooth marks are present on the ribs of one of the juvenile skeletons.
Jobaria doesn't fit into any recognized family of long-necked dinosaurs, or sauropods. Rather Jobaria represents an ancient sauropod lineage that survived and flourished only in Africa during the Cretaceous. Unlike other Cretaceous sauropods, Jobaria has spoon-shaped teeth and a relatively short neck composed of only 12 vertebrae. Jobaria's backbone and tail are simple, compared with the complex vertebrae and whiplash tail of the older North American sauropods Diplodocus and Apatosaurus.
"Jobaria is a real survivor, a relic in its own day," said Jeff Wilson, a sauropod expert on Sereno's team from the University of Michigan. An analysis of the dinosaur record in general by Sereno and co-authors of the journal article revealed an uneven pace of skeletal change. "Some dinosaurs change a lot in a short amount of time, whereas others -- like Jobaria -- change very little over millions of years," he said.
Extrapolating from observations it made of elephants, Sereno's team believes that despite its enormous size, Jobaria moved gracefully, with its feet set close to each other under the body. "Its proportions were elephant-like, and its bones could have supported its body mass when rearing during feeding or in courtship contests," said Sereno. Jobaria's flexible neck and spoon-shaped teeth were well adapted for nipping the smaller branches of trees.
Sereno's field and lab work was supported by the National Geographic Society, the David and Lucile Packard Foundation, the Pritzker Foundation and the Women's Board of the University of Chicago. Sereno won additional support by competing in the 1999 Chicago Marathon Celebrity Challenge and from pledges of children and other contributors.
NOTE: The adult and juvenile Jobaria tiguidensis will be on display at the National Geographic Society's Explorers Hall museum, 17th and M Streets N.W., Washington, Nov. 13 through 28.
National Geographic EXPLORER will premiere an exclusive, shot-on-location film about the dinosaur's discovery at 8 p.m. PT/ET Sunday, Nov. 14, only on CNBC. Visit Dinorama in Geographic cyberspace for all the Society's resources on dinosaurs: http://www.nationalgeographic.com/dinorama.More information on Jobaria is available at http://www.jobaria.org.
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