For centuries, nomadic Tuareg tribesmen in camel caravans have crossed the Sahara in Niger, passing rocky terrain with protruding bones of a mysterious giant animal, telling their children the bones belong to a mythical monster named “Jobar.”
In Western cultures, says University of Chicago paleontologist Paul Sereno, the equivalent to Jobar would be the bogeyman, the evil, unseen spirit lurking in the imaginations of children. In 1990, a Tuareg chieftain–amused to find Sereno poking through the Sahara for dinosaur fossils– took him to Jobar’s bone yard.
The bones of the giant Sereno found there are described in Friday’s edition of the research journal Science as a new species of dinosaur that was so perfectly designed for the world it lived in 130 million years ago that it anatomically remained the same for millions of years.
Given the name Jobaria tiguidensis, the monster is a plant-eating sauropod. Other species around it had to heed the laws of natural selection, changing their anatomy through evolution to adapt to changing environments. But Jobaria, able to rear up elephant-like to chew the tops of trees, was so perfectly adapted that it never needed to change and didn’t.
In short, it’s sort of the duckbilled platypus of the Cretaceous Period.
“Like the duckbilled platypus of modern times, some animals remain the same for millions and millions of years,” Sereno said. “Twenty million years ago the platypus looked exactly as it does today. By contrast, if you look at human lineage, we hardly resemble where we were 5 million years ago.”
Sereno for two decades has been rewriting the history of dinosaurs because of spectacular finds he has been making in the southern hemisphere, finding bones in Africa and South America, where few have looked before.
Jobaria represents a new chapter in the history of the biggest of all dinosaurs, the sauropods. With his Jobaria skeleton, amazingly 95 percent complete, Sereno can show how it looked and acted quite differently from other giant sauropods on other continents in its time.
“It’s very rare for a Cretaceous sauropod,” Sereno said. “Its jaws are filled with spoon-shaped teeth that really resemble the sauropods from the Jurassic (190 to 135 million years ago) and earlier periods.”
Fifteen feet tall at the shoulders and 70 feet long, it is a pipsqueak compared to the 60-foot-tall-sauropod–the biggest dinosaur ever found–discovered in southeastern Oklahoma and unveiled last week. But Jobaria, weighing 40,000 pounds, was a graceful giant that could rear up on its hind legs to more than 30 feet high, possibly to eat from tall trees and to show off and mount others in mating rituals.
With just 12 vertebrae in its neck, compared with up to 19 in other, more advanced sauropods like Apatosaurus, Jobaria’s tail also was shorter, heavier and less flexible than most known sauropods.
“Jobaria is a real survivor, a relic in its own day,” said Jeff Wilson, a University of Michigan sauropod expert who accompanied Sereno on his 1997 expedition. They brought back portions of eight Jobarian individuals, both adults and juveniles.
Because fossils of several individuals of varying ages were found at the site, Sereno believes Jobaria may have moved around in herds. Their primary predator may have been Afrovenator, a 27-foot-long meat eater Sereno’s team discovered previously in the same area.
“We have a juvenile (Jobaria) that has unhealed teeth marks across the ribs from teeth very much like Afrovenator’s,” Sereno said. “Either it died in an attack or was scavenged shortly after death.”
Primitive as it was for its time, Jobaria was easily the most dominant large plant-eating dinosaur of its era, he said. His team found no evidence of any other plant eaters at the desert site. The area 130 million years ago, when Jobaria lived, was a flat and wet forested area crisscrossed by broad rivers.
The Chicago expedition recovered the Jobaria fossils along a layer-cake-like cliff known as the Falaise de Tiguidi, running hundreds of miles across central Niger, with a hard, stony top layer covering a layer of soft soil.
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A barren, largely unpopulated region usually visited only by Tuareg nomads, the area had been little explored for dinosaurs before. In 1990, wanting to scout the Sahara as possible dinosaur hunting grounds, Sereno tagged along with British paleontologists who were searching central Niger for fossil fish bones.
“A Tuareg chieftain saw us poking around looking for bones out there,” Sereno said, recalling the 1990 expedition, “and told our interpreter that he knew where a lot of big `camel’ bones were laying around.”
Jumping into Land Rovers, the expedition team bumped for miles down dry riverbeds as they followed the Tuareg’s directions.
“Finally, we came to a place where you could see a huge backbone breaching the surface of a layer of very fine-grained green rock, an old flood plain, which is where dinosaur fossils usually are found,” Sereno said.
“It was one of those moments when you are left breathless.”
The group remained long enough to recover a 6-foot femur bone that was sticking out of the ground, part of what later would prove to be an adult Jobaria.
Once back in Chicago, Sereno worked for three years to bring together his own expedition to get back to the area, returning in 1995. Because of political unrest in the region, that expedition worked under extreme time constraints, but managed to bring out six tons of bones, most notably those of Afrovenator.
Knowing he had left behind an unexamined mother lode of sauropod dinosaur fossils, Sereno and his team returned in 1997, this time coming out with 30 tons of fossils, most of them Jobaria bones.
From the mass of bones, he and his team have been able to mount a 60-foot adult skeleton that is the most complete fossil of a sauropod of any kind ever assembled.
Sereno displayed that skeleton and one of a juvenile Jobaria at a news conference Thursday at the Washington headquarters of National Geographic, one of the sponsors of the expedition. He was accompanied by nine Chicago public school students who are Junior Paleontologists, an outreach program of Project Exploration, a non-profit science education organization operated by Sereno and his wife, Gabrielle Lyon.
On Jan. 14, the skeletons–along with an Afrovenator skeleton– will go on display at a free exhibition in the Crystal Gardens at Navy Pier.
Sereno has done important dinosaur research in North America and China, but his most significant discoveries have come from little-explored areas of Africa and South America.
“Ninety percent of what we know about dinosaurs comes from the northern hemisphere, mostly from fossil beds in North America and the Gobi Desert,” he said, “because those are the areas most thoroughly searched.
“So primarily paleontologists have only been telling the story of dinosaurs on the northern hemisphere. It’s clear that we have yet to discover what is going on on all the continents.”
He said that as early as next year he hopes to find more about African dinosaurs. From another Niger fossil bed on one of his earlier expeditions he already has recovered the skull of a very strange-looking sauropod with a duck-shaped bill for a mouth, a creature he has named Nigersaurus.
“It’s one of the most curious skulls I’ve ever found,” Sereno said. “We’re going to go back and get the rest of it in the fall of 2000, and we’ll unveil it after that expedition.”