Monday, July 9, 2007

Two Dinosaurs From Africa Give Clues To Continents' Split

Two Dinosaurs From Africa Give Clues To Continents' Split
Science Daily — The fossil skull of a wrinkle-faced, meat-eating dinosaur whose cousins lived as far away as South America and India has emerged from the African Sahara, discovered by a team led by University of Chicago paleontologist Paul Sereno. The find provides fresh information about how and when the ancient southern continents of Africa, South America and India separated.

"First wrinkle face," a new dinosaur species discovered in Niger by National Geographic Explorer-in-Residence Paul Sereno, would have looked something like this in life. The dinosaur's head was riddled with arteries and veins, leaving a web of grooves on the snout. Two rows of holes on the top of the snout may have supplied ornamental crests. (Credit: © 2004 Todd Marshall) The new species, which is 95 million years old, and a second new meat-eating species Sereno found on a separate expedition, help fill in critical gaps in the evolution of carnivorous dinosaurs on Africa. The species are described in a paper published online June 2 in the Proceedings of the Royal Society of London, Biological Sciences. The July issue of National Geographic magazine also will include an article on one of the dinosaurs. Sereno's research was funded by National Geographic, the David and Lucile Packard Foundation, the Pritzker Foundation and Nathan Myhrvold.

Sereno, a National Geographic Explorer-in-Residence, has named the ancient skull Rugops primus, meaning "first wrinkle face." Measuring about 30 feet long in life, the animal had a short, round snout and small, delicate teeth, he said. It belongs to a group of southern carnivorous dinosaurs called abelisaurids.

The head of Rugops had a tough covering of scales or surface armor and was riddled with arteries and veins, leaving a crisscross of grooves on the skull. "It's not the kind of head designed for fighting or bone-crushing," Sereno said. Instead, he believes Rugops was a scavenger, using its head to pick at carrion rather than fighting other animals for food.

Sereno is puzzled by the presence of two neat rows of seven holes along the dinosaur's snout. He speculates that the holes anchored something ornamental, used by the animal for display. "This may have been a scavenger with head gear," he said. "It's really a beautiful intermediate species of the group that later evolved into the first horned predators."

The authors of the scientific paper describing the two new dinosaur finds are Sereno, Jeffrey Wilson of the University of Michigan and Jack Conrad of the University of Chicago. The second new dinosaur species, named Spinostropheus gautieri, was found in Niger in the same 135-million-year-old rocks where Sereno's expeditions excavated the dinosaurs Jobaria and Afrovenator. The fossil is an articulated, or connected, spine of a dinosaur and represents an ancient relative of Rugops and other abelisaurids.

These finds provide fresh evidence about when Africa, Madagascar, South America and India finally split from each other as a result of continental drift. Before these discoveries, abelisaurids were virtually unknown on Africa, leading some to suggest that Africa had split off first from the southern landmass Gondwana, perhaps as early as 120 million years ago. The new fossils indicate that Africa and other southern continents that formed Gondwana separated and drifted apart over a narrow interval of time, about 100 million years ago.

Co-author and team member Jeffrey Wilson, assistant professor at the University of Michigan, said, "Until the continents fully separated, dinosaurs like Rugops and other animals used narrow land bridges to colonize adjacent continents and roam within a few degrees of the South Pole."

The fossils were discovered on two separate expeditions that Sereno led to Niger, one in 1997 and the other in 2000, which have brought to light many new dinosaurs and the 40-foot-long crocodilian Sarcosuchus, also known as "SuperCroc."

Sereno recalls the day in 2000 when team member Hans Larsson, now an assistant professor at McGill University in Montreal, spotted a jawbone and then, about two feet away, the rest of the skull. "It was hard to see which end was the front, but we quickly realized we were looking at a brain case, and that it was probably an abelisaur a huge find," Sereno said.

Both Rugops and Spinostropheus came from the Cretaceous Period, when this area of Africa featured broad rivers and lush plains. Today it is located in the southern Sahara Desert, part of the Republic of Niger. Expeditions to the Sahara led by Sereno in 1993, 1995, 1997 and 2000 unearthed a gallery of new dinosaurs, including the first from Africa's Cretaceous Period; they include Afrovenator, Jobaria, Deltadromeus, Carcharodontosaurus and Suchomimus.

A National Geographic Explorer-in-Residence since 2000, Sereno has received 11 research grants from the Society's Committee for Research and Exploration as well as two grants from the Society's Expeditions Council.

Note: This story has been adapted from a news release issued by University Of Chicago.

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University of Chicago paleontologist Paul Sereno is flanked by reconstructions of the head and skull of Rugops primus, a wrinkle-faced dinosaur. Sereno led an expedition that found the Rugops fossil skull in Niger in 2000.

Dinosaur skull sheds light on Africa’s birth
Continent split off later than thought, scientists say
By Eric Fidler
The Associated Press
Updated: 3:59 p.m. ET May 31, 2004
CHICAGO - The fossil skull of a peculiar, wrinkle-faced dinosaur unearthed four years ago in the Sahara is providing new evidence that Africa split from the other southern continents more recently than previously thought, scientists say.

“It was sort of a missing puzzle piece that serves to banish the notion that Africa was isolated earlier,” said Paul Sereno, a University of Chicago paleontologist who led the dinosaur-hunting expedition to a remote, desert region of Niger in 2000.

“It really completes the story very convincingly,” he said.

‘First wrinkle face’
The skull, found amid a wealth of dinosaur bones from the late Cretaceous period, came from a dinosaur Sereno named Rugops primus, or “first wrinkle face.” The meat-eater, believed to be about 30 feet (9 meters) long and 95 million years old, belonged to a group of southern dinosaurs called abelisaurids.

Before the discoveries, abelisaurids from that period had been found in South America, Madagascar and India, but none had been confirmed on Africa, supporting a theory that Africa split off first from the southern super-continent of Gondwana 120 million or more years ago.

The new fossil, however, and its close relation to a South American abelisaurid, indicate Africa was still connected to the other southern land masses, at least by a land bridge, 100 million years ago, Sereno and his co-authors said.

‘Valley of the Kings’
Sereno and his team were nearing the end of a 2½-month expedition when they focused on a football-sized area in a remote region of the Sahara. In a span of 10 days, he said, they dug up more dinosaurs of the early part of the Late Cretaceous period than the total of what had been found in Africa before.

“It was like the Valley of the Kings, except the kings were dinosaurs,” Sereno said. He said the team also found previously unknown species of crocodiles and a yet-to-be-named dinosaur that was about 60 feet (18 meters) long.

“Sometimes you run into the pot of gold,” he said. “That expedition I think was per pound of discovery the greatest expedition I ever took students on.”

Sereno, University of Chicago colleague Jack Conrad and Jeffrey Wilson of the University of Michigan published news of the finding, along with the discovery of another new species of dinosaur, in the edition of Proceedings of the Royal Society of London to be released Wednesday.

Sereno said Rugops probably was a scavenger that used its long snout to pick at carrion. One odd feature of the dinosaur, he said, was two rows of seven holes along its snout.

“It’s the most peculiar thing. We don’t know what was growing out of there,” Sereno said.

He said it was probably something ornamental, perhaps a fleshy crest.

© 2007 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.


Anonymous said...

wow very interesting, I have never understand those research, for example how can they know, how was the earth a thousand years ago, and the kind of life that dinosaurs had on that time ?

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Thanks for sharing.

Anonymous said...

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