Newly uncovered dinosaur had 'longest horns of all'

The 72-million-year-old herbivore has two large horns above its eyes measuring up to 1.22 metres long. (The University of Utah: Lukas Panzarin)

US palaeontologists say they have unearthed a new species of dinosaurs standing some 1.8 metres tall and weighing up to 4.5 tonnes, with the longest horns of all.

The 72-million-year-old herbivore, now named coahuilaceratops magnacuerna, has two large horns above its eyes measuring up to 1.22 metres long - the largest of any other species, providing fresh insight into the history of western North America.

Scientists uncovered fossils belonging to both an adult and a juvenile of the rhino-sized tubby creature at the Cerro del Pueblo Formation in Coahuila, Mexico.

It measured about 6.7 metres long as an adult.

"We know very little about the dinosaurs of Mexico, and this find increases immeasurably our knowledge of the dinosaurs living in Mexico during the Late Cretaceous," said the study's lead author Mark Loewen, a palaeontologist with the Utah Museum of Natural History.

His team is to release a book next week detailing the find, which took place during expeditions in 2002 and 2003 in the Coahuila desert. The study was funded by the National Geographic Society and the University of Utah.

When dinosaurs lived in this corner of Mexico, it was a lush, humid estuary where ocean water mixed with fresh water from rivers, similar to the US Gulf Coast today.

Many dinosaur bones unearthed in the area are covered with fossilised snails and marine clams, indicating that the creatures lived close to the seashore.

The rocks in which the palaeontologists found coahuilaceratops contained large fossil deposits of jumbled duck-bill dinosaur skeletons.

According to the scientists, the dinosaurs likely died en masse in the area due to storms similar to present-day hurricanes.

During most of the Late Cretaceous Period, 97 to 65 million years ago, high global sea levels led to flooding of the central, low-lying portion of North America.

Ultimately, a warm, shallow sea emerged, stretching from the Gulf of Mexico to the Arctic Ocean and splitting the continent into eastern and western landmasses.

"We are confident that Mexican dinosaurs will be a critical element in unravelling the ancient mystery of this island continent," said Scott Sampson of the Utah Museum of Natural History.

- AFP

Paleothermometer to take dinosaurs' temperatures

New technology should shed light on whether dinosaurs were cold-blooded or warm-blooded (www.flickr.com: Diegosaurius Rex)

New technology developed by US researchers should shed light on whether dinosaurs were cold-blooded or warm-blooded animals.

California Institute of Technology (Caltech) researchers have unveiled what they say is the first method for direct measurement of the body temperatures of large extinct vertebrates using analyses of isotopes in animals' bones, teeth, and eggshells.

The findings were published in the early edition of the Proceedings of the National Academy of Sciences (PNAS).

"This is not quite like going back in time and sticking a thermometer up a creature's back end. But it's close," said researcher John Eiler, a geochemistry professor at Caltech.

To study changes in temperature regulation in extinct animals requires knowing what their body temperatures once were. The team's method looks at the concentrations of two rare isotopes - carbon-13 and oxygen-18.

"Heavy isotopes like to bond, or clump together, and this clumping effect is dependent on temperature," said lead author Robert Eagle, a Caltech postdoctoral scholar.

"At very hot temperatures, you get a more random distribution of these isotopes, less clumping. At low temperatures, you find more clumping."

After proving their method on living elephants and sharks, the team turned to the extinct.

They examined a 12-million-year-old fossil from a relative of the rhinoceros, as well as from a cold-blooded member of the alligator family tree.

"We found we could measure the expected body temperature of the rhino-like mammal, and could see a temperature difference between that and the alligator relative, of about six degrees centigrade," Dr Eagle explained.

"When we look at tooth enamel, for instance, what we get is a record of the head temperature of the animal when the tooth grew," Professor Eiler said.

But "if you want to know what his big-toe temperature was two years later, too bad."

With an accurate paleothermometer working, the researchers want to look further back at body temperatures of less-known vertebrates.

"Before mammals and birds, we have no good idea what physiology these ancient creatures had," Dr Eagle said.

Now it is the dinosaurs' turn to get a closer temperature look.

"We're looking at eggshells and teeth to see whether the most conspicuous dinosaur species were warm- or cold-blooded," Professor Eiler said.

-AFP