Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dating sheds new light on dawn of the dinosaurs

25.01.2011
Careful dating of new dinosaur fossils and volcanic ash around them by researchers from UC Davis and UC Berkeley casts doubt on the idea that dinosaurs appeared and opportunistically replaced other animals. Instead -- at least in one South American valley -- they seem to have existed side by side and gone through similar periods of extinction.

Geologists from Argentina and the United States announced earlier this month the discovery of a new dinosaur that roamed what is now South America 230 million years ago, at the beginning of the age of the dinosaurs.

The newly discovered Eodramaeus, or "dawn runner," was a predatory dinosaur that walked (or ran) on two legs and weighed 10 to 15 pounds. The new fossil was described in a paper by Ricardo Martinez of the Universidad Nacional de San Juan, Argentina, and colleagues in the journal Science Jan. 14.

The fossils come from a valley in the foothills of the Andes in northwestern Argentina. More than 200 million years ago, it was a rift valley on the western edge of the supercontinent Pangaea, surrounded by volcanoes. It's one of the few places in the world where a piece of tectonically active continental margin has been preserved, said Isabel Montañez, a UC Davis geology professor and a co-author of the Science paper.

Montañez, with Brian Currie from Miami University, Ohio, and Paul Renne at UC Berkeley's Geochronology Center, have conducted earlier studies of the ancient soils from the valley, dating layers of ash and researching how the climate changed. Those climate studies have been published previously.

According to Montañez, there are two major temporal boundaries in the geology of the era: The Carnian-Norian boundary at 228 million years ago and the Triassic-Jurassic transition at about 210 million years ago. Geologists have long thought that dinosaurs jumped in number and variety at both points, opportunistically replacing other reptiles.

But the carefully aged fossils from South America show no such increase at the Carnian-Norian boundary, Montañez said. Rather, dinosaurs were as diverse and abundant before the transition as later in the Jurassic, although several species of both dinosaurs and other animals went extinct at the boundary.

At that time, the climate in the valley changed from semi-arid, like today's Mojave desert, to more humid. It's not clear whether that was a global phenomenon or local to that area, Montanez said.

"Those dinosaurs were perfectly happy before the Carnian-Norian transition," Montanez said. There's no indication that the dinosaurs appeared and wiped out other animals, which has been the prevailing hypothesis for the origin of dinosaurs based on fossils from North America and elsewhere in the world.

It may be that there are missing pieces from the fossil records elsewhere, Montanez said, noting that, "nowhere else is this well dated."

Other co-authors of the paper are Paul Sereno, University of Chicago; Oscar Alcober, Universidad Nacional de San Juan; and Carina Colombi, Universidad Nacional de San Juan and Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.

Media contact(s):
Isabel Montanez, Geology, (530) 754-7823, ipmontanez@ucdavis.edu
Andy Fell, UC Davis News Service, (530) 752-4533, ahfell@ucdavis.edu

Andy Fell | EurekAlert!
Further information:
http://www.ucdavis.edu

More articles from Earth Sciences:

nachricht Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

nachricht Shallow soils promote savannas in South America
20.10.2017 | Senckenberg Forschungsinstitut und Naturmuseen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>