Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Prehistoric tusks point to earliest fossil evidence of differences between sexes

24.01.2003


Image: R. Reisz


Findings point to complex social behaviour

The large tusks of an animal that roamed Earth before the dinosaurs may provide the earliest evidence yet of male-female distinctions in land animals that existed millions of years ago, say U of T scientists.

Robert Reisz, a biology professor at the University of Toronto at Mississauga, and his team have found convincing evidence of sexual dimorphism - different physical traits between the sexes of the same species - in their study of fossils from between 252 to 260 million years ago. They believe that the male Diictodon, a herbivorous barrel-shaped creature, had two large tusks extending down from the upper jaw. The tusks, Reisz says, were used as weapons, possibly for ritualistic or physical combat.



"Our findings give very clear evidence of complex social behaviour," Reisz says. "To see this kind of behaviour [physical combat] early in the history of the group that eventually gave rise to mammals is really quite startling."

Reisz’s study, which is featured on the cover of the January issue of the Proceedings of the Royal Society of London B, was based on detailed studies of nearly a hundred skeletons unearthed in South Africa over the last two decades.

Diictodon appeared during the Late Permian Period of the Paleozoic Era, at least 30 million years before dinosaurs existed. It was part of a group of animals described as mammal-like reptiles and was an evolutionary relative of the animals that evolved into mammals. Diictodon, which was covered in scales and measured about one metre in length, was a burrowing herbivore with a beaked skull and short tail.

In its investigation, the team was able to rule out other uses for the tusks, Reisz says. The tusks were not used for feeding because the females did not have them nor were they used for digging because the ends did not show signs of wear. It appears the tusks became longer, wider and thicker as the animals aged and extended well below the jaw line; those lost, possibly in combat, were never replaced, Reisz says. "All these factors are very strong indicators of armament."

Reisz says these findings go beyond the standard skeletal descriptions that accompany research on fossils. "This is a wonderful opportunity to study the biology of animals that lived so long ago. Rather than just simply looking at them and describing them, we can do more with their lifestyle, with their feeding habits, and with their general biology than just looking at their skeletons would suggest."

Along with Reisz, the study involved Corwin Sullivan, now a graduate student at Harvard University, and Dr. Roger M.H. Smith of the South African Museum in Cape Town, South Africa. The research was funded by the Natural Sciences and Engineering Council of Canada and by the American Museum of Natural History.

Nicolle Wahl is a news services officer with the department of public affairs.

CONTACT:

U of T Public Affairs, ph: (416) 978-6974; email: nicolle.wahl@utoronto.ca

Nicolle Wahl | EurekAlert!
Further information:
http://www.newsandevents.utoronto.ca/bin4/030123b.asp

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>