Featured Research

from universities, journals, and other organizations

Some mammals used highly complex teeth to compete with dinosaurs

Date:
March 14, 2012
Source:
University of Washington
Summary:
New research shows that at least one group of small mammals, the multituberculates, actually flourished in the last 20 million years of dinosaurs’ reign and survived their extinction.

An artist's conception depicts a multituberculate in its natural habitat at the time of the dinosaurs.
Credit: Jude Swales/Burke Museum of Natural History and Culture

Conventional wisdom holds that during the Mesozoic Era, mammals were small creatures that held on at life's edges. But at least one mammal group, rodent-like creatures called multituberculates, actually flourished during the last 20 million years of the dinosaurs' reign and survived their extinction 66 million years ago.

New research led by a University of Washington paleontologist suggests that the multituberculates did so well in part because they developed numerous tubercles (bumps, or cusps) on their back teeth that allowed them to feed largely on angiosperms, flowering plants that were just becoming commonplace.

"These mammals were able to radiate in terms of numbers of species, body size and shapes of their teeth, which influenced what they ate," said Gregory P. Wilson, a UW assistant professor of biology. He is the lead author of a paper documenting the research, published March 14 in the online edition of Nature.

Some 170 million years ago, multituberculates were about the size of a mouse. Angiosperms started to appear about 140 million years ago and after that the small mammals' body sizes increased, eventually ranging from mouse-sized to the size of a beaver.

Following the dinosaur extinction, multituberculates continued to flourish until other mammals -- mostly primates, ungulates and rodents -- gained a competitive advantage. That ultimately led to multituberculate extinction about 34 million years ago.

The scientists examined teeth from 41 multituberculate species kept in fossil collections worldwide. They used laser and computed tomography (or CT) scanning to create 3-D images of the teeth in very high resolution, less than than 30 microns (smaller than one-third the diameter of a human hair). Using geographic information system software, they analyzed the tooth shape much as a geographer might in examining a mountain range when charting topography, Wilson said.

The work involved determining which direction various patches of the tooth surfaces were facing. The more patches on a tooth the more complex its structure, and the most complex teeth show many bumps, or cusps.

Carnivores have relatively simple teeth, with perhaps 110 patches per tooth row, because their food is easily broken down, Wilson said. But animals that depend more on vegetation for sustenance have teeth with substantially more patches because much of their food is broken down by the teeth.

In multituberculates, sharper bladelike teeth were situated toward the front of the mouth. But the new analysis shows that in some multituberculates these teeth became less prominent over time and the teeth in the back became very complex, with as many as 348 patches per tooth row, ideal for crushing plant material.

"If you look at the complexity of teeth, it will tell you information about the diet," Wilson said. "Multituberculates seem to be developing more cusps on their back teeth, and the bladelike tooth at the front is becoming less important as they develop these bumps to break down plant material."

The researchers concluded that some angiosperms apparently suffered little effect from the dinosaur extinction event, since the multituberculates that ate those flowering plants continued to prosper. As the plants spread, the population of insect pollinators likely grew too and species feeding on insects also would have benefited, Wilson said.

The paper's coauthors are Alistair Evans of Monash University in Australia, Ian Corfe, Mikael Fortelius and Jukka Jernvall of the University of Helsinki in Finland, and Peter Smits of the UW and Monash University.

The research was funded by the National Science Foundation, the Denver Museum of Nature and Science, the University of Washington, the Australian Research Council, Monash University, Academy of Finland and the European Union's Synthesis of Systematic Resources.


Story Source:

The above story is based on materials provided by University of Washington. The original article was written by Vince Stricherz. Note: Materials may be edited for content and length.


Journal Reference:

  1. Gregory P. Wilson, Alistair R. Evans, Ian J. Corfe, Peter D. Smits, Mikael Fortelius, Jukka Jernvall. Adaptive radiation of multituberculate mammals before the extinction of dinosaurs. Nature, 2012; DOI: 10.1038/nature10880

Cite This Page:

University of Washington. "Some mammals used highly complex teeth to compete with dinosaurs." ScienceDaily. ScienceDaily, 14 March 2012. <www.sciencedaily.com/releases/2012/03/120314142044.htm>.
University of Washington. (2012, March 14). Some mammals used highly complex teeth to compete with dinosaurs. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2012/03/120314142044.htm
University of Washington. "Some mammals used highly complex teeth to compete with dinosaurs." ScienceDaily. www.sciencedaily.com/releases/2012/03/120314142044.htm (accessed October 2, 2014).

Share This



More Fossils & Ruins News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

German World War II Bomber Found in Croatia's Adriatic

German World War II Bomber Found in Croatia's Adriatic

AFP (Oct. 2, 2014) A rare, well-preserved German World War II bomber has been found in Croatia's central Adriatic more than seven decades after it was shot down, the national conservation institute said on Wednesday. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Raw: Japan Celebrates 'bullet Train' Anniversary

Raw: Japan Celebrates 'bullet Train' Anniversary

AP (Oct. 1, 2014) A ceremony marking 50 years since Japan launched its Shinkansen bullet train was held on Wednesday in Tokyo. The latest model can travel from Tokyo to Osaka, a distance of 319 miles, in two hours and 25 minutes. (Oct. 1) Video provided by AP
Powered by NewsLook.com
Battle of New Orleans Cannon Gets New Carriage

Battle of New Orleans Cannon Gets New Carriage

AP (Sep. 30, 2014) A Spanish cannon used in the Battle of New Orleans and weighing nearly 3 tons was lowered Tuesday by pulleys, chains and muscle onto a new gun carriage like one that might have held it once aboard a navy ship. (Sept. 30) Video provided by AP
Powered by NewsLook.com
2,000 Year Old Pre-Inca Cloak on Display in Lima

2,000 Year Old Pre-Inca Cloak on Display in Lima

AFP (Sep. 27, 2014) A 2,000 year-old Pre-Inca cloak that is believed to represent an agricultural calendar of the Paracas culture is on display in Lima. Duration: 00:39 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins