Navigation Links
Size of mammals exploded after dinosaur extinction

Researchers demonstrate that the extinction of dinosaurs 65 million years ago made way for mammals to get bigger - about a thousand times bigger than they had been. The study, which is published in the prestigious journal Science, is the first to show this new pattern of increased body size of mammals after the exit of the dinosaurs.

"Basically, the dinosaurs disappear and all of a sudden there is nobody else eating the vegetation. That's an open food source and mammals start going for it, and it's more efficient to be an herbivore when you're big," says paper co-author Dr. Jessica Theodor, associate professor in the Department of Biological Sciences at the University of Calgary.

Theodor says as well as confirming the dramatic growth in mammalian size after the dinosaurs, the study shows that the ecosystem is able to reset itself relatively quickly.

"You lose dinosaurs 65 million years ago, and within 25 million years the system is reset to a new maximum for the animals that are there in terms of body size. That's actually a pretty short time frame, geologically speaking," she says. "That's really rapid evolution."

Theodor says mammals grew from a maximum of about 10 kilograms when they were sharing the earth with dinosaurs to a maximum of 17 tonnes afterwards.

"Nobody has ever demonstrated that this pattern is really there. People have talked about it but nobody has ever gone back and done the math," says Theodor one of the 20 researchers from around the world who worked on the study. "We went through every time period and said OK, for this group of mammals what's the biggest one? And then we estimated its body mass."

In order to document how big mammals grew after the 'competitive release' caused by the extinction of dinosaurs, researchers collected data on the maximum size for major groups of land mammals on each continent, including Perissodactyla, odd-toed ungulates such as horses and rhinos; Proboscidea, which includes elephants, mammoth and mastodon; Xenarthra, the anteaters, tree sloths, and armadillos; as well as a number of other extinct groups.

The results give clues as to what sets the limits on mammal size on land; the amount of space available to each animal and the climate they live in. The colder the climate, the bigger the mammals seem to get, as bigger animals conserve heat better. It also shows that no one group of mammals dominates the largest size class the absolute largest mammal belongs to different groups over time and space.


Contact: Leanne Yohemas
University of Calgary

Related biology news :

1. Dinosaur-chewing mammals leave behind oldest known tooth marks
2. Carnivorous mammals track fruit abundance
3. Small mammals -- and rest of food chain -- at greater risk from global warming than thought
4. Large mammals need protected areas, forest cover in India
5. Tree-dwelling mammals climb to the heights of longevity
6. Researchers use new acoustic tools to study marine mammals and fish
7. Study shows loss of 15-42 percent of mammals in North America
8. Climate-caused biodiversity booms and busts in ancient plants and mammals
9. After dinosaurs, mammals rise but their genomes get smaller
10. CU-Boulder study shows 53 million-year-old high Arctic mammals wintered in darkness
11. Climate change driving Michigan mammals north
Post Your Comments:
Related Image:
Size of mammals exploded after dinosaur extinction
(Date:11/18/2015)... New York , November 18, 2015 ... Market Research has published a new market report titled ... Growth, Trends, and Forecast, 2015 - 2021. According to the ... in 2014 and is anticipated to reach US$29.1 bn ... to 2021. North America ...
(Date:11/16/2015)... Calif. , Nov 16, 2015  Synaptics ... of human interface solutions, today announced expansion of ... TouchView ™ touch controller and display driver ... revolution of smartphones. These new TDDI products add ... TD4100 (HD resolution), TD4302 (WQHD resolution), and TD4322 ...
(Date:11/10/2015)... LONDON , Nov. 10, 2015 /PRNewswire/ ... segmented on the basis of product, type, ... segments included in this report are consumables, ... this report are safety biomarkers, efficacy biomarkers, ... in this report are diagnostics development, drug ...
Breaking Biology News(10 mins):
(Date:11/24/2015)...  Clintrax Global, Inc., a worldwide provider of clinical research services ... that the company has set a new quarterly earnings record in ... growth posted for Q3 of 2014 to Q3 of 2015.   ... , with the establishment of an Asia-Pacific ... United Kingdom and Mexico , ...
(Date:11/24/2015)... ... 2015 , ... This fall, global software solutions leader SAP and AdVenture Capital ... and pitch their BIG ideas to improve health and wellness in their schools. , ... win the title of SAP's Teen Innovator, an all-expenses paid trip to Super Bowl ...
(Date:11/24/2015)... Massachusetts , November 24, 2015 SHPG ... will participate in the Piper Jaffray 27 th Annual Healthcare ... Tuesday, December 1, 2015, at 8:30 a.m. EST (1:30 p.m. GMT). ... , Chief Financial Officer, will participate in the Piper Jaffray 27 ... , NY on Tuesday, December 1, 2015, at 8:30 a.m. ...
(Date:11/24/2015)... -- Tikcro Technologies Ltd. (OTCQB: TIKRF) today announced that its Annual General Meeting ... Israel time, at the law offices of ... th Floor, Tel Aviv, Israel . ... Izhak Tamir to the Board of Directors; , election of ... approval of an amendment to certain terms of options granted to our ...
Breaking Biology Technology: