A fossil of a chipmunklike animal discovered in China is now helping reveal how this group of mammals reigned as long as the dinosaurs did, researchers say.
A group of mammals known as the multituberculates flourished across the planet from about 170 million to 35 million years ago, a span of 135 million years. This is about as long as dinosaurs were the dominant species on Earth.
Much like today's rodents, multituberculates occupied an extremely diverse range of habitats, such as below the ground, on the ground and in trees. [See Photos of Newfound Creature & Other Ancient Mammals]
"Some could jump, some could burrow, others could climb trees and many more lived on the ground," said researcher Zhe-Xi Luo, a paleontologist at the University of Chicago.
By the end of their time, these creatures — the most abundant mammalian lineage in the fossil record — had evolved complex teeth that allowed them to enjoy vegetarian diets, as well as treetop-climbing abilities. Both of these adaptations helped the animals to become dominant among their contemporaries.
"Paleontologists are always interested in how certain superabundant, superdiverse groups of animals got started," Luo told LiveScience.
Now, Luo and his colleagues have revealed a new 160-million-year-old chipmunklike fossil that represents the earliest known multituberculate skeleton. This oldest ancestor on the multituberculate family tree, now named Rugosodon eurasiaticus, apparently possessed many of the adaptations that subsequent multituberculate species came to rely on, helping to set the stage for the group's dominance.
The fossil of Rugosodon eurasiaticus is preserved in two shale slabs in part (left) and counterpart (right). It is about 6.5 inches (17 cm) long from head to rump, and is estimated to have weighed about 2.8 ounces (80 grams).
For instance, multituberculates that lived 100 million years or more after R. eurasiaticus and were capable of tree climbing and jumping "had the most interesting ankle bones, capable of 'hyper-back-rotation' of the hind feet." Luo said. "What is surprising about this discovery is that these ankle features were already present in Rugosodon — a land-dwelling mammal."
R. eurasiaticus had relatively short, thick fingers, like those typically found on creatures that lived mostly on the ground. However, its highly flexible ankles suggest it could at least occasionally scamper up trees.
"If you look at squirrels, you see similar adaptations," Luo said.
In addition, R. eurasiaticus had wrinkled teeth ornamented with ridges, pits and grooves that would have enabled it to eat many different types of food, including both animals and plants. These teeth would have allowed later multituberculates to diversify from an animal-dominated diet to a plant-dominated one.
"A modern rodent species that had very similar ornaments on its teeth, the African dormouse, are seedeaters that also eat some fruit as well as worms, arthropods [creatures such as insects and crustaceans] and so forth — the perfect omnivore," Luo said.
The wrinkled teeth and flexible ankles that R. eurasiaticus possessed suggest adaptations that arose very early in the evolution of multituberculates helped pave the way for later members of the order (a scientific classification of organisms that includes families of genuses). Judging by other fossils discovered near the location where the R. eurasiaticus fossil was found, the multituberculate apparently lived in a temperate area rich in plants by the shores of shallow lakes. The animals could have fed on the seeds and leaves of ferns and cycads, or perhaps fished out clamlike creatures known as conchostracans from the water for food, Luo said.
The scientists detailed their findings in the Aug. 16 issue of the journal Science.
Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.
Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. ]]>
Our 2024 Coverage Needs You
It's Another Trump-Biden Showdown — And We Need Your Help
The Future Of Democracy Is At Stake
Our 2024 Coverage Needs You
Your Loyalty Means The World To Us
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
The 2024 election is heating up, and women's rights, health care, voting rights, and the very future of democracy are all at stake. Donald Trump will face Joe Biden in the most consequential vote of our time. And HuffPost will be there, covering every twist and turn. America's future hangs in the balance. Would you consider contributing to support our journalism and keep it free for all during this critical season?
HuffPost believes news should be accessible to everyone, regardless of their ability to pay for it. We rely on readers like you to help fund our work. Any contribution you can make — even as little as $2 — goes directly toward supporting the impactful journalism that we will continue to produce this year. Thank you for being part of our story.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
It's official: Donald Trump will face Joe Biden this fall in the presidential election. As we face the most consequential presidential election of our time, HuffPost is committed to bringing you up-to-date, accurate news about the 2024 race. While other outlets have retreated behind paywalls, you can trust our news will stay free.
But we can't do it without your help. Reader funding is one of the key ways we support our newsroom. Would you consider making a donation to help fund our news during this critical time? Your contributions are vital to supporting a free press.
Contribute as little as $2 to keep our journalism free and accessible to all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. Would you consider becoming a regular HuffPost contributor?
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. If circumstances have changed since you last contributed, we hope you'll consider contributing to HuffPost once more.
Support HuffPostAlready contributed? Log in to hide these messages.