Featured Research

from universities, journals, and other organizations

Early Land Animals Could Walk And Run Like Mammals, New Study Finds

Date:
March 9, 2006
Source:
Ohio University
Summary:
Salamanders and the tuatara, a lizard-like animal that has lived on Earth for 225 million years, were the first vertebrates to walk and run on land, according to a recent study by Ohio University researchers.

The tuatara, a lizard-like animal that has lived on Earth for 225 million years, was one of the first vertebrates to run and walk, scientists found.
Credit: Courtesy of Steve Reilly, Ohio University

Salamanders and the tuatara, a lizard-like animal that has lived on Earth for 225 million years, were the first vertebrates to walk and run on land, according to a recent study by Ohio University researchers.

Related Articles


After studying the creatures at the Toledo Zoo, Stephen Reilly, associate professor of biological sciences, and doctoral student Eric McElroy determined that they use both forms of locomotion, which are energy-saving mechanisms generally believed to be important only in fast-running animals such as mammals and birds.

The research was published in the March 8 issue of the journal Proceedings of the Royal Society B: Biological Sciences. Andrew Odum, curator of herpetology at the Toledo Zoo, and Valerie Hornyak, head herpetology keeper, were co-authors of the study.

Tuataras, which are usually about 1 to 2 feet long, look like large lizards with green or brown scales and short spikes on their backs. They have unique anatomical features that are somewhere between those of lizards and birds. The critters are found only in New Zealand, where the cool climate is ideal for these animals that can’t survive in temperatures above 25 degrees Celsius (77 degrees Fahrenheit). The animals can grow as old as 100 years, and live mostly off of insects, eggs and small birds. Fossil records show that the tuatara lived on Earth as early as 225 million years ago and hasn’t changed significantly over time.

“Tuataras are the oldest living models of early tetrapods (four-legged animals) still alive today; that’s what makes them so interesting,” Reilly said.

In the recent study, the tuataras and salamanders walked and ran on a trackway with an integrated plate that measured the force with which the animals hit the ground with each step. From videotapes and the force measurements, the researchers could tell when the animals were walking or running. The difference is not obvious in these critters, which tend to move with a slow, lumbering gait. That’s led scientists to believe that the primitive animals could only walk.

But force data used to study the movement of these creatures’ center of mass showed otherwise. In walking, the center of mass vaults up and over the limbs with each step. In running, the center of mass dips with each step, and tendons and joints in the legs act as biological springs. Mammals such as humans, dogs and horses can use both mechanisms to conserve up to 50 percent of their energy needed to walk and run.

When studying salamanders and tuataras, the researchers spotted the telltale vault and dip of center of mass movements in different strides – confirmation that the creatures mechanically walk and run. Because they are the oldest living examples of four-legged animals, the new findings suggest that both energy saving mechanisms appeared when the first vertebrates moved onto land, Reilly explained. In comparison to previous research on other vertebrates, this also suggests that all terrestrial vertebrates – except for turtles, which are limited by their shell – can walk and run.

The researchers also showed, however, that walking and running in tuataras occur at the same speed and use about the same amounts of energy. Reilly believes that this could be a pre-adaptation in these primitive animals that have not evolved the need for speed, unlike other animals.

The research, which was funded by the National Science Foundation and the Research Challenge Program at Ohio University, also shows for the first time a clear difference in locomotor mechanics between “lumbering” animals with clumsy, ungraceful gaits and “cursorial” animals that move fast and smoothly. In lumbering animals, up and down movements dominate the mechanical energy of locomotion. These movements are smoothed out in cursorial animals such as in dogs and horses, where more energy is shifted to forward movement, and the center of mass oscillates relatively less with each step.

Reilly and McElroy were interested in tuataras not only because they are a “living fossil,” but also because tuataras are a threatened species, according to the World Conservation Union.

“Tuataras only survive on a few small islands off New Zealand, and I would really like to study their locomotor behavior in the wild,” Reilly said. “Given their status as the world’s oldest known living tetrapod, knowing more about how these animals move in nature is critical to our understanding of vertebrate evolution.”


Story Source:

The above story is based on materials provided by Ohio University. Note: Materials may be edited for content and length.


Cite This Page:

Ohio University. "Early Land Animals Could Walk And Run Like Mammals, New Study Finds." ScienceDaily. ScienceDaily, 9 March 2006. <www.sciencedaily.com/releases/2006/03/060308210330.htm>.
Ohio University. (2006, March 9). Early Land Animals Could Walk And Run Like Mammals, New Study Finds. ScienceDaily. Retrieved March 6, 2015 from www.sciencedaily.com/releases/2006/03/060308210330.htm
Ohio University. "Early Land Animals Could Walk And Run Like Mammals, New Study Finds." ScienceDaily. www.sciencedaily.com/releases/2006/03/060308210330.htm (accessed March 6, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, March 6, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Praying Mantis Looks Long Before It Leaps

Praying Mantis Looks Long Before It Leaps

Reuters - Innovations Video Online (Mar. 5, 2015) Slowed-down footage of the leaps of praying mantises show the insect&apos;s extraordinary precision, say researchers. Video provided by Reuters
Powered by NewsLook.com
Octopus Grabs Camera and Turns It Around On Photographer

Octopus Grabs Camera and Turns It Around On Photographer

Buzz60 (Mar. 5, 2015) A photographer got the shot of a lifetime, or rather an octopus did, when it grabbed the camera and turned it around to take an amazing picture of the photographer. Jen Markham (@jenmarkham) has the story. Video provided by Buzz60
Powered by NewsLook.com
Ringling Bros. Eliminating Elephant Acts

Ringling Bros. Eliminating Elephant Acts

AP (Mar. 5, 2015) The Ringling Bros. and Barnum & Bailey Circus is ending its iconic elephant acts. The circus&apos; parent company, Feld Entertainment, told the AP exclusively that the acts will be phased out by 2018 over growing public concern about the animals. (March 5) Video provided by AP
Powered by NewsLook.com
Raw: Tourists Visit Rare Grey Whales in Mexico

Raw: Tourists Visit Rare Grey Whales in Mexico

AP (Mar. 4, 2015) Once nearly extinct, grey whales now migrate in their thousands to Mexico&apos;s Vizcaino reserve in Baja California, in search of warmer waters to mate and give birth. Tourists flock to the reserve to see the whales, measuring up to 49 feet long. (March 4) Video provided by AP
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