Featured Research

from universities, journals, and other organizations

How turtles got their shells: Fossil of extinct South African reptile provides clues

Date:
May 30, 2013
Source:
Cell Press
Summary:
Through careful study of an ancient ancestor of modern turtles, researchers now have a clearer picture of how the turtles' most unusual shell came to be. The findings help to fill a 30- to 55-million-year gap in the turtle fossil record through study of an extinct South African reptile known as Eunotosaurus.

The skeleton of the South African reptile Eunotosaurus africanus fills a gap in the early evolution of turtles and their enigmatic shell.
Credit: Tyler Lyson

Through careful study of an ancient ancestor of modern turtles, researchers now have a clearer picture of how the turtles' most unusual shell came to be. The findings, reported on May 30 in Current Biology, a Cell Press publication, help to fill a 30- to 55-million-year gap in the turtle fossil record through study of an extinct South African reptile known as Eunotosaurus.

"The turtle shell is a complex structure whose initial transformations started over 260 million years ago in the Permian period," says Tyler Lyson of Yale University and the Smithsonian. "Like other complex structures, the shell evolved over millions of years and was gradually modified into its present-day shape."

The turtle shell isn't really just one thing -- it is made up of approximately 50 bones. Turtles are the only animals that form a shell through the fusion of ribs and vertebrae. In all other animals, shells are formed from bony scales on the surface; they don't stick their bones on the outsides of their bodies.

"The reason, I think, that more animals don't form a shell via the broadening and eventually suturing together of the ribs is that the ribs of mammals and lizards are used to help ventilate the lungs," Lyson says. "If you incorporate your ribs into a protective shell, then you have to find a new way to breathe!" Turtles have done just that, with the help of a muscular sling.

Until recently, the oldest known fossil turtles, dating back about 215 million years, had fully developed shells, making it hard to see the sequence of evolutionary events that produced them. That changed in 2008 with the discovery of Chinese Odontochelys semitestacea, a reptile about 220 million years old, which had a fully developed plastron -- the belly side of the shell -- but only a partial carapace on its back.

Eunotosaurus takes the turtle and its shell back another 40 million years or so. It had nine broadened ribs found only in turtles. And like turtles, it lacked the intercostal muscles running between its ribs. But Eunotosaurus didn't have other features common to Odontochelys and turtles, including broad spines on their vertebrae.

Lyson says he and his colleagues now plan to investigate various other aspects of turtles' respiratory systems, which allow them to manage with their ribs locked up into a protective outer shell. "It is clear that this novel lung ventilation mechanism evolved in tandem with the origin of the turtle shell," he says.


Story Source:

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


Journal Reference:

  1. Tyler R. Lyson, Gabe S. Bever, Torsten M. Scheyer, Allison Y. Hsiang, Jacques A. Gauthier. Evolutionary Origin of the Turtle Shell. Current Biology, 2013; DOI: 10.1016/j.cub.2013.05.003

Cite This Page:

Cell Press. "How turtles got their shells: Fossil of extinct South African reptile provides clues." ScienceDaily. ScienceDaily, 30 May 2013. <www.sciencedaily.com/releases/2013/05/130530132431.htm>.
Cell Press. (2013, May 30). How turtles got their shells: Fossil of extinct South African reptile provides clues. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2013/05/130530132431.htm
Cell Press. "How turtles got their shells: Fossil of extinct South African reptile provides clues." ScienceDaily. www.sciencedaily.com/releases/2013/05/130530132431.htm (accessed October 23, 2014).

Share This



More Plants & Animals News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Working Mother DIY: Pumpkin Pom-Pom

Working Mother DIY: Pumpkin Pom-Pom

Working Mother (Oct. 22, 2014) — How to make a pumpkin pom-pom. Video provided by Working Mother
Powered by NewsLook.com
Goofy Dinosaur Blends Barney and Jar Jar Binks

Goofy Dinosaur Blends Barney and Jar Jar Binks

AP (Oct. 22, 2014) — A collection of dinosaur bones reveal a creature that is far more weird and goofy-looking than scientists originally thought when they found just the arm bones nearly 50 years ago, according to a new report in the journal Nature. (Oct. 22) Video provided by AP
Powered by NewsLook.com
San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) — The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Raw: Bear Cub Strolls Through Oregon Drug Store

Raw: Bear Cub Strolls Through Oregon Drug Store

AP (Oct. 22, 2014) — Shoppers at an Oregon drug store were surprised by a bear cub scurrying down the aisles this past weekend. (Oct. 22) 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:

More Coverage


Scientists Discover That Turtles Began Living in Shells Much Earlier Than Once Thought

May 30, 2013 — Unique among Earth's creatures, turtles are the only animals to form a shell on the outside of their bodies through a fusion of modified ribs, vertebrae and shoulder girdle bones. The turtle ... read more

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