Featured Research

from universities, journals, and other organizations

Scientists discover that turtles began living in shells much earlier than once thought

Date:
May 30, 2013
Source:
Smithsonian
Summary:
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 shell is a unique modification, and how and when it originated has fascinated and confounded biologists for more than two centuries. Scientists have recently discovered that the beginnings of the turtle shell started 40 million years earlier than previously thought.

This is a living South African sideneck turtle (Pelusios niger) next to its 260-million-year-old relative, Eunotosaurus africanus.
Credit: Luke Norton

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 shell is a unique modification, and how and when it originated has fascinated and confounded biologists for more than two centuries. A Smithsonian scientist and colleagues recently discovered that the beginnings of the turtle shell started 40 million years earlier than previously thought.

The team's research is published in the May 30 issue of Current Biology.

The oldest known fossil turtle dated back about 210 million years, but it had an already fully formed shell, giving no clues to early shell evolution. Then a clue came in 2008 when the 220 million-year-old fossil remains of an early turtle species, Odontochelys semitestacea, were discovered in China. It had a fully developed plastron (the belly portion of a turtle's shell), but only a partial carapace made up of distinctively broadened ribs and vertebrae on its back. With this knowledge the scientists turned to newly discovered specimens of Eunotosaurus africanus, a South African species 40 million years older than O. semitestacea that also had distinctively broadened ribs. Their detailed study of Eunotosaurus indicated it uniquely shared many features only found in turtles, such as no intercostal muscles that run in between the ribs, paired belly ribs and a specialized mode of rib development, which indicates that Eunotosaurus represents one of the first species to form the evolutionary branch of turtles.

"Eunotosaurus neatly fills an approximately 30-55-million year gap in the turtle fossil record," said Tyler Lyson, a Peter Buck Postdoctoral Fellow at the Smithsonian's National Museum of Natural History. "There are several anatomical and developmental features that indicate Eunotosaurus is an early representative of the turtle lineage; however, its morphology is intermediate between the specialized shell found in modern turtles and primitive features found in other vertebrates. As such, Eunotosaurus helps bridge the morphological gap between turtles and other reptiles."

Ribs in most other animals protect internal organs and help ventilate the lungs to assist breathing. Because the ribs of turtles have been modified to form the shell, they have also had to modify the way they breathe with specialized muscles. This presents the team with their next challenge. They plan to examine the novel respiratory system in turtles and see how it evolved in conjunction with the evolution of the turtle's shell.


Story Source:

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


Journal Reference:

  1. TylerR. Lyson, GabeS. Bever, TorstenM. Scheyer, AllisonY. Hsiang, JacquesA. Gauthier. Evolutionary Origin of the Turtle Shell. Current Biology, 2013; DOI: 10.1016/j.cub.2013.05.003

Cite This Page:

Smithsonian. "Scientists discover that turtles began living in shells much earlier than once thought." ScienceDaily. ScienceDaily, 30 May 2013. <www.sciencedaily.com/releases/2013/05/130530132433.htm>.
Smithsonian. (2013, May 30). Scientists discover that turtles began living in shells much earlier than once thought. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2013/05/130530132433.htm
Smithsonian. "Scientists discover that turtles began living in shells much earlier than once thought." ScienceDaily. www.sciencedaily.com/releases/2013/05/130530132433.htm (accessed July 22, 2014).

Share This




More Plants & Animals News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

San Diego Zoo Welcomes New, Rare Rhino Calf

San Diego Zoo Welcomes New, Rare Rhino Calf

Reuters - US Online Video (July 21, 2014) An endangered black rhino baby is the newest resident at the San Diego Zoo. Sasha Salama reports. Video provided by Reuters
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 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:

More Coverage


How Turtles Got Their Shells: Fossil of Extinct South African Reptile Provides Clues

May 30, 2013 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 ... read more
from the past week

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