Featured Research

from universities, journals, and other organizations

Earliest ancestor of land herbivores discovered: 300-million-year-old predator showed way to modern terrestrial ecosystem

Date:
April 16, 2014
Source:
University of Toronto
Summary:
New research demonstrates how carnivores transitioned into herbivores for the first time on land. Previously unknown, the 300-million-year old fossilized juvenile skeleton of Eocasea martini is less than 20 cm long. Found in Kansas, it consists of a partial skull, most of the vertebral column, the pelvis and a hind limb. By comparing the skeletal anatomy of related animals, scientists discovered that Eocasea martini belonged to the caseid branch of the group Synapsid. This group, which includes early terrestrial herbivores and large top predators, ultimately evolved into modern living mammals. Eocasea lived nearly 80 million years before the age of dinosaurs.

The smallest and largest caseid: this is a reconstruction of 300-million-year-old tiny carnivorous Eocasea in the footprint of 270-million-year-old largest known herbivore of its time, Cotylorhynchus.
Credit: Artwork by Danielle Dufault

New research from the University of Toronto Mississauga demonstrates how carnivores transitioned into herbivores for the first time on land.

"The evolution of herbivory was revolutionary to life on land because it meant terrestrial vertebrates could directly access the vast resources provided by terrestrial plants," says paleontologist Robert Reisz, a professor in the Department of Biology. "These herbivores in turn became a major food resource for large land predators."

Previously unknown, the 300-million-year old fossilized juvenile skeleton of Eocasea martini is less than 20 cm long. Found in Kansas, it consists of a partial skull, most of the vertebral column, the pelvis and a hind limb.

By comparing the skeletal anatomy of related animals, Reisz and colleague Jörg Fröbisch of the Museum für Naturkunde and Humboldt-University in Berlin, discovered that Eocasea martini belonged to the caseid branch of the group Synapsid. This group, which includes early terrestrial herbivores and large top predators, ultimately evolved into modern living mammals.

Eocasea lived nearly 80 million years before the age of dinosaurs. "Eocasea is one of the oldest relatives of modern mammals and closes a gap of about 20 million years to the next youngest members of the caseid family," says Fröbisch. "This shows that caseid synapsids were much more ancient than previously documented in the fossil record."

It's also the most primitive member and was carnivorous, feeding on insects and other small animals. Younger members were herbivorous, says Reisz, clear evidence that large terrestrial herbivores evolved from the group's small, non-herbivorous members, such as Eocasea.

"Eocasea is the first animal to start the process that has resulted in a terrestrial ecosystem with many plant eaters supporting fewer and fewer top predators," he says.

Interestingly, Reisz and Fröbisch also found that herbivory, the ability to digest and process high-fibre plant material such as leaves and shoots, was established not just in the lineage that includes Eocasea. It arose independently at least five times, including twice in reptiles.

"When the ability to feed on plants occurred after Eocasea, it seems as though a threshold was passed," says Reisz. "Multiple groups kept re-evolving the same herbivorous traits."

The five groups developed the novel ability to live off plants in staggered bursts with synapsids such as Eocasea preceding reptiles by nearly 30 million years. This shows that herbivory as a feeding strategy evolved first among distant relatives of mammals, instead of ancient reptiles -- the branch that eventually gave rise to dinosaurs, birds, and modern reptiles.

The adoption of plant-eating also caused dramatic shifts in the size of early herbivores. When the team mapped the animals on an evolutionary tree, they found that four of the groups showed a tremendous increase in size during the Permian Period, at the end of the Paleozoic Era.

Caseids were the most extreme example of this size increase, says Reisz. The oldest member of the group, Eocasea, was very small, less than 2 kilograms as an adult, while the youngest, last member exceeded 500 kilograms.

Reisz says that the discovery of Eocasea creates questions even as it answers them. "One of the great mysteries to my mind is: why did herbivory not happen before and why did it happen independently in several lineages? That's what's fascinating about this event. It's the first such occurrence, and it resulted in a colossal change in our terrestrial ecosystem."


Story Source:

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


Journal Reference:

  1. Robert R. Reisz, Jörg Fröbisch. The Oldest Caseid Synapsid from the Late Pennsylvanian of Kansas, and the Evolution of Herbivory in Terrestrial Vertebrates. PLoS ONE, 2014; 9 (4): e94518 DOI: 10.1371/journal.pone.0094518

Cite This Page:

University of Toronto. "Earliest ancestor of land herbivores discovered: 300-million-year-old predator showed way to modern terrestrial ecosystem." ScienceDaily. ScienceDaily, 16 April 2014. <www.sciencedaily.com/releases/2014/04/140416172243.htm>.
University of Toronto. (2014, April 16). Earliest ancestor of land herbivores discovered: 300-million-year-old predator showed way to modern terrestrial ecosystem. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/2014/04/140416172243.htm
University of Toronto. "Earliest ancestor of land herbivores discovered: 300-million-year-old predator showed way to modern terrestrial ecosystem." ScienceDaily. www.sciencedaily.com/releases/2014/04/140416172243.htm (accessed August 1, 2014).

Share This




More Fossils & Ruins News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Where Did The World Trade Center Shipwreck Come From?

Where Did The World Trade Center Shipwreck Come From?

Newsy (July 31, 2014) — Scientists say a ship remnant discovered underneath Ground Zero dates back to the 18th century. Why it sank is still uncertain. Video provided by Newsy
Powered by NewsLook.com
Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) — Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
Powered by NewsLook.com
London's Famed 'Gherkin' Goes on Sale for £650 Mln

London's Famed 'Gherkin' Goes on Sale for £650 Mln

AFP (July 29, 2014) — London's "Gherkin" office tower, one of the landmarks on the British capital's skyline, went on sale for about £650 million ($1.1 billion, 820 million euros) on Tuesday after being placed into receivership. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) — The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
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:
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