Featured Research

from universities, journals, and other organizations

Working On The 'Porsche Of Its Time': New Model For Species Determination Offered

Date:
December 31, 2003
Source:
Washington University In St. Louis
Summary:
How much different do the bones of similar animals have to be for the classification of a new species? That is the question that drove Stephanie Novak, a new doctoral candidate in the Department of Earth and Planetary Sciences in Arts & Sciences at Washington University in St. Louis, to develop a novel model to determine classification of a new species.

When a paleontologist wishes to define a new species, all he or she has to rely on is 'dem bones. ' Unlike with animals living today, paleontologists can't look into the past to document an ancient beast's physiology or mating habits. Using all of the information available, paleontologists must confront the fossil world reality that the classification of a new fossil species is subjective and varies among taxonomists.

Related Articles


But how much different do the bones of similar animals have to be for the classification of a new species?

That is the question that drove Stephanie Novak, a new doctoral candidate in the Department of Earth and Planetary Sciences in Arts & Sciences at Washington University in St. Louis, to develop a novel model to determine classification of a new species. Novak presented details of her model at the annual meeting of the Geological Society of America, held Nov.2-5 in Seattle.

Her discovery began in 2002 while Novak pursued her master's degree at the University of North Carolina at Chapel Hill. She was studying a fascinating critter that competed with early dinosaurs 220 million years ago but went extinct at the boundary of the Triassic and Jurassic eras. Postosuchus (post-o-SOOK-us), though appearing superficially to resemble a classic meat-eating dinosaur with a huge skull and powerful flesh -tearing jaws, was actually a member of the Rauisuchia (raw-ih-SOO-kee-a), the dominant terrestrial predators during the Middle and Late Triassic , and the "Porches" of their time. The beast moved mainly on four legs and looked like, as Novak refers to it, "an alligator on stilts." It thrived at a time when there were no hardwood trees, grass, or flowers and dinosaurs were just coming onto the scene. Postosuchus is estimated to have reached a length of 25 feet, and was distinguished from dinosaurs by hip structure and a special ankle structure enabling it to walk heel-toe as alligators and crocodiles do today, as opposed to the on-the-tips-of-the-toes-walking observed in dinosaurs.

Novak investigated a Postosuchus specimen excavated from the Coelophysis Quarry of Ghost Ranch, New Mexico, a famous locality teeming with dinosaur fossils (mainly Coelophysis bauri) as a result of a mass death. While comparing the Ghost Ranch specimen with the two specimens of Postosuchus kirkpatricki from Texas, she noticed some differences in the bones. Not sure whether these differences were numerous enough or skeletally important enough to make the Ghost Ranch Postosuchus a new species, she decided to do a little more research before making a final decision.

Because the Rauisuchian fossil record is generally sparse, Novak instead dove into the dinosaurian fossil record in attempts to quantify the amount of skeletal difference historically regarded as valid to erect a new species within the same genera. She analyzed 28 genera containing 68 species from both the saurischian (lizard-hipped) and ornithischian (bird-hipped) orders. Using the fact that the skeleton of a dinosaur generally contains approximately 338 different bones, she catalogued the number of differences as well as where the differences were found on the skeleton. Calculations indicated that, on average, two species of dinosaur that are members of the same genera varied from each other by just 2.2 percent. Translation of the percentage into an actual number results in an average of just three skeletal differences out of the total 338 bones in the body. Amazingly, 58 percent of these differences occurred in the skull alone.

"This is a lot less variation than I'd expected," said Novak, whose advisor is Josh Smith, Ph.D., Washington University assistant professor of earth and planetary sciences. "As a concept, this is not statistically perfect. But I think it's something taxonomists can consider if they are in doubt over classifying something. It's a kind of benchmark with historical validity."

Novak was able to determine, using her Archosaurian Morphospecies Concept, that the Ghost Ranch Postosuchus was indeed the same species, Postosuchus kirkpatricki, as the two specimens from Texas.


Story Source:

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


Cite This Page:

Washington University In St. Louis. "Working On The 'Porsche Of Its Time': New Model For Species Determination Offered." ScienceDaily. ScienceDaily, 31 December 2003. <www.sciencedaily.com/releases/2003/12/031231082553.htm>.
Washington University In St. Louis. (2003, December 31). Working On The 'Porsche Of Its Time': New Model For Species Determination Offered. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2003/12/031231082553.htm
Washington University In St. Louis. "Working On The 'Porsche Of Its Time': New Model For Species Determination Offered." ScienceDaily. www.sciencedaily.com/releases/2003/12/031231082553.htm (accessed October 25, 2014).

Share This



More Fossils & Ruins News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Fossil Treasures at Risk in Morocco Desert Town

Fossil Treasures at Risk in Morocco Desert Town

AFP (Oct. 23, 2014) Hundreds of archeological jewels in and around the town of 30,000 people prompt geologists and archeologists to call the Erfoud area "the largest open air fossil museum in the world". Duration: 02:17 Video provided by AFP
Powered by NewsLook.com
Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Newsy (Oct. 23, 2014) A 45,000-year-old thighbone is showing when humans and neanderthals may have first interbred and revealing details about our origins. Video provided by Newsy
Powered by NewsLook.com
Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Newsy (Oct. 23, 2014) You've probably seen some weird-looking dinosaurs, but have you ever seen one this weird? It's worth a look. 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:

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