Featured Research

from universities, journals, and other organizations

New Fossil Snake With Legs, Reported In Science

Date:
March 17, 2000
Source:
American Association For The Advancement Of Science
Summary:
Appearing like the punchline to an evolutionary riddle, a new fossil snake with legs has emerged from 95 million year-old deposits near Jerusalem. Its sedimentary surroundings suggest a seafaring lifestyle for this ancient reptile, but its advanced anatomy could overturn a current theory about the marine origin of snakes.

Washington, D.C. -- Appearing like the punchline to an evolutionary riddle, a new fossil snake with legs has emerged from 95 million year-old deposits near Jerusalem. Its sedimentary surroundings suggest a seafaring lifestyle for this ancient reptile, but its advanced anatomy could overturn a current theory about the marine origin of snakes.

This intriguing new species, dubbed Haasiophis terrasanctus in the 17 March issue of Science, is the second limbed snake to come from the site of Ein Yabrud, an ancient marine environment broadly similar to the still, coastal waters of today's Bahamian reef.

The first such species, Pachyrhachis problematicus, plays a pivotal role in a scenario that places the ancestor of snakes in the sea. In support of Pachyrhachis' position at the base of the serpent family tree, some paleontologists have noted features in its skull that they believe single it out as a transitional link between mosasaurs--gigantic swimming lizards of the Cretaceous (144-65 million years ago)--and true snakes. This view contrasts dramatically with the traditional view of small terrestrial or burrowing lizards as snake ancestors.

A group of scientists, led by Olivier Rieppel of the Field Museum in Chicago, Illinois and Eitan Tchernov of the Hebrew University of Jerusalem in Israel, brought Haasiophis into the midst of this origins controversy after the fossil had spent years in nameless limbo in a museum drawer. Their description of the extremely well-preserved fossil, along with an analysis of its evolutionary relationships, led the scientists to conclude that their new species was close kin to Pachyrhachis. Their analysis also indicates, however, that these two snakes were not primitive ancestors, but advanced snakes similar to modern boas and pythons. The new anatomical interpretation suggests that neither Pachyrhachis nor Haasiophis have anything to do with snake origins.

The finding does undermine the theory that Pachyrhachis represents an evolutionary link between marine reptiles and true snakes. Snakes like boas and pythons have a distinctively mobile skull structure that allows them to nearly unhinge their jaw in a formidable gape and "walk" their skull over their prey, dining on meals larger than the diameter of their own head. The two species of fossil snakes from Ein Yabrud appear to have skull architecture similar to these modern serpents. Previous studies of Pachyrhachis had concluded that the snake was incapable of such kinetic feats, instead adopting a modified gape similar to that of the mosasaurs as an intermediate step between the rigid skull of lizards and the mobile skull of higher snakes.

"We went back and looked very carefully at the skulls of Pachyrhachis, Haasiophis, and lizards like mosasaurs, especially features like the braincase, the dentition, and the joint in the middle of the lower jaw," says Rieppel. "The better preservation of Haasiophis allowed us to use its anatomy as a guide, and gave us the background to see just how much these fossils looked like advanced snakes."

But a riddle remains: why do these two snake species have hind limbs? If legs were the norm for snake ancestors, it would make sense to see the species' advanced anatomy as only superficially similar to more modern snakes. On the other hand, the stubby limbs on the fossil snakes might represent an evolutionary reversal, where snakes with advanced skull design regain hindlimbs that were lost or perhaps greatly reduced in their ancestors. Rieppel and his colleagues counted the number of evolutionary steps involved in each possible scenario, and concluded that the redevelopment of limbs was a more likely story.

"We know of at least 62 lizard and snake lineages that have undergone some degree of limb reduction," Rieppel notes. "Since our fossil record of snakes is very poor, we can't exclude the possibility that limbs in snakes were lost not just once in the beginning, but several times throughout their history."

Rieppel said that it is difficult to tell how the legs themselves might have been used, since they are too small in relation to the animal's whole body to have any locomotor function. Modern pythons have a rudimentary hindlimb, usually little more than a "claw" of cartilage tipped with bone that they use during mating and occasional fighting, and it is possible that Haasiophis' leg served a similar purpose.


Story Source:

The above story is based on materials provided by American Association For The Advancement Of Science. Note: Materials may be edited for content and length.


Cite This Page:

American Association For The Advancement Of Science. "New Fossil Snake With Legs, Reported In Science." ScienceDaily. ScienceDaily, 17 March 2000. <www.sciencedaily.com/releases/2000/03/000317051940.htm>.
American Association For The Advancement Of Science. (2000, March 17). New Fossil Snake With Legs, Reported In Science. ScienceDaily. Retrieved August 21, 2014 from www.sciencedaily.com/releases/2000/03/000317051940.htm
American Association For The Advancement Of Science. "New Fossil Snake With Legs, Reported In Science." ScienceDaily. www.sciencedaily.com/releases/2000/03/000317051940.htm (accessed August 21, 2014).

Share This




More Plants & Animals News

Thursday, August 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Possible Ebola Patient in Isolation at California Hospital

Possible Ebola Patient in Isolation at California Hospital

Reuters - US Online Video (Aug. 20, 2014) — A patient who may have been exposed to the Ebola virus is in isolation at the Kaiser Permanente South Sacramento Medical Center. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) — Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. Video provided by Reuters
Powered by NewsLook.com
Unsustainable Elephant Poaching Killed 100K In 3 Years

Unsustainable Elephant Poaching Killed 100K In 3 Years

Newsy (Aug. 20, 2014) — Poachers have killed 100,000 elephants between 2010 and 2012, as the booming ivory trade takes its toll on the animals in Africa. Video provided by Newsy
Powered by NewsLook.com
Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) — Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. 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