Snakes Don't Have Legs: There's an Explanation For That

"How Snakes Lost Their Legs"
Jennifer Viegas, Animal News, Discovery News (February 7, 2010)

"Some, if not all, snakes used to have legs, and now new research suggests snakes lost their limbs by growing them more slowly or for a shorter period of time.

"The research, outlined in the latest issue of the Journal of Vertebrate Paleontology, strengthens the belief that snakes evolved from a lizard that either burrowed on land or swam in the ocean.

"In either case, its legs must have become less useful as the animal evolved over time.

" 'If something is not useful it can regress without any impact on the (animal's) survival, or regression can even be positive, as for here if the leg was disturbing a kind of locomotion, like for burrowing snakes or swimming snakes,' lead author Alexandra Houssaye told Discovery News...."

That's a somewhat carefully-qualified statement. The Lemming suspects that folks studying life on Earth over the last few hundreds of millions of years have gotten a trifle cautious - since what was 'absolutely known' within living memory has, in quite a few cases, to be revised. And sometimes re-revised. The Lemming's posted about that sort of thing before:

• "Teeth: Human, Very Old, and in an Unexpected Place"
  (December 29, 2010)
• "Age of the Earth, Illustrated: Almost A Century Ago"
  (August 10, 2010)
• "Himalayan Frogs Shake Up Geologists' Assumption"
  (August 9, 2010)

The article tells how researchers used high-energy radiation to get a thee-dimensional image of a 90,000,000-year-old snake pelvis. And the critter's abbreviated legs. Based on these scans, and educated guesswork, it looks like snakes - or critters whose descendants became the snakes we know - had already lost their front limbs by then. And were in the process of losing their back set.

As to just what happened, or where: That's something that Alexandra Houssaye says will probably take well upwards of a decade.

Meanwhile, it's pretty definite that snakes started out as lizard-like critters that lived in water.

Or land.

Sort-of-related posts:

• "Cambrian Explosion Evidence: Burgess Shale Fossils aren't Alone"
  (September 12, 2010)
• "Gliding Lizard and a Snake that 'Swims' Through the Air"
  (March 29, 2010)
• "Big Snake, Small Dinosaur, and a Professor from Michigan"
  (March 2, 2010)
• "Snakes - With Tentacles - That They 'See' With"
  (February 16, 2010)
• "Hurdia Victoria: Cambrian Supercritter of the Burgess Shale"
  (March 20, 2009)

More related posts:

• "Change, American Culture, Trilobites, Humanity's History, and the Big Picture"

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Why the Lemming doesn't have conniptions over the 'e-word.'

• "Faith and Reason, Religion and Science"
  A Catholic Citizen in America (March 20, 2009)
• "Catholic Church, Creationism, Evolution, Facts and Faith"
  A Catholic Citizen in America (March 5, 2009)