Evolution in Action: Lizards Losing Limbs

[n2doc]

By Robin Lloyd, Senior Editor
posted: 12 November 2008 09:31 am ET

Some slender Australian lizards called skinks have gone from being five-fingered to legless (like most snakes) in just 3.6 million years, a new study finds. That's a blink of an eye in geologic time.

For comparison, if a 1,000-sheet roll of toilet paper represented all of Earth's geologic history, it is only on the last square of paper that bipedal ancestors of Homo sapiens showed up — about 4.5 million years ago, said Penn State geologist Robert Giegengack, who was not involved in the study.

There are 75 species of these fast-evolving skinks called Lerista. These skinks have been crawling and slithering around Earth for about 13.4 million years, and even today, some have five fingers, some have four and some have none, or tiny stubs for legs. So researchers from the University of Adelaide used genetic sequences to arrive at a new family tree for the skinks that showed when and how fast they had lost their fingers or entire legs throughout their evolution.

"At the highest rate, complete loss of limbs from a pentadactyl condition is estimated to have occurred within 3.6 million years," said researcher Adam Skinner of the University of Adelaide, adding that compared to similarly dramatic evolutionary changes in other animals, this is blisteringly fast.

The analysis, detailed in the journal BMC Evolutionary Biology and funded by the Hermon Slade Foundation, suggests that the skinks’ way of life might have driven the dramatic and rapid changes in their body shapes.

http://www.livescience.com/animals/081112-limbless-lizards.html

[liberalmuse]

1. My sister and I...

used to catch blue tail lizards in the Mesa's of Albuquerque. We'd catch them by the tails, but sometimes they would escape, leaving a wriggling tail in our hands. One time we caught several lizards which we let loose in the house. As my mom was cleaning, we heard a blood curdling scream. She had tried to catch a lizard that was on our couch, but ended up with that wriggling blue tail in her hand.

[NorCalDem]

2. You goober!

God hid the legged lizard fossils in the radioactive Carbon-dated rock (that allows for precious measurement of it's "age") as a means to trick you! Hail Satan!

:sarcasm:

[amyrose2712]

3. I thought Satan put them there to trick us...

On the same note, my born-again friend once told me "I don't think I believe in dinosaurs any more." That was painful to hear.