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catsittingstillWow. Found this via Pharyngula-- (a great site all on its own, by the way, as long as you don't mind atheism).
A fossil of a snake with two hind legs has been found in Lebanon. One hind leg's bones were visible in the fracture plane of the fossil, the other was buried in the rock that cradled the fossilized bones, and was imaged with an intense beam of x-rays from the Grenoble (France) synchrotron.
However, according to Wikipedia, snakes with hind limbs are already known from the fossil record. Plus some existing speciles of snakes, like pythons and boas, have vestigial hind legs called anal spurs that are used in mating.
A fossil of a snake with two hind legs has been found in Lebanon. One hind leg's bones were visible in the fracture plane of the fossil, the other was buried in the rock that cradled the fossilized bones, and was imaged with an intense beam of x-rays from the Grenoble (France) synchrotron.
The 85cm-long (33in) creature, known as Eupodophis descouensi, comes from the Late Cretaceous, about 92 million years ago.(For comparison, amphibians ventured onto land about 360 million years ago, birds showed up about 150 milliion years ago and the non-avian dinosaurs died out 65 million years ago.)
However, according to Wikipedia, snakes with hind limbs are already known from the fossil record. Plus some existing speciles of snakes, like pythons and boas, have vestigial hind legs called anal spurs that are used in mating.
The new fossil is still cool, but may be a bigger deal for what it has to tell is about gradual changes in the development of snakes than because it confirms a previously unconfirmed hypothesis.
For instance modern snakes are practically all thorax (chest)--which is why they have ribs all the way down. A non-snake spine develops with neck vertebrae, thorax vertebrae, lumbar vertebrae sacral (pelvic) vertebrae and caudal (tail) vertebrae in that order, and their types are controlled by gradients of (probably proteins but I don't know for certain) laid down by Hox genes in a certain order from head to tail before the vertebrae start forming. Changes in these Hox gene product gradients during embryo formation are reflected by changes in body type--geese have lots more neck vertebrae than we do, and the combination of Hox gene products that tell proto-vertebrae "become neck vertebrae" is more stretched out in the goose embryo.
Well, snakes have become practically all thorax and other vertebra types have been crowded down to a few spots at the ends. Some modern snakes have some pelvis left--a lot of them don't. Some modern snakes have anal spurs, but the bones involved don't actually connect to the pelvis bits (if they are even present). Ancient snake ancestors can presumably help clear up what happened in what order.
So this is very interesting, but not the earth-shaking breakthrough that I thought at first.
For instance modern snakes are practically all thorax (chest)--which is why they have ribs all the way down. A non-snake spine develops with neck vertebrae, thorax vertebrae, lumbar vertebrae sacral (pelvic) vertebrae and caudal (tail) vertebrae in that order, and their types are controlled by gradients of (probably proteins but I don't know for certain) laid down by Hox genes in a certain order from head to tail before the vertebrae start forming. Changes in these Hox gene product gradients during embryo formation are reflected by changes in body type--geese have lots more neck vertebrae than we do, and the combination of Hox gene products that tell proto-vertebrae "become neck vertebrae" is more stretched out in the goose embryo.
Well, snakes have become practically all thorax and other vertebra types have been crowded down to a few spots at the ends. Some modern snakes have some pelvis left--a lot of them don't. Some modern snakes have anal spurs, but the bones involved don't actually connect to the pelvis bits (if they are even present). Ancient snake ancestors can presumably help clear up what happened in what order.
So this is very interesting, but not the earth-shaking breakthrough that I thought at first.
