|
|
A missing link settles debate over the origin of frogs and salamanders (5/22/2008)
 |
| The Gerobatrachus hottoni fossil. - Photo Credit: Ken Bendiktsen |
The description of an ancient amphibian that millions of years ago swam in quiet pools and caught mayflies on the surrounding land in Texas has set to rest one of the greatest current controversies in vertebrate evolution. The discovery was made by a research team led by scientists at the University of Calgary.
The examination and detailed description of the fossil, Gerobatrachus hottoni (meaning Hotton's elder frog), proves the previously disputed fact that some modern amphibians, frogs and salamanders evolved from one ancient amphibian group called temnospondyls.
The discovery is described for the first time in the prestigious international research journal Nature.
"The dispute arose because of a lack of transitional forms. This fossil seals the gap," says Jason Anderson, assistant professor, University of Calgary Faculty of Veterinary Medicine and lead scientist in the study.
The Gerobatrachus fossil provides a much fuller understanding of the origin and evolution of modern amphibians. The skull, backbone and teeth of Gerobatrachus have a mixture of frog and salamander features-the fossil has two fused bones in the ankle, which is normally only seen in salamanders, and a very large tympanic ear (ear drum). It also has a lightly built and wide skull similar to that of a frog. Its backbone is exactly intermediate in number between the modern frogs and salamanders and more primitive amphibians.
The new fossil also addresses a controversy over molecular clock estimates, or the general time salamanders and frogs evolved into two distinct groups.
"With this new data our best estimate indicates that frogs and salamanders separated from each other sometime between 240 and 275 million years ago, much more recently than previous molecular data had suggested," says Robert Reisz, professor, University of Toronto Mississauga and second author on the paper.
Gerobatrachus was originally discovered in Texas in 1995 by a field party from the Smithsonian Institution that included the late Nicholas Hotton, for whom the fossil is named. It remained unstudied until it was "rediscovered" by Anderson's team. It took countless hours of work on the small, extremely delicate fossil to remove the overlying layers of rock and uncover the bones to reveal the anatomy of the spectacular looking skeleton.
"It is bittersweet to learn about frog origins in this Year of the Frog, dedicated to informing the public about the current global amphibian decline," continues Anderson. "Hopefully we won't ever learn about their extinction."
Note: This story has been adapted from a news release issued by the University of Calgary
Comments:
| 1. |
Rockstar107 |
5/24/2008 1:45:00 PM MST |
Response from AiG
"...supposedly 290 million years old, the frogamander fossil was collected in Texas a decade ago, then “rediscovered” in the National Museum of Natural History in 2004. Comparative biologist Jason Anderson of the University of Calgary led the new analysis of the fossil, claiming he recognized the “froggy slamander-y sort of look” of the fossil— now dubbed Gerobatrachus hottoni.
The creature is said to fit a “noted gap” in the amphibian fossil record—one of those gaps the media never reports on until it’s filled! Anderson judges that the animal would have looked like a stubby-tailed salamander with froglike ears and that it “pretty convincingly settles the question [that the] frog and salamander shared origins from the same fossil group.”
A couple of thoughts for creationists. First, although the find has been reported with typical evolutionary fanfare and certainty on the surface, that’s not to say everyone agrees with the complete analysis. For example, read what National Geographic News reported from the Field Museum’s John Bolt, a curator for fossil amphibians and reptiles:
Bolt, the Field Museum expert, cautioned that it is difficult to say for sure whether this creature was itself a common ancestor of the two modern groups, given that there is only one known specimen of Gerobatrachus, and an incomplete one at that.
“At this point I would say it is by no means certain that this is representative of a common ancestor to frogs and salamanders, although it might be,” Bolt said.
Bolt also says, intriguingly, “The most astonishing thing to me about this study is that this animal is far more froglike than I would ever have expected from its age. Nothing this nonprimitive has ever been described from this age. It's just amazing.” (Emphasis added.)
Our second thought is that it is possible that, assuming the incomplete fossil has been interpreted accurately and truly shares frog and salamander features (and such assumptions often fail to hold true), frogs and salamanders descended from the same amphibian kind—that is, selective pressures gradually exploited the genetic variation in an original amphibian kind, resulting in the two modern groupings. If not, it is possible God created an amphibian kind with features in common with both salamanders or frogs.
As always, though, Christians must separate the actual finding from the interpretation. There are several creation-based explanations for an incomplete fossil with salamander and frog features, but all too often, well-meaning Christians swallow the evolutionary propaganda whole, facts and worldview, without trusting God over man’s often-foolish speculation."
|
| 2. |
Creationism_are_smart |
6/22/2008 8:14:32 PM MST |
Please, ignore the retarded comment above this one. |
Leave a Reply:
|
|
Subscribe
