|The "frogamander" fossil may solve a debate about the link among frogs, salamanders, and other amphibians. (Michael Skrepnick)|
CHICAGO - The discovery of a "frogamander," a 290 million-year-old fossil that links modern frogs and salamanders, may resolve a longstanding debate about amphibian ancestry, Canadian scientists said last week.
Modern amphibians - frogs, salamanders, and earthworm-like caecilians - have been a bit slippery about divulging their evolutionary ancestry. Gaps in the fossil record have led to a lot of scientific debate.
The fossil Gerobatrachus hottoni or elderly frog, described in the journal Nature, may help set the record straight.
"It's a missing link that falls right between where the fossil record of the extinct form and the fossil record for the modern form begins," said Jason Anderson of the University of Calgary, who led the study. "It's a perfect little frogamander," he said.
Gerobatrachus has a mixture of frog and salamander features, with fused ankle bones as seen only in salamanders, a wide, frog-like skull, and a backbone that resembles a mix of the two.
The fossil suggests that modern amphibians may have come from two groups, with frogs and salamanders related to an ancient amphibian known as a temnospondyl, and worm-like caecilians more closely related to the lepospondyls, another group of ancient amphibians.