Paleontologists believe that, over millions of years, lamprey-like creatures evolved into jawed, bony fish.
If these proto-lampreys were the first vertebrates, they may be the common ancestors to all animals with backbones, including humans.
The evolutionary split between jawless and jawed fish probably happened close to 500 million years ago, according to Michael Miyamoto and colleagues at the University of Florida in Gainesville.
During a genetic study reported in a February issue of the journal Proceedings of the National Academy of Sciences, Miyamoto discovered that the cartilaginous lamprey backbone and the human backbone are built from the same essential protein, collagen.
This seems to confirm that lampreys and humans share an ancient common ancestor that produced collagen, he says.
Not Quite Twins
Though the ancient lamprey is remarkably similar to modern varieties, there are differences.
The fossilized fish is just 1.7 inches (4.2 centimeters) long. Modern adult lampreys measure anywhere from about 6 to 40 inches (15 to 100 centimeters) long.
The ancient lamprey had a much larger mouth, proportionately speaking, than modern lampreys do. In addition, the prehistoric fish had one long dorsal fin, whereas many lampreys today have more. And the fossil creature had 14 teeth, compared with the modern lamprey's 19.
Though the newfound fossil is significant, the discovery of almost any lamprey fossil is cause for celebration.
Unlike with bony fish, only a handful of lamprey fossils have ever been found, because cartilage usually decays too fast to become fossilized.
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