Convergent evolution: 359 million year old eel fossil had spine like land-dwellers
|May 30, 2012||Posted by News under Evolution, Intelligent Design, News|
From “Human-Like Spine Morphology Found in Aquatic Eel Fossil” ( em>ScienceDaily, May 22, 2012), we learn
For decades, scientists believed that a spine with multiple segments was an exclusive feature of land-dwelling animals. But the discovery of the same anatomical feature in a 345-million-year-old eel suggests that this complex anatomy arose separately from — and perhaps before — the first species to walk on land.
Tarrasius problematicus was an eel-like fish that lived in shallow bodies of water in what is now Scotland, in the Carboniferous period between 359 million and 318 million years ago. Like many fish, Tarrasius was thought to have a vertebral column divided simply into body and tail segments. But in a new description of Tarrasius published in Proceedings of the Royal Society B, Lauren Sallan describes a five-segment column much more similar to the spinal anatomy of land-dwelling animals called tetrapods, including humans.
The surprising find argues against a common assumption paleontologists use to determine from fossils whether an ancient species lived on land or in water.
“It’s the last trait to fall,” said Sallan, a graduate student in the Program in Integrative Biology at the University of Chicago Biological Sciences. “First, limbs were thought to show that a species was on land and walking, and now the vertebral morphology doesn’t mean that they’re on land either. So a lot of the things we associate with tetrapods actually arose first in fishes, and this is another example of that.”
Common descent? Maybe. Common design: Clearly.