It’s a remarkable reversal — literally. Going back to Darwin’s time, scientists assumed they had it all figured out. They knew how the backbone of the earliest tetrapods, those pioneering four-limbed creatures who presumably clambered out of the water onto land less than 400 million years ago, was constructed. Now a report in Nature (“Vertebral architecture in the earliest stem tetrapods“) reverses everything. Parts oriented back to front turn out to have been front to back. Others thought to be front to back were back to front. That’s a pretty radical revision of the way we imagine a key piece of anatomy.
The revelation was achieved by X-ray scans of fossils representing Ichthyostega, Acanthostega and Pederpes.
The BBC talked to one of the researchers:
The researchers from the University of Cambridge and the Royal Veterinary College (RVC) used the European Synchrotron Radiation Facility (ESRF) to bombard the 360-million-year old fossils with high energy X-rays.
This enabled them to create detailed computer reconstructions of the prehistoric animals.
RVC’s Prof John Hutchinson said: “Their vertebrae are actually structurally completely different from what everyone for the last 150 or so years has pictured. The textbook examples turn out to be wrong.”
The news is interesting in its own right but more so as a reminder of how, in lightning fashion, an assumption in science going back a century and a half can be flipped right around.