Ancient fingers were discovered in a fish fossil, using a medical CT scan. The discovery sheds light on the evolution of the entire terrestrial lineage
The fish, our ancient ancestors, evolved 385 million years ago into four-legged animals. These animals, called tetrapods, got their name thanks to their four limbs and are the ancestors of all the birds, amphibians, reptiles and mammals that exist today. Because limbs and fingers play such an important role during evolution, many researchers have wondered whether these features first appeared in tetrapods, or whether they evolved from organs that already existed in primitive fish.
Previous studies that examined, among other things, the genes necessary for the development of fins in zebrafish and compared them to the gene controlling the development of limbs in mice, revealed that zebrafish lack the genetic mechanisms necessary for the development of fingers. The obvious conclusion was that fingers first appeared in tetrapods, and it was supported by 'circumstantial evidence' obtained from a Pandrichthys fossil. This fossil represents a 'transitional stage' between a fish and a tetrapod, and no remains of fingers were found in its fins.
In the current study, published in the online version of the respected scientific journal Nature, the researchers from Uppsala University and Tallinn University used CT scans to obtain a reconstructed XNUMXD image of the Pandrichtis fins. The resulting images reveal previously undiscovered parts of the fossil, which appear as initial fingers inside the fins.
Similar fingers were discovered two years ago in Tictalyx, which is closer to the tetrapod-like group. When combining the variety of new evidence in the field, together with the existing knowledge about the development of fins in the sharks and the Australian lungfishes, we receive final confirmation of the belief that fingers did not arise spontaneously in tetrapods. According to Kathryn Boisvert, the lead author of the study, "This was the missing piece of the puzzle, confirming that first fingers already existed in the ancestors of the tetrapods."
2 תגובות
Is the "proof" a reconstructed image?
I mean computer processing creates the tetrapod and then they say the proof of ancient fingers was found???
An opinion, idea or theory would be more appropriate for the situation!
Amazing! I so love huge discoveries that are seemingly discovered through simple actions... almost as elegant as mathematics.