Four-legged animals earlier than expected (apparently)

2010/01/07 Lakar Iraizoz, Oihane - Elhuyar Zientzia

• Eboluzioa
• Zoologia
• Paleontologia
• Arkeologia

Researchers from Warsaw University of Poland and the Swedish Uppsala University have discovered traces of 395 million years ago in an abandoned limestone mine in Poland. The finger shapes that appear in some of these footprints and the paths that suggest several clusters of feet have made scientists think that they were abandoned by some four-legged animal. So far, experts considered that tetrapods appeared 18 million years later.

The discovery has been published in the journal Nature and, according to the researchers, will radically modify some of the beliefs that were considered true about the origin of tetrapods. For example, until now it was thought that the first tetrapods moved from freshwater areas to land. On the other hand, the discovered traces are found in an area of saltwater lagoon, as it follows from the surrounding surface and invertebrates.

However, some experts who have not participated in this study have been very cautious with the news. Nature itself has revealed the opinions of several paleontologists. Some say that they do not have to be the traces of an animal, but the traces produced by natural processes. Others claim that until fossils are found they cannot be considered true. However, the scientists who have conducted the research have firmly maintained their conclusions and claim that it is not possible to create signs of such a clean fingerprint through natural processes.

Image courtesy of: In the image above you can see the details of a footprint found and, next to it, the image made from it. In the lower one appears a taco of traces, next to which you can observe the operation of the animal to leave them. Per Ahlberg et al. Nature