More than a century ago, scientists were shocked by the discovery of an unusual fossil from the Scottish quarry. The debris suggested a toothless eel-shaped creature, potentially with a cartilage skeleton, and named after a mysterious creature 130 years later. Palaeospondylus gunni – was buried, continued to face classification. Now, using high-resolution images, a research team has finally determined that this mysterious fish may well be one of our first ancestors.
“Location Paleospondylus In the evolutionary tree, the identification of each bone element is essential, “said Tatsuya Hirasawa, an associate professor of paleontology at the University of Tokyo in Japan and the lead author of a new study describing the fossil. , With a body 4 inches (6 centimeters) long, and the unfortunate fossilization compressed its skeleton tremendously, squeezing the individual bones into a distorted mass, a paleontological nightmare to be clarified, Hirasawa told Live Science in an email.
Before the new research, scientists knew this Paleospondylus It lived during the Middle Devonian period, approximately 398 million and 385 million years ago. The fish had well-developed fins but no limbs. Oddly enough, the teeth seemed to be missing, unlike most vertebrates of this era.
Repeated attempts to locate the fish in the evolutionary tree settled the whole map. In 2004, researchers reportedly reported in the journal American scientist (Opens in new tab) that Paleospondylus it was a primitive lung fish. However, a 2016 study was published in the journal Hirasawak Zoological letters (Opens in new tab), suggested instead that he was a relative of the hagfish. A year later, a team from the Australian National University questioned the state of the fish, and instead cartilaginous fish like modern sharks.
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This taxonomic game of tennis is also not a new phenomenon. “This strange animal has fascinated scientists since its discovery in 1890 as an impossible puzzle to solve,” said Yu Zhi (Daisy) Hu, co-author of the Department of Materials Physics at the Australian National University of Canberra. he said in a statement (Opens in new tab).
The truth is that the only thing paleontologists could agree on was that no one really knew the identity of this animal.
Recently, Hirasawa and Hu, armed with micro-computed tomography (CT) scanning technology, were able to produce high-resolution digital images. Paleospondylus to date. To gather the most accurate data, they had to select the best fossils. Since 1890, a lot Paleospondylus grains have been found, but most have been damaged in some way — fossilizations or excavations — which may lead to errors in the previous classification. To avoid this problem, the authors of the new study chose specimens that had heads completely embedded in the stone. “I searched for beads that only exposed the tails, and eventually I found two specimens that only exposed part of the tail on the skin,” Hirasaw said.
The scanning of these specimens revealed several key features. One was that the inner ear was made up of several half-channels, like the ears of modern-day fish, birds, and mammals. This is significant, as the authors point out, because it puts an evolutionary gap Paleospondylus and more primitive jawless fish, like fish, which do not have this characteristic. Researchers were also able to identify features of the skull at the site Paleospondylus in a group called tetrapodomorphs, which includes all four horned creatures and their closest relatives. Most importantly, a phylogenetic study of these significant traits suggests this Paleospondylus it may not be any tetrapodomorph in the garden; it can be the ancestor of all tetrapods.
“It simply came to our notice then Paleospondylus He was a close relative of vertebrates with fins (fins) and fins similar to limbs, also known as “fish nests,” Hirasawa said. According to the researchers’ findings, Paleospondylus It is likely that it was more closely related to tetrapods with limbs than to fish and lung species than to ancient species, which would have an effect. Paleospondylus close to the previous water of the first animals that crawled ashore.
Although this phylogenetic mystery has been unraveled today, there are still many questions. Tetrapodomorphs usually have teeth, however Paleospondylus it did not have, or if it did, it failed to fossilize. He also had no apparent attachment, while his closest relatives usually did.
What can explain these anomalies? One possibility, Hirasawa suggested, is that he has lost his teeth and limbs evolutionarily. Paleospondylus. Another option is well known Paleospondylus fossils can represent the shape of the animal’s larvae or young.
“Whether these traits were lost in evolution or whether normal development was half-frozen in fossil development may never be known,” Hirasawa said. he said in a statement.
Now we have a better idea of where Paleospondylus sitting in the evolutionary tree, there is still a lot of work to be done. At this point, as at the time of the discovery, this fish is well guarded by many of its ancient secrets.
This study was published in the May 25 issue of the journal Nature (Opens in new tab).
Originally published in Live Science.