Paleontologists in Canada have found the remains
Scientists from Britain and Canada found in Western Canada remains of fish, which is probably the ancestor of all modern and extinct inhabitants of the seas and freshwater bodies. Description of fossils and assumptions about its significance to the history of the evolution of life on Earth published in an article in the journal Nature .
Jean-Bernard Caron of the University of Toronto and his colleague Simon Morris from Cambridge University has for decades carried out excavations in South-Eastern British Columbia (province in Western Canada), where lie the rocks of the so-called Burgess shale. They were formed at the bottom of the primary ocean of the Earth 509-505 million years ago, in the Cambrian era, during which he conceived and began to develop multicellular life.
The Burgess shales and their Chinese counterpart, Maotianshan are considered a kind of El Dorado of modern paleontology — only in strata preserved imprints of cartilage, bones and soft tissues of the first vertebrates. Despite the richness of these shales, scientists know almost nothing about how it looked the first fish as they emerged and evolved in the first era after the Cambrian explosion.
Caroni Morris found, apparently, the final answer to these questions by studying the fossilized remains of the ancient inhabitants of the oceans found in the so-called marble Canyon — previously unknown to scientists parts of the Burgess shale, which is open by the authors in 2020 in the national Park of Kootenay. In just two weeks of excavation in the canyon they found hundreds of fossils of large marine animals, including a creature that scientists have ranked as the mind Metaspriggina walcotti.
This is not a new kind: the first fossils of Metaspriggina walcotti had been discovered on the territory of “big” Burgess two years ago. The remains are preserved so poorly that their discoverers could not recover the General features of his appearance, or even to understand whether their owner vertebrates. The Caron and Maurice managed to find over a hundred prints Metaspriggina walcotti shales in Marble Canyon, many of which are preserved so well that they can see the smallest details of the structures of the eye, the muscles and other soft tissues.
After studying these fossils, the authors concluded that Metaspriggina walcotti is the most primitive form of fish that was ever opened by man. This is evidenced by archaic teardrop body “perparimi”, almost not decorated skull, as well as the lack of fins and many other features of the modern inhabitants of the sea. Other anatomical features of this creature — the device head, V-shaped arrangement of muscles and a rudimentary nostrils — make her related to fish and not allow to carry Metaspriggina walcotti of the chord to a more primitive animals, from which up to the present day survived only lanzetti.
“Pervolia” has several features that may force scientists to rethink current ideas about the evolution of ancient vertebrates. So, a large number of muscle fibres in her body shows that Metaspriggina walcotti was able to swim quickly, which is contrary to the ideas of slow and sedentary fish ancestors. From the point of view of science more important discovery was that “Pervolia” had not one, but two sets of Gill arches.
As explained by paleontologists, first fish on Earth had no jaws, and they ate the food, sucking the pieces through the mouth or swallowing it whole. Jaws came only after millions of years of evolution in the result of merging the “petals” in the lower pair of Gill arches. Modern lampreys and hagfish, which have always been considered analogous to the most ancient fishes, have only one set of gills, forcing many scientists to believe that the second pair of arcs appeared in fish.
The remains of Metaspriggina walcotti show that the first fish of the Earth possessed two sets of Gill arches from the very beginning of their existence on the planet. According to Caron and Maurice, it no longer allows you to liken the ancient fish lampreys and mixins, and suggests that the evolution of jaws could begin almost from the moment of appearance of the first fish.
“It is obvious that modern jaw fish appeared much later, but the emergence of Metaspriggina in the primary ocean of the Earth was the first step towards this — it has all traits of anatomy, which were necessary for the appearance of jaws. This is not only a key discovery, which will play a key role in uncovering the history of the emergence of the first vertebrates, but also a vivid testimony to the fact that Marble Canyon has enormous scientific potential,” concludes Caron.