(ORDO NEWS) — In China, scientists have discovered fossils of a creature that turns out to be the oldest jawed vertebrate ever discovered. This fossil is 439 million years old. Such an ancient creature turned out to be a fish that vaguely resembles a shark.
The vertebrate was discovered in the Rongxi Formation, a famous site where many different fossils have already been found. The Rongxi Formation is located in Guizhou Province in southern China. The scientists named this fish Fanjingshania renovata after a nearby mountain called Fanjingshan.
Thanks to the large number of surviving skeletal elements, teeth and even scales, scientists were able to accurately recreate the appearance of this creature and even simulate its movements.
What was the oldest fish
As scientists report in the journal Nature, the ancient fish F. renovata belongs to an extinct group of shark-like animals known as acanthodes, or “spiny sharks.” According to the researchers, the creature had sharp fins in the form of spikes and bony plates, which were located near their shoulder regions.
“Acanthodes” are a related species to chondrichthians, to which modern sharks and rays belong, and also have a relationship with bony fish (osteichthians).
In terms of body structure, they are similar to modern sharks, but the scales and some features of the skeleton have the features of bony fish. Scientists suspect that F. renovata is a close relative of the common ancestor of Chondrichthians and Osteichthians.
When the ancient ancestor of sharks lived
An ancient species of fish lived during the Silurian period – between 443.8 and 419.2 million years ago, about 200 million years before the dinosaurs appeared on Earth.
F. renovata is fifteen million years older than the oldest known jawed fish, and also older than the sea scorpion we talked about earlier. Therefore, at present, the find is the oldest fish and, in general, the oldest jawed vertebrate.
The discovery of a new species is of great importance for science, as it will help scientists gain more information about the stages of development of vertebrates, as a result of which they adapted to certain environmental conditions. In particular, they evolved jaws, sensory systems, and paired appendages.
Ancient fish – a unique specimen
As we said above, F. renovata belongs to the Acanthodia, as evidenced by many similarities with other fish of this species.
But at the same time, the researchers said that the fish has features that distinguish it from other fish in the group. In particular, the shoulder armor is very different from other Acanthodia. It covers a larger area than the shell of other fish. In addition, they have several fused spines that form fins.
The fish’s fins were covered with unusual tooth-like scales, which, according to the researchers, fell out and then grew back. Modern sharks have similar scales, but they do not fall out and do not grow back. Fossils of F. renovata also show evidence of resorption, the researchers said.
This process involves the destruction of part of the teeth or bones, and then their replacement with new hard tissues. Moreover, this level of resorption is unprecedented for cartilage.
Apparently, the skeleton and bones of the fish were more plastic than those of modern fish. Thus F. renovata is an excellent indicator of how the early mineralized skeletons developed.
Obviously, over time, they became more solid and durable. By the way, all skeletons that exist in nature are divided into four types, which you can learn more about here.
Finally, we note that F. renovata is not the only fish found in the Zhongxi Formation. Scientists also found fossils of the extinct jawed fish Qianodus duplicis here. It is about the same age as F. renovata – lived about 439 million years ago. However, much fewer fragments of its hard tissues have been preserved.
The researchers were only able to identify fossilized teeth and scales. Therefore, they cannot be completely sure which species the fossils belong to. It is possible that more information about them will appear in the future.
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