(ORDO NEWS) — The first vertebrates with jaws appeared on Earth in the early Silurian period, and it is from these fish-like creatures that all modern terrestrial vertebrates, from frogs to humans, originate.
The earliest representatives of this group are poorly known, but recently Chinese scientists were lucky to discover what may be the oldest jawed animal on the planet: the shark-like fish is about 420 million years old.
Acanthodes were strange fish, distant relatives of modern sharks, but combining features of both cartilaginous and bony fish in the skeletal structure. Unlike modern sharks, these animals had bone armor, and long sharp spikes grew in front of each fin, except for the tail.
Despite their bizarre appearance, acanthodes are directly related to modern terrestrial vertebrates, including humans: they were the oldest vertebrates that developed toothy jaws. In the future, this anatomical danger will determine the dominant position of the jaws on Earth.
Fossils of a new fish species found in the southern Chinese province of Guizhou , they represent thousands of skeletal fragments that scientists had to painstakingly put together. The fish was named fanjingshania ( Fanjingshania renovata ) – in honor of the famous UNESCO World Heritage Site located in the same province.
The body of the fanjingshan bristled with many bone spikes, and dentin was revealed in its scales, a substance that strengthens our teeth and is part of the scales of modern sharks.
Curiously, although the skeletal structure of the fish resembled sharks and rays, scientists found signs of resorption and remodeling in its bones, processes that are still observed in the development of the skeleton of bony fish and land vertebrates.
Thus, the structure of fanjingshan combined features of cartilaginous and bony fish, although phylogenetically it was still closer to sharks than to sturgeons and crucian carp.
Located at the very base of the evolutionary tree of jawed jaws, this amazing fish allows us to understand what the first animals of the Earth looked like, armed with toothy jaws – the common ancestors of all modern land vertebrates.
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