The scientists named the species renewed fanjingshania, after a nearby mountain known as Fanjingshan. Researchers in China preserve the remains of a 439-million-year-old shark-like fish with unusual features that “set it apart from any known vertebrate,” or animal with a backbone.
The bizarre creature, covered in spines and “bone armor,” is some 15 million years older than previously known jawed fossils, making it the oldest jawed vertebrate ever discovered, according to a new study. Experts will find the remains of the newly identified and extinct species in the Rongxi Formation, a well-known fossil bed in southern China’s Guizhou province.
The fossils date back to the Silurian, a very important geological period in Earth’s life that ended 419 million years ago. It belongs to an extinct group of shark-like creatures known as acanthodiusalso called “spiny sharks”, which have spiny fins and bony plates around the shoulder area.
On the fish family tree, acanthods are placed between the chondrichthyans, which include modern sharks and rays, and the osteichthyans, or bony fish. Acanthodians have a body similar to that of sharks, but their skin plates and bony skeletons are similar to those of bony fish. Researchers suspect that F. renovata may be a close father of the undiscovered common ancestor of the two groups.
Specialists are especially interested in the appearance of jawed fish because their evolution was an important point in the diversification of vertebrates. The discovery helped researchers “obtain much-needed information about the evolutionary steps that led to the origin of important vertebrate adaptations, such as jaws, sensory systems, and paired suspects,” Min Zhu, a co-author of the study, said in the statement. and paleontologist from the Chinese Academy of Sciences.
Although F. renovata shares multiple characteristics with acanthodiums, the researchers said they also had other traits that set them apart from others in the group. One of the main differences it’s in the fish’s shoulder armor, which covers a larger area than the armor of other acanthodians and is fused with multiple spines, according to the researchers. The creature’s spiny fins were also covered in unusual scales, tooth-like clumps, which the team suspect fall off and grow back. Similar scales are seen in modern sharks, but they are not replaced in this way, according to the statement.
The team collected thousands of fossilized skeletal fragments, scales and teeth from the site and then painstakingly recreated the look that the ancient fish might have had.
The fossilized bones of F. renovata also show evidence of a process known as reabsorption, when parts of the bones or teeth break and are posterior later, often during the development of the organism. “This level of hard tissue modification is unprecedented in chondrichthyans,” lead study author Plamen Andreev, a paleontologist at Qujing Normal University in China, said in the statement. And he concluded: “It shows a greater plasticity than is currently understood of how the first mineralized skeletons develop and points to the evolutionary origins of modern skeletons, including those of humans.”
