Researchers from Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing have found a fossil that rewrites an early part of human evolutionary history. The fish is being hailed as the ancestor of every gnathostome (creatures that have a jaw and a backbone). The discovery of this missing link, published in Nature, will shake up evolutionary history in the same way as it did when we found out that dinosaurs were covered in feathers.
The fish, hailing from the late Silurian period is about 20 centimeters (7.9 inches) long. Researchers have named it Entelognathus primordialis (which translates to primordial complete jaw). It had no teeth and a skull that was made of several small bones. Its complex arrangement of bones made Entelognathus heavily armored. It had small eyes and a scaly tail.
It had long been assumed that the ancestor of all jaws and backbones had been a creature with a cartilage skeleton, resembling a shark, and other fish evolved their bony skeletons separately. Instead, the ancestor was a less sleek animal with a bony skeleton and appears to be the “prototype of all vertebrates.” The animals that were the ancestors of fish like sharks and rays did not retain their cartilage skeletons. It appears that as they evolved, those fish abandoned the bony skeleton and reverted to a cartilaginous skeleton. This information will spark a major review of early gnathostome history.
The nearly-complete fossil has been hailed as a remarkable discovery from paleontologists from around the world. Professor John Long of Flinders University in Australia has said the discovery of Entelognathus is “the most exciting news in palaeontology since Archaeopteryx or Lucy. A true 'missing link' fossil fish has been found in China, dated at 425 million years old, which finally solves an age old problem about the origin of modern fishes.”