Scientists believe an ancient variety of shark may explain why humans have jaws.
Scientists have revealed that an ancient shark that lived 439 million years ago could be the earliest ancestor of humans. What may seem like a bizarre statement is the result of the study of a Paleozoic fossil that was recovered from a site in Shiqian county in southern China’s Guizhou province.
Fanjingshania renovata , as the particular fish has been renamed, with spines on the fins and bony plates that cover it, taking its cue from the well-known site of Fanjingshan, a UNESCO World Heritage Site. It was a predecessor of the current gnathostomes , infraphylum of vertebrates characterized by the presence of a mouth equipped with jaws which is responsible for what can be defined as an evolutionary success that has led to a certain dominance on earth. Among the agnathostomes, there are also us ,as well as thousands of other mammals, fish and birds. It is distinguished from jawed fish, sharks and rays, and bony fish by its bony outer shell and numerous pairs of fin spines.
The theoretical hypothesis on the fossil is that the unusual morphological traits are a sort of missing link, the “first evolutionary branch of primitive cartilaginous fishes”.
Dr Ivan J. Sansom of the University of Birmingham concluded that the discovery ‘challenges existing models of vertebrae evolution’. He also said the discovery would have a “profound impact” on the evolutionary history of early vertebrates.
- Spiny chondrichthyan from the lower Silurian of South China. (nature.com)
