Evolutionary Relationship between Fish Scales and Vertebrate Teeth

According to a research it has been found that teeth grew from the ancient fish scales. The research found striking similarities between teeth and small spiky scales found on cartilaginous fish such as shark and skate. These spiky scales are known as dermal denticles since they are made up of dentine. Dentine is a hard calcified tissue that makes up the majority of a tooth. The researchers made use fluorescent markers to track cell development in the embryo of a skate.

They found that the teeth and the thorny scales were made from the same type of cells known as the neural crest cells. The spiky scales called dermal denticles on sharks and skates and the vertebrate teeth are remains of the earliest mineralised skeleton of vertebrates. This skeleton is known as superficial armour plating. It is predicted that this armour would have peaked in the presently extinct jawless vertebrate species to provide protection against predation by sea scorpions. The early armour plating is supposed to be made up of multiple layers. The layers consisted of a foundation of bone along with an outer layer of dentine.

Over the course of evolution, these layers were reduced, retained or lost in different linages of the vertebrates. The dermal skeleton has gone through various alterations and reductions over time. While most of the fish have lost the dentine outer layer, the sharks and the skate have lost the bony under layer.

Content: www.sciencedaily.com –

By: Anuja Arora