Question

What are Cosmoid scales?

Answer 1

Cosmoid Scales

1. This type of scale is more common in lungfishes and a few fossil fishes.
2. Anatomically, it consists of two basal layers of bone, a layer of cosmine and a layer of vitrodentine which makes up the outer layer.
3. Only fossil lungfish and Crossopterygii, which include the extant coelacanth, have this form of scale.