scute

A scute is an external bony or horny plate or large scale. The term is also used for a bony, horny, or chitinous plate. Scales, which are similar to scutes, are small plates or shields that form part of the outer skin layers of certain animals, providing protection.123

Horny scutes are found in reptiles and on the legs of birds, derived from the upper skin layer. In some reptiles, bony scales lie beneath these external scales. Bird feathers are essentially modified epidermal scales. Mammals can also have scaly surfaces made of keratin, though mammalian hair is not a modified scale.3

The dinosaur Scutellosaurus, from the Early Jurassic Period, is characterized by small scutes along its back and sides. These scutes were embedded in the skin and likely not very visible.4