plástrum

Plástrum is a term with varied meanings depending on the context, primarily found in ancient Roman culture and modern biological classification. In ancient Roman history, a plástrum referred to a type of chariot or wagon, often used for carrying goods or in parades. These vehicles were typically two-wheeled and drawn by horses. The specific design and purpose of a plástrum could vary, but the common thread was its utility as a transport or ceremonial conveyance.

In biology, plástrum is a more specific term referring to the ventral (lower) shell of a turtle or tortoise. This part of the shell is composed of fused bones, including the clavicles, interclavicles, and gastralia, and it lies beneath the plastron. The plástrum, along with the dorsal carapace, forms the protective shell that is characteristic of chelonians. Its structure and morphology can be important for taxonomic identification and understanding the evolutionary history of these reptiles. The term is derived from the Latin word for a plate or shield.