Pentamerida

Pentamerida

Pentamerida is an order of shelled animals called brachiopods. These animals have two shell halves that fit together. You can find them in rocks from very old seas, from the Middle Cambrian period through the Devonian period.

Pentamerids have a short line where the two shell halves meet. This line is called the hinge line. They also have special areas on their shells. One valve has a raised platform inside for muscle attachment. This platform is called a spondylium. These animals have feeding arms called lophophores. Their lophophores are looped like those in the Orthida.

The short hinge line helps scientists tell pentamerids apart from older brachiopods called orthids. It is not as short as in other groups like the Rhynchonellida or Athyridida.

In older science books, Pentamerida was placed in a group called Class Articulata. It was split into two smaller groups. Today, scientists place Pentamerida in the Class Rhynchonellata. They divide it into two suborders: Syntrophiidina and Pentameridina. The Syntrophiidina are the simpler and older of the two groups.