Pentamerida

Pentamerida is an order of shelled animals called brachiopods. These animals have two shell halves that fit together and are found in rocks formed from ancient seas, dating from the Middle Cambrian period through the Devonian period.

Pentamerids have a short line where the two shell halves meet, called the hinge line. They also have special areas on their shells and a raised platform inside one valve for muscle attachment. This platform is called a spondylium. These animals have feeding arms called lophophores, which 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 and split into two smaller groups. Today, scientists place Pentamerida in the Class Rhynchonellata and divide it into two suborders: Syntrophiidina and Pentameridina. The Syntrophiidina are the more simple and older of the two groups.