The hinges come to a point, a superficial resemblance to many (phylogenetically unrelated) bivalve mollusk shells.

The loss of the hinge line was an important evolutionary innovation, rhynchonellids being the first truly non-strophic shells with a purely internal articulation (teeth-sockets).

This means that the commissure, the line between the two valves or shells, is zigzagged, a distinguishing characteristic of this group.

It seems to have evolved from pentamerids, and in turn gave rise to the first atrypids and athyrids, both of which are characterized by the development of a complex spiral brachidium.

Although much diminished by the terminal Paleozoic extinction, it experienced a revival during the Early Jurassic period, and became the most abundant of all brachiopods during the Mesozoic Era.