Isopterygia (lit. "equal flippers") are a clade of Thalattotheria.
Isopterygians are pelagic filter-feeders, possessing a comb-like sieve to strain plankton from the water. They are the largest clade of animals yet observed on TIRA 292b, measuring around 13 meters in length. As their name would suggest, their eight flippers are of roughly equal size, providing a balance between speed and maneuverability.
Upon their emergence around 4230ma, Isopterygians have largely replaced the Ptilopods as the top-level filter feeders within the ocean, although they are restricted by their respiration to shallower waters.