Bulongosetus is known from a single fragmentary head and trunk shield, the anatomy of which differs from other selenosteids. The fragments connected form a shield with a length of over 18 cm (7.1 in), though the size and features of its full body are unknown. It is identified as a member of the family by its large orbitals and slender posterior. Its plating is smooth and featureless. It most resembles the selenosteids Pachyosteus and Melanosteus.[1]
Paleoecology
Pachyosteomorphids had previously only been found in marine strata, indicating they were saltwater group. However, the Zhulumute Formation in which Bulongosteus was found was a braided river environment, indicating Bulongosteus could tolerate freshwater.[1][2] This corroborates earlier research which indicated placoderms could tolerate a wide range of salinities, and implies Bulongosteus may have traveled between salt and freshwater ecosystems as well.[1][3]