Acregoliathidae (Osteichthyes, Teleostei), a new family of fishes from the Cenozoic of Acre State, Brazil

A new fossil fish family (Acregoliathidac) with only one known species ( Acregoliathidac rancii gen. et sp.n.) is described. The material consists of large Scales coming from the Plio‐Pleistocene of Acre State, Northern Brazil. Studies involving X‐ray radiograph, SEM and optical microscopic methods demonstrated the peculiarity of the new materia1. whose affinities with the classical fish scale models are hardly evident. The scales of A. rancii are round, with large exposed and emberddted areas. They bear concentric circuli and the posterior fields is covered with many layers of a glassy and birefringent tissue. Two bony layers are clearly distinguishable: the basal isopedin and, above, an important cell‐containing spongiosa (protohaversian bone tissue). The affinities of the fossil with both sarcopterygian and actinoplerygian fishes are discussed and the Acregoliathidac are considered to be teleostean fishes of uncertain systematic relationships with other families or oders of this subdivision.