Morphology of theSemionotus elegansspecies group from the Early Jurassic part of the Newark Supergroup of eastern North America with comments on the Family Semionotidae (Neopterygii)

We describe the morphology of Semionotus, focusing on the Semionotus elegans group from the Newark Supergroup of eastern North America. Our description is based largely on specimens from the Boonton Formation (Early Jurassic) of New Jersey because they are particularly well-preserved and include good material of both the dermal skeleton and the endoskeleton. A single anamestic suborbital distinguishes Semionotus from its sister-genus Lepidotes. We restrict the Semionotidae, defined by the presence of dorsal ridge scales between the nape and dorsal fin as well as a large posteriorly directed process on the epiotic, to two genera, Semionotus and Lepidotes. We restrict the Semionotiformes, defined by four characters and five character losses, to the Lepisosteidae, Macrosemiidae, and Semionotidae. Our study of Semionotus and previous work on Watsonulus suggest new interpretations of characters and character polarities. These data support the hypothesis that the Semionotiformes as we define them are more closely related to teleosts than either is to Amia. Analysis of the same data using PAUP suggests an equally parsimonious hypothesis that the Semionotiformes and Amia form a monophyletic group that, in turn, forms the sister-group to teleosts.