The discovery of Heterotidinae (Teleostei: Osteoglossidae) from the Paleocene Paskapoo Formation of Alberta, Canada

Abstract

A new fossil genus of Osteoglossidae, named dagger Joffrichthys gen. nov., is described based mainly on three articulated specimens from the Paskapoo Formation of central Alberta, Canada. This discovery suggests the occurrence of Heterotidinae in the Paleocene of western North America. The inclusion of dagger Joffrichthys gen. nov. in the Heterotidinae is supported by at least four synapomorphies: maxilla posteriorly lying on dentary part of lower jaw, horizontal arm of preopercle about as long as vertical arm, a large, irregularly wide, and trapezoidal io2, and approximately equal-sized dorsal and anal fins. The presumed dagger Sinoglossus-Scleropages-Osteoglossum relationship is not supported. This paper recognizes a Heterotidinae relationship of dagger Sinoglossus based on shared derived character slates. Three features (io1 used with antorbital. a typical ''cheek wall'' formed by io1 to io3 and covering all the area below the orbit from the antorbital to the anterior edge of the preopercle, and reticulate scales) even suggest that the eastern Asian Eocene-Oligocene dagger Sinoglossus is probably sister to the clade consisting of Heterotis and Arapaina. Two Late Jurassic and/or Early Cretaceous eastern Asian teleosts (dagger Huashia and dagger Kuntulunia) and one mid-Cretaceous South American primitive osteoglosso-morph (dagger Laeliichthys) might have some relationship with the ancestral lineages of Heterotidinae. However, evidence remains inconclusive about the early evolution of Heterotidinae.