EXPLORING A NEW SPECIES OF ONYCHODONTID FOSSIL FISH FROM THE LATE DEVONIAN (382-360 MILLION YEARS AGO)

Onychodontids are an enigmatic group of lobe-finned fish from the Devonian Period(407-358 million years ago) characterized by a parasymphysial tusk whorl at the rostral end of the lower jaw. The group Onychodus comprises onychodontid species with a dentary ridge, and visible rib microstructure on the parasymphysial tusks. Though first described in 1857 by J.S. Newberry, species diagnosis in Onychodus is still imprecise, and many forms are described on relatively little material. Building on earlier research, the focus of this study is on fossil material recovered from the Frasnian-age, Nordstrand Point Formation on Devon Island, Nunavut, Canada, in 2011. Recent publications have further illuminated diversity of onychodontids, yet new material in this study appears to greatly deviate from described forms. We propose that this material comprises a new species within the Onychodus grouping. This new species can be distinguished from other members of Onychodus by features including a single row of dentary teeth, closely spaced parasymphysial tusks, and relatively diminutive size. This research project assembles a review of known taxa, describes a new species, and expands understanding of morphological diversity among onychodontids.