DIFFERENTIATING THE PARASYMPHYSIAL TEETH OF TWO SPECIES OF EIFELIAN †ONYCHODUS (OSTEICHTHYES, SARCOPTERYGII) FROM THE ONONDAGA-UNION SPRINGS CONTACT OF CENTRAL NEW YORK

The study of Devonian †Onychodontiformes of New York, particularly of the genus †Onychodus, remain understudied in light of new discoveries, particularly in the Eifelian Stage of the Dundee Formation of Ontario, Canada, and the Frasnian Stage of the Gogo Formation of Western Australia. Two species, †Onychodus sigmoides (Newberry, 1857 ) and †Onychodus hopkinsi (Newberry, 1889), were identified from the Eifelian Stage of the Onondaga-Union Springs Contact (OUSC) at the Hanson Jamesville Quarry in Jamesville, New York. Although both species were initially described from poor, partial material, †O. sigmoides is well cited in the primary literature, whereas †O. hopkinsi is considered to be an invalid species by most authors. An analysis of 55 †Onychodus parasymphysial teeth was conducted to identify representative specimens of the two species using diagnostic characters first postulated by Newberry. Teeth identified to the species level with confidence were compared to specimens of questionable taxonomic affinity. Data shows that †O. sigmoides is much more common than †O. hopkinsi. Among the previously known diagnostic features of †O. hopkinsi, the absence of sigmoidal curvature, new unique characters were identified, including a root-apex length less than 0.8 cm and presence of a distal notch. However, the rare occurrence of †O. hopkinsi, the lack of distinguishing characteristics, as well as the loose definition of the degree of sigmoidal curvature present in †O. sigmoides all indicate that †O. hopkinsi is either (1) absent from the Eifelian Stage of the OUSC or (2) not a valid species, but instead its teeth have been mistakenly identified as worn, non-sigmoidal †O. sigmoides teeth. Further sampling of and better fossils from the Hanson Jamesville Quarry would begin to address the taxonomic status of †O. hopkinsi.