The 31 crania of the agriochoerid oreodont from the Hancock Mammal Quarry (HMQ) possess character states unique among described agriochoerid species. Characters unique to the HMQ agriochoerid include a triangular P2; a P3 with a posterolingual cone and heart-shaped occlusal outline; a P4 with separate anterolabial and posterolabial cones, but without a posterolingual conule; upper molars with large styles and lacking paraconules; lower molars without lingual cingulids, but possessing small metastylids and parastylids; and a mandibular symphysis that is perpendicular to the tooth row without ventral displacement of the p1. We subjected previous size comparisons to an F-test and Welch's t-test and found that the tooth row lengths of the HMQ agriochoerid have significantly different variance and means from Agriochoeus matthewi crassus (P = .005), a taxon to which this population has previously been assigned. Taken together, these characters are diagnostic of a new species, which we describe here as Diplobunops kardoula. The HMQ specimens show that some of the diagnostic dental characters of agriochoerids currently in use change with wear and may be biased by taphonomy. Furthermore, characters diagnostic of both Agriochoerus and Diplobunops are present in the HMQ agriochoerid, and many of the species-level diagnostic characters of agriochoerids are continuously variable or polymorphic within the HMQ population.
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1 April 2016
Systematic Reassessment of an Agriochoerid Oreodont from the Hancock Mammal Quarry, Clarno (Eocene, Duchesnean), Oregon
Meaghan M. Emery,
Edward B. Davis,
Samantha S. B. Hopkins
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