Referred Material

41240.

Distal right humerus, DMNH

provenance Location 1349, Mark's Sink, level 27.

DESCRIPTION This specimen is similar in size and most characters to the living Podiceps auritus (Horned Grebe) but differs in having a relatively shallower impression of brachialis anticus and deep fossa on the entepicondylar prominence. It may represent an extinct species. However, of the five known fossil species that have been described from North America, all are either larger and more robust than P. auritus or are not represented by the humerus (see Murray [1967] and Emslie [1995] for a review of these fossil species). It is unlikely that DMNH 41240 represents any of these species. One extinct genus and species, Pliolymbus baryosteus Murray, 1967, is smaller than P. auritus and has a deep impression of brachialis anticus (Murray, 1967). Additional material is needed to assess further the taxonomic position of this fossil specimen.

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