Diatryma, Cope, 1876

Mayr, Gerald, Mourer-Chauviré, Cécile, Bourdon, Estelle & Stache, Michael, 2024, Resurrecting the taxon Diatryma: A review of the giant flightless Eocene Gastornithiformes (Aves), with a report of the first skull of Diatryma geiselensis, Palaeontologia Electronica (a 57) 27 (3), pp. 1-19 : 4

Genus DIATRYMA Cope, 1876

Type species. Diatryma gigantea Cope, 1876 , by monotypy.

Emended differential diagnosis. Differs from Gastornis Hébert, 1855 (as exemplified by the specimens from the Reims area, which were originally assigned to G. edwardsii ) in that the scapulocoracoid is straight, with essentially no mediolateral or dorsoventral curvature; the body of the coracoid is dorsoventrally flattened (curved in Gastornis ) and pierced by a large foramen (which may or may not be homologous to the foramen nervi supracoracoidei; see description); the tarsometatarsus is stouter, with an elongation index (ratio length of bone to mediolateral width of proximal end) of less than 2.8 (2.9‒3.8 in the species of Gastornis ), the proximal and distal ends are much wider mediolaterally than the shaft, the midsection of the shaft shows a mediolateral constriction, and the trochlea metatarsi IV is more laterally splayed and the incisura intertrochlearis lateralis is wider.

Remarks. The above diagnosis is based on material referred to Diatryma gigantea , even though all of the above-listed diagnostic features also pertain to D. geiselensis . For Gastornis parisiensis , the type species of the taxon Gastornis , comparisons are made with material originally assigned to G. edwardsii .