FIGURE 1. Skull remains of Diatryma geiselensis from the middle Eocene of the Geisel valley, Germany. A-B, the newly identified, almost complete skull GMH XVIII-1178-1958 in left lateral (A) and right lateral (B) view. C- F, the upper beak GMH XLI-200-1968 in left lateral (C), right lateral (D), dorsal (E), and ventral (F) view; the arrow indicates an enlarged detail of the nostril. G, detail of the upper beak of GMH XVIII-1178-1958, the dotted line denotes the superimposed shape of the culmen of GMH XLI-200-1968. H, upper beak (ventral view) of D. gigantea from the early Eocene of Wyoming, USA (AMNH 6169); from Matthew and Granger (1917).
Abbreviations: cdo, condylus occipitalis; ftp, fossa temporalis; fur, furrow rostral to nostril; nfh, nasofrontal hinge; nos, nostril; par, processus paroccipitales; ppo, processus postorbitalis. The scale bars equal 50 mm.
FIGURE 2. Skulls, upper beaks, and mandibles of gastornithiforms. A, skull of Diatryma geiselensis from the middle Eocene of the Geisel valley, Germany (GMH XVIII-1178-1958). B, upper beak and mandible of D. geiselensis (GMH XLI-200-1968) superimposed on the skull of D. gigantea (mirrored, from Matthew and Granger, 1917). C, skull and mandible of D. gigantea from the early Eocene of Wyoming, USA (AMNH 6169); from Matthew and Granger (1917), modified. D, upper beak (right lateral view) of Gastornis laurenti from the early Eocene of La Borie, France (MHNT.PAL.2013.15.1). E, upper beak fragment (left lateral view) from Cernay-lès-Reims (MNHN R2583), which was tentatively referred to G. russelli by Martin (1992).
Abbreviations: ftp, fossa temporalis; nos, nostril; orb, orbit; pco, processus coronoideus; ppo, processus postorbitalis. The scale bars equal 50 mm.
FIGURE 3. Gastornithiform mandibles. A-B, Diatryma geiselensis from the middle Eocene of the Geisel valley, Germany (GMH XLI-200-1968) in left ventrolateral (A) and right dorsomedial (B) view. C‒E, D. geiselensis (GMH XIV-4730-1956) in right ventrolateral (C) and left dorsolateral (D) view; E, left mandibular ramus in lateral view (the right ramus was digitally removed). F-G, Gastornis parisiensis from the late Paleocene of Mont de Berru, France (MHNT.PAL.2012.1.1) in dorsal (F) and left lateral (G) view.
Abbreviations: pco, processus coronoideus; pra, processus retroarticularis. The scale bars equal 50 mm.
FIGURE 4. Scapulocoracoids and coracoids of gastornithiforms. A‒E, nearly complete right scapulocoracoid of Gastornis parisiensis from the late Paleocene of Mont de Berru, France (MNHN BR15750 [erroneously given as 45750 by Martin, 1992]) in ventrolateral (A) and dorsomedial (B) view (the arrow denotes an enlarged detail of the bone), right coracoid in ventral (C), medial (D), and sternal (E) view. F, left coracoid of G. parisiensis from the late Paleocene of Mont de Berru (MNHN R4151) in dorsal view. G‒J, Gastornithiformes, gen. et sp. indet., right coracoid from the late Paleocene of Walbeck, Germany (MLU_GeoS WAL347.2007) in dorsal (G), ventral (H), omal (I), and sternal (J) view. K-L, partial scapulocoracoid of D. geiselensis from the middle Eocene of the Geisel valley, Germany (GMH XLI-200-1968, right side) in ventral (K) and dorsal (L) view. M-N, partial scapulocoracoid of D. geiselensis from the middle Eocene of the Geisel valley (holotype, GMH Dia 2, right side), in ventral (M) and dorsal (N) view. O‒Q, nearly complete scapulocoracoid of D. gigantea from the early Eocene of Wyoming, USA (AMNH 6169, right side) in ventral (O-P) and dorsal (Q) view; O is from Matthew and Granger (1917) and shows the original condition of the specimen, which has experienced damage to exposed parts.
Abbreviations: cor, coracoid; cts, cotyla scapularis; fah, facies articulares humerales of scapula and coracoid; fns, foramen nervi supracoracoidei; fur, furcula; ntc, notch in the scapulocoracoid of D. gigantea; sca, scapula. The scale bars equal 50 mm.
FIGURE 5. Tarsometatarsi of gastornithiforms; the specimens in the top row are shown in their relative sizes to each other, those in the bottom row (except for P and Q) are scaled to the same size to illustrate different proportions; except for H, the top row shows the dorsal view, whereas the plantar view is depicted in the bottom row and in H. A‒D, Gastornis parisiensis from the late Paleocene of Mont de Berru (France), casts of tarsometatarsi from private collections (A-B: MNHN L3093, right side; C-D: MNHN L3092, left side). E-F, G. russelli from the late Paleocene of Mont de Berru (MNHN R3560, left side). G, G. laurenti from the early Eocene of La Borie (France) (MHNT.PAL.2018.22.2, right side). H-I, Diatryma geiselensis from the middle Eocene of the Geisel valley, Germany (GMH Dia 12, left side). J-K, D. geiselensis from the middle Eocene of the Geisel valley (GMH XLI-200-1968, right side). L, distal end of left tarsometatarsus of D. sarasini from the early Eocene of Monthelon (France), uncatalogued cast in GMH; the dotted line indicates the reconstructed trochlea metatarsi IV, which is not preserved in the fossil. M-N, D. gigantea from the early Eocene of Wyoming, USA (AMNH 6169, right side); the erroneously restored midsection of the shaft was digitally removed and the bone was shortened to match its original proportions (see Martin, 1992: figure 5 and Andors, 1992: figure 8 for a complete tarsometatarsus of the species). O, Diatryma sp. from the early Eocene of the Isle of Sheppey (left side, collection of Scott Moore-Fay; additional figures of the specimen can be found on http://sheppeyfossils.com/pages/gastornis_sp.htm). P, D. geiselensis (GMH XLI-200-1968), distal end of mirrored right tarsometatarsus in plantar view. Q, D. sarasini (cast in GMH), distal end of left tarsometatarsus in plantar view; the dotted line indicates the reconstructed trochlea metatarsi IV, which is not preserved in the fossil. The trochleae metatarsorum are identified by Roman numerals.
Abbreviations: fvd, foramen vasculare distale; iil, incisura intertrochlearis lateralis. The scale bars equal 50 mm.
FIGURE 6. Schematic hypothesis of the interrelationships of gastornithiforms as proposed in the current study; the grey bars indicate the stratigraphic and temporal relationships of the species. Note that this tree is not based on a formal analysis and merely serves to visualize the phylogenetic proposal made in the study. The nodes can be characterized as follows: 1 - coracoid with poorly developed processus acrocoracoideus and with mediolaterally very wide body; 2 - scapula and coracoid co-ossified to form a scapulocoracoid; 3 - tarsometatarsus short and stocky (elongation index of less than 2.8), with wide proximal and distal ends and mediolaterally waisted shaft, straight scapulocoracoid; scapula and coracoid are situated in the same plane and are not angled relative to each other.
FIGURE 7. Femora (A‒C) and tibiotarsi (D‒F) of Diatryma geiselensis from the middle Eocene of the Geisel valley, Germany, to illustrate the different sizes of the specimens. A, GMH XLI-200-1968; right side, caudal view. B, GMH XXXV-481-1963; right side, carnial view. C, GMH XIV-2042-1956; left side, cranial view. D, GMH XLI-200-1968; right side, craniolateral view. E, GMH XIII-40-1954; right side, cranial view. F, GMH XXXV-481-1963; left side, cranial view. The scale bars equal 50 mm.
FIGURE 8. A, Partial synsacrum of Diatryma geiselensis from the middle Eocene of the Geisel valley (GMH XLI-200-1968, ventral view) with a preserved gastrolith in the framed area. B, Enlarged detail of the framed area in A. The scale bars equal 50 mm.
