Morphotype b

Fournier, Morgane, Ladevèze, Sandrine, Verger, Kévin Le, Fischer, Valentin, Speijer, Robert P. & Solé, Floréal, 2020, On the morphology of the astragalus and calcaneus of the amphicyonids (Carnivora, Mammalia) from the Paleogene of Europe: implications for the ecology of the European bear-dogs, Geodiversitas 42 (18), pp. 305-325 : 316

Morphotype B ( Fig. 4 F-J)

Dorsal view

The sagittal groove is rather visible. The tuber calcanei is proximodistally quite elongated. The ectal facet is more inclined relative to the proximodistal axis than in other morphotypes, as well as in Cynodictis lacustris . It is strongly convex in the middle and very slightly concave in its proximal part. The edges of this facet are rather well pronounced, except the distal edge, which merges with the body of the calcaneus and is therefore difficult to delimit. The sustentacular facet is rounded and extends slightly on the proximal edge of the sustentaculum tali. It is placed more proximal on the body of the calcaneus than in the other two calcaneal morphotypes. The peroneal process and its proximal and distal edges are quite well defined. The cuboid facet is inclined with respect to the mediolateral axis and its lateral edge rises over the body of the calcaneus. The plantar tubercle is distally very long and clearly visible in dorsal view. It is longer than that of Cynodictis lacustris .

Lateral view

The dorsal and ventral edges of the tuber calcanei are very slightly concave. The cavity, proximal to the ectal facet, is deep and positioned higher on the tuber than in Morphotype A.

Medial view

The tendinous plantar groove is quite excavated.

Distal view

The cuboid facet is smaller than in Morphotype A. The plantar tubercle is ventrally quite broad. The edge separating these two structures is not very clear.

Proximal view

The proximal part of the tuber calcanei has a rather oval surface that is slightly dorsoventrally elongated.

Figures

FIG. 4. — Calcanei of undetermined amphicyonids from the Quercy (France; Priabonian-Chattian, MP18-MP30): A-E, Morphotype A, MNHN.F.Qu9845, left calcaneus (reversed views): A, dorsal view; B, lateral view; C, medial view; D, distal view; E, proximal view; F-J, Morphotype B, KUL.PLV1542_28, left calcaneus (reversed views); F, dorsal view; G, lateral view; H, medial view; I, distal view; J, proximal view; K-O, Morphotype C, KUL.PLV1542_29, left calcaneus (reversed views): K, dorsal view; L, lateral view;M, medial view; N, distal view; O, proximal view. Abbreviations:cf, cuboid facet; ef, ectal facet; lpt, lateral process of tuber; mpt, medial process of tuber; pp, peroneal process; plt, plantar tubercle; ptg, tendinous plantar groove; sg, sagittal groove; sf, sustentacular facet; st, sustentaculum tali; tc, tuber calcanei. Scale bar: 1 cm.