Morphotype 1

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 : 313

Morphotype 1 ( Fig. 3 A-E)

Dorsal view

The trochlea is somewhat shallow. Its medial and lateral edges are more or less parallel to each other and are of different proximodistal lengths, the lateral edge being much shorter than the medial one. The proximal plantar tuberosity is present and slightly broad. The neck is thin, short and more mediolaterally extended than the head. The head is broad and projected on the medial side. It has strongly pronounced edges, rising on the neck at the medial side of the astragalus and reaching the level of the most distal edge of the trochlea.

Ventral view

The medial and lateral edges of the ectal facet have fairly strong curvatures. The foramen at the proximal level of this sinus is visible on some specimens.The sustentacular facet is quite large and occupies a large part of the neck width. It looks almost rhomboidal and its edges are strongly marked. The facet is slightly convex except on its proximomedial extension, where it becomes concave.

Lateral view

The proximomedial edge of the fibular facet forms a nearly right angle with the distal edge.The distal edge is flat, giving the facet a rectangular appearance. The ectal facet is shallow.

Distal view

The head has a groove in the center. The axis of elongation of the head is in the mediolateral axis of the astragalus. The lateral process is poorly broad.

Proximal view

The proximoventral part of the medial edge of the trochlea forms a ventral tip. The trochlear foramen is absent. The tendinous plantar groove is strongly excavated, rather mediolaterally thin, inclined with respect to the axis of the trochlea, and very deep.