Morphotype 4

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 : 314-316

Morphotype 4 ( Fig. 3 P-T)

Dorsal view

The trochlea is shallow. The medial and lateral lips are more or less parallel to each other, but of different proximodistal lengths, and have a distal edge of the medial lip that is more proximal than the lateral lip. The proximal plantar tuberosity is a little broader than in Morphotype 3. The neck is longer than in Morphotype 3. The head is quite large and a little projected on the medial side. It has more pronounced edges than in Morphotype 3 and extends much less on the neck of the medial side of the astragalus. The medial edge of the head is well separated from the distal edge of the medial lip of the trochlea.

Ventral view

The medial and lateral edges of the ectal facet have a strong curvature. The sustentacular facet has a rhomboidal area. Its edges are well pronounced. This facet is slightly convex except on its proximomedial extension, where it becomes concave.

Lateral view

The proximomedial edge of the fibular facet is less rounded than in Morphotype 3 and therefore displays a somewhat rectangular shape. The ectal facet is sharply convex.

ll ml A B ppt tr sf n sit C D ef lp ff E h ptg F G H I J K L P Q f M N O R S T

Distal view

The axis of elongation of the head is along the mediolateral axis of the astragalus. The lateral process is very little broad.

Proximal view

The trochlear foramen is absent. The proximoventral edge of the medial lip of the trochlea forms a ventral tip. The plantar tendon groove is well marked, very inclined relative to the axis of the trochlea, and well excavated.

CALCANEUS DESCRIPTIONS

For all morphotypes, the medial process of the tuber calcanei is proximally longer than the lateral process. A groove on the proximal surface of the tuber calcanei, positioned rather ventrally, is clearly visible. The cuboid facet is larger mediolaterally than proximodistally. Three different morphotypes have been determined based on differences in size and morphology.