Table 4 Description of morphological differences for domesticated and wild equids for the studied sample (for a detailed sample composition see Table 2)
From: Shape variation and modularity of skull and teeth in domesticated horses and wild equids
Type | Domesticated equids | Wild equids | |||||
|---|---|---|---|---|---|---|---|
Draft horses (n = 37) | Ponies including Falabella (n = 40) | Medium horses (n = 38) | Light horses (n = 14) | Przewalski’s horses (n = 5) | Donkeys (n = 33) | Zebras (n = 47) | |
Trait | |||||||
Average skull length based on studied sample (±SD) | 56 (±2.5) cm | 43 (±3.6) cm | 52 (±4.5) cm | 51 (±2.3) cm | 46 (±2.1) cm | 41 (±4.6) cm | 48 (±4.1) cm |
General skull shape | Skull breadth is half of skull length | Skull breadth is half of skull length | Elongated | Elongated | Skull breadth is half of skull length | Skull breadth is almost skull length | Very elongated in the Grevy Zebra |
Frontals | Broad | Broad in some breeds | Broad in some breeds | Narrow | Narrow | Narrow | Narrow |
Degree of cranial flexion (after Bennett, 1980) | High | High in smaller breeds | Medium | High | Medium | High | Low |
Nasals | Convex; End at ventral end of premaxillary-maxillary suture | Concave in smallest breed, straight in larger breeds; End before ventral end of premaxillary-maxillary suture | Straight with exceptions in some breeds; End at ventral end of premaxillary-maxillary suture | Concave; End at ventral end of premaxillary-maxillary suture | Straight or slightly concave; End at ventral end of premaxillary-maxillary suture | Straight or slightly concave; End at ventral end of premaxillary-maxillary suture | Straight or slightly concave; End at ventral end of premaxillary-maxillary suture |
Angle between premaxilla and maxilla | Obtuse | Obtuse, almost straight | Straight | Straight | Right to obtuse | Obtuse to straight | Obtuse to straight |
Facial crest | Prominent | Prominent | Prominent | Less prominent | Prominent | Prominent | Prominent |
Zygomatic, temporal and postorbital bars | Very broad, Horizontal to skull midline | Broad to normal; Horizontal to skull midline | Thin, with the temporal being broader; Horizontal to skull midline | Very thin; Horizontal to skull midline | Normal; Angled to skull midline | Normal; Angled to skull midline | Very broad; Angled to skull midline |
Orbit shape | Roundish with a more squared part at the dorso-posterior edge | Almost round | Egg-shaped | Oval | Oval | Oval | Round to egg-shaped |
Zygomatic process of the temporal bone | Flat | Flat | Curved | Curved | Flat | Flat | Flat |
Length of the lambdoidal crest | Does not overlap the condyles in lateral view | Does not overlap the condyles in lateral view | Does not overlap the condyles in lateral view | Does not overlap the condyles in lateral view | Overlaps the condyles in lateral view | Overlaps the condyles in lateral view | Overlaps the condyles in lateral view |
Cranial vault | Flat | Rounded in smaller breeds | Flat | Flat | Flat | Rounded | Flat |