The Skull of Quadruped and Bipedal Vertebrates. Djillali Hadjouis

by the development of its third digit (also in the Rhinoceros and Tapirs), the second and fourth being vestigial. The last phalanx ending in a powerful hoof supporting a body with symmetrical postural balance in each leg (Figure 2.4). The cephalo-caudal axis shows a template whose withers and rump illustrate a masterful structure reminiscent of the suspension bridge (Figure 2.3). In fact, the fore and rear-end are in a front-to-rear axis at equidistant height. The spine, from the first four thoracic vertebrae to the caudal vertebrae, shows a curvature with a lower concavity. The cantilevered head is positioned high, due to a verticalized cervical spine, exceeding in height the withers by five cervical vertebrae. Because of this balance, the gravitational forces have developed the same robustness in the fore and hind limbs, including both sexes. In spite of a little apparent sexual dimorphism on the bones, only the absence of canines in the mare constitutes a difference.

Figure 2.3. Posture of the horse’s head and quadruped body. The Equidae are often used as an example to represent perfectly balanced posture and locomotion. The withers and the rump are located at the same height with a center of gravity positioned in the middle; the head is held high up by a verticalized neck that passes the withers by five cervical vertebrae (© Hadjouis and Le Bihan)

Figure 2.4. Probable hybrid calvarium of a horse (Equus sp.) and mandible from above showing the symmetry of the paired dental and cranial parts (© Hadjouis)

      The wild and domestic forms, free of transport, draught and pack work, do not present any particular post-cranial asymmetries. Similarly, occlusion is perfectly balanced and only animals in captivity develop abnormalities or particular dental pathologies due to tooth wear against the bars of menageries.

      2.1.4. Joint pathologies in service horses

Among domestic horses, with the exception of riding horses, many castrated forms that have allowed for increase in size have been used since Antiquity for multiple jobs. Those used for the transport of heavy loads or ploughing have developed severe arthropathies (osteoarthritis and/or arthritis) in the thoracolumbar spine and in the distal segments (carpals and metacarpals, tarsus and metatarsus). These osteo-articular manifestations have in some individuals stiffened entire regions (vertebral welds, carpo and tarso-metapodal welds, etc., Figures 2.5 and 2.6). Other bone diseases known to occur in horses include osteomalacia, developed especially in the brood mare during gestation, laminitis (inflammation of the flesh of the foot which deforms the hoof) most often resulting from forced labor on poor ground, recessed foot (tightening of the posterior parts of the foot) or bleeding (bruising produced by the tightening of the heels (Blanc 1983)).

Figure 2.5. Inflammatory lesions involving osteoarthritis on a horse’s lumbar spine, caused by heavy service work during the 19th century in Arcueil (draught and/or ploughing). Note the intervertebral osteophysical formation (© Hadjouis)

Figure 2.6. Inflammatory lesions involving osteoarthritis on the L4-L5 of horses, caused by heavy service work during the 19th century in Arcueil (draught and/or ploughing). Note the intervertebral osteophysical formation (© Hadjouis)

The archeological sites of the Paris Basin have yielded skeletons of horses, donkeys and hybrid forms from all periods presenting important pathologies related to various jobs.

      2.1.5. Introduction to animal bone pathologies and zoonoses

      Since the Paleolithic, mosquitoes and animals have been in contact with humans through which the majority of infectious or parasitic agents have had as breeding grounds different species, whose great contamination revealed its first symptoms during the Neolithic period.

      Some of these infectious diseases, especially those of epidemic origin such as the plague (Yersinia pestis) or parasitic diseases such as malaria (Plasmodium falciparum), are systematically researched by laboratory teams, and particularly the skeletons that are part of the burial complexes that are currently being excavated. Because zoonoses (diseases transmitted by animals), vectors of parasitic illnesses developed after the sedentarization and breeding of animals since Neolithic times, are becoming more and more significant by promoting the emergence of pathologies carried by domesticated species: mange, roundworms, ringworm in dogs, bovine tuberculosis, measles, chickenpox, distomatosis in cattle, Malta fever, small fluke in goats and sheep, tapeworm in pigs, influenza in migratory birds and plague in rodents (Biraben 1995). While the epidemic spread has occupied these territories for several centuries, we must not neglect thalassemia, also known in this same Mediterranean region, particularly in Greece since the Bronze Age. For Biraben (1976), the existence of the plague before its penetration into Europe can be traced back to the 2nd century BCE. Its traces were found in the Mediterranean all along the route corresponding to the late Phoenician expansion, and also to the Roman conquest. The example of tuberculosis is well known in Egypt through DNA, radiography and macroscopy, while elsewhere it remains unknown as for other infections, because it is not systematically researched due to the lack of adequate programs.

      2.1.6. The horse’s status over the centuries

      The horse’s status during Antiquity was very high, to the point where the binomial of the species Equus (name of the genus) and caballus (name of the species, designating gelding or pack horse) took on a double meaning. The qualities and virtues of the horse were praised in the Middle Ages, considering the species as faithful to its master and ardent in combat. The horse was also used as a service animal, in daily life (an animal for transport, draught and pack animal) (Duchet Suchaux and Pastoureau 2002). The place occupied by the horse during the Middle Ages was linked to the development of equestrian enterprises.

      In the foreword by Assia Djebar of the académie française, written for Salah Guemriche’s dictionary of French words of Arabic origin (2007), she says about horses:

      I give myself the free pleasure of parading in front of you, precisely in equestrian art, the 9 terms of which at least 6 are a summary of the different breeds of horses. Imagine, dear reader, that you dreamed of having, supreme luxury, in your stable, 6 exceptional horses: one day you would ride the chestnut – which, according to its Arabic root, is distinguished by the reddish-fawn color of its coat; on the second day, your choice would be a zain horse – whose coat is of a single color without white fur; on the third day, your preference would be for a strawberry roan horse – with a grayish, but mottled color; on the fourth day, you would be proud of your aubin, which is a small horse from Ireland … Then perhaps your gelding – which is