Print ISSN: 0031-0247
Online ISSN: 2274-0333
Les traces de pas de Dinosaures et autres Archosaures du Lias inférieur des grands Causses, Sud de la France
Les traces de pas d'amphibiens, de dinosaures et autres reptiles du Mesozoïque Français
Field trip guides/EAVP Annual Conference/2023
Werneburg et al. New Permian Caseid from France
Hypoplasia: CT-scan or naked eye?
Reconstruction of the cervical skeleton posture of the recently-extinct litoptern mammal Macrauchenia patachonica Owen, 1838biomechanics; cervical posture; functional anatomy; Litopterna; Macrauchenia
Macrauchenia patachonica was among the largest litopterns. It had a long neck with elongated cervical vertebrae, unique among endemic South American ungulates. We calculated the pattern of stress in the joints between the vertebral centra along the neck of the recently-extinct litoptern mammal M. patachonica for various hypothetical neck postures to determine which one is optimal. We also determined the zygapophyseal alignment positions for the neck, assuming a wide range of values for the thickness of the intervertebral discs. We concluded that a vertical posture is the one that best meets the requirements of nearly constant stress. This upright posture was probably a frequently adopted posture by M. patachonica while feeding or standing. It is also possible that occasionally it could adopt a gerenuk-like posture. In almost any other position, the standard deviations of stress values (SD) divided by mean stress (MS) have values between 0.4 and 0.5. Since it was a mixed feeder, M. patachonica probably used different postures to reach resources at different heights. However, an almost horizontal posture was required for the optimal articulation of the neck vertebrae. It probably represents the posture during fast locomotion, as suggested in a previous biomechanical study of locomotion.