Spataru Mihaela-Claudia

Morpho-functional adaptations of the tiger skull (Panthera tigris) in relation to forceful biting

Alexandra-Andreea Cherșunaru, Mihaela Claudia Spataru, Constantin Spataru

ABSTRACT. The anatomical peculiarities of the tiger’s skull reflect the ecological and behavioural needs of this predator. The study aims to observe the morphological adaptations that grant it exceptional hunting and survival abilities. The anatomical study was conducted on the skulls of two adult male tigers. The tiger’s skull is wide and rounded, providing a robust base for the attachment of masticatory muscles, which is essential for powerful bites. The sagittal crest, a bony prominence located on the upper part of the skull, serves as an attachment point for the temporal muscles. A distinct process is present on the maxillary tubercle, from which a strong tendon of the masseter muscle originates. The nasal bones are elongated, extending beyond the frontal processes of the maxillae, while the frontal area is elevated in the region of the postorbital processes. The anterior nasal opening is narrow, and the lower margin of the mandible is typically concave, with a prominent mental process. The front part of the mandibular symphysis is concave. Compared to other large felines, tigers have a more rounded skull and a downward-sloping dorsal surface. The tiger’s skull exhibits remarkable morpho-functional adaptations, such as a robust bony head, a prominent sagittal crest, a strong mandible, and well-developed insertions for masticatory muscles. These features are essential for their predatory lifestyle, allowing them to capture and control large prey efficiently.

Keywords: adaptation; mandible; skull; tiger.

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Peculiarities of the Masticatory Apparatus of Guinea Pigs (Cavia porcellus)

Constantin Spataru, Mihaela-Claudia Spataru

ABSTRACT. Guinea pigs (Cavia porcellus) are rodents that feed on grassy plants, buds and sprouts, with cheek teeth having specialised abrasive surfaces for plant grinding. In analysing the prehension and trituration ways of guinea pigs, many differences concerning mandible conformation, the positioning of cheek teeth and the morphology of the masticatory muscles compared to other rodents were found. Masticatory muscles of guinea pigs are predominant compared to the mimetic muscles which are reduced. Compared to other rodents, in guinea pigs, inside the tendon thickness of the superficial part of the masseter muscle there are two rounded cartilaginous structures such as sesamoids. The dorsal one is larger, measuring about 3–4 mm in diameter having the role of reducing pressure on the tendon when it passes over the mandible ridge. The other is ventrally placed, about 2–3 mm in size and protects the tendon of the superficial part of the masseter muscle when it passes over the ventral tubercle of the mandible.

Keywords: guinea pig; mandible; masseter; masticator muscles; skull.

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The Morpho-Functional Peculiarities of the Synsarcosis Muscles in Red Squirrels

Constantin Spataru, Mihaela-Claudia Spataru, Ozan Gündemir

ABSTRACT. In terrestrial species, body propulsion is mostly performed via the pelvic limbs. In semiaquatic species, both pairs of limbs are used in swimming and diving, whereas in arboreal species, the pelvic limbs are used to maintain body stability. Thus, in squirrels, the synsarcosis muscles participate in body propulsion during climbing, as they have well-developed muscular bellies. Among these, the pectoral transverse muscle, which originates along the entire sternum and is inserted on the humeral crest, stands out for its width. The cervical parts of the trapezius and rhomboideus muscles are reduced and their thoracic parts more developed. As a result, muscles such as the occipitoscapularis or atlantoscapularis coordinate forelimb protraction and neck displacement. The serratus ventralis muscle is very well developed and clearly divided into cranial (cervical) and caudal (thoracic) parts; it produces a strong adduction of the thoracic limbs when the parts contract, and when they relax, a large abduction of the forelimbs is produced, enlarging the body size during jumping.

Keywords: rodent; squirrel; muscle; scapula; flexion.

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