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The jugal bone is located on either side of the skull in the circumorbital region. It is the origin of several masticatory muscles in the skull. [1] The jugal and lacrimal bones are the only two remaining from the ancestral circumorbital series: the prefrontal, postfrontal, postorbital, jugal, and lacrimal bones. [2]
The middle ear, separated by the outer eardrum in the back of the rabbit's skull, contains three bones: the hammer, anvil, and stirrup, collectively called ossicles, which act to decrease sound before it hits the inner ear; in general, the ossicles act as a barrier to the inner ear for sound energy. [71]
The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. [1] In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. [2] The bone forms an ancestral component of the dermal roof and is typically thin compared to other skull bones. [3]
Rabbits and hares move by jumping, pushing off with their strong hind legs and using their forelimbs to soften the impact on landing. Pikas lack certain skeletal modifications present in leporids , such as a highly arched skull, an upright posture of the head, strong hind limbs and pelvic girdle, and long limbs. [ 19 ]
Like other jackrabbits, the black-tailed jackrabbit has distinctive long ears, and the long powerful rear legs characteristic of hares.Reaching a length about 2 ft (61 cm), and a weight from 3 to 6 lb (1.4 to 2.7 kg), the black-tailed jackrabbit is the third-largest North American jackrabbit, after the antelope jackrabbit and the white-tailed jackrabbit.
Diagram of a wolf skull with key features labelled. In mammals, the rostrum is that part of the cranium located in front of the zygomatic arches, where it holds the teeth, palate, and nasal cavity. [6] Additionally, the corpus callosum of the human brain has a nerve tract known as the rostrum.
Cephalic index viewed from above the head. The cephalic index or cranial index is a number obtained by taking the maximum width (biparietal diameter or BPD, side to side) of the head of an organism, multiplying it by 100 and then dividing it by their maximum length (occipitofrontal diameter or OFD, front to back).
From top to bottom (A) a skull of an Anapsid, (B) a Synapsid (stem-mammal) skull, and (C) a Diapsid skull. [a] Temporal fenestrae are openings in the temporal region of the skull of some amniotes, behind the orbit (eye socket). These openings have historically been used to track the evolution and affinities of reptiles.