Question

Dicondylic skull is characteristic of
a. Amphibia and Mammalia
b. Aves and Mammalia
c. Amphibia and reptilia
d. Reptilia and aves

Answer 1

Hint: Dicondylic skull derives its name due to the presence of two occipital condyles in the skull. The condyles connect the skull with Atlas (first vertebral column). A condyle is the round prominence at the end of a bone that forms an articulation with another bone.

Complete answer:The human skull is composed of 22 bones. The skull protects the brain. The skull incorporates the mouth and nose. The name of 22 skull bones are the: Sphenoid, Frontal bone, temporal bones parietal bones, occipital bone, ethmoid, lacrimal bones, nasal bones, vomer, inferior nasal conchae, mandible, hyoid bone, zygomatic bones, palatine bones.
Parts of the skull: The human skull consists of two main parts - the neurocranium and the viscerocranium (facial skeleton). The skull may be divided into a calvarium and facial skeleton. The space within the skull is known as the cranial cavity and it contains the brain, the cranial nerves, the blood vessels supplied to the brain, the meninges, and the cerebrospinal fluid.
Junctions of the skull: Sutures are the fibrous junctions that connect the bones of the skull. 33 sutures are present in the human skull. The most important sutures in the skull are:
1) coronal suture
2) sagittal suture
3) lambdoid suture
4) Sphenozygomatic suture
5) Sphenofrontal suture
6) Sphenosquamous suture
7) Frontonasal suture
8) Lacrimal Maxillary suture
9) Nasomaxillary suture
10) Frontozygomatic suture
The temporomandibular joint is the only synovial joint found between bones of the skull.
Openings of the skull: The skull has openings called foramina and canals. These openings serve as passages for cranial nerves, their branches and accompanying blood vessels. The largest opening of the skull is the foramen magnum in the cranial base, through which the spinal cord as an extension of the medulla oblongata exits the cranial cavity. The foramen magnum is a single opening, while most of the foramina of the skull are two (bilateral) and some are multiple, for example, the foramina of the cribriform plate. Listed below are the most important openings of the skull:
1) Supraorbital foramen (notch)
2) Foramen cecum
3) Foramina of cribriform
4) Anterior ethmoidal foramen
5) Posterior ethmoidal foramen
6) Optic canal
7) Superior orbital fissure
8) Foramen rotundum
9) Incisive foramen
10) Greater palatine foramen
11) Foramen sphenopalatinum
12) Lesser palatine foramina
13) Inferior orbital fissure
14) Infraorbital foramen
15) Foramen ovale
16) Foramen spinosum
17) Foramen lacerum
18) Internal acoustic meatus
19) Jugular foramen
20) Hypoglossal canal
21) Foramen magnum
22) Stylomastoid foramen

So, the correct answer is (A) Amphibia and Mammalia.

Note: The skull forms the head and supports the face and protects the brain. The skull forms the anterior-most portion of the skeleton and is a product of cephalisation. Functions of the skull include protection of the brain, allow stereoscopic vision, and fi ears to enable sound localization of the direction and distance of sounds. The skull is made up of several fused flat bones and contains many foramina, fossae, processes, and several cavities or sinuses. The openings in the skull are called fenestrae.