Comparison of Skull in Various Vertebrates

Learn about the comparison of skull in various vertebrates.

Comparison: Vertebrate # Bufo (Fig.22):

1. The back part of the skull bears a large hole posteriorly, the foramen magnum. The foramen is bounded by two exoccipitals at the sides, each bearing an occipital condyle.

Anteriorly, there is a cartilage bone, the sphenethmoid.

2. The roof of the cranium is formed by a pair of fronto-parietals and the floor by a dagger-shaped paraphenoid.

3. The auditory capsule is ossified and consists of a single bone, the prootic. Behind the Otic Process a fenestra ovalis is present.

4. The nasal capsules are in front of the cranium and separated by the mesethmoid bone. They are roofed by two broad tapering nasals and floored by two vomers.

5. The upper jaw consists of two series of bones. The outer series of each side bears, premaxilla, maxilla and quadratojugals and the inner series of each side bears, a palatine, a pterygoid and a quadrate. A squamosal connects the otic capsule with the angle of the upper jaw.

6. The lower jaw consists of a pair of rods, the Meckel’s cartilages. The two cartilages are joined by ligament. The bones are dentary, angulosplenial and mentomeckelian cartilage bone.

7. The sutures are distinct.

Comparison: Vertebrate # Calotes (Fig. 23):

1. The back part of the skull bears a large hole posteriorly, the foramen magnum. The foramen is bounded by two exoccipitals at the sides, the supraoccipital above and the basioccipital below which form the single condyle. The sphenethmoid is absent.

2. The roof of the cranium is formed by paired frontals and parietals. The parietals enclose a median hole, the parietal foramen. On each side, in front and behind the forntals are pre- and post-frontals. The floor is made of much reduced basis phenoid and parasphenoid.

3. The auditory capsule bears three ossification; prootic, epiotic and opisthotic. The exoccipital and the opisthotic bear horizontal processes, the parotic processes.