TABLE 191 PROMINENT FEATURES OF SKULLs OF APES AND HUMANS Fe

TABLE 19.1 PROMINENT FEATURES OF SKULLs OF APES AND HUMANS Feature Apes Sagittal crest Brow ridge Foramen magnum Prognathism Canines Canine diastema incisors Chin Arrangement of teeth Humans

Solution

Prominent features of skulls of apes and humans

Feature

Apes

Humans

Sagittal crest

On the top of the skull there is a ridge of bone running lengthwise along the midline. Its presence indicates that the jaw muscles are exceptionally strong. Primarily it is for attachment of the temporalis muscle, which is one of the main muscle for chewing.

Sagittal crests are found in robust great apes, and some early hominins

Sagittal crests are found reduced or absent

Brow ridge

This is a bony ridge located just above the eye sockets. The purpose is to strengthen or support the weaker bones of the face (thus reduces vertical stress).

This is large due to the tremendous strain put on the cranium by their temporal (jaw) muscles. Without its support the eye sockets would collapse.

The brow ridge was lost in the path to modern humans

Foramen magnum

This is the hole at the base of the skull from where the spinal cord enters the brain.

It is towards the back of the skull in apes, posture was not fully upright. Thus it is at the rear of the skull in apes

It is at the fulcrum (balance point). The bones of the skull that balance on the vertebra / spine (occipital condyles) also show the same trend. Thus it is exactly at the

center in humans

Prognathism

Pronounced muzzle, the teeth protrudes out from their face.

Present

This is common in early Hominins also,

ABSENT, characterized by Flatter face

Canines

Teeth

The canines of males are considerably larger than females- Sexual dimorphism with thinner enamel

Sharper

And

have thick enamel, this is an adaption for chewing harder or tougher food materials

Inscisors

Teeth

Much larger incisors and also have a gap diastema between the upper incisors and canines

No such gap and are smaller.

Chin

The mandible or Lower jaw

is much larger supporting its food habits

is small and developed to protect a weak point in our less robust skulls.

Arrangement of teeth

more U shaped dental arcade with diastema, a gap.

V shaped dental arcade

Feature		Apes	Humans
Sagittal crest	On the top of the skull there is a ridge of bone running lengthwise along the midline. Its presence indicates that the jaw muscles are exceptionally strong. Primarily it is for attachment of the temporalis muscle, which is one of the main muscle for chewing.	Sagittal crests are found in robust great apes, and some early hominins	Sagittal crests are found reduced or absent
Brow ridge	This is a bony ridge located just above the eye sockets. The purpose is to strengthen or support the weaker bones of the face (thus reduces vertical stress).	This is large due to the tremendous strain put on the cranium by their temporal (jaw) muscles. Without its support the eye sockets would collapse.	The brow ridge was lost in the path to modern humans
Foramen magnum	This is the hole at the base of the skull from where the spinal cord enters the brain.	It is towards the back of the skull in apes, posture was not fully upright. Thus it is at the rear of the skull in apes	It is at the fulcrum (balance point). The bones of the skull that balance on the vertebra / spine (occipital condyles) also show the same trend. Thus it is exactly at the center in humans
Prognathism	Pronounced muzzle, the teeth protrudes out from their face.	Present This is common in early Hominins also,	ABSENT, characterized by Flatter face
Canines	Teeth	The canines of males are considerably larger than females- Sexual dimorphism with thinner enamel	Sharper And have thick enamel, this is an adaption for chewing harder or tougher food materials
Inscisors	Teeth	Much larger incisors and also have a gap diastema between the upper incisors and canines	No such gap and are smaller.
Chin	The mandible or Lower jaw	is much larger supporting its food habits	is small and developed to protect a weak point in our less robust skulls.
Arrangement of teeth		more U shaped dental arcade with diastema, a gap.	V shaped dental arcade