Hominim Evolution

Question 1

What is the classification of primates?

Answer 1

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates

Question 2

What are characteristics of primates

Answer 2

Unspecialised pentadactyl limbs
Nails instead of claws
Forward-facing eyes
Decreased olfaction
Reduced snout (excepting lemurs and prosimians)
4 incisors in upper +l ower law
Well-developed brain
Cyclical reproduction
Long period of parental care of young

Question 3

What is the significance of nails instead of claws in primates?

Answer 3

Nails allow prehensile capabilities - claws cut into palms

Question 4

What is the significance of forward-facing eyes in primates?

Answer 4

Enables overlapping fields of vision (stereoscopic vision)

Which allows for accurate judgement of distances.

Question 5

What are prosimians? Give 3 examples.

Answer 5

Primitive primates

Lemurs
Lorises
Tarsiers

Question 6

What are new world monkeys? Where are they found? What are some characteristics?

Answer 6

Marmosets, spider monkeys, howler monkeys, capuchins

Found in Central and South America

Prehensile tails
Quadrupeds

Question 7

What are old world monkeys? Where are they found? What are some characteristics?

Answer 7

Baboons, rhesus monkeys

Asia and Africa

Don’t have prehensile tails
Social, live in troupes
Have ischael callosities

Question 8

What are hominoids? What are some characterstics?

Answer 8

Apes and humans

Lack tails
Brain proportionally larger, w more convolutions
Lower-crowned teeth
Semi-erect posture
Scapula on back, not sides
More efficient placenta.

Question 9

What is the trend of size of the cerebral cortex, going from prosimians to anthropoids?

Answer 9

Generally increases (larger + rounder head)
More highly evolved primates have more convolutions in the brain

Question 10

What are the trends in digits, going from prosimians to anthropoids?

Answer 10

Increased independent movement
Nails instead of claws, better for grasping

Humans have lost opposable big toe, result of bipedalism
Also have large amount of contact between index finger and thumb
Allows for power + precision grip

Question 11

What is the trend in prognathism and dentition, going from prosimians to anthropoids?

Answer 11

Reduction, face becomes flatter
A chin appears in recent hominim fossils - attachment point for lip muscles
Size of zygomatic arch decreases
Relative size of jaw decreases
Dental arcade moves from “deep u” to parabolic shape