Human origins exam 2

Primate characteristics

General adaptive traits

Arboreal — (tree-dwelling niche) live in trees

Highly social

Forward facing orbits (forward facing eyes) for binocular vision

Reduced snout = Reduced olfaction

Primate anatomy charectristics

Large brains

Grasping hands

Forward facing eyes

Rotating shoulder joints

Fully enclosed orbital plates (chew with eyes closed)

2 unfused bones in lower arms (allow for rotation)

Primate generalized dentition

Lack of dietary specialization

Mostly omniviroius diet

Primate trait - Encephalization

Larger brain compared to body size

more complex brains

Visual areas expanded

Social implications of Encephilization

Longer gestation periods

-Singleton births (one fetus in utero)

K-Selection (Emphasis on parenting)

Learning flexibility

Greater socialability

R-selection

Energy goes into egg-production

Many off-spring with little emphasis on parenting

Lemuriforms

(Lemurs + Lorises)

Most primitive of the primate groups

Greater olfaction

Rhinarium (Moist hairless nose pad)

Reliance on scent marking

Lemuiform diet

Insectivitory

Fruit, leaves, bark.

Lemuiform charecteristics

Monogamy to large social groups

Shorter gestation lengths/litters

Tarsiers

-Grouped with anthropoids as haplorrhines

-Share behaviors with lorises/lemurs

Nocturnal behavior (large eyes)

Old-world monkey teeth (Dental formulae)

2 incisors

1 canine

2 pre-molars

3 molars

(2.1.2.3)

New world dental

2 incisors, 1 canine, 3 pre-molars, 3 molars.

(2.1.3.3.)

Other features of new world monkeys

Sideway facing nostrils

3 pre-molars

Grasping tail

Other features of old-world monkeys

downward facing nostrils

2 pre-molars

Isachail callosites

Anthropoids

“Resembling human”

-Larger bodysize/Brains

(Monkeys, apes, humans)

Features of anthropoids

No moist nose pad (Rhinarium)

-Reduced smell

Forward eyes/Color vision

Fully enclosed eye orbit

More features of anthropoids

Fused mandible at midline of chin

More generalized teeth

Longer gestation/maturation

Increased parental care

More mutual grooming

Arboreal quadrupedality

-Feature of anthropoids

Using all 4 limbs to climb trees

Terrestrial quadrupedality

-Anthropoid charecteristic

Using all 4 limbs to walk on ground

Vertical clinging/leaping

-Feature of anthopoids

Type of aboreal locomotion

Clinging to vertical surface then leaping to another

Brachiation

Type of movement; swinging from tree limb to tree limb with arms

Hominoids

Apes and humans

Absence of tail and shortened trunk

Hominoids

Altered position of shoulders allowing for suspensory feeding, behavior and locomotion.

Hominioids (apes+humans)

Greater cognitive ability, behavioral complexity.

Delayed maturation, greater infant dependency

-High emphasis on parental care (K-selected)

Last common ancestor

evolutionary link between 2 related groups

Stem group

all taxa before a major speciation event

Crown group

all taxa that stems from a SINGLE speciation event

Taxa

a group of organisms at any taxonomic rank

Flourine analysis

Bones exposed to ground water (which contains flourine)

Potassium-argon

Half-life of 1.25 billion years to produce argon

Argon-Argon

More precise can date the entire hominin record

Radio carbon

Half-life of 5,730 years any organic material can be used

Plesiadapiforms

Paleocene family

Proto-primates : Plesiadapiforms resembled modern day tree-shrews and are believed to be the first step in primate evolution

Plesiadiafiroms charecteristics

long snout, claws, absence of post-orbital bar.

-Flexible limbs and primate like molars

Paleocene

First archaic primates

Eocene

First euprimates, early strepsirrhines, haplorrhines

Oligocene

early catarrihines, precursors to monkeys + apes

Miocene

monkeys and apes, first human-like taxa

Pilocene

early hominin diversification

Plestiocene

early homo and descendents

Holocene

modern humans

Purgatorius

oldest recognized archaic arboreal primate

Euprimates charecteristics

“True primates”

Post-orbital bar, forward facing eyes, opposable fingers, greater encephilization, nails.

Sexual dimorphism

The differences we can see in physical characteristics of females/males of the same species

Sociobiology

biological basis of social behaviors

Sivapithecus

Genus of extinct apes

Orangutan like apperance, thick enemal, spent time in trees/ground

Gigantopithecus

Lived in the Pleistocene epoch in southern china

Miocene hominoid charecteristics

large body, thick enamel, primitive/derived features