Ancient Primates

These flashcards cover key vocabulary and concepts related to ancient primates, their evolution, and classification.

Epochs

Periods of time in geological history marked by significant events or changes in the Earth's life forms.

New World Monkeys

Primates found in the Americas that possess features such as prehensile tails and downward-facing nostrils.

Old World Monkeys

Primates primarily found in Africa and Asia characterized by downward-facing nostrils and the presence of ear tubes.

Orthograde posture

A body posture where the body is positioned upright, typically seen in humans and other great apes.

Last Common Ancestor

The most recent individual from which all organisms in a group are directly descended.

Crown Group

All taxa that stem from a single major speciation event.

Stem Group

All taxa existing before a major speciation event, not including the crown group.

Absolute Dating

A method of determining the age of an object in years using physical or chemical properties.

Radiocarbon dating

A technique for determining the age of an object containing organic material by measuring the amount of carbon-14 it contains.

Plesiadapiforms

Early ancestors of primates resembling modern trees shrews; crucial in the study of primate evolution.

Euprimate

True primates that exhibit advanced physical traits such as forward-facing eyes and opposable fingers.

Adaptive Radiation

The evolution of diverse species from a common ancestor in response to environmental changes.

Adapoids

An early group of primates known for their arboreal leaping abilities; related to modern lemurs.

Oligocene

A geological epoch characterized by emerging anthropoid primates and significant climate changes.

Ischial callosities

Thickened skin on the buttocks of some primates, providing support while sitting.

Biostratigraphy/Faunal Correlation

A relative dating method that compares the fossils of different locations to establish their relative ages.

Morphology

Study of the form and structure of organisms, crucial in understanding evolutionary relationships.

Stratigraphy

The analysis of soil and sediment layers to determine the chronological sequence of geological or archaeological events.

Prosimian Radiation

The diversification of primates often associated with the Eocene epoch.

Hominins

Early human ancestors and their relatives, particularly those in the evolutionary lineage leading to modern humans.

Anthropoids

A sub-group of primates that includes monkeys, apes, and humans.

defining traits of mammals

body hair, live birth, mammary glands, long gestation, heterodontal teeth

what is a species

a group that can reproduce and produce fertile offspring

reproductive isolation

when populations cannot interbreed to produce fertile offspring

geographic isolation

physical barriers prevent populations from interbreeding

binomial nomenclature

two-part naming system: genus + species

general characteristics of primates

flexible limbs, grasping hands/feet, forward facing eyes, large brains

brachiation

swinging from branches using arms, seen in monkeys

knuckle-walking

walking on knuckles, seen in apes and gorillas

primate diet

generalized, omnivorous

primate vision

color vision, stereoscopic

primate dental formula

2.1.2.3 / 2.1.2.3

bunodont teeth

teeth with rounded cusps, typical in omnivores

key primate developmental traits

long gestation, few offspring, slow maturation, long lifespan

primate social tendencies

large social groups, high learning capacity

ape characteristics

no tail, longer arms than legs, large body size, complex behavior, flexible shoulders

ape habitat

africa and asia

postorbital bar

a bony ring around the eye socket

dental comb

the joint where the two halves of the lower jaw meet, fused or unfused

what leads to speciation

reproductive isolation or geographic isolation

major contributors to primate behavior

genetics and environment

sociobiology

the idea that behavior is influenced by genetics and shaped by natural selection

what questions help evaluate behavior form a sociobiological perspective

does it increase fitness? does it vary by environment? is it consistent across individuals?

altruism

behavior that benefits others but reduces the individual’s fitness

kin selection

helping relatives to increase the chance of shared genes being passed on

hamilton’s rule

altruism occurs when rB > C (relatedness x benefit > cost)

relatedness value for identical twins

1.0

relatedness value for parent/child

0.5

relatedness for grandparent/grandchild

0.25

relatedness for great relatives

0.125

reciprocal altruism

helping others with the expectation they will help you later

behavioral ecology

the study of how behavior evolves in response to environmental pressures

behavior

a response to internal or external stimuli

factors that influence primate social structure

metabolism, diet, resource distribution, predation risk

what leads to larger primate goups

high predation and small body size

why do primates disperse from their natal group

reduce inbreeding, reduce competition for mates

sexual selection

competition for mates that leads to traits increasing reproductive success

sexual dimporphism

physical differences between males and females of a species

when is the degree of sexual dimorphism high

when competition for mates is high

examples of sexually dimorphic traits

canine size, body size, sagittal crest

why might infanticide occur in primates

as an adaptive strategy to increase reproductive success

how do primates socialize

vocalizations, gestures, facial expressions, grooming

two types of social interaction

aggressive and affiliative

encephalization index

ratio of brain to body size

part of the brain that is especially developed in primates

neocortex

culture in primates

learned behaviors passed between individuals

examples of tool use in primates

macaques washing potatoes, chimps using sticks/anvils, capuchins using hammers

is culture genetic

culture is learned, but the ability to learn is genetic

solitary social group

primates live mostly alone and interact only occasionally, usually for mating

monogamous social group

one male and one female form a long-term pair bond

polyandrous social group

one female mates with multiple males

one male, multi-female social group

one dominant male lives and mates with several females

aggressive social interaction

behavior intended to threaten, compete, or harm another individual

affiliative social interaction

friendly or bonding behaviors that strengthen social relationships

tool used to reconstruct past environments

palynology (study of pollen)

principle of superposition

lower layers are older than layers above them

taphonomy

study of what happens to remains after death

what affects remains after death

weathering, animal activity, plant/botanical changes

best bones for estimating sex

skull, pelvis is most accurate

lithics

stone tools

types of lithic tools

core, flake, pressure-flaked tools

how do scientists study stone tools

experimental archaeology, microwear analysis, scanning electron microscopy, phytolith analysis

mosaic evolution

different traits evolve at different rates

hominin characteristics

bipedalism, larger brain than apes, reduced teeth size, tool use

where were the earliest hominins found

africa

when did tool use begin

around 2.6 mya

why is bipedalism important

most important adaptive shift in human evolution

spine shape in bipedal primates

s-shaped spine

where is the foramen magnum in bipedal primates

under the skull (more centered)

femoral angle in bipedal primates

angled inward <90 degrees

foot feature that supports bipedalism

longitudinal arch

how is the pelvis adapted for bipedalism

short and broad to support organs

benefits of bipedalism

carrying objects, hunting/foraging, thermoregulation, predator awareness, endurance

pre-australopiths

lived 6.01-4.4 mya

sahelanthropus tchadensis

found in chad, key traits are ape like brain size, brow ridges, reduced honing complex, more vertical spine

ardipithecus

found in ethiopia, key traits are grasping big toe, broad pelvis, early bipedal traits

australopithecus

lived 4.2-1.2 mya

australopith traits

bipedal, small brain, large teeth, thick enamel

australopithecus afarensis

lived 3-4 mya, small brain, long arms, primitive teeth

australopithecus africanus

larger brain than afarensis, smaller canines, larger molars, less brow ridge