Anthro196 Final Exam

Deep Time

Created by Carl Sagan and places the entire existence of the universe (15 billion years) in one calendar year

Geological Time Scale of Vertebrae Evolutionary History

Dividing up deep time into eras: precambrian, paleozoic, mesozoic, cenozoic, then periods, then epochs

Pre Cambrian Era

Before 570 mya

Paleozoic Era

570 - 225 mya

Mesozoic Era

225 - 65 mya

Cenozoic Era

65 mya to present

What happens during the Pre-cambrian era?

First fossil life appears with the appearance of prokaryotic cells (bacteria) 3.7 billion years ago (stromatolite) and eukaryotic cells 1.2 billion years ago

What happens during the Paleozoic era?

Trilobites, jellyfish, worms into fish, jawed fishes, first amphibians, reptile radiation and mammal-like organisms

What happens during the Mesozoic era?

Dinosaurs appear (great age of dinosaurs), egg-laying mammals, dinosaurs disappear, and placental/marsupial mammals appear

What happens during the Cenozoic era?

The age of mammals and divided into 7 epochs

Adaptive Radiation of Mammals

Dinosaurs disappear, leaving many adaptive niches and mammals diversify

How to Identify Primate Fossils

No bony protection, post-orbital bar, fully enclosed orbit (post-orbital closure)

How to Identify Primate Teeth

Different teeth types (heterodont) with small incisors and large canines

How to Identify Primate Feet

Nails instead of claws and prehensile hands and feet

Primate Brain Sizes

Bigger brain size than expected for body size

Mammalian Ears

Auditory bulla = bone encasing the middle ear bones and found in most mammals

Primate Ears

Extant (living) primates: petrosal bulla (auditory bulla formed by petrosal bulla) that’s formed by tympanic bone in other mammals

Primate Adaptations

Arboreal hypothesis, visual predation hypothesis, and rise of angiosperms hypothesis

Paleocene (65-55 mya) Epoch Order

Plesiadapiforms

Paleocene (65-55 mya) Epoch Locations

5 continents

Paleocene Epoch Primate Fossil (65-55 mya)

Similar to tree shrews: had claws, specialized teeth, no post orbital bar, had a petrosal bull however

Eocene Epoch (55-34 mya)

Euprimates = true primates

Eocene Epoch (55-34 mya) Families

• Omomiydae (ancestral to tarsiers)

• Adapidae (ancestral to lemurs, possibly anthropoids)

Eocene Epoch (55-34 mya) Primates

• Basal Anthropoids (found in asia and africa and considered ancestors to anthropoids = eosimias and biretia)

Oligocene Epoch (34-23 mya) Identifier

Diversification of Primates

Oligocene Epoch (34-23 mya) Location

Possibly found in El Fayum, Egypt

Oligocene Epoch (34-23 mya) Groups

• Oligopithecids (oldes, not much known)

• Parapithecids (small bodied and similar to new world monkeys)

• Proliopithecids (likely ancestor to catarrhines with sexual dimorphism and canines - links oligocene to miocene)

New World Monkey Dentition

2.1.3.3.

Old World Monkey Dentition

2.1.2.3

Oligocene New World Monkeys

Branisella

• Location: Bolivia 26 mya

• 2.1.3.3. (platyrrhine)

New World Oligocene Primate Origin

Possibly North American eocene primates or Africa to Antarctica to South America or cross Atlantic Ocean on land mass during oligocene

Miocene Epoch (23-5 mya) Identifiers

• East African deposits

• Hominoids emerge

• Apes : Monkeys = 20 :1

Miocene Epoch (23-5 mya) Monkey

Family: Victoriapithecus

Miocene Epoch (23-5 mya) Monkey Identifiers

• Location: Africa

• Orbit enclosed in bone

• Bilophodont lower molars

Miocene Epoch (23-5 mya) Characteristics

“Golden age of hominoids”

• Apes not monkeys

• Many species

• Move into Asia from Africa

Miocene Epoch (23-5mya) Hominoids

• Geographically widespread

• Numerous species

• Mostly large bodied

• No clear cut ancestors to hominoids

• Apes with y-5 molars

African Forms (23-14 mya) of Miocene Epoch

• Proconsulids of genus preconsul

• Several species

• Teeth = 2.1.2.3. and y-5 pattern

• Ancestral to hominoids

Proconsul Genus

Range of body sizes, likely arboreal quadruped, and large range within Africa

European Forms (16 -11 mya) of Miocene Epoch

• Genus = dryopithecus

• Frugivores

• Larger brain and slow growth

European Forms (8-7 mya) of Miocene Epoch

• Genus = oreopithecus

• From Italy

• Folivores

• Medium size

• Brachiator

Asian Forms (12.5 - 8.5 mya) of Miocene Epoch

• Genus = sivapithecus

• Multiple species

• Turkey, Pakistan, Asia

• Large (90-200 lbs) and similar to orangutan

• Wrinkled occlusal surface of molars, small second incisors, and thick enamel on cheek teeth

Asian Forms (8-0.5 mya) of Miocene Epoch

• Genus = gigantopithecus (largest primate ever)

• China to India

• Known only from teeth

• 3 meters tall: 300-500 kg

• Quadrupedal

• Diet of leaves, fruits, and nuts (hard foods)

End of Miocene for Living Hominoids

Major climate changes at the end of the miocene so many apes go extinct

Human Ancestors vs Great Ape Ancestors

Hominoid (great ape ancestors) and Hominin (human ancestors) : split at 6mya

Emergence of Hominins

• Pilocene when hominins start

• Fossil characteristics for hominins: bipedal locomotion, larger brain size, non honing canine, toolmaking (lithic, hunting), language, and eventual domestication

Early Hominin Trends

• Brain size increase

• Facial reduction

• Reduced canine

• Prognathism vs orgonathism

• Post orbital constriction

Early Hominin Trends Continued

• Foramen magnum moves

• Parallel vs parabolic

• Non honing chewing

• Chin shapes change

• Muscles of mastication

• Fingers, wrist, hands become human like

• Arch of foot and big toe adducts

Number One Distinguishing Characteristic of a Hominin

Bipedalism

Morphological (anatomical) Changes Associated with Bipedalism

• Foramen magnum underneath the base of the skull

• S-shaped vertebral column

• Trunk and weight centered over pelvis

• Lumbar curvature helps bring center of gravity to midline

• Basin shaped pelvis

• Femurs angled inward (angle medially to place foot under body mass for balance)

• Stand with knee fully locked (less work for quads and bad for ACL)

Bicondylar Angle

• Femurs angled inwards

• Babies aren’t born with this angle

• Develops as they start to walk

Bipedal Adaptation

• Lower limbs are longer than upper limbs

• Big toe in line with other toes

• Opposable big toe

Foot Arch for Shock Absorption

Humans arch and chimps don’t

Hominin Features

• Straight phalanges

• Longer femoral neck

• Pendulum gait not swinging (more efficient)

Pendulum Gait for Hominins

More efficient

• Advantages: low energy

• Disadvantages: vulnerable to aging and disease

Environmental Changes at End of Miocene

Drier, cooler, forest to savannah

Patchy Forest Hypothesis for Bipedalism

Environmental changes led to seasonality stress, environment as selective pressure favoring bipedalism (traveling further, more efficient, seeing further over grasses)

Male Provisioning Hypothesis for Bipedalism

Males travel far distance to gather foods, female can have more offspring (suggests monogamy?), and low sexual dimorphism

Free Hands Hypothesis for Bipedalism

Can carry objects (tools, offspring), hunting, and gathering

Thermoregulation Hypothesis for Bipedalism

Standing leads to reduced surface area exposed to sun

Multicultural Explanation for Bipedalism

• Each hypothesis fails to explain the initial origin of bipedalism and no single origin best explains it

• Ultimately allows other developments such as LARGE BRAIN

Endurance Running Hypothesis for Bipedalism

Early hominins are scavengers not hunters, not intimidating, can run for a long time for prey/food

When Did Bipedalism Emerge?

Several species that push origins of bipedalism as far back as 7 mya (however there’s debate)

Australopithecus (confirmed bipeds and hominins) Location

Eastern and Southern Africa

What are Australopithecus Considered?

Earliest human line at 4.1 mya

Australopithecus Epoch

Plio - pleistocene (pliocene and pleistocene epochs)

Australopithecus Species

Gracile and Robust

Gracile Australopithecus Species

A. amanesis, A. afarensis, A. africanus, A. garhi

Robust (paranthropus) Australopithecus Species

A. robustus, A. boisei, A. aethiopicus

A. anamensis (gracile) Location

Only found in East Africa (Kenya) from pliocene sediments dated to 4.2 - 3.9 mya

A. anamensis (gracile) Identifiers

Large canines, canine honing, parallel tooth rows, and thick tooth enamel

A. anamensis (gracile) Post Cranial Adaptations

Flexible elbow joints and weight bearing tibia

A. anamensis (gracile) Time Span

4.2 - 3.9 mya

A. afarensis (gracile) Location

Only found in East Africa (Ethiopia and Tanzania) from 100 specimens of fossils discovered (largest collection of early hominin)

A. afarensis (gracile) Teeth Features

Parallel tooth rows (slightly more parabolic), large canines/incisors, and cranial capacity = 350 to 500cc

A. afarensis (gracile) Features

Prognathic, sexually dimorphic (sagittal cresting in males), anteriorly placed foramen magnum, knee and pelvis indicate bipedalism, curved phalanges = arboreal too?

A. afarensis (gracile) Example

Lucy (1974) from Ethiopia = adult with third molar and stature of 3.5-4 feet

A. afarensis (gracile) Example 2

Laetoli footprints (1978) from Tanzania = 75 feet long preserved in volcanic ash 3.6 mya from 2-3 individuals

Bipedal Characteristics of Laetoli Footprints

• Big toe in line with others

• Well developed arch (shock absorbing)

• Similar step cycle to humans (heel strike, toe off)

• Slow moving (strolling) and short gait (stride)

A. afarensis (gracile) Time Span

3.6 - 3.0 mya

A. africanus (gracile) Time Span

3.0 - 2.0 mya

A. africanus (gracile) Location

Only found in South Africa (first australopithecine to be described)

A. africanus (gracile) Features

Less prognathic, large molars/premolars, parabolic teeth rows, and longer arms than legs (more than afarensis)

A. africanus (gracile) Example

Raymond Dart in 1925 - Taung child (3 years old based on dentition and foramen magnum shifted forward)

A. garhi (gracile) Location

Ethiopia

A. garhi (gracile) Time Span

2.5 mya

A. garhi (gracile) Features

Longer legs than arms and large molars/premolars

A. garhi (gracile) Link to Humans

Stone tools: earliest stone tools 2.5 mya from nearby site and animal remains with cutmarks

A. aethiopicus (robust) Time Span

2.5 mya

A. aethiopicus (robust) Location

Ethiopia from a mandible found with no teeth

A. aethiopicus (robust) Features

Hyper robust, prognathic face, flaring face with large cheek bones, and sagittal crest

A. boisei (robust) Location

Tanzania, Kenya, and Ethiopia

A. boisei (robust) Time Span

2.3 - 1.2 mya

A. boisei (robust) Features

Hyper robust, large molars, sagittal crest, supraorbital tori (shelf of bone above eyes / heavy brow ridge), no forehead and dished face

A. robustus (robust) Location

South Africa and first found in 1938

A. robustus (robust) Time Span

2.0 - 1.5 mya

A. robustus (robust) Features

Massive, flat, dished face, large molars, small incisors, and thick enamel

A. robustus (robust) Tools

Possibly bone tools - abrasions on stick shaped bones that come from digging up roots/termites

Robust vs Gracile Debate

Mostly different in face and cranium but are likely both same body size

A. africanus (gracile) vs. A. aethiopicus (robust)

Robust have large sagittal crest with chewing muscle space and cheekbones for support

Robust vs Gracile Difference in Teeth

Robust: deep jaws and large molars (premolar = 200% bigger than canine)

Gracile: larger front teeth (premolar = 20% bigger than canine)