Pre history final

Process of fossilization

A long term process of turning organic remains into stone. Must have been rapidly buried to avoid decomposition. Then the remains get permineralized( minerals replace organic material over thousands of years.

Fossil bone versus trace fossils

Fossil bones are the physical remains of an organism- Trace fossils are records of biological activity rather than the organism itself (Footprints, Trails, Burrows)

Sedimentation

The process where particles of soil, rock, or organic matter settle out of a fluid like water or air due to gravity. This forms a distinct layer of sediment

Absolute dating vs Relative dating

Relative determines what is older or younger by stratigraphy, law of superposition fossil succession.

Absolute determines the numerical age through radiometric decay, dendrochronology, thermoluminesence

how do we determine which radiometric dating technique to use for specimens from 1.8 Ma, or 30,000 years ago, or 4 billion years ago?

Match the estimated age of a specimen with the half life of radioactive isotopes present in the sample

how does radiometric dating function

determines the age of materials by measuring the ratio of radioactive "parent" isotopes to stable "daughter" products within a sample.

what is a hominin

modern humans, extinct human species, and all our immediate ancestors (genera Homo, Australopithecus, Paranthropus, Ardipithecus) that are more closely related to us than to chimpanzees

what is bipedalism

a form of flocomotion where an organism moves on its two rear limbs

Inferiorly Facing Foramen Magnum

Positions the head directly over the spinal column rather than dangling in front.

Quadruple Curve Vertebral Column

An "S-shaped" curvature that positions the center of gravity over the pelvis.

Bowl-Shaped Pelvis & Flaring Iliac Blade

Short, broad iliac blades provide lateral stability for the hips when supporting body weight on one leg.

Bicondylar Angle

The medially angled femur (valgus knee) keeps the feet directly under the center of gravity.

Large Calcaneus

(Heel Bone): Supports weight bearing and shock absorption, indicating a "heel-strike" step.

Inline/Large 1st Toe

The big toe is aligned with the other toes, providing a "toe-off" step, rather than acting as a grasping

East Africa vs South Africa vs Central Africa

East- Early stage for australopithecus (lucy)

South- Early homosapiens

Central(chad)- contains the oldest known early hominin fossil outside the east/south axis

-What environmental changes happened in between the Pleistocene and Pliocene?

Early pliocene warmth was replaced by cooler and variable late pliocene. this marked the onset of northern hemisphere glaciation

What do all the species with the genus Australopithecus have in common?  Homo?

Bipedal locomotion, small canine teeth, and facial features between apes and humans

What are the major differences between the gracile and the robust Australopithecus species?

Gracile have smaller jaws, teeth, and lighter facial structure

Robust have massive cheek teeth, heavily built jaws, and a sagittal crest for strong chewing muscles.

How did height change throughout human evolution?

For the most part we have gotten taller than our early ancestors

how did brain size change throughout human evolution

We have increased our brain size. Some say we have tripled since early ancestors

In what species do we see evidence of care?

Neaderthals ’ and early homo sapiens ( they would help injured or aged group members indicated by healed bones and dental loss. Started to practice burial of the dead

How do tooth proportions change from Australopithecus to Homo?

Change from large megadont cheek teeth to smaller reduced teeth

Who has short legs compared to arms?  Long legs compared to arms?

Australopithecus had long arms compared to legs

Homo erectus was the first to exhibit long legs compared to arms

Who’s the first to leave Africa?

Homo erectus

Who has the largest supraorbital torus we’ve ever seen?

Kabwe (broken hill 1) A homo heidelbbergensis fossil from 200-600,000 years ago

-Who is the first species to live in a cold environment?

early primates

What are all the species that have been found in Asia?

Homo erectus, denisovans, homo floresinsis, homo luzonesis, homo neaderthalensis, homo longi, and homo sapiens.

What are all the species that have lived in Europe?

Early archaic humans, neandethals, eventually modern humans

Why do we group species into the same genus?

Because they are closely related, sharing a recent common ancestor and key physical or genetic charecteristic

Sahelanthropus tchadensis

• When: ~7–6 million years ago

• Where: Chad (Central Africa)

• Bipedal evidence: Forward-positioned foramen magnum (hole where spine connects)

• Key traits: Small brain, ape-like face but reduced canines

• Cranial capacity: ~350 cc

• Environment: Woodland/savanna mix

• Relationships: Possibly one of the earliest hominins (near human–chimp split)

Orrorin tugenensis

• When: ~6 million years ago

• Where: Kenya (East Africa)

• Bipedal evidence: Femur structure suggests upright walking

• Key traits: Thick enamel teeth (diet shift)

• Cranial capacity: Unknown (fragmentary fossils)

• Environment: Woodland

• Relationships: Possibly ancestral to later hominins OR side branch

Ardipithecus ramidus

• When: ~4.4 million years ago

• Where: Ethiopia

• Bipedal evidence: Pelvis + foot show facultative bipedalism (also climbed)

• Key traits: Opposable big toe, less aggressive canines

• Cranial capacity: ~300–350 cc

• Environment: Forest (not open savanna)

• Relationships: Likely ancestor to Australopithecines

AUSTRALOPITHECINES (Clear Bipedalism

• When: ~3.9–3 million years ago

• Where: East Africa (Ethiopia, Tanzania, Kenya)

• Bipedal evidence: Laetoli footprints, pelvis, femur

• Key traits: “Lucy”; long arms but fully bipedal

• Cranial capacity: ~400–500 cc

• Environment: Mixed woodland/savanna

• Relationships: Ancestor to later Australopithecines and possibly Homo

Australopithecus africanus

• When: ~3–2 million years ago

• Where: South Africa

• Bipedal evidence: Pelvis + skull position

• Key traits: More human-like face, smaller teeth

• Cranial capacity: ~450–550 cc

• Environment: Woodland/savanna

• Relationships: Likely ancestor to Homo

ROBUST AUSTRALOPITHECINES

Australopithecus aethiopicus

• When: ~2.7–2.3 million years ago

• Where: East Africa

• Bipedal evidence: Same skeletal pattern as other australopiths

• Key traits: Sagittal crest, huge chewing muscles

• Cranial capacity: ~410 cc

• Environment: Open environments

• Relationships: Ancestor to boisei/robustus

Australopithecus boisei

• When: ~2.3–1.2 million years ago

• Where: East Africa

• Bipedal evidence: Fully bipedal skeleton

• Key traits: Massive molars (“nutcracker man”)

• Cranial capacity: ~500–550 cc

• Environment: Savanna

• Relationships: Side branch (not human ancestor)

Australopithecus robustus

• When: ~2–1.2 million years ago

• Where: South Africa

• Bipedal evidence: Same as other australopiths

• Key traits: Heavy jaw, large teeth

• Cranial capacity: ~500 cc

• Environment: Mixed environments

• Relationships: Side branch

GENUS HOMO (Big Brain + Tools)

• When: ~2.4–1.4 million years ago

• Where: East Africa

• Bipedal evidence: Human-like postcranial skeleton

• Key traits: First clear stone tools (Oldowan)

• Cranial capacity: ~600–700 cc

• Environment: Variable (savanna/woodland)

• Relationships: Likely evolved from Australopithecus → ancestor of Homo erectus

Homo erectus

• When: ~1.9 million – 100,000 years ago

• Where: Africa, Asia, Europe (first to leave Africa)

• Bipedal evidence: Fully modern walking body

• Key traits: Fire use, Acheulean tools, long-distance travel

• Cranial capacity: ~800–1100 cc

• Environment: Wide range

• Relationships: Ancestor to later Homo species (including us)

Homo neanderthalensis

• When: ~400,000–40,000 years ago

• Where: Europe & Western Asia

• Bipedal evidence: Fully modern

• Key traits: Stocky, cold-adapted, culture & burial

• Cranial capacity: ~1200–1750 cc (larger than modern humans)

• Environment: Ice Age Europe

• Relationships: Sister species to Homo sapiens (interbred)

Denisovans

• When: ~300,000–50,000 years ago

• Where: Asia (Siberia, Tibet, SE Asia via DNA evidence)

• Bipedal evidence: Assumed fully bipedal (Homo)

• Key traits: Known mostly from DNA

• Cranial capacity: Unknown

• Environment: Varied

• Relationships: Closely related to Neanderthals; interbred with Homo sapiens

Homo sapiens

• When: ~300,000 years ago – present

• Where: Origin in Africa → global

• Bipedal evidence: Fully modern skeleton

• Key traits: Language, art, complex culture

• Cranial capacity: ~1200–1400 cc

• Environment: All environments

• Relationships: Descended from earlier Homo (likely erectus via African populations)

what human species first showed signs of larger brains

Homo Habilis

did humans and neandertals interbreed

Yes they did

What is Skhul V

Skhūl V is a fossilized cranium and mandible of an adult male Homo sapiens discovered in 1932 in the Skhūl Cave, Mount Carmel, Israel. Dating to approximately 90,000–130,000 years ago, it is one of the oldest modern human fossils found outside Africa. It is known for its mix of modern, high-browed features with a robust, primitive-like appearance.

what are denisovans

Denisovans are an extinct species or subspecies of archaic humans, closely related to Neanderthals, that lived across Asia during the Pleistocene epoch

What happened during pliocene 5.3-2.6 MA

Warmer and wetter than today but gradually cooling. Grasslands expand. Most common hominin was the australopithecines. Bipedalism becomes fully established.

hominins still partly adapted to trees but increasingly terrestrial

Pleistocene( 2.6 million- 11,700 years ago

Much colder than today(Ice Ages)

unstable climate

Hominins (genus homo{habilis- erectus- later species)

Bigger brains, advanced tools, global dispersal