The Emergence of Primates and Early Hominin Evolution Flashcards
What does the term primates include?
humans, apes, monkeys, and prosimians
State 5 characteristics of primates.
opposable thumbs, quadrupeds, decently large brains, smaller snout, reduced sense of smell, social, flattened nails grasping hands and feet, expanded visual areas, forward facing eyes, reduced ears, rotating forearm, ridged fingertips with nerve endings
What is the definition of a prosimian?
Give an example.
Pre-monkey; for examples lemurs
Define the term arboreal.
Adapted to life in the trees
True or false? Humans and chimps are the only bi-pedal primates.
False; only humans are
Describe generalized dentition.
Different teeth allows for varied diet
What is phylogeny?
the evolutionary history of a species
Genetics diverged with chimps about ___ million years ago.
True or false? Humans are more closely related to chimps than gorillas.
6; true
How old is the first fossil with primate characteristics?
65 mya
What is considered by some as the earliest primate?
Purgatorius: a proto-primate that resembles a weasel or a rodent-like creature
What time range are the first fossils with monkey characteristics from?
30 to 40 mya
What time period did primates with ape characteristics emerge and what trait signified this?
20 mya; lack of tail
What time period is known as “The Golden Age of Hominoids” and why did it get this term?
Miocene Epoch 23-5 mya; thousands of fossils in Africa, Asia, and Europe
What is the meaning of homonoid and hominin?
Homonoid: “ape-like”
Hominin: “human-like”; humans and any creature in direct human line
At what point in the Miocene did bipedal hominins appear?
the end
When did bipedalism emerge?
7mya
What skeletal characteristics indicate bipedalism?
Hint: Human
(1) S-shaped spine for balance with curves at cervical and lumbar
(2) foremen magnum positioning is at the base of the skull
(3) pelvis; ilium is short and broad
(4) femur is curved inward so feet are at the centre of gravity
(5) shortened big toe and straight toes; foot is arched to absorb shock and energy; more tightly bound foot bones
(6) Tibia articular surface (where it connects to femur) is larger in bipeds
What are the skeletal characteristics of apes?
(1) c-shaped vertebral column creating the tendency to fall forward
(2) ape pelvis ilium is long and narrow
(3) foremen magnum is positioned out the back of the skull
(4) straight angle of the femur
(5) thumb-like, grasping big toe for climbing; flat footed
What are the 4 theories for the explanation of bipedalism.
(1) the upright provider: bipedalism allowed males to carry more food back to camp
(2) the upright scavenger: higher vantage point, free hands to gather, more energy efficient
(3) The efficient walker: requires a 1/4 of the energy of an ape, travel great distances for food (like grazers)
(4) The endurance runner: adapted for more efficient and faster running (hunting)
True or false? Half of early hominin sites are in Africa.
False; All of early hominin sites are in Africa
Note: mostly in the East, some in the south, recent discovery in Chad
True or false? Upright walking emerged way before human characteristics of the brain.
True
Explain the theory that bipeds originated in the woodlands instead of the savannah.
Skeletal features in the hands and feet show continued life in the trees
What are the Australopithecines?
Diverse genus of hominins that existed in the time period 4.2-1.9 mya. Possessed small brains and prognathic faces, and large teeth and jaws. Bipeds but maintained the ability to climb. All located on the African continent.
Describe diastema.
Space in the jaw that allows space for large teeth
What is sexual dimorphism?
Difference in size/physical characteristics between males and females
There have been no artifacts of stone tools correlated to the Australopithecine, what evidence suggest they may have used tools?
Hand bone analysis; metacarpal bones (specifically trabecular bone under the joint remodels)
What are three characteristics of robust australopithecines?
(1) Megadontia (really large teeth–molars + premolars– and jaws
(2) broad zygomatic (wide cheekbones make room for chewing muscles)
(3) Large sagittalcrest (ridge alongtop of skull to anchor chewing muscles)
Robust Australopithecines eat a ____ diet, but are able to eat softer _____ material.
course, fibrous; plant
What is Olduvai Gorge, Tanzania and why is it important?
Important hominin site in the Serengeti plain of Northern Tanzania (in the Great Rift), where sediment layers are pronounced producing reliable dating; exposing 2 million years of Earth’s history.
Volcanic processes provide better preservation through rapid sedimentation & Gorge makes the artifacts more easily accessible.
Discovered by the Leakeys.
What are four trends in hominin evolution?
(1) Bipedalism
(2) Expansion of the brain (eating more protein for brain growth)
(3) Reduction of the face, teeth, and jaws
(4) tool making and utilization
Compared to Australopithecines, what traits do Homo habilis exhibit?
Hint: theres four
Larger brain, smaller teeth and jaws, less prognathic faces, and the presence of material culture
Homo ______ is the earliest proven user of stone tools.
habilis
Homo ______ is the earliest proven user of stone tools, however evidence of stone tools date ____ mya.
habilis; 3.3
What are the different kinds of Oldowan tools and how were they made?
Manufactured by percussion flaking; include hammer stones, choppers, and flakes
What species was the first to leave the continent of Africa?
Homo erectus
