ANT 201 Quiz 5 Study Guide

Early Primate Environments

What are three main ways to find out about extinct organisms and ecosystems?

• Genetics
• Behavioral ecology
• Morphology

What are the bony (e.g. skeletal) characteristics that unite ALL PRIMATES

• Postorbital bar 
• Postorbital closure 
• Olfaction in primates
• Smelling is reduced
• Face located beneath the brain case 
• Primates have more upright posture 
• Foramen magnum rotated beneath the skull 

What are three main hypotheses for the origin of the Primate order? Which one does the fossil evidence most strongly support and why?

The arboreal Theory

• Arboreal life was the key context in which natural selection would favor primate attributes
• Example
• Grasping hands and feet could hold onto branches 
• Running and leaping in an arboreal environment required binocular vision for judging distances
• Sophisticated brains were needed to process the complex three dimensional space 
• Sense of smell was of diminished value in the shifting air of tree tops 
• Problems
• Many other organisms are also arboreal 

Visual predation hypothesis

• Orbit convergence and hand mobility 
• Animals that hunt and track prey items tend to have high degrees of optic convergence and prehension in their extremities (grasping in their hands and feet)
• Stereoscopy or parallax view 
• Extreme convergence actually diminishes depth perception 
• This traits would be most useful in animals that needed a wide field of stereoscopic vision at close range 
• Therefore cartmill suggested that the ancestral primate was an insect hunting specialist that hunted in fine branches in the forest copy or undergrowth 
• Thus, already arboreal mammals came to rely on visually directed predation to capture arthropods and other small prey. 
• Problematic because this suggest that the earliest primate did not depend of fruit flowers or other plant matter  although primitive lemurs do just that 

Angiosperm hypothesis

• Megachiroptera (fruit bats) have primate like vision system but eat exclusively from angiosperm products
• Angiosperms which are flowering plants 
• Evolved in the late cretaceous 
• Had a radiation in the paleocene- followed by the appearance of the first primates
• Sussman hypothesized that 
• The new availability of rich and abundant fruits and flowers in the terminal branches of tropical forests provided a windfall of resources that were utilized by the earliest primate ancestors 
• Fits with all of the primate traits because it 
• Required sophisticated vision to spot colorful flowers and fruits at a distance 
• Demanded significant olfactory capabilities to assess fruits and flowers close up
• Grasping hands and feet were favored in the terminal branches 

What were probable characteristics of the primate common ancestor?

• Primate traits likely caused by angiosperm and insect radiations

What was the climate like when primates first evolved, when monkeys evolved, and when apes evolved? (e.g. very warm, cooling off, etc.)

• Primates: started off very warm 
• Monkeys: cooler global temps
• Apes: gradually got cooler 

Early Primate Environments

In what kinds of depositional environments are bones found and how do they preserve?

• Volcanoes, rivers, and lakes deposit sediment

Know the geological Epochs in which primates, monkeys, apes, and hominins evolved.

• Primates: eocene
• Monkeys: oligocene
• Apes: miocene 
• Hominins: miocene

Why is the Fayum an important fossil location?

• Fayum paleoecology 
• Subtropical to tropical lowland coastal plain 
• Riverine forests and possibly swampy conditions 
• Brackish streams flowing to the tethys Sea 
• Monsoonal conditions 

What is paleoecology, and what are at least two kinds of evidence we can use to reconstruct past environments?

• Paleoecology is the study of interactions between organisms and/or interactions between organisms and their environments across geologic timescales.
• Advancement in techniques such as dating, dna, paleoenvironmental reconstruction 
• We can use isotopes to determine diet 
• Excavation and recovery methods are far more systematic 

The First Hominins

What are some of the main features of the apes (that can be found in skeletons)?

• No tail 
• Broad nose 
• Fewer lumbar vertebrae 
• Simple molars 
• Larger brain 
• Y-5 molar pattern

What was the environmental context of ape evolution (e.g. in the early, middle, and late Miocene)?
Miocene - time of ape evolution 

• Early miocene 23-16 mya 
• Warmer global temperatures 
• Expansion of forests northward 
• Early ape diversification 
• Apes in africa, asia, and europe!

Miocene - the time of ape evolution

• Middle miocene - 16 - 11.6 mya
• Gradually cooling climate 
• Forests still widespread 
• Apes in africa, asia, and europe 

Miocene - time of ape evolution

• Late miocene - 11.6 - 5.3 mya
• Much cooler, drier climate
• Forests shrink 
• Mediterranean sea completely dries up completely 
• Monkeys diversify at the expense of apes 

What does an extinct Asian relative of the orangutan have to do with Bigfoot legends?

• Sivapithecus
• Evolved from a sivapithecus-like ancestor is this giant: Gigantopithecus 
• This is not from the miocene time period 
• This is “bigfoot”
• Some people have tried to argue that bigfoot legends derive from a late-surviving gigantopithecus

What was different about one group of African apes in the late Miocene?

• By 3.3 Million years ago there was an upright walking ape in africa with a brain a bit larger than a chimp 
• This ape had many other human like characteristics such as increased manipulative ability and reduced canines 
• It did NOT have all bipedal adaptations 
• Bipedalism preceded all other HUMAN adaptations 

Why is bipedalism such a focus of early hominin evolution research?

• Tells you about the environment 
• Bipedalism preceded all other human adaptations 

The First Hominins

What is a hominin? Why do we blame genetics and different species concepts on the change from the term “hominid” to “hominin”?

Hominins

• Humans and our upright walking ancestors 

Genetically, we are far more closely related to chimps than they are to anything else

• Humans and chimps form a clade that excludes other apes 

Hominid v Hominin

• Used to be that chimps were grouped with other great apes, based on superficial similarities 
• Thus humans and all our upright walking ancestors were considered hominids
• Now the distinction must be finer; thus we move up two levels and use the tribe hominin

Know at least three reasons it might be advantageous to walk on two legs?

• Allows carriage of fruits
• Allows carriage of babies
• Allows organisms to forage at higher heights
• Less solar radiation 

Know six ways to tell from a fossil if an organism was bipedal from its skeleton (three above the neck and three below the neck).  

Major modifications for bipedalism above the waist

• Inner ear bone shape 
• Foramen magnum placement
• Curvature of spine (lordosis)
• Barrel chest 
• Relatively shorter arms 
• Below the waist
• Broad short pelvis
• long femoral neck 
• Valgus angle 
• Convergent toe and arch
• Short, straight phalanges

What are three traits of bipedalism that humans have but the earliest bipedal hominins did not?

• Convergent big toe 
• Relatively shorter arms 

Know the following about Sahelanthropus, Orrorin, and Ardipithecus: region where it was found and what evidence was found (e.g. just a skull, some pieces of teeth and leg bones, nearly a whole skeleton, etc.)

Sahelanthropus tchadensis (7-6 mya)

• Oldest known hominin 
• Bipedal 
• Foramen magnum (spinal cord skull connection) under the skull 
• Brain similar to chimps 
• From chad 

Orrorin tugenensis (6 mya)

• Fragmentary postcrania and some teeth 
• Chimp-like teeth in some ways, human-like in others 
• Bipedal 
• Features of the femur 
• From kenya 

Ardipithecus Kadabba

• Terminal miocene 
• Teeth and a few postcranial bones
• Honing premolar complex
• Bipedal
• Features of the toe 
• Ethiopia 

Ardipithecus ramidus

• Spectacularly complete skeleton
• Several different individuals 
• Bipedal
• Still a small brain 
• Divergent big toe
• Little sexual dimorphism (pair bonded? )
• Thicker enamel and larger posterior teeth (human like)
• Woodland habitat 
• Unanticipated feeding/ locomotor ecology 
• Ethiopia 

Australopithecus and Paranthropus

Why were some scientists willing to accept that Piltdown Man was a genuine human ancestor? How did this influence their thinking about the Taung Child?

• Most scientists were based in europe and they were mostly white men, so they want to believe that humans originated from europe this made them reject taung child

What were some of the main factors that made the Taung Child come into greater acceptance?

Piltdown man was revealed to be a forgery!

• Fluorine testing discovered its hoax 
• Orangutan jaw with shaved down teeth 

1947 an adult A. africanus specimen was discovered and called Mr. Ples

• Big brain first idea was not holding true 
• Instead bipedalism is first! 

Know at least three “lessons learned” that are now common practice in modern paleoanthropology.

• Advancement in techniques such as dating, dna, paleoenvironmental reconstruction

Know how many genera of hominins were present between 4 – 2 million years ago in Africa. What does this tell us about diversity in the hominin lineage at this time?

Between ~4-2 mya we find many hominin species, sometimes living at the same time

• Australopithecus
• Paranthropus
• Kenyanthropus
• Homo (for later)

In what parts of Africa have most hominin fossils been found?

• East, south, and north central africa 
• Ethopia 
• Kenya 
• Tanzania 

Australopithecus and Paranthropus

What are the key characteristics shared by all australopithecines? Know two from the teeth, two from the postcranial skeleton, and two “other things” (e.g. life history, locomotion, behavior)

Teeth

• intermediate diastema between apes and later hominids
• Palate shape In between U shape (apes) and parabolic shape(humans)
• Intermediate canine size between apes and later hominids
• Canines are sexual dimorphisms 

Postcranial Skeleton

• Bipedal
• Small bodies
• Pronounced sexual dimorphisms 

Other things

• ‘Somewhat’ ape-like development patterns but longer period of growth
• Woodland / scrub / grassland habitat
• Still adept in trees 

What are the two main branches of australopith?

Australopithecus anamensis

• First australopith
• Dry woodlands, riverine gallery forests, open grasslands
• Kenya to ethiopia 
• Adaptations for both bipedality 

Australopithecus afarensis

• Lucy 
• Ethiopia, kenya, tanzania
• Remains from more than 300 individuals 
• Brain slightly larger than a chimp 
• Long strong arms
• “Dikika Child” or “selam” you can see the eruption rate, matured more like an ape, small canines and anterior teeth like humans 
• Males 1.5m females 1.1m 

Where did the following species live and were they gracile or robust? Can you name a fossil that represents at least four of them? Au. anamensis, Au. afarensis, Au. africanus, Au. sediba, P. robustus, P. aethiopicus, P. boisei . Which was the earliest one? Which was the latest one? Did they live side-by-side? Which has the best fossil record and what were at least two famous fossils found for it?

Au. anamensis

• Earliest
• Gracile
• Kenya ethiopia

Au. afarensis

• Gracile
• Lucy
• Dikka child
• East africa

Au. africanus

• Gracile
• South africa
• Mrs. Ples

Au. sediba

• Gracile
• MH1
• South africa

P. robustus

• Robust
• South Africa
• Eurydice 

P. aethiopicus

• Robust
• Black Skull
• East africa

P. boisei

• Latest 
• Robust
• Zinj
• East and central africa 

Why was Paranthropus mainly called robust?

Not likely ancestral to homo

• Really big jaws and teeth 
• Specialized in chewing 
• Jaw required massive musculature to operate 
• This is why they are called the robust, face is strong looking 
• Prevalent skull 

Which lineage was most likely the one that led to Homo? Why

Gracile