Mammals, Primates and Humans Flashcards by Zaraa Shaikh

7 shared, derived traits of mammals?

Mammary glands
Hair or fur covering the body
3 middle ear bones
Endothermy
Dentary-squamosal jaw joint
Specialized teeth
Larger brain

How well did you know this?

Not at all

Perfectly

What did mammary glands evolve from?

sweat glands

How well did you know this?

Not at all

Perfectly

What is hair made of and what does it do?

fine, cylindrical keratin fibres
- insulates, protects and functions in sensory perception

How well did you know this?

Not at all

Perfectly

Ear structure and origin?

middle ear bones formed from leftover jaw bones
- allows detection of higher frequency sounds
- eardrum is better protected as it is deep inside the head

How well did you know this?

Not at all

Perfectly

What is the dentary-squamosal jaw joint?

Dentary (lower jawbone with teeth) and squamosal (small cranial bone) meet to form the haw joint
Articular and quadrate are reduced in size and incorporated into the ear

How well did you know this?

Not at all

Perfectly

Teeth structure and function?

adapted for different functions reflecting diet
occlude closer than reptiles allowing fine grinding which increases surface area and digestion of food
2 sets of teeth; milk teeth and adult teeth

How well did you know this?

Not at all

Perfectly

What is the significance of a larger brain?

more development of neurocortex for higher functions such as
- sensory perception
- motor commands
- language

How well did you know this?

Not at all

Perfectly

Other characteristics of mammals?

limbs positioned vertically under the body for better support, enables more efficient movement
diaphragm contributes to lung ventilation
copulate using intromittent organ for internal fertilization
viviparous
synapsids

How well did you know this?

Not at all

Perfectly

Significance of palate-bone partition between nasal and oral cavity?

allows mammals to chew and breathe simultaneously allowing efficient food processing

How well did you know this?

Not at all

Perfectly

What are the 3 lineages of mammals?

Order Monotremata, Order Marsupiala, Clade Eutheria

How well did you know this?

Not at all

Perfectly

Monotreme characteristics?

oviparous but provide milk to young after hatching
no nipples, milk secreted from specialized hair patches
have cloacas
lack teeth as adults
feed on invertebrates

How well did you know this?

Not at all

Perfectly

Shared derived traits of Theria?

Viviparous development
Placenta consisting of extraembryonic membranes and uterus lining
Post-birth nursing from nipples

How well did you know this?

Not at all

Perfectly

Placenta function?

Provides initial nourishment to embryo by exchanging nutrients, metabolic waste and dissolved gases between the mothers and embryos blood.

How well did you know this?

Not at all

Perfectly

Marsupial characteristics and embryo development?

embryo development in placenta in uterus is brief
born as partially developed embryos and complete development in marsupium (mothers pouch)
nipples and milk glands are inside the pouch
males and females possess cloaca

How well did you know this?

Not at all

Perfectly

Eutherian characteristics and embryo development?

more complex placenta (shared, derived trait)
embryos complete development in uterus and placenta provides nourishment throughout development
post-birth young suckle milk from nipples
separate urinary and anal openings

How well did you know this?

Not at all

Perfectly

4 clades of Eutherians?

Clade Afrotheria
Clade Xenartha (SA)
Clade Euarchontoglired
- Orders Primates and Rodentia
Clade Laurasiatheria
- hooved mammals, marine mammals, bats

4 shared derived characteristics of primates

Hands and feet adapted for grasping
Large brain and short jaws
Forward-looking eyes positioned close together
Complex social behaviours

How are primate hands and feet adapted?

thumb/big toe is separate from other fingers aiding in grasping
- monkeys and apes have opposable thumbs
- enable fine manipulation facilitated by flat nails

How is primate vision adapted?

eyes provide depth perception critical for judging distances
- stereoscopic vision: field of vision from each eye overlaps
- vision increased, smell decreased

What are the 3 main groups of primates?

Lemurs, lorises and bush babies
Tarsiers
Anthropoids - monkeys, apes and humans

What are hominioids?

Non-monkey anthropoids commonly called apes

Ape characteristics?

diverged from Old World anthropoids
lack tails and have large brains
gibbons (lesser apes) and hominids (great apes)
Great apes - orangutans, gorillas, chimps, bonobos, humans

What are humans? Phylogeny and characteristics?

member of genus Homo
descended from great apes
large brains and bipedal
monophyletic
chimps and bonobos are closest relatives

4 shared derived traits of humans?

Upright posture and bipedal locomotion
Larger brains
Reduced jawbone and jaw muscles
Shorter digestive tract

Where did hominins originate and Ardipithecus traits?

Africa - bipedalism but small brains - long arms and grasping feet for arboreal life

What are some trends in hominin evolution?

- bipedalism - expansion of brain and increased brain complexity - pelvis modification - reduction of teeth, face and jaws - extended infant and child dependency - increased hairlessness - increased reliance on meat - emergence of tool use

Factors favouring bipedalism? (3)

- Large mammalian predators - Compeition from terrestrial primates - Change in habitat; decline in arboreal environmnts and expansion of open grasslands

Adwantages and disadvantages of bipedaism?

Advantages: - enhanced visibility of predators - energy efficient locomotion for long-distance travel - better thermoregulation in open habitats - freed hands for carrying infants and tool use Disadvantages: - vulnerable to foot injuries - increased strain on hips, backs, knees and ankles

Skeletal adaptations for bipedalism? (5)

Skull attachment - repositioning of foramen magnum for balanced skull placement atop vertebral column Spinal curvature to align weight over pelvis Pelvis reconfigured to support internal organs in upright posture Legs lengthened for efficient locomotion with larger knee hoints for weight support. Legs repositioned right underneath body Narrower foot shape, enlarged heel and larger big toe for stability and propulsion

Australopith characteristics?

- fully bipedal - short, bowl-shaped pelvis and aligned toes - short, small brains, large and portruding jaws - sexual dimoprhism - tool use

What are the 2 types of Australopiths?

Robust - sturdy skulls and powerful jaws Gracile - slender with lighter jaws

What is the earliest species in Genus homo and its characteristics?

Homo habilis - larger brain capacity - shorter jaw - short in stature

Homo ergaster characteristics?

- first fully bipedal and large-brained hominin - long, slender legs and hip joints adapted for long-distance walking - smaller teeth, shift towards increased meat consumption - more sophisticated tools - decrease in sexual dimorphism; pair-pair bonding and reduced male-male competition

Homo erectus characteristics?

- first hominin species to migrate out of Africa - hunter-gatherer societies - ability to control fire; significant cultural and behavioural complexity - larger brain

Homo heidelbergensis characteristics?

- evolved from Homo erectus - similar to Homo sapiens in body proportions, dental adaptations and cognitive ability - large-animal hunter with sophisticated tools - Neanderthals and Homo sapiens likely evolved from H. heidelbergensis

Neanderthal characteristics?

- cold-adapted hominins - robust physiques, thick bones - complex behaviours such as burying the dead and crafting hunting tools - smaller brains than Homo sapiens - coexisted with Homo sapiens

Homo Sapien characteristics?

- large brains - increased behavioural complexity (symbolic, sophisticated thought, artistic carvings) - originated in Africa - little genetic variation