Ch. 34 Flashcards
(42 cards)
Defining characteristic of mammals (get name from)
mammary glands
(produce milk for offspring)
derived characters of mammals
mammals have:
mammary glands
hair
high metabolic rate (due to endothermy)
larger brain than other vertebrates of equal size
differentiated teeth (wide variety)
Synapsids
mammal-like reptiles
what mammals evolved from
two bones that formerly made up the jaw joint were incorporated into the mammalian middle ear
3 living lineages of mammals that emerged by the early cretaceous
monotremes
marsupials
eutherians
monotremes
lay eggs
spiny echidna, duck-billed platypus (only in Australia and New Guinea)
Marsupials
include opposums, kangaroos, and koalas
embryo develops within a placenta in the mother's uterus
born very early in development
completes its embryonic development while nursing in maternal pouch called a marsupium
Eutherians
placental mammals - young nourished through placenta
in Australia, converegent evolution has resulted in a diversity of marsupials that resemble the eutherians in other parts of the world
3 main groups of living primates
lemurs, lorises, pottos
tarsiers
anthropoids (monkeys and apes)
derived characters of primates
most have hands and feet adapted for grasping
flat nails
large brain
forward-looking eyes close together on face (for depth perception)
complex xocial behavior and parental care
a fully opposable thumb (monkeys and apes)
Old World Monkeys
colonized in Africa
New World Monkeys
colonized in South America
Lucy
Australopithecus afarensis
3.24 million years ago (rock layers this old)
oldest, most complete fossil that helped show these species were bipedal
extant
not extinct
hominins
fossils of extinct species that are more closely related to humans than chimps
australopiths
hominins that existed during the time period when hominin diversity drastically increased (4-2mya)
Which developed first, bipedal or large brain?
Bipedal before large brain
What does greater or lesser sexual dimorphism suggest about the social behavior of a species?
Greater dimorphism equates to more male-male competition. Less dimorphism (more similar sizes between male and female) equeates to more pair-bonding. They could pair-bonding because their young require greater parental care from both parents
Homo sapiens
originated in Africa
160,000 year-old skull (195,000 earliest known fossil)
began migration out of Africa about 50,000 (100k?) years ago and went to Asia then Europe and Australia
hominid evolution is like a bush, not linear
species often coexisted
mtDNA (mitochondrial DNA) suggests we all share a common female ancestor (about 200,000years ago)
Homo habilis
650 cc brain
simple stone tools
H. ergaster/H.erectus (taxomic status still debated)
brain gradually increases (reaches 1200cc)
more sophisticated tools
originated in Africa and migrated to Indonesia
H. neanderthalensis
evolved in Eurasia from H. erectus (about 200,000 years ago)
disappeared about 30,000years ago
humans didn't derive from Neanderthals
mammary glands
(produce milk for offspring)
Defining characteristic of mammals (get name from)
mammals have:
mammary glands
hair
high metabolic rate (due to endothermy)
larger brain than other vertebrates of equal size
differentiated teeth (wide variety)
derived characters of mammals
mammal-like reptiles
what mammals evolved from
two bones that formerly made up the jaw joint were incorporated into the mammalian middle ear
Synapsids
