Mod 3 Quiz (3.1, 3.2, 3.3) (SG) Flashcards
cenozoic era
66 million years ago, dominance of mammals, birds, and angiosperms
paleocene epoch
65 million years ago, overall cooling (with fluctuations), changing temperatures caused by plate tectonics & ocean currents
eocene epoch
56 million years ago, northern latitudes had tropical climates, tropical climates caused rain forests in north america, up to present-day alaska, >200 species of eocene primates
oligocene epoch
34 million years ago, surface seawater much cooler, antarctic ice cap developed, northernmost tropical forests disappeared
miocene epoch
23 million years ago, kelp forests and grasslands, warming at end of oligocene, northern tropical forests returned miocene ape radiation 23 – 5.3 million years ago
pliocene epoch
5 million years ago, dramatic modernization of mammals, development of ice caps
pleistocene epoch
2.5 million years ago, extensive ice sheets and other glaciers formed repeatedly on the landmasses, aka great ice age
holocene epoch
10,000 years ago, development of major civilizations, impacts of human species worldwide
oreopithecus
late miocene (8mya), found in tuscany, long arms/short legs, short trunk, mobile joints, possibly bipedal, inner ear bony labyrinth consistent with bipedalism, foot shows unique adaptation for stability on two feet: a very widely displaced big toe
angiosperm (hypothesis)
just had an adaptive radiation, the availability of abundant fruits and flowers in the terminal branches of tropical forest trees provided a windfall of foods (fruit AND insects) that were eaten by the earliest primate ancestors
gymnosperm
non-flowering trees with no fruit or flowers
plesiadapiforms
65-54 million years ago, diverse, successful group, found in north america and europe during paleocene, probably a sister taxon to euprimates
adapiformes
resembled lemurs, generalized arboreal quadrupeds with some leaping, folivorous, diurnal
omomyiformes
extinct, resembled tarsiers, insectivorous, nocturnal, leapers
eosimiidae
tiny primates, possibly ancestors of haplorhines, 2 species ~10 grams, in Asia
fayum
elwyn simons, rich in early oligocene fossils, haplorrhine primates (earliest unambiguous haplorrhines 36-33 million years ago, reduction of snout compared to strepsirrhines, post-orbital closure, mandibular fusion)
rafting hypothesis
small african mammals were washed out to sea during storms and floated to madagascar on trees or large mats of vegetation, possibly while hibernating
proconsul
genus found in about 6 localities, ranges from 20 to 17 million years ago, several species known, tail or no tail?, Y-5 molar pattern (ape-like), largish brain (ape-like), flexible shoulder (ape-like)
what are the different epochs within the cenozoic era, and when did each start and end?
the paleogene (65 million years ago), the neogene (23 million years ago), and the quaternary (2.6 million years ago)
what is the order of the epochs within the cenozoic era, from oldest to most recent?
paleocene (65 million years ago), eocene (56 million years ago), oligocene (34 million years ago), miocene (23 million years ago), pliocene (5 million years ago), holocene (10,000) and, pleistocene (2.5 million years ago)
during the cenozoic era, did the earth became gradually cooler or warmer?
the climate started out warm and gradually cooled to today
what is the difference between gymnosperms and angiosperms?
seeds of the angiosperm develop in ovaries but seeds of the gymnosperms are formed in unisexual cones
what are angiosperm forests like (compared to gymnosperm forests)?
lush, many layers, closed cooler, many niches, dominant animals: mammals & birds
when did angiosperms have an adaptive radiation, and what were the consequences for the earliest primates?
paleocene (65 million years ago), animals eat them and inadvertently spread seeds
what were the characteristics of the plesiadapiformes, and what epoch did they live in?
65-54 million years ago, 75 species, insectivorous & frugivorous, found in north america and europe during paleocene
were plesiadapiforms the ancestors of primates, or a sister group?
sister taxon to euprimates
which living mammals are most closely related to primates?
flying lemurs
what was the climate like at the start of the eocene? what consequences did this have for tropical forests, and primate evolution?
a) northern latitudes had tropical climates, tropical climates caused rain forests in north america, up to present-day alaska.
b) increases in plant diversity created new environmental niches favorable for primates
what are the two major groups of eocene primates and which living primates did they resemble?
- adapiformes - resembled lemurs
- omomyiformes (extinct) -resembled tarsiers
which group of very small primates was likely to be the ancestors of all haplorrhines?
eosimiidae
where and when were the earliest unambiguous haplorrhines found?
the fayum, egypt, 36-35 million years ago
what is the most likely scenario for primate evolution in south america? when did the earliest s. american primates live?
a) rafted from africa – a fayum ancestor → caviomorph rodents appear in s. america at about the same time
b) 34 million years ago
how did the climate change at the end of the oligocene/start of the miocene? what consequences did this have for forests and primates
a) warming at end of oligocene
b) northern tropical forests returned ; ape diversity decreasing everywhere
in the miocene, there was a huge radiation of which primate group?
extant apes (primates: hominoidea)
was proconsul an ape or a monkey? what traits did it have that tell us this? what continent did it live on?
a) an ape
b) Y-5 molar pattern (ape-like), largish brain (ape-like), flexible shoulder (ape-like)
c) eastern africa
where did oreopithecus live, and why do scientists think it might have been bipedal?
a) tuscany
b) long arms/short legs, short trunk, mobile joints
have scientists found any significant ape fossils in africa from between 15-8 million years ago?
no, there is a gap in fossil record
foramen magnum
hole in the middle of the skull base that the spinal cord passes through
bipedality
the ability to walk on two legs
lumbar lordosis
the natural curve of the lower back (lumbar) area of the spine
sacrum
a triangular bone in the lower back formed from fused vertebrae and situated between the two hipbones of the pelvis
center of gravity
the average location of the weight of an object/animal/thing
quadrapedal
using all four feet for walking and running
Iliac blades
attachment site for both hindlimb and caudal musculature
valgus knee
angle on the knee
convergent toe
big toe is parallel to the rest of the toes
divergent toe
a deformity which occurs when two or more toes splay in opposing directions (mostly big toe)
hominid
modern humans and all great apes
hominin
modern humans, extinct human species and all our immediate ancestors
honing premolars
teeth sharpened by lower third premolars ; used as weapons
intermembral index (imi)
forelimb length / hindlimb length X 100 –> human: imi = 70 ; ape: imi = 106
how can one determine whether a primate is a habitual biped, and why?
walk on all fours, foramen magnum in the middle of the skull base, barrel-shaped rib cage, shape of spine (more curvature) is vertebral column, lordosis and the sacrum, pelvis shape, limb proportions, valgus knee = angle on the knee, arch in foot = shock absorber, convergent big toe (close to other toes), straight toe bones
mate provisioning hypothesis (evolution of hominin bipedality)
males would gather food and bring it back to females – hence, their hands needed to be free to carry these items ; but, this would mean that pair-bonding evolved early and sexual dimorphism suggests otherwise
tool use hypothesis (evolution of hominin bipedality)
hands needed to be free to make and use tools to hunt ; but, don’t find evidence of stone tools until long after bipedalism
thermoregulation hypothesis (evolution of hominin bipedality)
reduced heat gain, increased heat loss ; but, lots of quadrupedal animals in savannahs
climbing mechanical model hypothesis (evolution of hominin bipedality)
retention of suspensory morphology ; perhaps arboreal habitat became patchy and arboreal ancestors had to travel on the ground and had to walk bipedally because of their morphology
do we know why bipedality evolved?
the freeing of the hands to use and carry tools, threat displays, sexual dimorphism in food gathering, and changes in climate and habitat
what is a hominid?
humans and all great apes
what is a hominin?
bipedal hominids
what were the general characteristics of early hominins
bipedal, slightly increased cranial capacity (brain size), trend toward non-honing premolars
sahelanthropus tchadensis
north central africa, chad ; 6 – 7 million years ago ; reduced canine-premolar (becoming non-honing), bipedal
orrorin tugenensis
tugen hills, kenya ; biped femur shape (curved phalanges), reduced canine, less-honing premolar ; 6.2-5.8 million years ago
ardipithecus kadabba
the middle awash, ethipoia ; reduced canine (3rd premolar has small honing facet,) long toes ; 5.55 -5.2 million years ago
ardipithecus ramidus
the middle awash, ethipoia ; premolar less honing than in ar. kadabba, bipedal, but has a divergent big toe, really long fingers ; 4.8 – 4.4 million years ago
canine diastema
a space between the upper incisor and the upper canine that allows the lower canine a space so that the jaw can close
carbon isotopes
C4: grasses
C3: trees & shrubs
temporalis muscle
elevate the mandible and crush objects between the molars
prognathism
an extension of maxilla beyond the zygomatic bone
phytoliths
microscopic minerals in plant cells
honing premolar
a premolar that sharpens upper canine (monkeys and apes)
zygomatic bones
one of a pair of bones on each upper side of the face that forms the cheek and part of the eye socket
sagittal crest
attachment site for major chewing muscle, can be indicative of diet or sexual dimorphism
masseter muscle
between zygomatic arch and lower jaw
temporal fossa
a shallow depression on the temporal region of the skull
when did australopithecus species live, and on which parts of what continent?
inhabited the african continent between approximately 4.2 and 1.9 million years ago
what are the general characteristics of australopithecus species?
anteriorly positioned foramen magnum, slight brain increase, strong sub-nasal prognathism, robust jaws (larger and thicker than human mandibles), reduced honing premolar, reduced canine diastema
australopithecus anamensis
northern kenya ; age 4.2 – 3.8 million years ago ; oldest australopithecus species
australopithecus afarensis
hadar, ethiopia ; age 3.8 – 2.95 million years ago ; laetoli footprints - bipedal
australopithecus africanus
recovered from cave sites in south africa ; age– 2.8 – 2.2 million years ago ; youngest ; foramen magnum like a biped (found by raymond dart)
australopithecus sediba
malapa, south africa ; dated to 1.9 million years ago
what do we know about australopithecus species?
very small teeth ; diet = grasses, trees, shrubs ; they have cut marks on bone but nothing is certain about why
when did the australopithecines become extinct?
1.9 million years ago
where have paranthropus specimens been found (in general)?
ethipopia, kenya, and tanzania (east africa)
what are the characteristics of paranthropus?
larger cheek teeth and smaller incisors in straight line ; wide, flared, and anteriorly positioned zygomatic bones (cheek bones) ; sagittal crest (anchored cheek bones) in males; temporal fossa is very deep
what do these traits tell us about muscles and bite force of paranthropus?
strong chewing muscles and greater bite force
what did paranthropus probably eat?
nuts, seeds, and hard fruit
when did paranthropus become extinct?
1.4 million years ago
