Exam 2 Flashcards
what is an amniote
egg with extraembryonic membranes and a shell
what are the 3 types of skull fenestration in amniotes
anapsid (no openings)
synapsid (1 opening)
diapsid (2 openings)
which type of skull fenestration characterizes mammals
synapsid
what are synapsids
pelycosaurs, mammals, therapsids, and cynodontia
what are some synapsid traits
-maxilla contacts quadratojugal bone
-single fenestra
-caniniform maxillary teeth
-post dentary bones modified for hearing
what are the 3 main groups of synapsids
pelycosaurs, therapsids, mammals
what are pelycosaurs
eothyrididae, caseidae, varanopeidae, sphenacodontidae
what are therapsids
biarmosuchia, dinocephalia, dicynodontia, gorgonopsia
what are some defining features of therapsids
-enlarged temporal opening
-sagittal crest and zygomatic arches
-upper canines enlarged
-feet shortened
-more upright limb posture
which group of therapsids are ancestral to mammals
cynodonts
what are some defining features of cynodonts
-dentary bone becomes major lower jaw element
-partial secondary palate
-zygomatic arches flare laterally
-teeth absent from pterygoid bone
what was the permian mass extinction
climate change due to large scale volcanism
what are some reasons why cynodonts survived the permian mass extinction
-small body size
-fast life history (grow quick, reproduce early)
-burrowers
-mammalian (heterodont teeth, large brain, warm blooded, fur)
what kinds of terrestrial vegetation characterized the mesozoic
ferns, cycads, ginkgophytes, bennettitaleans
conifers first appeared
early angiosperms appeared
what are some skeletal and inferred soft tissue features of early mesozoic mammals
skeletal:
-double rooted cheek teeth w/ premolars and molars
-diphyodont dentition
-mandibular symphysis reduced
soft tissue:
-mammary glands
-viviparity
-anal and urogenital openings
what are therian mammals
marsupials and eutherians
what are the anatomical traits of therian mammals
-tribosphenic molars
-protocone of the upper molar occludes with the talonid basin of the lower molar
-supraspinous fossa on scapula
-spiral cochlea
what is the evolution of a new dentary squamosal jaw joint
articular bone of lower jaw > malleus
quadrate bone of lower jaw > incus
angular bone of lower jaw > tympanic ring
what is the evolution of more complex molars
primary cusp, accessory cusp, cutting trigonid, crushing talonid
what is the evolution of the secondary palate
facilitated suckling
what is the evolution of parasagittal movement of limbs
sprawling vs erect
what is the evolutionary history of mesozoic mammalian radiations
-all continents except antarctica
-small bodied
-premolars/molars
-large brain
-lactation/suckling
what are the basic characteristics of haramiyidans
-earliest known herbivores
-teeth resemble multituberculates
-molars are parallel rows of cusps
-jaw moved with powerful backstroke
what are the basic characteristics of morganucodontids
-small, shrew like
-cheek teeth differentiated into premolars and molars
-premolars preceded by deciduous teeth
-chewing on one side of jaw at a time
what are the basic characteristics of docodonts
-highly derived roughly quadrate teeth, cusps not aligned anteroposteriorly
in what ways were haramiyidans, morganucodontids, and docodonts ecologically diverse
-docodonts swim and fish feed
-ambulatory carnivory or scavenging in large gobiconodontids
-scratch digging and feeding on colonial insects in fruitafossor
-climbing locomotion in basal eutherians and metatherians
-gliding adaptation in volaticotherium
australosphnidans are ancestral to which modern mammals
monotremes
what are the basic characteristics of eutriconodonts
unique molars
what are the basic characteristics of multituberculates
-herbivores or omnivores
-similar in appearance to rodents
-jaw movement similar to haramiyidans
define the clade boreosphenida
early mammals that originated in the northern hemisphere and has three cusped cheek teeth (metatherians and eutherians)
what is the significance of juramaia sinensis
earliest known marsupial
what is the significance of eomaia scansoria
earliest known placental mammal
what is the early rise hypothesis
ecological radiation of early mammals began prior to K-Pg boundary, driven by broadly coincident ecological radiations of flowering plants and some insect groups
what is the suppression hypothesis
mammals experienced ecological release following the end-Cretaceous mass extinction event at 66M
what is the delayed rise hypothesis
an ecological radiation occured in the eocene, possibly spurred by the paleocene-eocene thermal maximum at 56Ma
what is the basic climate of the epoch in the plaeocene
cretaceous subtropical
what is the importance of the site of corral bluffs, CO
K-Pg boundary
which paleocene mammals are considered ancestral to modern ungulates
condylarths
which paleocene mammals are considered ancestral to modern carnivores
miacids
which groups in the paleocene were the first to attain large body size
pantodonts and uintatheres
which modern groups of the paleocene are mesonychids and plesaidapiformes related to
artiodactyls
what is the basic climate of the epoch in the eocene
5-8 degree C global average temp rise, creatceous subtropical climate persisted
which group of ungulates has its peak of diversity in the eocene
perissodactyls
which modern group got its start in the eocene with the origin of the group archaeocetes
hippos
what are the 2 eocene groups of early primates
adapids (lemurs) and omomyids (tarsiers)
what is the basic climate of the oligocene
development of antarctic ice and changes in ocean circulation, brought about increased seasonality/overall cooling and drying
what was the grand coupure
eocene-oligocene climate driven extinction even
what is the significance of the paraceratherium
largest land mammal ever
which groups of primates originated during the eocene
aegyptopithecus and apidium
what is the basic climate of the epoch in the miocene
savannah woodlands dominate north america, semideserts, mountain building
which group of mammals had its peak of diversity in the miocene
proboscidean
which group of primates originated during the miocene
apes
what was the basic climate of the epoch in the pliocene
warming followed by continued global cooling, extensive glaciation
which south american group had its peak of diversity in the pliocene
ungulates
what was the great american biotic interchange
north america and south america attatched and northern mammals colonized a lot
which group of primates originated during the pliocene
hominids
what was the basic climate of the epoch during the pleistocene
periods of lowered temperatures alternated with periods of relative warmth, increased precipitation
what were the pleistocene megafauna
-saber tooth cats and imperial mammoths
-saber tooth cats and litoptern ungulates
-marsupial lions and short faced kangaroos
what is the evidence that supports the idea that humans caused the extinction of many pleistocene mammals
-archaeological evidence of co-occurrence and hunting
-non random extinctions
-immigrant species from asia less affected than native species
-dates of last known occurrence coincide with human migrations
what are basic mammalian trends
-endothermy/hair
-lactation
-sensory specializations
-heterodont dentition
what is the function of mammary glands in mammals
produce milk
what is the difference in milk delivery between monotremes and metatherians/eutherians
monotremes dont have external nipples
what is the function of sweat in mammals
promote evaporative cooling, eliminates some waste
what is the function of sebaceous in mammals
oily secretion that lubricates hair and skin
what is the function of scent and musk glands in mammals
attracts mates, marks territory, communication, protection
what is hair made of in mammals
keratin
what are the three layers of an individual hair in mammals
hair cuticle, cortex, medulla
countershading
upper body is darker than lower body
camouflage
hides an animal
disruptive coloration
strongly contrasting markings to break up the outline of an animal
warning coloration
warns predators
intraspecific communication
colors that mean something to another species
what is adipose tissue (fat) used for
-energy storage
-source of heat and water
-thermal insulation
where is fat often stored in mammals
tail or abdomen
what is the basic setup of the mammal circulatory system
systemic and pulmonary circuits
4 chambered heart
what is the basic setup of the mammal respiratory system
trachea > bronchi > bronchioles ? alveolar ducts > alveoli
what structures characterize the mammalian brain
-highly developed neocortex
-corpus callosum present
what characterizes the various mammalian sense organs
olfaction: receptors distributed across mucosal surfaces of mesethmoid and vomeronasal organ areas
hearing: high acuity, used in communication/orientation/food/enemies
sight: retina with photoreceptors
what 2 adaptations for fermentation are found in ungulates
foregut fermentation
hindgut fermentation
what are the characteristics of the mammalian skull
-akinetic
-zygomatic arch
-single crainomandibular jaw joint
-turbinal bones in nasal cavities
-foramina pass cranial nerves and vessels
what kinds of vertebrae are found in the mammalian axial skeleton
cervical
thoracic
lumbar
sacral
caudal
what are the 2 girdles for the limbs
pectoral and pelvic
what is the ancestral number of digits in the mammalian manus and pes
5
define crown
top of tooth
define root
portion of tooth underneath gum
define pulp cavity
inner tissue of tooth
define enamel
outer layer of tooth
define dentin
essential for support of the enamel layer
define cementum
outer layer of root
define rootless vs rooted teeth
rootless teeth continue growing (rodents)
what are the basic surface features of mammalian teeth
cusp - highest point of tooth
basin - lowest point of tooth
which bones produce teeth in mammals
dentary (lower jaw), premaxilla
define homodont
all teeth are the same shape
define heterodont
4 different tooth types
define diphyodont
two sets of teeth
define polyphyodont
several sets of teeth
what are some exceptions to the typical mammal pattern of teeth
-toothed whales
-manatees
-pinnipeds
-some rodents
-elephants
-kangaroos
define dental placode (what cells make up this)
where a tooth starts (interaction between epidermis and dermis)
define enamel knots
signals center to appear, marks the location sites of cusp formation
define ameloblasts
cells that produce enamel
define odontoblasts
produces dentin
define periodontal ligament
ligament that holds tooth in socket
what are the characteristics of tribosphenic upper and lower molars
upper - paracone and metacone on top, protoconule, metaconule, protocone on bottom
lower- protoconid and hypoconid on top, paraconid, hypoconulid, metaconid, entoconid on bottom
how do tribosphenic upper and lower molars occlude
the upper molar fits inside of the lower molar
what does the addition of hypocone have to do with tribosphenic upper and lower molars
cusp added to the primitively triangular upper molar teeth of therian mammals
cone vs conid
cone - upper cusp
conid - lower cusp
what is the function of the masseter muscle
close the jaw
what is the function of the temporalis muscle
close the jaw
what is the function of the medial pterygoid muscle
close the jaw
what is the function of the lateral pterygoid muscle
open the jaw and pull jaw forward
what is the function of the digastric muscle
raises tongue, opens jaw for chewing and speech
what are the diet related differences in mastication
how they chew determines what they can eat
dental formula?
goes from front to back, incisiors, canines, premolars, molars
what are the primitive placental and marsupial dental formulas
marsupial: 5/4, 1/1, 3/3, 4/4
placental: 3/3, 1/1, 4/4, 3/3
what are some edentulous mammals
-mysticete whales
-pangolins
-anteaters
-monotremes
what are some variations in mammal incisor teeth
rodents: large and chisel like
lemurs: tooth comb
aye-ayes: rootless
elephants: tusks
what are some variation in mammal canine teeth
modern carnivores: enlarged
define brachydont
short crowned teeth
define hypsodont
tall crowned teeth
define bunodont
rounded cusps on molars
define lophodont
cusps form ridges
define selenodont
cusps form crescents
define zalambdodont
v shaped crest
define dilambdodont
w shaped ectoloph
carnivory vs herbivory
carnivory: cheek teeth are blade like
vertical shearing
herbivory: cheek teeth become quadrate
jaw action became horizontal and transverse
what hormone is produced by male testes
testosterone
what are spermatogonia
sperm
what is spermatogenesis
mitosis of sperm
what are the differences in testes locations across mammals
abdominal:
-monotremes
-endentates
-elephants
-sirenians
-cetaceans
scrotum in:
most mammals
what is a baculum
bone
what are the greater number of functions required by females for reproduction
-make eggs
-receive and transport sperm
-gestate young
-birth/egg lay
-lactation
-parental care
what are the basics of oogenesis
ova mature in paired ovaries, takes place in fetus during gestation
what is the anatomy of the monotreme reproductive system
right and left uteri enter urogenital sinus, cloaca present
what is the anatomy of the marsupial reproductive system
pair of uteri enter into vaginal sinus, duplex cervix, two vaginas
what is the anatomy of the placental mammal reproductive system
retain paired ovaries, single vagina
what are the four different kinds of placental mammal uteri
duplex
bipartite
bicornuate
simplex
what are the ancestral characteristics of monotreme reproduction
-yolk with shell
-more yolk
-fetal egg tooth
-embryos at somite stage when laid
what is the sequence of events in fertilization and early embryonic development in monotremes
fertilized in infundibulum > mucoid coating added > thin shell of ovokeratin added > second shell membrane added > uterine secretions aid embryogenesis > third shell layer added prior to birth
what is the blastoderm
outer layer of egg
how do marsupials and placentals differ in length of gestation and lactation
eutherians have longer gestation, shorter lactation
define monoestrous
one estrous cycle per year
define polyestrous
more than one estrous cycle per year
4 phases of the estrous cycle
proestrus - development of endometrium and ovarian follicles
estrus - ovulation (luteinizing hormone LH)
metestrus - LH maintains corpus luteum, secretes hormones
diestrus - uterus is prepared for implantation
which hormone is responsible for ovulation
LH (luteinizing hormone)
what is the corpus luteum and what is its function
secretes hormones to prepare endometrium for implantation
what is spontaneous ovulation
occurs without copulation, occurs widely among mammals
compare and contrast the 3 types of marsupial estrous cycles
1: short gestation, no ovulation during lactation
2: gestation and estrous cycle length same, postpartum estrus and ovulation, embryonic diapause
3: same as 2 but w/ further development not controlled by lactation
what is the sequence of events in fertilization and early embryonic development in marsupials
spontaneous ovulation > fertilization > cleavage divisions > mucoid layer > shell membrane > shell membrane becomes placenta
what is the sequence of events in fertilization and early embryonic development in placental mammals
fertilization > cleavage divisions > blastocyst reaches uterus > outer layer adheres and erodes > forms placenta > forms embryo
what is the protoderm
a unique developmental layer in marsupials
what are the inner cell mass and trophoblast
inner cell mass forms embryo
trophoblast forms placenta
what is the chorioviteline placenta
highly vascularized portion of yolk sac
what is the chorioallantoic placenta
highly vascularized chorioallantoic membrane
describe the macropodidae placenta
choriovitelline
describe the peramelemorphia placenta
choriovitelline and chorioallantoic
describe the placental mammal placenta
chorioallantoic
define epitheliochorial placenta (which mammals have this?)
oxygen and nutrients pass through walls of uterine blood vessels and through layers of connective tissue and epithelium
-lemurs, some ungulates, cetaceans
define endotheliochorial placenta (which mammals have this?)
epithelium of the chorion is in contact with endothelial lining of uterine capillaries
-carnivorans
define the hemochorial placenta (which mammals have this?)
endothelial lining of the blood vessels in villi separate fetal blood from surrounding maternal blood sinuses
-insectivorans, rabbits, bats, higher primates, rodents
define the diffuse shape of eutherian placenta (which mammals have this?)
villi occur over large surface area
-lemurs, artiodactyla, perissodactyla
define the cotyledonary shape of eutherian placenta (which mammals have this?)
villi in regularly spaced clusters
-ruminant artiodactyla
define the zonary shape of eutherian placenta (which mammals have this?)
band of villi encircles chorion
-carnivorans
define the discoidal shape of eutherian placenta (which mammals have this?)
villi in disk shaped zone
-insectivorians, bats, primates, rodents, rabbits
what are the hormonal pathways involved in metatherian parturition
corpus luteum
which hormones trigger uterine contractions in metatherians
mesotocin
how does the fetus get into the pouch and what happens once it is in there
crawls into pouch, attaches to bud at tip of teat
what are the hormonal pathways involved in eutherian parturition
estrogen and lowering of progesterone
which hormones trigger uterine contractions in eutherians
estrogen
what is the difference between a deciduous or nondeciduous placenta
non: villi pull out of uterine pits
deciduous: placenta is torn away at birth
which hormones promote mammary gland development
estrogen, progesterone, insulin, placental lactogen
which hormone regulates lactation
prolactin
what are the three stages of metatherian lactation
mammogenesis: prep
early lactogenesis: young attach to teat
late lactogenesis: young are detatched
how do metatherians and eutherians differ in milk composition across the lactation period
eutherians: uniform
marsupials: varies
how do metatherians and eutherians differ in milk composition across species
marsupials: varies little
eutherians: varies lot
which requires more energy: pregnancy or lactation
lactation
what are the various costs of reproduction on female mammals
-increase food intake
-decrease activity
-metabolize fat
-shift diet
-anatomical changes
what is the foraging cycle strategy (and in which pinnipeds is this found?)
females forage at sea but return to nurse
-sea lions, fur seals
what is aquatic nursing strategy (and in which pinnipeds is this found?)
suckling at sea
-walrus
what is the fasting cycle strategy (and in which pinnipeds is this found?)
females rely on blubber and fast during lactation
-seals
what is the combination of fasting and foraging strategy (and in which pinnipeds is this found?)
fast sometimes, forage sometimes
-seals
what are the details of delayed fertilization and in which mammals does it occur
mate and store sperm in fall, fertilize in spring
-rhinolophid and vespertilionid bats
what are the details of delayed implantation and in which mammals is it found
development paused at blastocyst stage
-metatherians, carnivora, chiroptera, pilosa, artiodactyla
what is the difference between obligate and facultative delayed implantation
obligate: consistent part of reproductive cycle
facultative: occasions when animal is nursing large litter
what are the details of delayed development and in which mammals does it occur
blastocysts stops growing until newborn leaves pouch
-kangaroo
how does photoperiod affect the timing of reproduction
day > night
what is the effect of melatonin on reproduction
day > night
what is the effect of temperature on reproduction
warmer > colder
what is the effect of energy/nutrition on reproduction
plant secondary compounds and phyoestrogens
how do plant secondary compounds and phytoestrogens play a role in reproduction
PSC: chemicals that trigger reproductive behavior
phyto: plant compounds that mimic animal estrogens
how do behavioral controls influence reproduction
pheremones produced attract mates, signal receptivity
what is the bruce effect and in what mammals is this seen
unfamiliar male in habitat, females reenter estrus more quickly
why is it advantageous for a new male in a group to commit infanticide
male brings females into estrus more quickly
what are the characteristics of the altricial young strategy
-helpless at birth
-nearly naked
-ears/eyes closed
-cannot locomote or thermoregulate
how does the semelparity strategy affect males
death, males lose significant body weight and fur
what are the characteristics of the precocial young strategy
fur
eyes and ears functional
locomote and thermoregulate
what is the general rule relating gestation length and body size in mammals
positive correlation
what are some exceptions to the body size/gestation length rule in mammals
elephant shrews, sloths, baleen whales, primates
why is inbreeding avoidance important
mortality, susceptible to disease, genetic issues
what are some ways inbreeding is avoided
dispersal from natal area, kin recognition
how does environment influence the timing of reproduction
good season > more breeding
in what way does reproductive effort vary with residual reproductive value
varies inversely
define endothermy
internal heat production
define homeothermy
constant heat production
how are ectotherms different than endotherms
ecto- heat gained from environment
endo- heat produced
what are the advantages and disadvantages of being ectothermic
advantages:
-no high basal metabolic rate
-endure shortages of food/water/O2
-elongate shape or tiny
disadvantages:
-rapid exhaustion
-brief activity
what are the advantages and disadvantages of being endothermic
advantages:
-high work capacity
disadvantages:
-lots of food, water, O2
define regional heterothermy
core body temp is maintained well above that of other body regions
define temporal heterothermy
mammals modify their body temp in response to fluctuations daily seasonal environmental temp
how do core body temperatures vary within mammal groups
core body temp is constant but body temp varies
how do core body temperatures vary between metatherians and eutherians
metatherians - lower body temp
eutherians - higher body temp
what is the thermoneutral zone
zone in which little or no metabolic energy is expended on temp regulation
what does a mammal need to do if its body temp fluctuates below the lower critical temperature
additional heat production
what does a mammal need to do if its body temp fluctuates above the critical temperature
additional heat dissipation
how does food quality affect metabolic rates
better food quality = higher metabolic rates
4 strategies to dealing with cold
1) large body size
2) decrease rate of heat loss
3) increase metabolic heat production
4) abandon normal body temp
what does bergmann’s rule describe
boreal mammals larger than tropical counterparts
what is the relationship between surface area and volume
surface area increases with square of linear dimension
volume increases with cube of linear dimension
what kinds of mammals have trouble staying cool
large
what kinds of mammals have trouble staying warm
small
what is the relationship between body size and a mammal’s lower critical temperature
small: lower critical temp
large: higher critical temp
what is the difference between the basal metabolic rate and the field metabolic rate
basal- measured under controlled lab conditions
field - free living animals eating, digesting, moving
how does the mass specific metabolic rate vary with body size
smaller mammals have higher metabolisms
how does the absolute metabolic rate vary with body size
larger mammals have higher metabolisms
what kinds of insulation do mammals have
blubber
how can water decrease the usefulness of insulation
fur gets compressed when wet and doesn’t insulate anymore
how does vasoconstriction promote regional heterothermia
decreases blood flow to skin
how do countercurrent heat exchange systems decrease heat loss
cool blood warmed by arterial blood as it returns to core
how does shivering counteract heat loss
heat production by cold induced involuntary muscle contraction
what is the purpose of daily torpor
body temp, metabolic rate, respiration, and heat rate are lowered
what is seasonal torpor triggered by
food deprivation, short day length, low temps in environment
what are the 3 phases of seasonal torpor
rapid entry, prolonged period, rapid arousal
how do shallow hibernation and profound hibernation differ
shallow: hibernation for a short period
profound: hibernation for a long period
what are the 2 types of arousal
alarm- ambient temp drops beyond animal’s ability to compensate
periodic- absence of external cues
how does non shivering thermogenesis work
metabolic heat produced by metabolizing fat
what are some temperature regulation methods used by bats
heterothermy, hibernation
what are other ways mammals deal with cold environments
migration
what is behavioral thermoregulation
using the environment to warm up or cool down
