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94 Cards in this Set

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dentine
inner soft layer of the tooth
enamel
-outer hard part of the tooth
parts of a thecodont tooth
-crown and root
pulp cavity
-innermost part of the tooth
-blood supply and nerve
brachydont
-low crowned
-blood supply is cut off, tooth stops growing
hypsodont
-teeth do not stop growing
-require occlusion to wear tooth
teeth on which part of mouth?
-incisors on the premaxilla
-canine and premolars/molars on maxilla
differences in eutherian and metatherian teeth: deciduity
- molars nondecidious, all others diphyodont in eutherians
- only last premolar deciduous, all others monophyodont in metatherians
carnassials made up of what teeth?
-fourth premolar on top
-first molar on bottom
primitive dental formula for metatherians
-5/4i, 1/1c, 3/3p, 4/4m
primitive dental formula for eutherians
-3/3i, 1/1c, 4/4p, 3/3m
tooth loss
-incisors - posterior are lost first
-premolars - anterior to posterior loss
-molars - posterior to anterior loss
what is the primitive molar of therians?>
-tribosphenic molars
lophodont
-molars slide forward and backward across each other
-ridges of tooth move horizontally
-Elephantidae
selenodont
-grind teeth from side to side
-ridges run vertically across tooth
-Cervidae
selenolophodont
-Bovidae and Equidae
-ridges run in all directions
Inner ear
-contains sensory cells for hearing and balance
-contained in cochlea, coiled in some mammals and embedded in brain case in petrosal bone
Middle ear
-houses 3 ear ossicles
-convert sound waves into vibrations in cochlea that fire sensory cells
-bounded by tympanum, supported by tympanic bone
outer ear
-tympanum outward
-includes canal and pinnae
Common features of evolution
-gradual process
-modification of existing structures
--novel structures, which bud off from existing structures (derivation of masseter)
-coadapted systems (imposes constraints)
functional morphology
-using physics principles to analyze biological structures
Force vectors
-convey directionality and strength
equilibrium
-all forces are opposed by offsetting forces
ancestral condition of ear
-early synapsids including Pelycosaurs
-small temporal fenestra
-many bones in mandible (angular and articular)
-quadrate/articular jaw joint
-no tympanic bone - angular bone instead on lower jaw
-very large stapes (connects inner ear to quadrate)
-lacked tympanum
ancestral auditory path
-dentary (rested on ground) --> articular -->[jaw joint]-->quadrate-->stapes-->inner ear
effect of bite resistance on early synapsid jaws
-simple jaw adductor (temporalis), low coronoid emminence
-bite resistance and force of adductor offset
-generates stress on lower jaw
-quadrate and articular constrained to be large and robust to withstand jaw stresses
-animal probably didn't hear well
jaws of cynodonts
-larger, more complex jaw adductors
-masseter (splits off from temporalis)
-gradual expansion of coronoid process
-temporalis now attaches back and up (vs. straight up)
forces involved in cynodont jaws
-all 4 force vectors intersect directly over the bite point
-horizontal and vertical components cancel
-no stress at the jaw joint
-quadrate and articular free to respond to selection favoring increased transmission of sound vibrations
more cynodont jaw/ear stuff
-first evidence of tympanum (begin to see evolution of laminar process of angular bone, which supports the tympanum)
-quadrate and articular become gradually smaller, d/s expand backwards to fill space left by q/a
-d/s eventially touch to form current jaw joint
-articular migrates off lower jaw = malleus
-quadrate migrates off upper jaw = incus
-angular bone migrates off lower jaw= tympanic bone
fossils which obtained both types of jaw joint
-Probainognathus and Diarthragnathous
Didelphis jaw/ear stuff
-can watch changes in ear/jaw during development
-malleus first ossifies on lower haw
-incus first ossifies on upper jaw
-angular first ossifies on lower jaw
-expansion of brain case pulls inner ear away from jaw, induces migration of ancestral jaw elements and generates the inner ear cavity
chain of transmission in cynodonts
-tympanum -> angular ->articular -> [jaw joint] -> quadrate -> stapes -> inner ear
chain of transmission in mammals
-tympanum -> malleus -> incus -> stapes -> inner ear
-articulation between malleus and incus homologous to ancestral jaw joint
flight
-airfoil is asymmetric (disstance from leading edge to trailing edge is longer over top surface than bottom)
-relies on presence of laminar flow (parallel movement of air streams)
-simultaneous arrival at trailing edge
-velocity across upper surface greater then velocity across lower surface
Bernoulli's theorem
P=C-.5(dv^2) where P is air pressure, d is density of air, v is velocity
-air moving over top of wing exerts less pressure than bottom
PL-PU = Lift
-when lift defeats force of gravity, flight is achieved
-ultimately relies on differential of velocity
Speed of flight in bats
-lift is greater at high speeds than low speeds
-bats are slow flyers
-Myotis lucifugus = 20 mph
-Eptesicus fuscus = 40 mph
-Tadarida brasiliensis = 60 mph
How to achieve lift at low flight speeds
-alter camber (curvature) of wings
-Increase angle of attack
-Wing loading and aspect ratio
-Leading edge flaps
alter camber of wings
-bats have a thin air foil that can be flexible
-increasing camber increases velocity differential at low speeds
wing loading
-body weight / surface area of wing
-lower wing loading =easuer achievement of flight
-bats have low wing loadings
--House wren = .24 g/cm^2
--Glossaphaga = .11 g/cm^2
--Myotis = .06 g/cm^2
aspect ratio
-length / width of wings
-short, wide wings = better for slow, maneuverable flight (low AR)
-long, narrow wings = fast flyer (high AR)
leading edge flaps
-detiorate tendency toward turbulence
-turbulence caused by low flight speeds when the pressure differential is lost
downstroke
-power stroke
-powered by 3 muscles:
--pectoralis
--subscapularis
--serratus
7 parts of a bat wing
-propatagium
-dactylopatagium brevis
-dactylopatagium minus
-dactylopatagium longus
-dactylopatagium lattus
-plagiopatagium
-uropatagium
dactylopatagium longus
-thrust generator
-not well-braced
-leading edge pulled down faster during downstroke, trailing edge lags behind leading edge
--this generates thrust by pushing air backward
dactylopatagium lattus
-may also assist with thrust
propatagium, d. brevis, and d. minus
-form leading edge flaps
plagiopatagium
-primary lift generator
-5th digit strong and well-braced, maintains angle of attack
-muscularized - allows camber to be adjusted during flight
uropatagium
-rudder
-catching insects
upstroke
-recovery stroke
-passive
-shoulder-locking mechanism - greater tuberosity (halts upstroke passively)
differences in greater tuberosity in species of bats
-Molossidae and Vespertilionidae = greater tuberosity very well-developed
-Phyllostomatidae = moderately developed greater tuberosity
-Craseonycterus = no shoulder locking mechanism
other adaptations for flight
-keeled manubrium
-stiffening of axial skeleton
keeled manubrium
-anchoring point for pectoralis attachment
-first segment of sternum
Natalidae
-funnel-eared bats
-well represented stiffening of axial skeleton
-thoracic vertebrae extremely compressed = no flexibility
-fusion of sacral and lumbar vertebrae = only one flexion point in spinal column
in-force
-force muscles can generate = resultant vector
out-force
-force limb can generate against ground
relationship between in-force and out-force mediated by..
-lever arms
-In-lever and out-lever
In-lever
-perpendicular distance between line of action of the in-force and the fulcrum
out-lever
-perpendicular distance between line of action of out-force and fulcrum
Torque
-turning force
-In-torque generated by In-lever
--product of In-force and In-lever
-Out-torque generated by out-lever
--product of Out-force and Out-lever
-at equilibrium, out-torque = in-torque
optimized limb for digging
-want to optimize the out-force
-long in-lever (elbow), short out-lever (ulna)
how to optimize the out-force?
-increase in-force (diameter of muscle fibers)
=limited means
-increase in-lever/out-lever
=long in-lever, short out-lever
why aren't all mammals optimized like the mammals optimized for digging?
-Vo = out velocity = velocity at end of Lo
-Vi = in velocity = velocity at end of Li
-at equilibrium, VoLi = ViLo
-Vo is the phenotype on whicih selection can operate
-optimizing Vo optimizes mammal for speed
how do you optimize for speed?
-optimize Vo
--increase Vi (proportional to rate at which muscles can contract - physiologically limited)
--increase gear ratio (Lo/Li) - make Lo long and Li short

-short olecranon processes and long limbs
types of in terrestrial mammals
-saltation (bipedal hopping)
-cursorial (running)
-volant (gliding)
-scansorial (climbing)
-swimming
saltatorial locomotion
-aka richochetal locomotion
-long hind limbs
-reduction of number of digits
-front limb generalized
-stiffened spinal column
-hind limb ligaments and tendons have elasticity
-tails usually long
long hind limbs in saltatorial locomotion
-optimizes Vo
-long distal portion of limb (Lo)
-short Li (calcanea)
-maximize Fi (as much muscle as possible)
front limb generalized in saltatorial mammals
-used in grooming
stiffened spinal column in saltatorial mammals
-cervical vertebrae fused
-lumbar vertebrae thick and robust
-sacrum strongly fused to pelvis
-ligaments between regions in spinal column for shock absorption
tails long in saltatorial mammals
-serve as counterbalance
-tufted in many --> great amount of mobility
adaptations in cursorial mammals that increase stride length
-elongated limb bones
-change in foot posture
-expansion of metapodials
-pectoral girdle adaptations
-increased dorso-ventral flexion of spine
pectoral girdle adaptations in cursorial mammals
-loss of clavicle
-scapula can rotate
-muscular sling for scapula
--trapezius
--rhomboideus
--serratus
--pectoralis
--also absorbs shock of front limb striking ground during gait
adaptations for increasing stride rate of cursorial mammals
-optimizing Vo (long Lo, short Li)
-increase in number of joints (wrist, ankle, scapula as joints)
-decrease in distal inertia of limb (concentrating muscles to proximal portion, loss of peripheral digits)
-range of motion in single plane (front to back)
loss of peripheral digits in ungulates
-Cetardiodactyls - only 3rd and 4th remain
-Perrisodactyls - 3rd digit remains
Astragalus
-range of motion in single plane well-developed
two ways cursorial mammals increase speed
-increase stride length
-increase stride rate
scansorial locomotion
-danger of falling increases with larger animals (terminal velocity greater in larger animals = sa/v ratio)
-increase friction between substrate and hands/limbs
-stiffened trunks to resist bending
-elongated forelimbs
increasing friction between subtrate and hands/limbs in scansorial mammals
-friction pads (Procyon, Primates, porcupines)
-well-developed claws (Sciurus)
-prehensile organs (opposable digits, prehensile tails)
-suction disks (Myzopodidae)
stiffening of trunks in scansorial mammals
-robust vertebral column
-ribs expanded and overlapping
-elongated thoracic region
-lumbar shortening - decreased movement between pelvis and ribs
gibbons
-brachiation - locomotion relying on arms with no assistance from legs
Gliding
-Petauridae, Rodentia (Sciuridae), Dermoptera
-stylar cartilage manipulates "flaps" that counter induced drag
Induced drag
-downward pressure on tips of wings by boundary layer
-more a problem for gliders than powered fliers
Glaucomys
-can glide up to 50m
Eupetaurus
-cat-sized glider
-lives in caves above tree line in Pakistan
pressure drag
-displacement of water
-proportional to cross-sectional area of animal
-long thin rod-shaped minimizes pressure drag
frictional drag
-property of laminar flow
-caused by friction of parallel streams in water
-proportional to total surface area
-sphere = minimizes friction drag
what shape optimizes the trade-off between pressure drag and frictional drag?
-spindle-shaped
-fusiform body
adaptations in semi-aquatic mammals and some examples
-webbing -> increases thrust
-water shrews, Lontra (otter), Castor, Hippopatamus
Adaptations in fully aquatic mammals
-limb modification
--front limbs modified into flippers
--hind limbs modified
-axial skeleton modifications
--reduction in cervical vertebrae (shortened, compressed, fused - atlas and axis fused)
--increase in size/robustness of vertebrae
-tail flukes
front limbs modified into flippers
-entirely syndactylous
-provide thrust (Otariidae)
-rudders for steering (Cetaceans, Sirenians)
hind limbs modified in aquatic mammals
-propulsion (Phocids)
-absent or extremely vestigial (pelvis floating in musculature)
Archaeocetes
-document gradual transition of aquatic mammals from terrestrial to aquatic
Pakicetus
-oldest Archaeocete found - 52 mya
-fully functional hind limbs
Ambulocetus
-49 mya
-around Pakistan
Basilosaurus
-40 mya
-60 feet long
-fully formed hind limb, but tiny