Skeletal considerations adaptations for locomotion
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Mammalogy (Fall 2012 Althoff - reference FDVM Chapter 6). LEC 05. SKELETAL CONSIDERATIONS & ADAPTATIONS FOR LOCOMOTION. Axial Skeleton. For terrestrial mammals: skeleton, muscles, and their associated structures can be viewed as one unit

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SKELETAL CONSIDERATIONS & ADAPTATIONS FOR LOCOMOTION

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Mammalogy (Fall 2012 Althoff - reference FDVM Chapter 6)

LEC

05

SKELETAL CONSIDERATIONS & ADAPTATIONS FOR LOCOMOTION


Axial Skeleton

  • For terrestrial mammals: skeleton, muscles, and their associated structures can be viewed as one unit

  • The ____________________ represents the deck or girders of a bridge & the legs are the pillars.

  • A major, distinguishing feature of mammals is that the “pillars” (legs) must move as ________, via muscle action, to provide locomotion


Fig. 8-3 p170 PJH


A neck!

thoracic

lumbar


Generalized primitive tetrapod condition

post-

  • ___________________ (zygapophysis singular)processes that interlock and resisttwisting (torsion) andbending (compression)to support weight ofviserca on land

pre-

spinal

cord

RIB

notocord

Better suspension…on land !!

Fig. 8-2 p169 PJH


Vertebral Column

  • Cervical, thoracic, lumbar, sacral, and caudal vertebrate. Exceptions (sloths and manatees don’t have cervical vertebrate)

  • 12-15 ribs which articulate with thoracic vertebrae

  • 4-7 lumbar vertebrae (_______________)

  • In most mammals, sacral vertebrae are ______ to form os sacrum to which pelvic girdle attaches

  • Pelvic girdle: ____________________

  • Caudal = tail (varies with tail length)


Bobcat: male or female ????


Atlas & Axis Junction

  • Relative to “lower” vertebrates, these two vertebrate (at junction of vertebral column and skull) allow for significantly increased _____________ of the skull

  • Increased movement translates to better positions for __________________ …doesn’t require that ________ body be moved


Axial & Appendicular Join

  • Attachment of forelimbs & hindlimbs to axial skeleton

  • __________—PECTORAL GIRDLE (clavicle & scapula)

  • __________—PELVIC GIRDLE (ilium, ishium, & pubis)


PERMITS ROTATION


Joints

  • End of joint bones covered by a smooth layer or articular ____________. Result: reduced friction

  • Bone within the joint is covered cancellous bone (i.e., not as dense)

  • Entire joint enclosed in a joint capsule containing synovial fluid which serves as a lubricant

more FLEXIBILITY !!

Fig. 8-1b p168 PJH


Appendicular Skeleton

  • FORELIMBS—__________ bone (humerus), 2 middle elements (radius and ulna), and the carpals, metacarpals, and phalanges.

  • HINDLIMBS—___________ bone (femur), lower leg bones (fibula & tibia), and the tarsals, metatarsals, and phalanges. In some species fibula & tibia are fused


Bobcat

Harbor Seal


Modes of Locomotion

  • Walking & Running

  • Jumping & Ricocheting

  • Swimming

  • Flying & Gliding

  • Climbing

  • Digging & Burrowing


Terms...

  • SALTATORIAL—leapinga) spring (jumping)—______ feet involvedb) richochet—___________ only

  • SEMI-FOSSORIAL

  • FOSSIORIAL

  • SEMIAQUATIC


more terms…con’t

  • SCANSORIAL—vertical movements on hard surfaces ___________________

  • BRACHIATING—swinging movements with forelimbs (? __________________?)


Walking & Running

  • Most are QUADRUPEDS

  • Some are BIPEDAL

  • Humans only ones habitually__________

  • Ambulatory = locomote mostly by _________ vs.

  • Cursorial = locomote at least part of time by __________


Note position of scapula A  B


Most Mammals…well adapted for _________________ locomotion

  • PLANTIGRADE—walk on soles of hands and feet (humans, opossums, etc.)

  • DIGITIGRADE—walk on digits (phalanges) (not always “all” digits) (coyotes)

  • UNGULIGRADE—hoofed animals, phalanges are elevated so that only hoofs (modified digital keratin) are in contact with the substrate (pronghorn)


Unguligrade

(pig)

Digigrade

(dog)

Plantigrade

(man)

SOURCE:Fishbeck and Sebastiani (2008) Fig. 5.20


Running Speeds

SpeciesSpeed (km/h)Locomotion

Cheetah 110 Pronghorn 98 Elk 72 Coyote 70 Europeon hare 65 Grizzly bear 50 Human 45 Tree squirrel 20 Three-toed sloth 1 “hang”


Patterns of Running

  • Gait--see p110, Fig. 6.14

  • Walking & Pacing & Trotting (different forms of symmetrical gaits = equal spacing of feet and contact with ground at even time intervalsvs.

  • Galloping & Bounding (different forms of asymmetrical gaits = contact with ground at uneven time intervals)


Jumping & Ricocheting

  • Saltatorial locomotion

  • Jumping = lagomorphs

  • Richocheting = kangaroos (p111, Fig. 6.15),kangaroo rats (p354, Fig. 18.10), and jumping mice a) most in _________ mode most of timeb) hind limbs larger than frontc) ________ tail for balance


Swimming

  • ___________ mammals--split time between aquatic & terrestrial:a) beavers and ottersb) _________ tailc) _________ feet (hind only)d) oscillatory propulsion

  • ____________ mammals--most time in water:a) seals, sea lions, walrusb) __________________c) __________________


Swimming…con’t

  • Marine mammals--all the time in water:a) baleen & toothed whalesb) no hind limbsc) no sacrumd) tails, in some, have horizontalfluke--used for propulsione) again—____________ forelimbs

human arm

pilot whale

blue whale

right whale


WHALE (mysticete)

vs.

TERESTRIAL

mammal


Gliding & Flying

  • Patagium - “the flight membrane”a) gliders: hind limbs to forelimbsb) volant mammals (bats): from forelimb digits (hand-wing) to the tail (p258, Fig. 11.1)

  • Gliding: patagium is thicker, position controlled by limbsa) evolved in 3 groups: Rodents(flying squirrels),Dermoptera (colugos), & marsupials (sugar/honey gliders)b) increase speed--decrease surfacearea…and vice versa


Colugos =

Flying lemurs

Philippines

Java

Borneo


Oddity - Bats

  • Only TRUE flying mammal

  • FORELIMB: ______________ forearm (radius), metacarpals, and fingers; __________ humerus (see lecture notes on Eutherian mammals)

  • Radius __________ rotate

  • HINDLIMB reduced, and unique among mammals, in being rotated 1800 so that the knees point backward—aids in flight maneuvers


Flying: 3 challenges

  • LIFT--generate with air stream over wing surface. Understand __________________….a) dorsal surface: curved upwardb) ventral surface: concave (camber)

  • DRAG--anything that __________ forward motion (friction at the leading edge, friction along the body surface, turbulence

  • POWER--moving the wings ___________ air


Lift, Aspect Ratio, & Maneuverability

  • Increasing “angle of attack” results in greater lift…up to the point of stalling

  • Bats generally have broad wings with a _______ aspect ratio--the surface area of the wing divided by its length

  • ________ wings, allow high degree of maneuverability needed to avoid obstacles and respond to detection of prey….

  • Bats are relatively ______ fliers


BIRD

BAT


Climbing - arboreal locomotion

  • Increased ______ & _______ of clawsa) squirrels: claws key to grasping& moving verticallyb) bears: must grasp tree aided by claws

  • Prehensile hands & feet (some primates)a) some have ________ pads & increasesensory receptors in hands & feetb) longer & stronger forelimbs

  • Prehensile tail--some


Digging & Burrowing--Using Teeth

  • Enlarged heads with strong rostrum and ________ ________ for muscle attachment to involve ______ ________ soil

  • Examples: bamboo rats and naked mole rats 


Digging & Burrowing--Using Limbs

  • ___________ typically reflect increased size and strength--relative to hindlimbs:a) clawsb) structure of limb, including pectoral girdlec) musculature of limb

  • Hind limbs reduced…but help move loosened soil

  • Examples: moles & pocket gophers


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