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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Skeletal considerations adaptations for locomotion

Mammalogy (Fall 2012 Althoff - reference FDVM Chapter 6)

LEC

05

SKELETAL CONSIDERATIONS & ADAPTATIONS FOR LOCOMOTION


Axial skeleton

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


Skeletal considerations adaptations for locomotion

Fig. 8-3 p170 PJH


Skeletal considerations adaptations for locomotion

A neck!

thoracic

lumbar


Generalized primitive tetrapod condition

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

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)


Skeletal considerations adaptations for locomotion

Bobcat: male or female ????


Atlas axis junction

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

Axial & Appendicular Join

  • Attachment of forelimbs & hindlimbs to axial skeleton

  • __________—PECTORAL GIRDLE (clavicle & scapula)

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


Skeletal considerations adaptations for locomotion

PERMITS ROTATION


Joints

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

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


Harbor seal

Bobcat

Harbor Seal


Modes of locomotion

Modes of Locomotion

  • Walking & Running

  • Jumping & Ricocheting

  • Swimming

  • Flying & Gliding

  • Climbing

  • Digging & Burrowing


Terms

Terms...

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

  • SEMI-FOSSORIAL

  • FOSSIORIAL

  • SEMIAQUATIC


More terms con t

more terms…con’t

  • SCANSORIAL—vertical movements on hard surfaces ___________________

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


Walking running

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 __________


Skeletal considerations adaptations for locomotion

Note position of scapula A  B


Most mammals well adapted for locomotion

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)


Skeletal considerations adaptations for locomotion

Unguligrade

(pig)

Digigrade

(dog)

Plantigrade

(man)

SOURCE:Fishbeck and Sebastiani (2008) Fig. 5.20


Running speeds

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

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

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

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

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


Skeletal considerations adaptations for locomotion

WHALE (mysticete)

vs.

TERESTRIAL

mammal


Gliding flying

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


Skeletal considerations adaptations for locomotion

Colugos =

Flying lemurs

Philippines

Java

Borneo


Oddity bats

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

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

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


Skeletal considerations adaptations for locomotion

BIRD

BAT


Climbing arboreal locomotion

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

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

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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