SKELETAL CONSIDERATIONS & ADAPTATIONS FOR LOCOMOTION Mammalogy (Fall 2012 Althoff - reference FDVM Chapter 6) LEC 05

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

lumbar thoracic A neck!

Generalized primitive tetrapod condition Fig. 8-2 p169 PJH ___________________ (zygapophysis singular) processes that interlock and resist twisting (torsion) and bending (compression) to support weight of viserca on land Better suspension…on land !! RIB post- pre- spinal cord notocord

Vertebral Column Cervical, thoracic, lumbar, sacral, and caudal vertebrate. Exceptions ( sloths and manatees don’t have cervical vertebrate ) 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 Fig. 8-1b p168 PJH 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 !!

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

Modes of Locomotion Walking & Running Jumping & Ricocheting Swimming Flying & Gliding Climbing Digging & Burrowing

Terms... SALTATORIAL—leaping a) spring (jumping)—______ feet involved b) 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 Walking & Pacing & Trotting (different forms of symmetrical gaits = equal spacing of feet and contact with ground at even time intervals vs. 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 ), and jumping mice a) most in _________ mode most of time b) hind limbs larger than front c) ________ tail for balance

Swimming ___________ mammals--split time between aquatic & terrestrial: a) beavers and otters b) _________ tail c) _________ feet (hind only) d) oscillatory propulsion ____________ mammals--most time in water: a) seals, sea lions, walrus b) __________________ c) __________________

Swimming…con’t Marine mammals--all the time in water: a) baleen & toothed whales b) no hind limbs c) no sacrum d) tails, in some, have horizontal fluke--used for propulsion e) again—____________ forelimbs pilot whale blue whale right whale human arm

WHALE (mysticete) TERESTRIAL mammal vs.

Gliding & Flying Patagium - “the flight membrane” a) gliders: hind limbs to forelimbs b) volant mammals (bats): from forelimb digits (hand-wing) to the tail (p258, Fig. 11.1) Gliding: patagium is thicker, position controlled by limbs a) evolved in 3 groups: Rodents (flying squirrels),Dermoptera (colugos), & marsupials (sugar/honey gliders) b) increase speed--decrease surface area…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 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 upward b) 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 claws a) squirrels: claws key to grasping & moving vertically b) bears: must grasp tree aided by claws Prehensile hands & feet (some primates) a) some have ________ pads & increase sensory receptors in hands & feet b) 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) claws b) structure of limb, including pectoral girdle c) musculature of limb Hind limbs reduced…but help move loosened soil Examples: moles & pocket gophers