SKELETAL CONSIDERATIONS & ADAPTATIONS FOR LOCOMOTION

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

3. 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

4. Fig. 8-3 p170 PJH

5. A neck! thoracic lumbar

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

7. 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)

10. Bobcat: male or female ????

11. 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

12. Axial & Appendicular Join • Attachment of forelimbs & hindlimbs to axial skeleton • __________—PECTORAL GIRDLE (clavicle & scapula) • __________—PELVIC GIRDLE (ilium, ishium, & pubis)

13. PERMITS ROTATION

14. 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

15. 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

16. Bobcat Harbor Seal

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

18. Terms... • SALTATORIAL—leaping a) spring (jumping)—______ feet involved b) richochet—___________ only • SEMI-FOSSORIAL • FOSSIORIAL • SEMIAQUATIC

19. more terms…con’t • SCANSORIAL—vertical movements on hard surfaces ___________________ • BRACHIATING—swinging movements with forelimbs (? __________________?)

20. 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 __________

21. Note position of scapula A  B

22. 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)

24. Unguligrade (pig) Digigrade (dog) Plantigrade (man) SOURCE:Fishbeck and Sebastiani (2008) Fig. 5.20

26. Running Speeds Species Speed (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”

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

28. 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 time b) hind limbs larger than front c) ________ tail for balance

29. 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) __________________

30. 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 human arm pilot whale blue whale right whale

31. WHALE (mysticete) vs. TERESTRIAL mammal

32. 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

33. Colugos = Flying lemurs Philippines Java Borneo

34. 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

35. 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

36. 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

37. BIRD BAT

38. 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

40. Digging & Burrowing--Using Teeth • Enlarged heads with strong rostrum and ________ ________ for muscle attachment to involve ______ ________ soil • Examples: bamboo rats and naked mole rats 

41. 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