Vertebrates 11.2 - Running Flashcards
Step/Pace
Distance between right foot and left foot.
Stride
Distance between position of one foot to that same foot again. (ie left foot to left foot)
Phases of step cycle
Propulsive phase (power) and swing phase (speed). Both affect stride length
Step cycle in amphibians and reptiles
Sinusoidal movements of trunk and tail. Need relatively thick body wall muscles and muscular limbs to support themselves off the ground.
Animals that have lost step cycle
Snakes. Still move in sinusoidal pattern.
Step cycle in salamander vs alligator
Gator has much less body motion and more of a step motion, therefore more limb muscles.
Step cycle in mammals
Limbs are under the body, therefore vertical plane of movement.
<p>
| Cursorial species</p>
<p>
Are able to run very fast (deer, pronghorn). Usually digitigrade or unguligrade. More joints and more places for muscles.</p>
Pronghorn
Fastest land animal in NA, >90kph over long distances. Probably had a fast predator anciently, but no longer.
Gaits
Combination of feet on or off the ground.
Walk vs run
Walk always has limb on ground, running has a suspension phase
Way of running
Trot = symmetrical (two legs in same step cycle) and gallop = asymmetrical. Gallop generally faster, longer suspension phase.
Formula for speed
V = FxL. F = stride frequency, L = stride length.
Cheetah adaptation for speed
Flexes the back a lot which adds to the stride length by bringing the hind limbs forward more. (stronger propulsive phase). Other animals do this to a smaller extent.
Limb length - arrangements
Plantigrade (wrist/ankle on ground), digitigrade (metacarpals/metatarsals off ground), unguligrade (just end of phalanges on ground). More joints results in more speed.
Adaptations for jumping (saltatory motion) in anurans
Modified skeleton. Long hindlimb, forelimbs fairly thick (fused radioulna), no tail, short strong trunk, pelvic girdle (Sacroiliac joint is flexible)
Steps in jumping in anurans
Steps: 1. Push off with forelimbs. 2. Hindlimbs relaxed as possible then contract. 3. Rotate legs horizontally to decrease drag. 4. Sacroiliac joint bends to bend head down. 5. Land on forelimb.
Adaptations for jumping kangaroos
Forelimb not used, not as much contraction of hindlimb, tail balances animal. Long achilles tendons with more elastic tissue recapture a lot of energy (O2 consumption doesn’t increase).
Reading: Baird’s law of Ichnology
The study of footprints, trackways burrows, etc. Tell us the anatomy of animal, but also posture (quad/bipedal, balance) and movement and speed
Reading: Tracks in Greenland
Found them in particularly muddy substrate - see more of how the foot interacted with the substrate
Reading: What dinosaur made the Greenland tracks?
A small therapod, Compsognathus, about turkey sized
Reading: How can you tell a therapod footprint from a bird’s?
The hallux in therapods are higher on the ankle, usually didn’t hit the ground.
Reading: What experiment did the researchers do to strengthen their idea of therapod locomotion?
They ran turkeys and guineafowl on hard and sloppy substrate to compare them to the dino tracks. Found it was similar. They can see the angle of entry and exit of the foot.
Reading: What was the conclusion of the dino study?
Birds and therapods walk essentially the same way, only birds’ hallux is lower and makes more of a mark in the ground
Video: What was the criticism with Jurassic Park?
The speed of the T-rex was able to catch up to a jeep going really fast. Based on its size this is too fast. It would require way too much muscle. It could only go up to 30kph
Study: Dinosaur max speed
Done with evolutionary robotics to make muscloskeletal models and compared to living creatures (as controls to see if their models were realistic). Predict T-Rex could max. do 30 kph
