Moving Around Flashcards
Name for modern animals that have a sprawling stance.
lizard, turtle, crocodile, salamander`
Name 2 (types of) animals that have an erect stance.
mammals, birds
Describe the sprawling stance.
humerus and femur project horizontally; elbows and knees strongly bent
Describe an erect stance.
humerus and femur project vertically (i.e. all limbs point straight down from their girdles)
Is it more advantageous to have an erect stance or a sprawled stance? Why? (I.e. what are the advantages?)
more advantageous: erect stance
- having the limb bones directly under the body allows the limb bones to passively support the body’s weight (without muscle strain)
- having straight limbs contributes to stride length, which increases speed (b/c stride is longer)
Why does it make sense for a lizard to have a sprawling stance?
relatively inactive; only rise to walk and run infrequently
What stance did the ancestor of all modern tetrapods assume?
sprawling stance
TRUE or FALSE: Birds and mammals evolved their erect stances independently of each other.
TRUE
What stance did dinosaurs assume?
erect stance
What are cursorial limbs specifically adapted for? Describe their strcture.
fast locomotion; long lower leg bones (below elbows and knees)
What posture describes cursorial animals that stand on their toes?
digitigrade posture
What posture describes cursorial animals that stand on their toenails/hoofs?
unguligrade posture
Name 2 modern animals with cursorial limbs and digitigrade posture.
Cheetahs and ostriches
Name 2 modern animals with cursorial limbs and unguligrade posture.
horses and antelopes
TRUE or FALSE: humans are cursorial.
FALSE
What posture do humans assume? Describe this posture.
plantigrade posture - standing simultaneously on our toes, flat of our feet, and our heels
Which dinosaurs show cursorial adaptions? What are the indications?
ornithomimid theropods; digitigrade stance and long metatarsals
What are graviportal limbs specially adapted for? Describe the bones and feet of these limbs. Are these limbs short or long? Do the joints bend a lot or very little?
adapted for: supporting extreme body weight
bones: robust and heavy
feet: large and padded
limbs: short
joints: bend very little
What is an example of a modern animal with graviportal limbs?
elephant
What is the term for an animal that walks and runs on 2 legs?
obligate bipeds
What is the term for an animal that walks and runs on 4 legs?
obligate quadrupeds
What is the term for an animal that walks on 4 legs but rises on 2 legs to run? What are some modern animal examples?
facultative bipeds; basilisk lizard, primates, kangaroos
TRUE or FALSE: The ancestor of all dinosaurs was a facultative biped.
FALSE: The ancestor of all dinosaurs was an OBLIGATE BIPED.