Limbs Flashcards
Q1: What are the two extremes of limb adaptations in land mammals for locomotion?
A: Graviportal limbs, which are adapted to support heavy loads (e.g., elephants), and cursorial limbs, which are adapted for quick movement (e.g., cats, deer).
Q2: What are graviportal limbs and which animals typically have them?
A: Graviportal limbs are thick, column-like limbs designed to support large loads. They are found in animals like elephants and large sauropod dinosaurs like Argentinosaurus.
Q3: What are cursorial limbs and how are they adapted for movement?
A: Cursorial limbs are longer, with lower leg bones, adapted for running. They are found in animals like cats, deer, and theropod dinosaurs like Ornithomimus.
Q4: How do horses’ hooves relate to cursorial limb adaptations?
A: Horses walk on their toenails (hooves), which is a feature of cursorial animals, designed for fast running.
Q5: In which dinosaurs can we find cursorial and graviportal limb adaptations?
A:
Cursorial dinosaurs: Ornithomimus.
Graviportal dinosaurs: Argentinosaurus.
Dinosaurs with intermediate limb adaptations: Massospondylus.
Q6: How does human locomotion illustrate the trade-off between speed and efficiency?
A: When humans walk, their legs are straight and feet flat (similar to graviportal animals), which is efficient but slow. When running, they rise onto their toes (similar to cursorial animals), which increases speed but requires more energy.
Q7: What is the caudofemoralis muscle, and how did it aid in dinosaur locomotion?
A: The caudofemoralis is a tail muscle that attaches to the femur. In dinosaurs like Tyrannosaurus and Hadrosaurus, it helped pull their legs backward, aiding in walking and running.
Q8: How did the size and attachment point of the caudofemoralis muscle affect dinosaur locomotion?
A:
In carnivorous dinosaurs like Tyrannosaurus, the muscle was large and attached high on the femur, allowing faster leg swings and longer strides, but they tired quickly.
In herbivorous dinosaurs like Hadrosaurus, the muscle attached lower, enabling more energy-efficient movement but at slower speeds.
9: What is the difference between obligate bipeds and quadrupeds?
A: Obligate bipeds are animals that must walk on two legs (e.g., Tyrannosaurus rex), while obligate quadrupeds must walk on four legs (e.g., sauropods like Brachiosaurus).
Q10: What are facultative bipeds or quadrupeds? Give an example.
A: Facultative bipeds or quadrupeds can switch between walking on two or four legs, depending on the situation. Examples include bears (facultative bipeds) and kangaroos (facultative quadrupeds).
Q11: How do we know that dinosaurs did not drag their tails when walking?
A: Fossilized footprints of dinosaurs often lack tail drag marks, indicating that dinosaurs, like most modern reptiles, kept their tails off the ground while moving.
