Dinosaur biomechanics

Question 1

What is ‘classic functional morphology’?

Answer 1

Inferring function from form.

Question 2

What is the problem with classic functional morphology? Give 2 main arguments.

Answer 2

1. Function doesn’t necessarily follow form so this makes major assumptions.
2. Other factor contribute to function that cannot be determined from fossils, e.g. cartilage, nerves, ligaments, muscles etc.

Question 3

Limbs can be made redundant. True or false?

Answer 3

True, e.g. the forelimbs of tyrannosaurs.

Question 4

There are 6+ degrees of freedom of movement. If there is a 90 degree arc of rotation that can be made in 1 degree increments, how many possible limb poses are there?

Answer 4

> 67 million. Thousands can be ruled out but thousands remain.

Question 5

Define stride length.

Answer 5

Distance between point that limb left the ground to point where same limb returns to the ground.

Question 6

Define stance phase.

Answer 6

Time spent with the limb planted on the ground.

Question 7

Define swing phase.

Answer 7

Time spent with the limb in the air.

Question 8

Explain the difference between tetrapods and quadrupeds.

Answer 8

Tetrapod refers to any organism with 4 limbs. A quadruped is an organism that uses all 4 limbs in locomotion.

Question 9

What comparisons can be made between a tyrannosaur’s locomotive abilities and that of an:

a) elephant
b) rhino
c) large birds

Answer 9

a) Long femur, short lower leg bones, mass of over 6000kg
b) Long metatarsals, large muscle attachments, bent limbs
c) Similar limbs (ancestral condition)

Question 10

Why is comparing dinosaur biomechanics to modern animal biomechanics a bit useless?

Answer 10

Extant animal locomotion is also poorly understood, plus dinosaurs were incredibly different so comparisons are vague and uncertain.

Question 11

What have we learned about dinosaur biomechanics from functional morphology? List 4 features.

Answer 11

1. Mostly had erect, bipedal stance
2. Mostly digitigrade
3. Tails off the ground
4. Vertebral column was horizontal

(basically describes a theropod)

Question 12

Scaling is a change of physiological systems in response to organism size. What is a) isometric and b) allometric scaling?

Answer 12

a) There is no shape change with size

b) There is shape change with size

Question 13

Scaling often changes from iso to allometric when size becomes extremely large. True or false?

Answer 13

True: this is when weight-baring, locomotive factors have most affect.

Question 14

What 2 things can footprints indicate about dinosaurs?

Answer 14

1. Speed

2. Bi or quadrapedal stance

Question 15

What are some problems with using footprints to infer locomotive information? Give 4 examples.

Answer 15

1. The same footprint looks different in different substrates
2. Wet substrate slows animals down, no indicative of top speed or stride length
3. Shows only one instance of behaviour, e.g. foraging
4. Only implies foot placement not whole leg motion

Question 16

You can infer the gait and speed of dinosaurs from their bones. True or false?

Answer 16

True.

Question 17

Comparing the bones of dinosaurs to extant species may help to understand their locomotive abilities. Give an example.

Answer 17

Elephants and the sauropod Apatosaurus: elephants have a bone strength of between 7 and 11. Apatosaurus had bone strength between 6 and 14. Thus they were probably similar in capability. Elephants can run, but not gallop or jump. Perhaps Apatosaurus was the same.

• Alexander, 1991

Question 18

A major limitation to speed is the capacity of limb muscles to generate force, in which case information on bones would be of little help. True or false?

Answer 18

True.

Question 19

‘A limb is only as strong as its weakest link’. Which component of a limb might this be?

Answer 19

The ankle.

Question 20

Posture is extremely important. Why might bipedalism aid running?

Answer 20

Straighter legs improve leverage.