Small protrusions, support structures. Series of segments called ptergiophores.
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Why did the development of fins provide a huge advantage?
Stabilised fish bodies, stopped body swinging from side to side. Faster turns. Predatory power increased.
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How did fins allow for particular benefits in sharks and bony fish?
Sharks = uplift. Bony Fish = braking.
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What is a U-Shaped Girdle?
Supports right and left side of body. Larger at pectoral fins.
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How do pelvic girlies differ?
Composed of fewer segments of cartilage.
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What are fins made up of?
Cartilage. Or bone, tipped with keratin.
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How do fins vary in bony fish?
Dermal Bone supports pectoral girdles. Two girdles are separated.
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What are the issues with having girdles that are separated? How was this overcome?
Difficult to support heavy fins. Pectoral Girdles attached to skull. Pelvic girdles ossify, become separated, remain unanchored. Suspended by ligaments and muscle.
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What is important about the extinct lobed-finned fish?
First creature that came onto land. Called Tiktaalik.
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What is manus?
Hands.
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What is pes?
Feet.
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What is tiktallik?
First 'lobed-finned fish' that entered land.
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What was the first evolutionary step for the tiktallik?
Pectoral fins were not attached to the skull, allowed them better.
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What happened to the pectoral girdle in the tiktallik?
Began to enlarge. Shift from front wheel drive, to rear wheel drive!
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What may determine the size of the pelvic girdle?
Size of offspring.
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Why was walking on land still difficult however?
The posture was still sprawled, not well articulated.
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Why is a lack of girdles better in limbless terrestrial vertebrates? Sprawled and Semi-Erect.
Easier to move on belly. Swallow prey easier without girdles. Can utilise water and land.
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How has sprawling developed in birds and mammals?
Supported directly under body. Changes in girdles, no outward limbs, but manus and pes that face forwards.
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Why did shoulder blades change and collar bones become smaller?
To reflect changes in the forces, what was required in terms of movement.
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Explain why in cats, the girdle does not brace against the skeleton, and there is a reduction in the clavicle.
Allows greater movement, can jump / fall from heights with less impact.
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Why are robust clavicles still important in many vertebrates?
The forelimbs need to be stable. A monkey swinging from a tree or a mole digging. The wings need to be braced, clavicles actually fuse together in birds to form stronger bracing.
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Why do some vertebrates have vertical flexion? What is this?
Curved vertebral columns, allowing more flex in the spine. Or they have less ribs. Stride Length, longer stride = faster movement. More strides = faster movement.
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How can stride rate be increased?
Larger Muscles, lengthening of limbs, more time off the ground allowing more time to stretch out stride.
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Other cards in this set
Card 2
Front
Why did the development of fins provide a huge advantage?
Back
Stabilised fish bodies, stopped body swinging from side to side. Faster turns. Predatory power increased.
Card 3
Front
How did fins allow for particular benefits in sharks and bony fish?
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