Leader: John
Course: A ECL 365
Instructor: Dr. Adams
Supplemental Instruction
Date: 8/28/12
Iowa State University
1. Cartilage is formed by chondrocytes (cells) surrounded by a gel-like matrix of protein and
fiber.
Origin of Tetrapods
Week 1.2
2. The axial skeleton is made up of the cranium, vertebrae, and the ribs & sternum.
3. The synsarcum is made up off fused lumbar + sacral + a few caudal vertebrae, while the
pygostyle is made up from the fusion of the remaining caudal vertebrae.
4. Fish have unpaired medial fins used for stabilization.
5. Bone is formed by osteocytes (cells) surrounded by a strong calcium carbonate matrix. It also
contains nerves and blood vessels.
6. The appendicular skeleton is made up of girdles and appendages.
7. In class, Dr. Adams talked about skeletal adaptations. What were these, and what were they
useful for (if anything)? Examples of each?
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Loss of bones
o Basic pattern of vertebrates if 5 digits, while many ampibians have 4
o Fusion of bones (think of the birds, i.e. furcula)
o Loss of limbs (cetaceans, snakes, etc.)
Variation in length of bones
o Longer length occurs in running animals (increased stride length)
o Climbers have shorter bones (lower center of gravity makes climbing easier)
Variation in thickness or robustness of bones
o Short, thick bones (stronger diggers)
o Flying vertebrates have hollow bones to reduce weight
8. Talk about the major skeletal changes and why they are important.
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Locomotion, 2 types
o Swimming to walking – allowed new niches to be invaded
o Sprawling limbs to limbs under the body – allowed more efficient and rapid
locomotion
Jaw articulations
o Multiple articulation points of fish jaws allow for tremendous movement and
diversification
o Snake jaw – much of jaw unfused, allowing snakes to disconnect (unhinge)
jaw bones and ingest prey larger than their head
Mammalian jaw and Middle ear