Your Inner Fish
What animals first evolved true skeletons?
Fish were the first animals with bony skeletons.
What are tetrapods? What part of the body do tetrapods, which include humans, owe to the early, transitional tetrapods?
A tetrapod Is a four legged animal. They evolved higher than fish. We owe the shoulder girdle to the transitional tetrapods.
Describe the fundamental, universal form of the limbs of tetrapods that Sir Owen observed. How many bones are in the parts of the anterior/superior limb, i.e. brachium, antebrachium, carpus, and manus? The form was one bone, two bones, little bones and then fingers. The brachium has one bone, the brachium two, the carpus has eight and the manus has 19.
What are the terms for these bones in the anterior/superior limb and in the posterior/inferior
The shoulder and the elbow.
What did Darwin predict based on Sir Owen's observations?
Darwin predicted that there must have been a transitional animal that gapped the bridge between fish and animals with arms and legs.
Describe the process that Shubin used to locate the fossils of these ancient, transitional fish. What were the two criteria he used to predict the location? What state did he search in? What was the name of the Hillhas? –He looked for places that had rocks of the right age and then looked in places that would have rocks of the right type. He knew rocks from the Devonian area were old enough to contain these fossils. He searched in a place in Pennsylvania, called Redhill. How many searches were necessary to find parts of an early tetrapod?
Ted found a part of a tetrapod on his second trip to Redhill.
What was the name of one of the earliest tetrapods discovered? Where did she discover them? How did they analyze its movements? One of the earliest was the Ichthyostega, discovered in Greenland. Pressure pads and high speed cameras were used to measure limb movements.
Where did they search next? What dangers do scientists face during field work? What was the region like 375 million years ago? Next they searched in the Arctic of Canada. As a scientist, there is the danger of being trapped places because of bad weather conditions, sparse resources and wildlife. The region was a giant floodplain 375 million years ago.
During development, what is a major structure that ancient fish and their descendants share in the cervical region? What do they develop into in fish? How are they modified in humans? The major structure is the pharyngeal area, the swelling is the gill arches becomes the gill apparatus. In people this becomes portions of the lower jaw, middle ear and voice box.
Where are the gonads in fish? Where are they in human fetuses? Where do the gonads travel in human males? Why did this evolve? What is a medical consequence of this?
The gonads in the fish are towards the heart. In human embryos they are deep in the body similar to where they would be found in a fish, then they travel down near the testes, because people are warm blooded and sperm can’t stand…