BIO 2135 Lecture Notes - Lecture 8: Dorsal Nerve Cord, Yoho National Park, Neural Crest
16 May 2016
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4 hallmark characterstics of chordates that they all have. One point they thought were also found in hemi only had half. They have : unique stomochord, front part as proboscis complex. Really funny worm like animal: 3 body region. Endostyle in chordates, sheath of mucus to trap the food. When we found out that not occurring in hemi we found at that water current is strictly a carrier for the food, and it has nothing to do with siving of the food. Also includes two sub phyla, extremely unusual: cephalachordates. Chordates have 3 autapomorphies, but they are complex. Go back 550 mya, pikaia only known in fossils, swam thru water, oldest of all chordates. Comes from fossil set burgess shales yoho national park. 100"s of fossils in the shales, dental tools, dissect fossil, take skin off, and look muscle blocks, then see reinforce structure underneath. First along this line cephalochordate: represent early stage, autapomorphy.
