Question

Phylum Chordata 8. What are the synapomorphies of chordates? What is the difference between a notochord and a nerve cord? 9. What were the advantages and challenges for vertebrates colonizing land? How did early amphibians partially solve them? Why might limbs rather than fins have been an advantage, even if the animal spent all or most of its time in the water? 10. How did early reptiles and mammals improve on the solutions that amphibians started? Now add adaptations of apes and hominins, including humans.

Answer 1

Q8. The synapomorphy is the possession of two or more organisms of a characteristic inheritance from their common ancestor. synapomorphies of the chordates are Notochord, single dorsal hollow nerve cord, pharyngeal pouches, endostyle postanal tail.

Difference between notochord and nerve cord are as follows:

1. The notochord is a solid enclosed in a sheath, dorsal rod of large vacuolated cells while the Nerve cord is a bundle of nerve fibers with chains of ganglia.
2. Notochord occurs in chordates while nerve cord occurs in invertebrates.
3. Notochord provides support and point of attachment to muscles while nerve cord gives rise to peripheral nerves.
4. Notochord forms the axial skeleton while the nerve cord forms a major part of the nervous system.

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