11.1.10 11.13–11.15: The phylum Chordata includes vertebrates, animals with a backbone.

All chordates have four characteristic structures: a notochord, a dorsal hollow nerve cord, pharyngeal slits and a post-anal tail.

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Question 11.27

Which came first, the chicken or the egg?

  • a) The chicken, because the amniotic egg did not evolve until the first chicken appeared.
  • b) The egg, because the amniotic egg evolved well before the first birds.
  • c) The chicken, because, during speciation, the adult stage always precedes the juvenile stage.
  • d) The egg, because the chicken is not a real species.
  • e) It is impossible to determine, because eggs leave no fossils.

Question 11.28

Marsupials and which of the following groups combine to make a monophyletic group?

  • a) birds
  • b) carnivores
  • c) primates
  • d) monotremes
  • e) placental mammals

Question 11.29

According to the fossil record, the first modern humans—Homo sapiens—appeared approximately _____ years ago.

  • a) 6 million
  • b) 6,000
  • c) 190 million
  • d) 200,000
  • e) 1 million