The Closest Model for the Vertebrate Ancestral Stock Is Something

Q22: Unlike most invertebrate phyla,the nerve cord of

Q23: One example of why a cladist is

Q24: All chordates have<br>A)a single,dorsal,tubular,nerve cord.<br>B)a ventral heart.<br>C)pharyngeal

Q25: The ostracoderms<br>A)are the adult form of the

Q26: The perforated pharynx of chordates first evolved

Q28: "Sea squirts," the most common kind of

Q29: Lancelets belong to the subphylum _.

Q30: Explain why fossil specimens of Haikouella lanceolata

Q31: The development of a new vertebrate head

Q32: Although several invertebrate groups have been proposed