Exam 32: Deuterostomes: Vertebrates and Their Closest Relatives

The internal skeleton of echinoderms is made of calcium-stiffened ____ that develop from mesoderm.

Lizards and snakes are living members of the ____ lineage.

Legless caecilians belong to the ____ lineage.

A four-chambered heart, hollow limb bones with supporting struts, and a keeled sternum are features associated with most modern ____.

Which substance is a waste product of nitrogen metabolism in some amniotes that is excreted as a semisolid paste, reducing water loss?

Two extant species of coelacanths and six species of lungfish are members of the ___ lineage.

The parasitic lampreys, living members of the ____ lineage, have shards of cartilage that partially cover the nerve cord, which may represent an early stage of the evolution of vertebrae.

Which lineage has the largest number of Hox genes, reflecting their complex anatomy?

The Anura, Caudata, and Gymnophiona clades are all part of the ____ lineage.

Two species of spiny anteaters (echidnas) and the duck-billed platypus are the only known living members of the ____ mammalian lineage.

Living members of the ____ lineage have fins supported by thin and flexible bony rays.

Why do vertebrates have more individual Hox genes than most invertebrates, and what is the general significance?

Vertebrates evolved from an invertebrate ancestor through _____.

The living members of the ____ lineage, the hagfishes, are jawless vertebrates with axial skeletons composed of only a cranium and a notochord.

The jawless vertebrates, referred to as agnathans, form a monophyletic group that includes an ancestor and all of its descendants.

Mammalian monotremes are limited to the Australian region.

Galagos, lemurs, and lorises are the living members of the ____ mammalian lineage.

Which cell type is unique to vertebrates, and distinct from endoderm, mesoderm, and ectoderm?

The ____ forms the skeleton of invertebrate chordates.