When we talk about classifying animals, we're really talking about their ___

What is the most complex class within the most complex phylum?

Traits that set a group of animals apart from its ancestors and from other groups are called ___

The lancelets are also known as cephalochordata, which literally means ___

The structure made of cartilage that runs between a chordates's digestive tube and its nerve cord is called ___

In humans, the notochord is reduced to the disks of cartilage that we have between our ___

The dorsal hollow nerve cord is a tube made of nerve fibers that develops into ___

In humans the post-anal tail shrinks during embryonic development into what is known as ___

When did the four synapomorphies that define chordates begin to appear?

Sea squirts belong to the invertebrate group of chordates, the urochordata, which literally means ___

What is the most complex sub-phylum of chordates?

Vertebrates with a head that contains sensory organs and a brain are called ___

The Myxini, or hagfish, is the only vertebrate class that has no vertebrae but is classified with us because it has ___

The oldest living lineage of vertebrates is the class petromyzontida, otherwise known as ___

Lampreys and other early vertebrates are agnathans, which literally means ___

Chondrichthyes, such as sharks, skates and rays, have a skeleton that is mostly made of ___

The majority of all vertebrates, including you, fall under Osteichthyes which technically means ___

Pretty much every fish you've ever heard of is in the group Actinopterygii, better known as ___

Tetrapods, which have adapted to land with four limbs, are filed under which group?

In 1938 Captain Hendrick Goosen caught a coelacanth, a fish that was thought to have become extinct ___

The first tetrapods to develop a three-chambered heart are found in which class?

Tetrapods that have eggs adapted for life on land are grouped together as ___

Animals, such as reptiles, that absorb external heat as their main source of body heat are called ___

Birds can crank up their metabolism to regulate their body temperature thanks to the evolution of a heart with ___

Mammals are vertebrate animals characterized by the presence of hair, mammary glands and ___

The creation of humans began with a simple ancestor more than 500 million years ago in the phylum ___