| A | B |
|---|
| acanthodian | group of ancient jawed fishes from the Devonian period |
| amniote | clade of tetrapods that have an amniotic egg containing specialized membranes that protect the embryo |
| amphibian | tetrapod class Amphibia |
| anthropoid | primate group made up of the apes |
| archosaur | reptilian group that includes crocodiles |
| chondrichthyan | group with mainly cartilagenous skeletons |
| chordate | animals with a notochord; a dorsal |
| cloaca | common opening for the digestive |
| condont | ancient lineage of jawless vertebrates that arose during the Cambrian period |
| craniate | chordate with a head |
| diapsid | amniote clade distinguished by a pair of holes on each side of the skull |
| dinosaur | extremely diverse group of ancient reptiles varying in body shape |
| ectothermic | organisms that do not produce enough metabolic heat to have much effect on body temperature |
| endothermic | organisms with bodies that are warmed by heat generated by metabolism |
| eutherian | mammal whose young complete their embryonic development within the uterus |
| extraembryonic membranes | membranes (yolk sac |
| gnathostome | vertebrate subgroup possessing jaws |
| hominid | species on the human branch of the evolutionary tree |
| hominoid | refers to great apes and humans |
| lancelet | subphylum Cephalochordata |
| lateral line system | mechanoreceptor system consisting along the sides of the body in fishes |
| lepidosaur | reptilian group that includes lizards |
| lobe-fin | osteichthyans with rod-shaped muscular fins |
| mammal | amniotes with mammary glands that produce milk |
| marsupial | young complete their embryonic development inside a maternal pouch called the marsupium |
| monotreme | egg-laying mammal |
| mosaic evolution | evolution of different features of an organism at different rates |
| neural crest | band of cells along the border where the neural tube pinches off from the ectoderm |
| notochord | long flexible rod that runs along the dorsal axis of the body in the future position of the vertebral column |
| operculum | protective bony flap that covers and protects the gills |
| opposable thumb | arrangement of the fingers such that the thumb can touch the ventral surface of the fingertips of all fingers |
| osteichthyan | vertebrate subgroup with jaws and mostly bony skeletons |
| oviparous | development in which young hatch from eggs laid outside the mother’s body |
| ovoviviparous | development in which young hatch from eggs that are retained in the mother’s uterus |
| paleoanthropology | study of human origins and evolution |
| parareptile | group of reptiles to emerge |
| pharyngeal clefts | grooves that separate a series of pouches along the sides of the pharynx and may develop into pharyngeal slits |
| pharyngeal slits | slits that form from the pharyngeal clefts and communicate to the outside |
| placenta | structure in the pregnant uterus for nourishing a viviparous fetus with the mother’s blood supply |
| placoderm | extinct class of fishlike vertebrates that had jaws and were enclosed in a tough |
| prognathic jaw | longer jaw found in our hominoid ancestors |
| prosimian | group of primatesthat probably resemble early arboreal primates |
| pterosaur | winged reptile that lived during the time of dinosaurs |
| ratite | group of flightless birds |
| ray-finned fish | aquatic osteichthyans with fins supported by long |
| reptile | clade of amniotes that includes tuatara |
| somites | paired blocks of mesoderm just lateral to the notochord of a vertebrate embryo |
| spiral valve | corkscrew-shaped ridge that increases surface area and prolongs the passage of food along the short digestive tract |
| swim bladder | an air sac that enables the animal to control its buoyancy in the water |
| synapsid | amniote clade distinguished by a single hole on each side of the skull |
| tetrapod | vertebrate with two pairs of limbs |
| tunicates | sessile marine chordates that lack a backbone |
| vertebrate | chordate animal with a backbone |
| viviparous | development in which the young are born alive after having been nourished in the uterus by blood from the placenta |
