- Acanthostega
- one of the earliest known tetrapods
- Actinopterygii
- ray-finned fishes
- allantois
- membrane of the egg that stores nitrogenous wastes produced by the embryo; also facilitates respiration
- amnion
- membrane of the egg that protects the embryo from mechanical shock and prevents dehydration
- amniote
- animal that produces a terrestrially adapted egg protected by amniotic membranes
- Amphibia
- frogs, salamanders, and caecilians
- ampulla of Lorenzini
- sensory organ that allows sharks to detect electromagnetic fields produced by living things
- anapsid
- animal having no temporal fenestrae in the cranium
- anthropoid
- monkeys, apes, and humans
- Anura
- frogs
- apocrine gland
- scent gland that secretes substances that are used for chemical communication
- Apoda
- caecilians
- Archaeopteryx
- transition species from dinosaur to bird from the Jurassic period
- archosaur
- modern crocodilian or bird, or an extinct pterosaur or dinosaur
- Australopithecus
- genus of hominins that evolved in eastern Africa approximately 4 million years ago
- brachiation
- movement through trees branches via suspension from the arms
- brumation
- period of much reduced metabolism and torpor that occurs in any ectotherm in cold weather
- caecilian
- legless amphibian that belongs to the clade Apoda
- Casineria
- one of the oldest known amniotes; had both amphibian and reptilian characteristics
- Catarrhini
- clade of Old World monkeys
- Cephalochordata
- chordate clade whose members possess a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail in the adult stage
- Chondrichthyes
- jawed fish with paired fins and a skeleton made of cartilage
- Chordata
- phylum of animals distinguished by their possession of a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail at some point during their development
- chorion
- membrane of the egg that surrounds the embryo and yolk sac
- contour feather
- feather that creates an aerodynamic surface for efficient flight
- Craniata
- clade composed of chordates that possess a cranium; includes Vertebrata together with hagfishes
- cranium
- bony, cartilaginous, or fibrous structure surrounding the brain, jaw, and facial bones
- Crocodilia
- crocodiles and alligators
- cutaneous respiration
- gas exchange through the skin
- dentary
- single bone that comprises the lower jaw of mammals
- diapsid
- animal having two temporal fenestrae in the cranium
- diphyodont
- refers to the possession of two sets of teeth in a lifetime
- dorsal hollow nerve cord
- hollow, tubular structure derived from ectoderm, which is located dorsal to the notochord in chordates
- down feather
- feather specialized for insulation
- eccrine gland
- sweat gland
- Enantiornithes
- dominant bird group during the Cretaceous period
- eutherian mammal
- mammal that possesses a complex placenta, which connects a fetus to the mother; sometimes called placental mammals
- flight feather
- feather specialized for flight
- frog
- tail-less amphibian that belongs to the clade Anura
- furcula
- wishbone formed by the fusing of the clavicles
- gnathostome
- jawed fish
- Gorilla
- genus of gorillas
- hagfish
- eel-like jawless fish that live on the ocean floor and are scavengers
- heterodont tooth
- different types of teeth that are modified for different purposes
- hominin
- species that are more closely related to humans than chimpanzees
- hominoid
- pertaining to great apes and humans
- Homo
- genus of humans
- Homo sapiens sapiens
- anatomically modern humans
- Hylobatidae
- family of gibbons
- Hylonomus
- one of the earliest reptiles
- lamprey
- jawless fish characterized by a toothed, funnel-like, sucking mouth
- lancelet
- member of Cephalochordata; named for its blade-like shape
- lateral line
- sense organ that runs the length of a fish’s body; used to detect vibration in the water
- lepidosaur
- modern lizards, snakes, and tuataras
- mammal
- one of the groups of endothermic vertebrates that possesses hair and mammary glands
- mammary gland
- in female mammals, a gland that produces milk for newborns
- marsupial
- one of the groups of mammals that includes the kangaroo, koala, bandicoot, Tasmanian devil, and several other species; young develop within a pouch
- monotreme
- egg-laying mammal
- Myxini
- hagfishes
- Neognathae
- birds other than the Paleognathae
- Neornithes
- modern birds
- notochord
- flexible, rod-shaped support structure that is found in the embryonic stage of all chordates and in the adult stage of some chordates
- Ornithorhynchidae
- clade that includes the duck-billed platypus
- Osteichthyes
- bony fish
- ostracoderm
- one of the earliest jawless fish covered in bone
- Paleognathae
- ratites; flightless birds, including ostriches and emus
- Pan
- genus of chimpanzees and bonobos
- Petromyzontidae
- clade of lampreys
- pharyngeal slit
- opening in the pharynx
- Platyrrhini
- clade of New World monkeys
- Plesiadapis
- oldest known primate-like mammal
- pneumatic bone
- air-filled bone
- Pongo
- genus of orangutans
- post-anal tail
- muscular, posterior elongation of the body extending beyond the anus in chordates
- primary feather
- feather located at the tip of the wing that provides thrust
- Primates
- order of lemurs, tarsiers, monkeys, apes, and humans
- prognathic jaw
- long jaw
- prosimian
- division of primates that includes bush babies of Africa, lemurs of Madagascar, and lorises, pottos, and tarsiers of Southeast Asia
- salamander
- tailed amphibian that belongs to the clade Urodela
- Sarcopterygii
- lobe-finned fish
- sauropsid
- reptile or bird
- sebaceous gland
- in mammals, a skin gland that produce a lipid mixture called sebum
- secondary feather
- feather located at the base of the wing that provides lift
- Sphenodontia
- clade of tuataras
- Squamata
- clade of lizards and snakes
- stereoscopic vision
- two overlapping fields of vision from the eyes that produces depth perception
- swim bladder
- in fishes, a gas filled organ that helps to control the buoyancy of the fish
- synapsid
- mammal having one temporal fenestra
- Tachyglossidae
- clade that includes the echidna or spiny anteater
- tadpole
- larval stage of a frog
- temporal fenestra
- non-orbital opening in the skull that may allow muscles to expand and lengthen
- Testudines
- order of turtles
- tetrapod
- phylogenetic reference to an organism with a four-footed evolutionary history; includes amphibians, reptiles, birds, and mammals
- theropod
- dinosaur group ancestral to birds
- tunicate
- sessile chordate that is a member of Urochordata
- Urochordata
- clade composed of tunicates
- Urodela
- salamanders
- vertebral column
- series of separate bones joined together as a backbone
- Vertebrata
- members of the phylum Chordata that possess a backbone