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Biology

Key Terms

BiologyKey Terms

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
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