- abdomen - The ventral part of the body between the thorax and the pelvis.
- altricial - Birds or mammals that are hatched or born in relatively undeveloped condition (eyes closed, natal down or minimal fur) and require prolonged parental care—as opposed to precocial.
- alveolar - Of or pertaining to an alveolus (plural, alveoli), a small cavity or pit, as a socket for a tooth. Alveolar length of a tooth-row therefore denotes the length of the row of the teeth, taken from the posteriormost place where the back tooth emerges from the bone to the anteriormost point where the front tooth in the row emerges from the bone—the overall length of the bony sockets for the row of teeth.
- arboreal - Inhabiting or frequenting trees—contrasted with fossorial, aquatic, and cursorial.
- aspect ratio - Ratio of length to width of a wing. Thus a high aspect ratio wing of 18:1 is long and narrow, while a ratio of 4:1 would be a relatively short and broad wing.
- auditory bulla (plural, auditory bullae) - A hollow, bony prominence of rounded form (in most mammals formed by the tympanic bone) partly enclosing structures of the middle and inner ear.
- biological species - A biological species consists of populations that can interbreed freely within and among themselves, but which are reproductively isolated from other such populations or groups of populations.
- biota - The living things of a place. It may refer to all living things or to some taxonomic group (e.g., the animal biota).
- canine - Of, pertaining to, or designating the tooth next to the incisors in mammals. Of or pertaining to dogs or to the family Canidae.
- carnivore - An animal that preys on other animals; an animal that eats the flesh of other animals; especially any mammal of the Order Carnivora.
- cheekteeth - Teeth posterior to the canines.
- common ancestor - A taxon that appears in the ancestry of all of the taxa under consideration. Usually the "most recent" common ancestor is the taxon of interest—e.g., if taxon "X" appears in the ancestry of both taxon "A" and taxon "B" and those two taxa share no more recent ancestor, taxon "X" is the most recent common ancestor.
- conch (plural, conchs) - The external ear of a mammal; sometimes the spelling is concha (plural, conchae); the origin of both spellings is conch or konch, originally a bivalve shell of a marine mollusk.
- condylar (articular) process - On a mandible, the process ending in the articular condyle.
- coronoid process - The upward projecting process of the posterior part of the mandible, giving attachment on its outward side to the masseter muscle and on its inner side to the temporal muscle.
- dental formula (plural, formulae) - A brief method for expressing the number and kind of teeth of mammals. The abbreviations i. (incisor), c. (canine), p. or pm. (premolar), and m. (molar) indicate the kinds in the permanent dentition, and the number in each jaw is written like a fraction, the figures above the horizontal line showing the number in the upper jaw, and those below, the number in the lower jaw. For deciduous teeth, the abbreviation is preceded by "d".
- dentine - A calcareous material, harder and denser than bone, which composes the principal mass of a tooth.
- dentition - The teeth, considered collectively, of an animal.
- deuterocone - One of the cusps of a premolar tooth of a mammal corresponding in position (anteromedial) to the protocone of a true molar. <
- diastema - A vacant place or gap between teeth in a jaw.
- digitigrade - Walking on the toes and distal ends of the metapodials.
- derived - A character state which has arisen (been derived from) a different, ancestral state. See apomorphic.
- diurnal - Active by day—opposed to nocturnal.
- enamel - Of teeth, the hardest substance of the mammalian body and forming a thin layer that caps or partly covers a tooth.
- epipubic - Paired bones extending from the anterior side of the pubic bones in prototherians and marsupials.
- feces - Intestinal excrement.
- femur (plural, femora) - The proximal bone of the hind limb.
- foramen magnum - The large opening in the back of a skull through which the spinal cord passes to become the medulla oblongata of the brain.
- forearm - The part of the forelimb between the elbow and wrist.
- fossorial - Adapted to digging and generally implying burrowing. At the extreme, an animal that spends most of its life underground.
- frontal - Pertaining to or designating the bone (paired) immediately in front of the parietal bone and behind the nasal.
- genus - A formal obligate rank of the taxonomic hierarchy lying between species and family. A genus consists of one or more species that are believed to be more closely related to one another than any is to any species of a different genus. The plural is genera.
- gestation period - The period of carrying young in the uterus, as applied to placental mammals; the period of pregnancy.
- guard hairs - The stiffer, longer hairs that grow up through the limber, shorter hairs (fur) of a mammal's pelage.
- habitat - The kind of environment in which a species of organism is normally found.
- hamular process of pterygoid - A hook-like process on the pterygoid bone.
- hibernation - Torpidity, especially in winter entered into by some kinds of mammals; the bodily temperature approximates that of the surroundings; the rate of respiration and the heart beat are much slower than in a non-hibernating mammal.
- hierarchy - A classification scheme wherein the whole is divided into smaller groups, each having some characteristic(s) in common and said to have the same rank; in turn, each of the smaller groups is divided into yet smaller groups of commonality, and so-on down to the smallest grouping. (It may also be viewed as the opposite process: as grouping smaller groups into larger and those into yet larger, etc.)
- horizontal ramus - In a lower jaw, the ramus bearing the teeth, and anterior to the vertical ramus.
- homologue - A feature found in different taxa that has been inherited from a common ancestor. Thus the finger nails of ourselves, the hooves of horses, and the claws of a tiger are homologous: these structures, though different in detail, have evolved from the claws of the common ancestor of the three taxa. On the other hand, the "claws" of an insect are not homologous with those of vertebrates.
- homoplasy - A similar structure in different taxa that is similar because of convergent or parallel evolution rather than having been inherited from a common ancestor. Thus the wings of birds and bats are homoplasies since the common ancestor of them did not have wings.
- incisor - Pertaining to or designating one of the teeth in front of the canine tooth; those in the upper jaw invariably are in the premaxillary bone.
- infraorbital canal - A canal through the maxillary bone from the orbit to the face.
- insectivorous - Eating insects; preying or feeding on insects (often also used when feeding on other terrestrial arthopods).
- insolation - Incoming radiation from the sun. Commonly applied to the heat portion of the spectrum, but may also include visible light. Be careful not to confuse it with "insulation"—something that tends to prevent the transmission of heat.
- interfemoral membrane - In a bat the fold of skin stretching from hind legs to tail. The uropatagium.
- interorbital constriction - The least distance across the top of the skull between the orbits (eye sockets).
- interorbital region - The region between the eye sockets; the region of the skull between the rostrum and the braincase.
- interparietal - Pertaining to or designating the bone (rarely paired) immediately in front of the supraoccipital bone and between the two parietal bones.
- litter - The two or more young brought forth at one birth by a female mammal.
- loph - A combining form used as the terminal part of certain words and denoting the ridges (or areas) composed of several cusps and styles on the occlusal face of a tooth, as protoloph.
- M2 - Designation of the second true molar in the upper jaw of a mammal.
- mammae (singular, mamma) - The glandular organs for secreting milk.
- mastoid - Designating or pertaining to the mastoid bone (paired) or its process. This bone is bounded by the squamosal bone, the exoccipital bone, and the tympanic bone.
- maxillary breadth - Width of skull from some designated place on the lateral face of the right maxillary bone (maxilla) to the corresponding place on the left maxillary bone; in shrews, across the ends of the zygomatic processes of the two maxillary bones.
- maxillary toothrow - The row of teeth in one maxillary bone; in most mammals all the premolars and molars on one side of the upper jaw.
- metabolic water - Water formed as an end product of cellular combustion of foodstuffs in an animal's body.
- midden - Basically, a garbage dump. Often used in regard to archaeological concentrations of discarded garbage, but also for the mounds of discarded food items mixed with urine and fecal pellets of woodrats.
- metacarpal - Of or pertaining to a metacarpal bone. A bone of the hand or forefoot between the wrist and fingers; when all the digits are present, there are five more or less elongated metacarpal bones, one at the base of each digit.
- molar - Of or pertaining to a molar tooth. One of the teeth behind the premolar teeth; a molar tooth is not preceded in embryological development by a deciduous (milk) tooth.
- molt (moult) - In a mammal, the act or process of shedding or casting off the hair, or outer layer of skin or horns; most mammals shed the hair once, twice, or three times annually. The cast off covering (obsolete). As a verb: to be shed (intransitive) or to shed (transitive).
- morphological species - Groups of individuals descended from a common ancestor that are as similar in appearance to one another as are members of a biological species and are separated from other such groups by a morphological gap as great as that between biological species.
- nasal - Of or pertaining to the nose, as a nasal bone (paired) on the dorsal surface of the skull at its anterior end. A nasal bone.
- nocturnal - Active by night (opposed to diurnal).
- obligate taxonomic category - Any of the seven taxonomic ranks that are necessary to minimally classify a species.
- occipitonasal length - Least distance between two vertical lines, one touching the posteriormost part of the skull above the foramen magnum (opening for the spinal cord) and the other touching the anteriormost part of the nasal bones or a nasal bone.
- occlusal - Of or pertaining to the grinding or biting (occluding) surface of a tooth.
- opposable - Capable of being placed opposite something else; said of the first toe of an opossum in the sense that it can be placed opposite each of the other toes on that same foot.
- orbit - The cavity in the skull in which the eye and its appendages are situated; the eye socket.
- osseous - Composed of, or resembling, bone; bony. Osseous tissue is bony tissue.
- overhairs - The longer hairs of the pelage of a mammal that project above the fur (shorter hairs).
- P3 - Designation of the third (next to last) premolar in the upper jaw of a mammal. Capital letters designate teeth in the upper jaw and lowercase letters designate teeth in the lower jaw.
- palatal - Of or pertaining to the palate (as generally used, the bony roof of the mouth made up of two palatine bones, two maxillary bones, and two premaxillary bones).
- palate - The roof of the mouth, consisting of the structures that separate the mouth from the nasal cavity. The bony palate is composed of the follow premaxillae, maxillae, and palatines.
- parietal - Pertaining to or designating the parietal bone (paired) roofing the braincase. This bone is behind the frontal bone and in front of the occipital bones.
- pectinate - In reference to nails or claws, having serrated edges (e.g., middle claw of a heron).
- pectoral - pertaining to, or situated or occurring in or on, the chest.
- pencil - Tuft of fur or hair, as a black pencil on the end of the tail of a mammal.
- penicillate - Having a pencil, or tuft of longer hair (see above).
- phalanx (plural, phalanges) - A bone, in a finger, distal to the metacarpus or a bone, in a toe, distal to the metatarsus.
- pinna (plural, pinnae) - The projecting part of an ear.
- plantigrade - Walking on the entire sole of the foot, as in humans and bears.
- Pleistocene epoch - The geological epoch encompassing the time span from about 1.8 million years ago to about 10,000 years ago. Often known as the Ice Age because of major advances (glacials) and retreats (interglacials) of continental glaciation during the Pleistocene.
- plesiomorphic - A "primitive" character state; a character state doesn't differ from the ancestral state. Contrasted with apomorphic.
- postauricular - Situated behind the auricle (pinna) of the ear, as a postauricular patch (ordinarily referring to a patch of fur differing in color from surrounding fur).
- postorbital - Situated behind the eye, as postorbital process of the frontal bone or postorbital process of the jugal bone.
- preadaptation - Having characteristics that fortuitously (that is, by chance) fit an organism for a different habitat or ecological niche. An example is the Rock Dove that in its native land nests on cliffs; on introduction to North America, city buildings proved to be a good substitution for cliffs. Also known as exaptation (to get away from any implication that preadaptation implies some process adapting an organism to a niche before such a niche is available.)
- premaxillary - Of or referring to the premaxilla. In mammals, a paired a bone bearing the incisor teeth (when present) of the upper jaw; the premaxilla is situated in front of the maxilla.
- premolar - Designating or pertaining to one of the teeth (a maximum of 4 on each side of upper jaw and lower jaw of placental mammals, or 16 in all) in front of the true molars. When canine teeth are present, premolars are behind these teeth; premolars are preceded by deciduous teeth, and in the upper jaw are confined to the maxillary bone.
- raptorial - In reference to the feet of a bird, the toes are deeply cleft and movable; claws (talons) are large, strong, and sharply curved, with scaly undersides. As in hawks and owls.
- reentrant angle - An infold of the enamel layer on the side, front, or back of a cheek-tooth, as in a molar of a muskrat or wood rat.
- riparian - Refers to organisms living along the floodplains or banks of streams and rivers. It's particularly used for such plants as willows and cottonwoods that may form extensive stands in those habitats.
- rostrum - Of a mammalian skull, the part projecting in front of the orbits.
- rut - The breeding period, as in deer.
- sagittal crest - The ridge of bone at the juncture of the two parietal bones resulting from the coalescence of the temporal ridges; in old individuals of many species of mammals, the crest extends from the middle of the lambdoidal crest anteriorly onto the frontal bones and divides there into two temporal ridges, each of which extends anterolaterally on the posterior edge of the postorbital process of the frontal bone.
- species - A taxonomic rank lying between the lower-level subspecies and the higher-level genus. There are various definitions, but in all it is a population-level term referring to individuals connected by some manner of genetic similarity. This similarity may be the reproductive, behavioral, or morphological, depending on the definition. The plural also is species. See Biological Species, Morphological Species
- subauricular spot - A spot, patch of hair, distinctively colored immediately below the ear.
- syndactyle - Refers to a foot which, in birds, has the outer and middle toes united for most of their length and with a broad sole in common (e.g., Belted Kingfisher). A similar situation occurs in some marsupials.
- supraorbital process of frontal - The process of the frontal bone on the top rim of the orbit, as in a rabbit.
- tarsus - The ankle.
- tarsus compressed - In birds: the tarsus is very flat from side to side with rather sharp edges in front and back.
- tarsus rounded - In birds: the tarsus is rounded in front but with a sharp ridge behind or is rounded in both the front and the rear.
- taxon - Any group of organisms formally named under the rules of taxonomic nomenclature. Thus Homo sapiens is a taxon; so is Mammalia. "Species" is not—it is a rank of the taxonomic hierarchy and does not denote a specific, named group of organisms. The plural of taxon is taxa.
- temporal ridge (paired) - A curved, raised line on the side of the braincase marking the upper limit of attachment of the fascia of the temporal muscle. The temporal ridge is prominent on the parietal bone, frequently extends forward onto the frontal bone, and in some kinds of mammals extends backward onto the interparietal bone. When present, the sagittal crest is formed by the coalescence of the two temporal ridges.
- terrestrial - Inhabiting the land, rather than the water, trees, or air.
- tibia (plural, tibiae) - The inner and usually the larger of the two bones of the hind limb (leg) between the knee and the ankle.
- torpid - Having lost most of the power of exertion; dormant. A ground squirrel is torpid when it is hibernating.
- tragus - a flap of skin near the base of the external ear in bats.
- tricolor - Having three colors. Said of hair on back of a mammal when the hair has three bands, each of a different color.
- type locality - The place where the type specimen for a species or subspecies (the holotype) was obtained. The holotype is a specimen that has the scientific name tied to it. If it turns out to belong to an already named species, then the name becomes a synonym; if a species turns out to include more than one species, the name belongs to whatever species the holotype belongs to, etc.
- underfur - The short hair of a mammal; in temperate and boreal climates, the underfur ordinarily is denser, made up of more hairs, than the longer and coarser overhair.
- underparts - The underneath (ventral) side of a mammal (not the back or sides), as of a woods mouse with white underparts.
- unicuspid - Mammalian teeth having a single (or single major) cusp, thus somewhat cone-like. Used particularly for the single-cusped teeth posterior to the anterior incisors in shrews, but may also be used for canines or other types of teeth with a single cusp.
- upper parts - The top (dorsal) surface and all of the sides (not the belly, chest, or throat), as of a woods mouse with reddish-brown upper parts.
- uropatagium - The interfemoral membrane of a bat; that is to say, the fold of skin that stretches from the hind legs to the tail.
- zygodactyle - In some birds. Also sometimes called "yoke-toed". Toes are arranged with two pointing anteriorly and two pointing posteriorly. Examples are in woodpeckers and roadrunner.
- zygomatic breadth - Greatest distance across zygomatic arches of cranium at right angles to the long axis of skull.
Adapted in part from Feldhamer et al. (1999) and Hall (1981)
Last Update: 27 Jun 2006