Glossary of Terms
alveolus (alveoli, plural) The depressions or sockets in the tooth-bearing skeletal elements such as maxillae and dentaries into which the roots of the teeth are inserted. Especially well developed in mammals and crocodilians.
auditory bulla (auditory bullae, plural) The bone that encloses the inner ear region of the mammalian skull and is found on the ventral surface of the posterior region of the skull. Typically fragile and thus rarely preserved in fossils; but inflated and composed of very solid bone in whales. For that reason, whale auditory bullae are commonly recovered as fossils. Alternatively called the tympanic bulla.
basicranium The posterior and ventral portion of the skull comprised of the basioccipital, basisphenoid, petrosal, and auditory bulla, and portions of the squamosal and pterygoid bones. The evolutionary relationships of mammals can often be deduced by careful study of the arrangement of these bones and the foramina through which pass blood vessels and nerves.
bilophodont Descriptive term for a tooth in which the crown is primarily comprised of two transverse ridges, for example, the lower molars of tapirs. Usually used only in conjunction with mammalian teeth.
brachyodont (brachydont, alt. sp.) Descriptive term for a tooth in which the crown is relatively short, especially one in which the crown is shorter than the roots; or an animal with such teeth. Usually used only in conjunction with mammalian teeth.
bone 1. Any single component of the vertebrate skeletal system, regardless of its compositio For example, the maxilla, humerus, and ribs are all bones. 2. A particular type of vertebrate skeletal tissue comprised of a mixture of inorganic hydroxyapatite crystals and proteins.
bunodont Descriptive term for a tooth in which the crown is comprised of low, rounded, isolated cusps or cones that are not connected by ridges or lophs. Usually used only in conjunction with mammalian teeth.
carnassial The specialized blade-like cheek teeth of carnivorous mammals, used to cut meat. Usually consists of a pair of teeth (one upper, one lower), and best developed in the families Felidae and Nimravidae. The carnassial pair in the mammalian order Carnivora consists of the fourth upper premolar and the first lower molar.
carnivore 1. Any animal whose diet principally includes vertebrate flesh and tissues. 2. Common name for a member of the mammalian order Carnivora, regardless of diet. To avoid ambiguity, the term “carnivoran” is sometimes used instead in this context.
carpal Any one of the skeletal elements making up the wrist, such as the unciform or trapezoid. Distally the carpals articulate with the metacarpals, proximally with the radius and ulna. Collectively they are referred to as the carpus.
cartilage A flexible, organic vertebrate tissue found in the skeletal system. Softer than bone, it is found in places of the skeleton where flexibility is a greater asset than strength, such as on movable joint surfaces, the external ears, and the tip of the nose. Because of its ability to reshape itself (unlike bone), the skeletons of fetal and very young juveniles consist primarily of cartilage, which is gradually replace by bone tissue as the animal matures. Some animals, such as sharks, retain an internal skeleton made of cartilage as adults. Unless it contains calcium-rich minerals, cartilage rarely preserves in the fossil record.
cement A relatively soft, fibrous tissue of the vertebrate skeletal system. It surrounds the roots in the alveoli of mammals and some reptiles, adhering the tooth to the bone. Also found on the crown of the tooth in some hypsodont or hypselodont mammals where it surrounds the enamel and fills in deep valleys and depressions, thus providing structural support.
cf. An abbreviation of the Latin word confer meaning “compare.” When placed in front of the scientific name of a taxon, it means that there is some uncertainty about the identification. It may mean that the fossil(s) are to incomplete to be identified with certainty, or that the available specimens are not adequate to distinguish between two or more similar species.
chordate Any member of the Chordata, a taxon of animals distinguished from other animals by having a notochord, pharyngeal gill slits, a dorsal main nerve chord, V-shaped segmented muscles, and a post-anal tail. Vertebrates are the best known group of chordates, but the taxon also includes several marine groups most notably the tunicates and the cephalochordates. Some of the chordate character states are found in vertebrates only during embryonic development and are either lost or highly modified in adults.
cingulum (cingula, plural) A ridge or shelf found on the cheek teeth of some mammals, located on the outer margin of the tooth. Cusps protruding from the cingulum are referred to as styles (or stylids on lower teeth), such as a parastyle or metastyle. In certain mammalian groups, the cusp referred to as the hypocone originally evolved on the posterolingual region of the cingulum.
clade A group of organisms believed to have evolved from a common ancestor. A clade often refers to any taxonomic level up to the genus level where members within that group are evolutionarily distinguishable from other clades of a similar taxonomic rank. On a cladogram, a clade is represented by all branches following a node.
cladistics A method in classification that defines taxa based on shared characteristics and arranges them using inferred evolutionary relationships so that all members of a given taxon share a closest common ancestor.
conspecific con- meaning ‘with’ and -specific, the adjective form of ‘species’. Of or relating to a single species. For example, if two specimens are identified as belonging to the same species, they would be described as conspecific; two members of a single species population are also conspecifics. Note that conspecific is an adjective, verb, and noun depending on its context.
cursorial Descriptive term for an animal well adapted for running, usually at high speed or over long distances; or for any anatomical feature found in such an animal, such as long, slender limb bones.
deciduous An anatomical structure, such as a tooth or antler, that is shed or dropped off the body. Especially refers to the deciduous tooth series of juvenile mammals, which consists of a set of incisors, canine, and premolars that erupt early in life (sometimes prior to birth) and which are usually shed sequentially as the animal approaches maturity and replaced by members of the adult or permanent tooth series.
dental formula The number of teeth a mammal has of each kind of tooth along one side of the sagittal axis (central line of symmetry). The formula denotes incisors, canines, premolars, and molars in that order. Dental formulas can be written in several ways where the top numbers represent the upper teeth and the bottom numbers represent the lower teeth, e.g. 2/2-1/1-2/2-3/3 in humans, where we have 2 sets of incisors, 1 set of canines, 2 sets of premolars, and 3 sets of molars. In some mammals, the number of upper and lower teeth may differ, hence the need to denote top and bottom number of sets.
dentine (dentin, alt. sp.) A hard vertebrate tissue similar in composition to bone but found only in teeth and dermal tissue. Dentine exists in a number of varieties with differing internal structures and hardnesses.
derived Refers to a feature or suite of features that evolved more recently compared to other conditions of the feature(s) in question. Older forms are considered more primitive.
derived character state When comparisons are made between differing character states found on two taxa, if one has evolved from (or is thought to have evolved from) the other, then the former is considered the derived character state.
describe The process by which species are formally defined and given a scientific name. Involves a systematic comparison of specimens of the same and different species and a description detailed enough that others can identify the species as well.
digitigrade The condition of supporting the body weight and walking on the digits or phalanges, as opposed to the metapodials (plantigrade). Dogs and birds are examples of digitigrade animals.
epoch One of the formal units of the geologic time scale, epochs are subdivisions of periods. The term is capitalized when it follows the formal name of such a time unit, for example, the Miocene Epoch.
era One of the formal units of the geologic time scale, eras are made up of two or more contiguous periods. The term is capitalized when it follows the formal name of such a time unit, for example, the Cenozoic Era.
estuarine Of or pertaining to an estuary. An estuary is a body of water where freshwater from rivers and/or streams flows into the ocean and mixes with the seawater. It is considered the transitionary environment between land and sea and is intermediate in salinity between the freshwater of rivers and the seawater of the ocean.
family The basic rank in the taxonomic hierarchy above the genus and below the order. The formal name of a family must end in the suffix “-idae” which is preceded by the root form of the generic name of the type genus of the family. A common name for most family names can be made by changing the terminal “ae” to an “s” and starting it with a lower case letter. For example, Felidae is the formal scientific name of a mammalian family, while felids is its informal equivalent. The species making up a family can be further subdivided into subfamilies, tribes, and subtribes. The well-known ranks, in order of most broadly classified to most specific, are life, domain, kingdom, phylum, class, order, family, genus, and species.
feral A once captive or domesticated species of animal or plant that is now living and breeding in the wild, usually in a region where it is not a native species. For example, the feral burros and horses living in the American Southwest.
formation The basic unit of rock in the geologic discipline of stratigraphy, it consists of one or more beds of same type of rock (limestone, sandstone, etc. [or alternately a distinctive combination of rock types]) with a lateral extent of at least several miles. Formal names of formations are capitalized and based on geographic names. Examples from Florida are the Anastasia Formation and the Suwannee Limestone.
generalization The combination of morphological or behavioral features that allow an organism to exist in a wider spectrum of environments or exhibit a wider range of behaviors, depending on its environment. Organisms of this nature are called generalists. Compare to specialists.
genus (genera, plural) The basic taxonomic rank immediately above the species level. A genus consists of a group of species more closely related to each other than any is to a species not included in the genus, but a genus may contain only a single species. A formal genus name is capitalized and written in italics, for example, Canis or Triceratops. Species making up a genus may be grouped into two or more subgenera. In that case, one of the subgenera will have the same name as the genus, while the other subgenera will have different names. The subgeneric names are formally written like generic names but follow the generic name and are enclosed in parentheses. For example, Hespertestudo (Hesperotestudo) and Hesperotestudo (Caudochelys) are two subgenera of tortoises found as fossils in Florida. A formal species name is made up by the genus and species name, such as Smilodon gracilis where Smilodon is the genus name and gracilis the species designation. Note that without the genus name, the second component of a formal species name is meaningless. For example, the species designation gracilis applies to more than 50 species of animals, plants, and bacteria.
group 1. A basic unit of rock in the geologic discipline of stratigraphy consisting of two or more contiguous formations. A group is therefore typically a larger and more widespread stratigraphic unit than a formatio An example from Florida is the Hawthorn Group. 2. An informal assemblage of species, more or less synonymous with the term taxon.
holotype The single specimen upon which the scientific name of a species is based, and was explicitly designated as such in the original published description. All other specimens are only referred to the species.
homonymy In biological taxonomy, when two different taxonomic groups have identically spelled scientific names. In such cases, the name that was published after the other one is invalid and must be replaced.
hypselodont Descriptive term for a tooth with a high-crowned, ever-growing crown lacking roots; or an animal with such teeth. Usually used only in conjunction with mammalian teeth. Found in xenarthrans, rabbits, some rodents, and a few ungulates.
hypsodont Descriptive term for a tooth with a relatively tall or high crown, especially one in which the crown is taller than the roots; or an animal with such teeth. Usually used only in conjunction with mammalian teeth.
index fossil Term used in biochronology to describe a species or genus whose chronologic range is restricted to a particular biochronologic unit. For example, the horse species Neohipparion eurystyle is an index fossil for the Hemphillian land mammal age, as it occurs only in Hemphillian fossils sites and does not occur at sites of any other age.
land mammal ages Refers to the North American land mammal ages (NALMA), a timescale established for prehistoric fauna in North America using geographic place names for where the initial fossils were collected.
member A basic unit of rock in the geologic discipline of stratigraphy consisting of a portion of a formation. The subdivision of a formation into two or more members is optional. As an example, in southern Florida the Arcadia Formation includes beds placed in the Tampa Member and the Nocatee Member.
metapodial The set of bones in the limbs of tetrapods found between the carpals or tarsals and the phalanges. The metapodials of the hand or forelimb are called metacarpals and those of the hind limb are called metatarsals. In the limbs of birds, the metacarpals and some of the carpals have fused to form a single bone called the carpometacarpus, while the fusion of the metatarsals and some of the tarsals forms a single bone called the tarsometatarsus.
mineral The inorganic, crystalline compounds that make up rocks. Common examples are quartz, calcite, gypsum, and feldspar. The mineral found in the vertebrate skeletal system is hydroxyapatite, a phosphatic mineral that is synthesized by special bone-producing cells.
molar One of the posterior-most series of mammalian teeth, usually with more than one root and a complicated occlusal surface with numerous cusps and cones. By definition, a molar does not have a deciduous precursor.
monogamy Not to be confused with the sociocultural definition of monogamy, it typically refers to the behavior exhibited by animals that pair-bond for a period of time, sometimes for life, but copulations outside of the pair-bonded unit is observed frequently in nature in numerous species of animals, ranging from birds to primates. It is a strategy used by animals who exhibit biparental care. Ecologists today prefer to use the term “pair-bonding” instead of monogamy because of the confusion coming from its vernacular meaning.
order Taxonomic rank used in classification of organisms. Members within a particular order are evolutionarily more closely related to each other than they are to any other order within their class. The well-known ranks, in order of most broadly classified to most specific, are life, domain, kingdom, phylum, class, order, family, genus, and species.
parallelism The independent acquisition of the same derived character state in two or more taxonomic groups not through a common ancestor. Also sometimes referred to as “convergence” or parallel evolution.
parsimony In systematics, the acceptance of one possible phylogenetic arrangement in deference to other arrangements because it requires the fewest number of character state reversals and parallelisms. parsimonious (adjective form).
pectoral girdle The bone(s) in the shoulder region in tetrapods that articulate with the proximal end of the humerus, and serve to structurally anchor the forelimb to the torso and as attachment sites for many of the muscles that move the forelimb. Individual elements of the pectoral girdle include the scapula, coracoid, and clavicle.
pelvic girdle The bone(s) in tetrapods that articulate with the proximal end of the femur, and serve to structurally anchor the hind limb to the torso and as attachment sites for many of the muscles that move the hind limb. Individual elements of the pelvic girdle are the ilium, ischium, and pubis; in adult mammals these three elements are fused together to form a single bone called the pelvis or innominate.
period One of the formal units of the geologic time scale, a subdivision of time between the ranks of era and epoch. The term is capitalized when it follows the formal name of such a time unit, for example, the Cretaceous Period.
petrosal The mammalian skull bone that houses the inner ear. Detailed analysis of these and other features of the ear region of the skull often reveal important evolutionary information. Alternatively called the periotic.
plantigrade The condition of supporting the body weight and walking on the metapodials, as opposed to the phalanges (digitigrade, op cite). Humans and bears are examples.
polygyny Comes from poly- meaning ‘many’ and -gyn meaning ‘female’. Refers to social systems where one or few males control reproductive access to most or all females within a social unit. Sexual dimorphism is characteristic of species that exhibit polygynous behavior because of increased competition between males for mating access to females.
premolar One of the mammalian teeth found posterior to the canine and anterior to the molars, usually with more than one root. They vary in morphology from simple to complicated and molariform depending on the type of mammal. Premolars usually have a deciduous precursor, but in some cases the deciduous premolar is retained in the adult.
preparation In paleontology commonly referred to as prep work or prepping, it is the process by which the surrounding rock or sediment is systematically removed from fossils, broken parts are glued back together, and weak areas are strengtheded with consolidents. Most fossils require some degree of preparation for future analysis and use in studies, and long-term storage or display. A person trained in these activities is called a preparator.
primitive Refers to a feature or suite of features that exhibit an older condition than seen in more recent representatives of a particular lineage. Those exhibiting more recent conditions of a feature are considered derived.
primitive character state When comparisons are made between two differing character states, if one has evolved from (or is thought to have evolved from) the other, then the latter is consider the primitive character state.
reworked Descriptive term for a fossil that eroded out of the sediments or rock enclosing it, and was subsequently deposited in younger sediments. By this manner, fossils of different ages can be found in the same rock unit. Reworked fossils can often be recognized by their worn appearance.
screen-wash The process of separating fossils from sediment by the use of running water and one or more sets of boxes with bottoms made of different size screens. Sedimentary particles smaller than the screen openings wash through, leaving a residue of concentrated grains and fossils that is sorted after it has dried. Screen-washing is a widely used method to collect fossils of small rodents, birds, lizards, snakes, salamanders, frogs, and fish.
serrated Having a notched or jagged edge similar to the cutting edge of a saw. In paleontology the term is most often used to describe teeth. For example, the canine teeth of some saber-toothed cats had serrated edges, as do the teeth of some species of sharks.
sesamoid A bone that forms in a joint capusule or tendon near a joint. The patella (or kneecap) is typically the largest sesamoid found in the body. In many medium- to large-sized mammals, there are well-formed sesamoids found in the joints between the metapodials and the proximal-most phalanges.
sister taxon (sister taxa, plural) A species or group that shares its most common ancestor with one or more other species or groups (e.g., sister clade, sister family, etc.). Sister taxa are more closely related to each other than to any other taxon.
specialization The presence of morphological or behavioral features that have a highly specific and narrow-ranged function. The term specialized is often used in a relative sense to describe groups or species where one is more specialized than the other, but both can be specialized when compared to an outgroup that is more generalized. Organisms who are specialized are called specialists and exhibit specializations as well.
species The lowest commonly used rank in the taxonomic hierarchy. A species is a group of morphologically similar individuals with one or more diagnostic character states that distinguish them from all other species. Some taxonomists define a species as a group of interbreeding individuals, although this is difficult to test in modern animals and impossible in fossils. A formal species name consists of two words written in italics, for example, Homo sapiens or Tyrannosaurus rex. Note that without the genus name, the second component of a formal species name is meaningless. For example, the species designation gracilis, as in Smilodon gracilis, applies to more than 50 species of animals, plants, and bacteria.
stable isotopes Isotopes that do not decay into other elements over time. Isotopes of an element have the same number of protons, which gives them their identity as that element, but vary in their number of neutrons. Unlike stable isotopes, radioactive isotopes are unstable and will decay into other elements over time. Stable isotope analysis use stable isotopes to learn about the chemical (elemental) make up of the past, such as in determining diets, environments (different plants produce different isotopic signatures), and climate.
subfamily Taxonomic rank of classification that denotes a level below family but falls above the genus level. Used when genera within a family can be further divided into subfamilies based on morphological or molecular similarities that groups them phylogenetically from one another. The well-known ranks, in order of most broadly classified to most specific, are life, domain, kingdom, phylum, class, order, family, genus, and species.
subspecies The lowest formal taxonomic rank, subdivisions of a species, used to separate different populations within a species usually on criteria such as color patterns or size. A formal subspecies name consists of three words written in italics, for example, Lynx rufus koakudsi. Subspecies are infrequently used in vertebrate paleontology but may be more commonly used among ecologists who want to differentiate a particular population within a species from another population within that same species.
synonymy In biological taxonomy, when a single taxonomic group has two or more scientific names. When species names are synonymized, all specimens under multiple names are henceforth referred to by the original scientific name given to the first described fossil. The original name is called the senior synonym, while all other names given after the first name are called junior synonyms.
tarsal Any one of the skeletal elements making up the ankle, such as the cuboid or astragalus. Distally the tarsal bones articulate with the metatarsals, proximally with the tibia and fibula. Collectively they are referred to as the tarsus.
taxon (taxa, plural) Any group of biologic organisms that together make up one of the scientific hierarchies of classification. For example, the genus Canis, the family Bovidae, and the class Actinopterygii are all taxa.
type locality The fossil site or locality where the holotype specimen of a species was collected.
type species The type of a genus or subgenus, and under modern rules of scientific names must be explicitly designated at the time a new genus or subgenus is formally named. If a scientist determines that the species placed in a single genus actually belong in two or more genera, then the group of species which includes the type species will remain in the original genus; the other species are assigned to a different genus.
type specimen A formally selected specimen intended to serve as the prinicipal reference for a particular species. Used to help identify that species in the fossil record. See also holotype.
unguligrade An extreme form of digitigrade posture where the body weight is supported by only the distal-most phalanx of one or a few digits. Fairly common in artiodactyls such as bison and deer, but otherwise rare among other mammals.
vertebrate Common name for a member of the monophyletic taxon Vertebrata, a group which includes the jawless fishes, bony fishes, sharks and rays, and tetrapods. Among animals, vertebrates uniquely possess a brain which coordinates the nerves and senses of the body and which is protected and supported by a chondrocranium. Almost all vertebrates have a series of bones known as vertebrae (hence the name) and the capacity to produce calcium phosphate crystals.