2.2.6: Key Terms

Key Terms

Adapoidea: Order: Primates. One of the earliest groups of euprimates (true primates; earliest records from the early Eocene).

Anthropoids: Group containing monkeys and apes, including humans.

Auditory bulla: The rounded bony floor of the middle ear cavity.

Bilophodonty: Dental condition in which the cusps of molar teeth form ridges (or lophs) separated from each other by valleys (seen, e.g., in modern Old World monkeys).

Catarrhines: Order: Primates; Suborder: Anthropoidea; Infraorder: Catarrhini. Group containing Old World monkeys and apes, including humans.

Clade: Group containing all of the descendants of a single ancestor. A portion of a phylogenetic tree represented as a bifurcation (node) in a lineage and all of the branches leading forward in time from that bifurcation.

Convergent evolution: The independent evolution of a morphological feature in animals not closely related (e.g., wings in birds and bats).

Crown group: Smallest monophyletic group (clade) containing a specified set of extant taxa and all descendants of their last common ancestor.

Diagnosis: The features that allow you to recognize a group.

Diastema: Space between adjacent teeth.

Diffuse coevolution: The ecological interaction between whole groups of species (e.g., primates) with whole groups of other species (e.g., fruiting trees).

Ectotympanic: Bony ring or tube that holds the tympanic membrane (eardrum).

Euprimates: Order: Primates. True primates or primates of modern aspect.

Haplorhines: Group containing catarrhines, platyrrhines, and tarsiers.

Hominins: Modern humans and any extinct relatives more closely related to us than to chimpanzees.

Mandibular symphysis: Fibrocartilaginous joint between the left and right mandibular segments, located in the midline of the body.

Old World: Africa and Eurasia.

Omomyoidea: Order: Primates; Superfamily: Omomyoidea. One of the earliest groups of euprimates (true primates; earliest record in the early Eocene).

Petrosal bone: Petrous portion of the temporal bone. It houses the inner ear apparatus, among other things.

Plagiaulacoid: Dental condition where at least one of the lower cheek-teeth (molars or premolars) is a laterally compressed blade.

Platyrrhines: Order: Primates; Suborder: Anthropoidea; Infraorder: Platyrrhini. Group containing New World monkeys.

Plesiadapiforms: Order: Plesiadapiformes. Archaic primates or primate-like placental mammals (Early Paleocene–Late Eocene).

Stem: Taxa are basal to a given crown group but are more closely related to the crown group than to the closest living sister taxon of the crown group.

Strepsirrhines: Order: Primates; Suborder: Stresirrhini. Group containing lemurs, lorises, and galagos (does not include tarsiers).

Toothcomb: Dental condition found in modern strepsirrhines in which the lower incisors and canines are laterally compressed and protrude forward at a nearly horizontal inclination. This structure is used in grooming.