Heliscomyidae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

s from the mid-

Tertiary Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may refer to: * Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago * Tertiary (chemistry), a term describing bonding patterns in organic ch ...

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

related to

pocket gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They ar ...

s (family Geomyidae) and

kangaroo rat Kangaroo rats, small mostly nocturnal rodents of genus ''Dipodomys'', are native to arid areas of western North America. The common name derives from their bipedal form. They hop in a manner similar to the much larger kangaroo, but developed thi ...

s and their relatives (family

Heteromyidae Heteromyidae is a family of rodents consisting of kangaroo rats, kangaroo mice, pocket mice and spiny pocket mice. Most heteromyids live in complex burrows within the deserts and grasslands of western North America, though species within the ...

). The family contains four genera, '' Apletotomeus'', '' Heliscomys'', '' Passaliscomys'', and '' Tylionomys'' (Korth et al., 1991; Korth and Eaton, 2004; Korth and Branciforte, 2007). McKenna and Bell (1997) placed the first two genera in synonymy, with ''Heliscomys'' as the senior synonym.

Characteristics

Heliscomyids are distinguished from other geomyoid rodents by several characteristics of the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

including the fusion of three

cranial Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Thi ...

foramina In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, arter ...

, elongation of the incisive foramina, and an unusual position of the

mental foramen The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels. Structure Th ...

(Korth et al., 1991).

Taxonomy

Heliscomyidae is a member of the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Geomyoidea, a group of rodents that also includes the families †Eomyidae, †Florentiamyidae, Heteromyidae, and Geomyidae. The following cladogram showing interrelationships among geomyoid families follows Korth et al. (1991):

References

*Korth, W.W. and C. Branciforte, 2007. Geomyoid rodents (Mammalia) from the Ridgeview Local Fauna, early-early Arikareean (late Oligocene) of western Nebraska. ''Annals of Carnegie Museum'' 76(3):177-201. *Korth, W.W. and J.G. Eaton, 2004. Rodents and a marsupial (Mammalia) from the Duchesnean (Eocene) Turtle Basin Local Fauna, Sevier Plateau, Utah. ''Bulletin of Carnegie Museum of Natural History'' 36(1):109-119. *Korth, W.W., J.H. Wahlert, and R.J. Emry, 1991. A new species of ''Heliscomys'' and recognition of the family Heliscomyidae (Geomyoidea: Rodentia) ''Journal of Vertebrate Paleontology'' 11(2):247-256. *McKenna, Malcolm C., and Bell, Susan K. 1997. ''Classification of Mammals Above the Species Level.'' Columbia University Press, New York, 631 pp. Geomyoid rodents Prehistoric rodent families Eocene first appearances Miocene extinctions {{geomyidae-stub