Ground squirrel

Ground squirrel
Ground squirrels
Temporal range: Early Oligocene to Recent
California ground squirrel (Spermophilus beecheyi) in the man-made rocky shoreline of the Berkeley Marina. The numerous crevices offer safety and shelter.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Subfamily: Xerinae
Tribe: Marmotini
Pocock, 1923
Genera

Ammospermophilus
Spermophilus
Cynomys
Marmota
Tamias
Sciurotamias
and see text

The ground squirrels are members of the squirrel family of rodents (the Sciuridae) which generally live on or in the ground, rather than trees. The term is most often used for the medium-sized ground squirrels, as the larger ones are more commonly known as marmots (genus Marmota) or prairie dogs, while the smaller and less bushy-tailed ground squirrels tend to be known as chipmunks. Together, they make up the "Marmot tribe" of squirrels, the Marmotini, and the large and mainly ground squirrel subfamily Xerinae, and containing six living genera. Well-known members of this largely Holarctic group are the marmots (Marmota), including the American groundhog, the chipmunks, the susliks (Spermophilus), and the prairie dogs (Cynomys). They are highly variable in size and habitus, but most are remarkably able to rise up on their hind legs and stand fully erect comfortably for prolonged periods. They also tend to be far more gregarious than other squirrels and many live in colonies with complex social structure. Most Marmotini are rather short-tailed and large squirrels, and the Alpine Marmot (Marmota marmota) is the largest living member of the Sciuridae, at 53–73 cm in length and weighing 5–8 kg.

The chipmunks of the genus Tamias frequently spend time in trees. Also closer to typical squirrels in other aspects, they are occasionally considered a tribe of their own (Tamiini).[1]

The ground squirrel is especially renowned for its tendency to rise up on its hind legs. It does this whenever it senses nearby danger, or when it must see over tall grasses. The squirrel then curls its paws flat against its chest and sends a screeching call to warn other family members about the presence of predators.

Ground squirrels may carry fleas that transmit diseases to humans (see Black Plague), and have been destructive in tunneling underneath human habitation[2][3] Though capable of climbing, ground squirrels spend little time in trees.[citation needed]

Contents

Evolution and systematics

20,000 year old Arctic ground squirrel mummy

Palaeosciurus from Europe is the oldest known ground squirrel, and it does not seem to be particularly close to any of the two to three living lineages (subtribes) of Marmotini. The oldest fossils are from the Early Oligocene, more than 30 mya (million years ago), but the genus probably persisted at least until the mid-Miocene, some 15 mya.

It is not clear where the Marmotini originated. The subtribes probably diverged in the early to mid-Oligocene, as primitive marmots and chipmunks are known from the Late Oligocene of North America. Unfortunately, the fossil record of the "true" ground squirrels is less well known, beginning only in the mid-Miocene when modern susliks and prairie dogs are known to have inhabited their present-day range already.

Whether the Marmotini dispersed between North America and Eurasia via "island-hopping" across the Bering Straits or the Greenland region—which both at that time were temperate habitat—and from which continent they dispersed to which, or if both continents brought forth distinct subtribes which then spread to the other, is not known and would probably require more fossil material to be resolved. In any case, that the fairly comprehensive fossil record of Europe—at the relevant time separated from Asia by the Turgai Sea—lacks ancient Marmotini except the indeterminate Palaeosciurus might be taken to indicate that an East Asian or western North American origin with trans-Beringia dispersal is the slightly more satisfying hypothesis. This is also supported by the enigmatic Chinese genus Sciurotamias, which may be the most ancient living lineage of this group, or—if the chipmunks are not included here—close to the common ancestor of the Tamiini and the Marmotini sensu stricto.

In any case, expansion of the Marmotini to Africa was probably prevented by competitive exclusion by their close relatives the Protoxerini and Xerini—the native terrestrial and palm squirrels of that continent—which must have evolved at the same time as the Marmotini did.

Subtribes and genera

A watchful "rock chuck" or Yellow-bellied Marmot (Marmota flaviventris) atop Mount Dana, Yosemite National Park in California

Basal and incertae sedis genera

Subtribe Tamiina: chipmunks (might be full tribe)

Subtribe Marmotina: marmots

  • Arctomyoides (fossil)
  • Miospermophilus (fossil)
  • Paenemarmota (fossil)
  • Palaearctomys (fossil)
  • Protospermophilus (fossil)
  • Marmota

Subtribe Spermophilina: true ground squirrels

  • Spermophilinus (fossil)
  • Ammospermophilus
  • Cynomys (Prairie Dogs)
  • Spermophilus

See also

Footnotes

References

  • Helgen, Kristofer M.; Cole, F. Russel; Helgen, Lauren E.; and Wilson, Don E (2009). "Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus". Journal of Mammalogy 90 (2): 270–305. doi:10.1644/07-MAMM-A-309.1. 
  • Steppan, Scott J.; Storz, B.L. & Hoffmann, R.S. (2004): "Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1". Mol. Phyl. Evol. 30(3): 703–719. doi:10.1016/S1055-7903(03)00204-5 PDF fulltext
  • Thorington, R.W. & Hoffmann, R.S. (2005): Family Sciuridae. In: Mammal Species of the World—A Taxonomic and Geographic Reference: 754–818. Johns Hopkins University Press, Baltimore.

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Ground squirrel — ground ground (ground), n. [OE. ground, grund, AS. grund; akin to D. grond, OS., G., Sw., & Dan. grund, Icel. grunnr bottom, Goth. grundus (in composition); perh. orig. meaning, dust, gravel, and if so perh. akin to E. grind.] 1. The surface of… …   The Collaborative International Dictionary of English

  • ground squirrel — ground ,squirrel noun count a type of North American SQUIRREL that lives on and under the ground …   Usage of the words and phrases in modern English

  • ground squirrel — ► NOUN ▪ a burrowing squirrel of a large group including the chipmunks …   English terms dictionary

  • ground squirrel — ground .squirrel n a ↑gopher …   Dictionary of contemporary English

  • ground squirrel — ☆ ground squirrel n. any of various small, burrowing squirrels (esp. genus Spermophilus) …   English World dictionary

  • ground squirrel — any of several terrestrial rodents of the squirrel family, as of the genus Citellus and chipmunks of the genus Tamias. [1680 90, Amer.] * * * Any of numerous relatively short legged, terrestrial rodents of the squirrel family (Sciuridae), found… …   Universalium

  • ground squirrel — noun 1. small striped semiterrestrial eastern American squirrel with cheek pouches • Syn: ↑eastern chipmunk, ↑hackee, ↑striped squirrel, ↑Tamias striatus • Hypernyms: ↑squirrel • Member Holonyms: ↑ …   Useful english dictionary

  • ground squirrel — Chipmunk Chip munk , n. [Indian name.] (Zo[ o]l.) A squirrel like animal of the genus {Tamias}, sometimes called the {striped squirrel}, {chipping squirrel}, {ground squirrel}, {hackee}. The common species of the United States is the {Tamias… …   The Collaborative International Dictionary of English

  • ground squirrel — sibirinis azijinis burundukas statusas T sritis zoologija | vardynas taksono rangas rūšis atitikmenys: lot. Tamias sibiricus angl. ground squirrel; Siberian chipmunk vok. Backenhörnchen; Burunduk; edles Backenhörnchen; eurasisches Erdhörnchen;… …   Žinduolių pavadinimų žodynas

  • ground squirrel — squirrel that lives in burrows under the ground (not in trees) …   English contemporary dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”