General Species Information Evolution- Squirrels/Sciuridae Roles Squirrels Play in their Different Environments 11 MYA South America had not been inhabited by squirrels before 3 million years ago.

Squirrel, (family Sciuridae), generally, any of the 50 genera and 268 species of rodents whose common name is derived from the Greek skiouros, meaning “shade tail,” which describes one of the most conspicuous and recognizable features of these small mammals. Tree squirrels were first, about 30 million years ago. Duke evolutionary biologists used DNA and fossil records to trace back the genealogies of all but one of today's groupings of squirrel species. Flying squirrels’ relatives date back to the Eocene period, which was between 38 and 55 million years ago. Evolution of the Flying Squirrel. To understand coevolution, Merriam-Webster dictionary defines it as “evolution involving successive changes in two or more ecologically interdependent species that affect their interactions.” Species that are closely associated – in this case, the squirrels and the rattlesnakes – can impact one another’s ability to change over time.

Extinct squirrel-like creatures from China suggest the earliest mammals originated more than 200 million years ago, much earlier than often previously … A well-supported basal clade, including Ammospermophilus and two species in the subgenus Otospermophilus , diverged from all other ground squirrels an estimated 17.5 million years ago. It was however pushed out of its native dwelling places to the edges of its habitat, to northern England and southern Scotland, when the eastern grey squirrel (Sciurus carolinensis) was introduced from America to England in the 1870s. The native red squirrel (Sciurus vulgaris) was once common throughout Britain. Then, a land bridge was believed to be formed as a result of geological shifts. These distinctive animals occupy a range of ecological niches worldwide virtually anywhere there is vegetation. The first-ever genetic delineation of nearly all existing squirrel groups suggests not only some surprising branchings in the squirrels' family tree.

The study also reveals strong evidence that geological and climatic change influenced how their ancestors … Followed by tree squirrels, between 28 and 2.5 million years ago. Classification and evolution According to most taxonomies, flying squirrels constitute tribe Pteromyini within the subfamily Sciurinae of the squirrel family (Sciuridae). Not only is the phylogeny at odds with previous hypotheses of ground squirrel relationships, but it suggests that convergence in morphology has been a common theme in ground squirrel evolution.