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Two species of squirrel are currently found in the UK, the native red, which has been reduced to a fraction of its former range, and the grey, an American species introduced in the 19th century. The larger grey both outcompetes the red in many habitats and carries a virus fatal to reds.
The skull of the grey squirrel is distinctly elongated in shape compared to the more globular skull of the red. The widest point of the red squirrel skull is near the centre of the zygomatic arch, whereas in the grey it is located on the temporal bone at the rear of the arch. In these specimens, the vestigial premolar is missing, but the socket can be seen at the front of the tooth row.
Skull Images - Click for enlargement
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1.
Red squirrel skull, lateral view.
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2.
Red squirrel skull, ventral view.
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3.
Grey squirrel skull, lateral view.
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4.
Grey squirrel skull, ventral view.
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Internet Resources
Standard references :
Wilson & Reeder's Taxonomic List
University of Michigan Animal Diversity Web
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Taxonomy:
Order - Rodentia (rodents)
Family - Sciuridae (squirrels)
Scientific Names:
Sciurus - from skia and oura, Greek words meaning "shade" and "tail"
vulgaris - "common" (Latin)
carolinensis - "of Carolina" (Latinised)
Dental Formula
U 1.0.2.3 - L 1.0.1.3
1st upper premolar is vestigial.
Measurements: (defined)
S. vulgaris
Overall length - 50.6mm
Overall width - 30.9mm (more)
S. carolinensis
Overall length - 58.9mm
Overall width - 33.6mm (more)
Collection Data
S. vulgaris (1 & 2)
Stage - adult
Sex - female
Area collected - Northumberland
Date collected - Oct. 96
Source - road casualty
Collector - WH
Collection ref. - 96.019
S. carolinensis (3 & 4)
Stage - adult
Area collected - Llandrindod Wells, Powys
Date collected - Aug. 91
Source - road casualty
Collector - WH
Collection ref. - 91.010
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