Skeleton of the squirrel, showing its relation to the body

Check out that skull and those teeth - the family Sciuridae is more closely related to beavers, dormice, and porcupines, than they are to your average household rodent, despite looking like “fancy-dress rats”.

The skull is often a key differentiating factor for comparative zoologists. The design of the inner ear and teeth/jaws can often point to a very different (and much more accurate) classification of a species than body type.

Animal Forms: A Textbook of Zoology. David S. Jordan and Harold Heath, 1902.

rhamphotheca:

Sciuropterus pulverulentus 

* now called “Smokey Flying Squirrel” (Pteromyscus pulverulentus), found in Brunei, Indonesia, peninsular Malaysia, and southern Thailand.

illustration from Proceedings of the Zoological Society of London (1873) by Joseph Wolf

Sciurus hypopyrrhus (subspecies of and may be synonymous with Sciurus aureogaster) - Mexican Red-Bellied Squirrel

This subspecies of the Mexican Gray Squirrel is possibly just a variation on Sciurus aureogaster. As it has no distinct population separate from the Mexican Gray, the Red-Bellied and melanistic “subspecies” (all of which interbreed) are often considered nothing more than color variants.

Biologia centralia-americana. Edward Richard Alston, 1882.

ofpaperandponies:

ofpaperandponies:

Merry Christmas, you damn fancy-dress rat. Consider my not pelting you with stones to be your gift.

No, it’s not historical, medical, or natural history. But squirrels stealing my birdseed is damn well zoology and anatomy. It takes over a year before the squirrels are big enough to jump onto the feeder, but when they get too big, they can’t balance worth a damn and fall off right away. This guy is both big enough to get up there and not too fat yet. He actually tends to eat upside-down (though he uses both feet to hang on when he does that).

Cat-squirrels. Used to refer to either red squirrel or the Easten gray squirrel, both shown here.

Squirrels are just fancy-dress rats. Trust me here…physiologically, they’re basically the same. Squirrels tend to be significantly larger than black rats, but some brown rats can get up to the size of even a grey squirrel. 

Quadrupeds of North America. John James Audubon, 1851.

Lesser Flying-Phalanger aka Sugar Glider

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From A Handbook to the Masupialia and Monotremata by Richard Lydekker. 1896.

Part of the Lloyd’s Natural History series.