Re: Is a squirrel rabbit cross-bread common?

Can there be a cross between a rabbit and a squirrel?

You mentioned that you have seen an animal that appears to be a mix 
between a rabbit and a squirrel. You ask if this type of cross is 
possible. As a scientist, I have to admit that a small possibility for 
this type of cross breeding probably does exist, but that the probability 
is so small as to be just this side of impossible.

The species is a fundamental unit in biology. Although there are several 
well known exceptions to the rule, the most commonly used definition of a 
species is a group of interbreeding individuals that are reproductively 
isolated from other such groups. That means that if two individuals that 
come from different animal groups can successfully produce offspring, then 
they must be members of the same species. This concept extends to how two 
species form from a parent group by developing reproductive isolating 
mechanisms. As species evolve these isolating mechanisms become firmer, so 
that they may range from the two groups simply not being sexually 
attractive to one another to complete incompatibility of the germ cells. 
Closely related species may, on occasion, produce offspring. For distantly 
related species cross breeding becomes next to impossible.

Although rabbits and squirrels may look something alike, they are actually 
very distantly related species. In the taxonomic scheme of things rabbits 
belong to the order "Lagomorpha" while squirrels belong to the 
order "Rodentia." To put this in context, humans belong to the 
order "Primates." That means that humans, rabbits and squirrels are all 
different at the same level of biological organization. In other words, 
the difference between a rabbit and a squirrel is about as biologically 
significant as the difference between a rabbit and a human, or between a 
squirrel and a human. A successful cross between a rabbit and a squirrel 
would be about as likely as a successful cross between a rabbit and a 
human. 

If you can make the picture of the animal you have seen available, I am 
sure that there is a Mad Scientist who can help you identify it.