Large Rat Fossils Found

[Catherine]

A Capybara is a close relative of the Guinea Pig.  The zoo has some and they are too funny. Picture a 60 pound guinea pig that can swim very well. They are more of a herd/grazing animal.

Rats are rodents, but they are more omnivorous. They form groups, but they are nocturnal and very clever.
Humans may have contributed to the extinction of the large rats, but I think the smaller ones would be more successful anyhow. 
The rats we have now can us tunnels left by other creatures. They can use natural caves and of course they can use human dwellings and structures. There smaller size allows them to sneak in and out with food. A larger rat would not have the strealth capabilities. Also the smaller rats use less food. They would be better able to survive in times when food is scarce. The smaller rats would be faster and harder to catch.

Many ancient species were larger(If I remember correctly).