What was the biggest mouse ever?

It's impossible to definitively say which mouse was the *biggest* ever, as there are many extinct species that we only know from fossils.

However, we can look at some contenders:

* The "giant" extinct mouse: This unnamed species is estimated to have weighed around 2 kg (4.4 lbs), making it roughly the size of a small cat. It lived in the early Pleistocene in what is now Germany.

* The Malagasy giant jumping rat** (*Hypogeomys antimena*): Although not a true mouse, this large rodent was the size of a small dog and weighed up to 3 kg (6.6 lbs). Sadly, it went extinct in the late 19th century.

* The Rattus norvegicus** (brown rat): This modern species is not the biggest in terms of body length but is known for its impressive size. It can weigh over 500 grams (1.1 lbs).

It's important to note that even within the same species, individual mice can vary in size.

So, while we don't have a clear "biggest" winner, these examples show just how large some rodents can get!