Animals are either extinct or they aren't, because extinct means that there is not one individual of that group (species, genus, etc) left. Thus, there is no such thing as a "most extinct" animal. Over the entire existence of the rainforest as we know it, many rainforest species have become extinct.
There are so many animals that have been extinct in the rainforest and most of them haven't been discovered yet - so its unlikely that anybody will answer this question. If you just want an extinct animal, then the Quaggas is a rather strange one.
Well, a Quagga is an extinct zebra with brown fur and stripes only on their belly, back and head. A quagga still existed in the 1800's.
no
The sloth is the most popular animal in the amazon rainforest.
yes
people
A panda
If you have ever been in the rainforest you would know that it is the penguin.
dinosours
probaly birds
lized
the mosquito
a crocodile probably
birds