There are many differing opinions on what cryptozoology is, but for our purposes the most fitting is as follows:-

Cryptozoology is the study and investigation of evidence for animals unexpected in time or place, or in size or shape.

Animals unexpected in time includes species which are known only from fossil records and species known to have existed in the past, but now believed to be extinct. The discovery of the 5 foot long Coelacanth fish living and thriving in the waters near Madagascar is perhaps the most famous case. The Coelacanth was previously believed to have died out at around the same time that the dinosaurs did - some 64 million years ago.

Animals unexpected in place include many mystery animals such as various types of big cat frequently seen living in the British Isles, wallabies and kangaroos spotted in various places around the world, and crocodiles and other reptiles appearing without explanation in many less than tropical waters.

Animals unexpected in size or shape covers the thousands of sightings of oversized, (or undersized) birds, mammals, reptiles, fish and a whole menagerie of creatures reported from all corners of the globe, sometimes of unusual shape or colour.

It is a popular misconception that our world is fully explored and its occupants catalogued. Even today there are in every part of the world inaccessible areas where there could certainly exist wild creatures which have remained completely unseen by the human eye. It is these places where the most astounding animals may be awaiting discovery.