As the monitors spread across the Earth experiencing different habitats and climates they diversified. Some of them appeared to have died out quickly, whilst other, apparently ancient, species have survived until the present.
Many monitor lizards appear to have evolved comparatively recently.
It would be nice to know where the monitor lizards first came from, what the early species looked like, how they behaved and why they died out. Fossils provide us with a tantalising glimpse of a world that we will never know. They have the unerring ability to create more questions than they answer. The chances of an animal or plant being preserved as a fossil is extremely slight. It must be covered with a protective layer as soon as it dies and many millions of years later it must somehow get back onto, or close to, the surface of the rock.