Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Varanidae
Genus: Varanus
Species: Varanus Komodoensis
The origin of the Komodo Dragon has been in question for many years with multiple hypothesis in play. One hypothesis is that the Komodo Dragon size derived from adaptive radiation, or "island effect" when it was assumed the evolved from the Varanus Priscus.
The second hypothesis is they were used to hunt elephants, and again, being isolated on an island then caused adaptive radiation within the elephants. Therefore allowing large lizards to eat them.
However, there is new research (2009) study by Scott Hocknull disproving the previous mentioned hypothesis. S. Hocknull was able to access fossil records of the Varanus Priscus (400 million years ago) and compared them to newly found fossils (dated from 300,00-400 million years ago) and came to the conclusion that the Varanus Priscus and Varanus Komodoensis walked this earth together.
Although their exact evolution has been questioned, it is important to mention that they fortunately didn't have the need to evolve to survive like most animals/plants that have lived this long.
References:
Hocknull, S. A., Piper, P. J., Bergh, G. D. van den, Due, R. A., Morwood, M. J., & Kurniawan, I. (n.d.). Dragon's paradise lost: Palaeobiogeography, evolution and extinction of the largest-ever terrestrial lizards (Varanidae). PLOS ONE. Retrieved May 8, 2022, from https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0007241#pone-0007241-g009
Program), J. I. (K. S., Ariefiandy, A., Azmi, M., Ciofi, C., Purwandana, D., & Jessop, T. (2019, August 5). The IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Retrieved May 8, 2022, from https://www.iucnredlist.org/species/22884/123633058
Site, T. R. (2017, May 25). Don't drag your feet: 8 things you might not know about komodo dragons. The Rainforest Site News. Retrieved May 8, 2022, from https://blog.therainforestsite.greatergood.com/cs-komodo-dragons-about/