Depending on the specific species, the size of the Zalmoxes differs greatly. Z. shqiperorum was the largest species and could grow up to four and a half meters long. However, the smallest, Z. robustus, would only grow up to three meters long. Z. robustus was thought to be so much smaller than the Z. shqiperorum because of insular dwarfism. Insular dwarfism was the theory that large animals evolved by decreasing in size when the food sources are limited due to lack of land mass. Since Zalmoxes lived on islands, they were said to evolve over generations by decreasing in size so they would not need to eat as much plant matter. This allowed for Zalmoxes to continue to populate and also have lots of available food.