Basiliskans were an intelligent lizardspecies native to the planetBasilisk in the Core. They were the creators of the Basilisk War Droids, that were rumored to be modeled after themselves. During their war with the Mandalorians, the Basiliskans chemically poisoned their own planet, in a last ditch effort to defeat their conquerors.
After the war the Mandalorians found a new use for the Basiliskans. With their tough hides and claws (not to mention how easily they could be trained) and their intelligence the Mandalorians used them as weapons for aerial and ground fighting during later wars including the New Sith Wars. Because of this the Basiliskans degenerated and became nothing more than beasts. As such, since the Battle of Basilisk in 3,997 BBY, they were re-named the Lagartoz War Dragons.