It should be noted that the fire lizards are actually the ancestors of the dragons of Pern. Scientists who had survived the crash on Pern quickly discovered their natural defense against the horrible Thread menace. Genetically altering the DNA of the little creatures they eventually ended up with the large beasts we read about in the books.
The lizards, after being rediscovered by the decendants of the survivors, are kept as pets. Eventually their ability to travel between is used to the advantage of their owners when they are used as messangers much like pigeons have been. The only difference of course being that the lizards teleport to their destination rather than fly the entire distance.