Dragonriders of Pern
Dragonsong by Anne McCaffrey Menolly lives on the planet Pern where dragon riders protect the planet from Threads. Menolly runs away from home after he ruins her chances of becoming a harper, because she is a woman. Menolly soon finds a groups of fire lizards (a dragon's smaller cousin) and teaches them how to sing.
DRAGONQUEST by Michael Whelan. The primary menace to the planet Pern is "Thread," a corrosive and devastating alien life form which falls from the Red Star and burrows its way into the soil, destroying all life and making the soil unusable. Only the dragons who are able to burn the Thread out of the sky can save the inhabitants. This seemed like a great scene for Michael to illustrate and it made an ...