Pterosaurs

Biblical references
Isaiah 14:29, 30:6

As Snakes
The Israeli saw-scaled viper is sometimes thought to be the "fiery flying serpent."

As Pterosaurs
Many Young Earth Creationists believe that the encounter in the desert with the fiery flying serpents describes an encounter with pterosaurs. They cite many cryptozoological reports of modern day pterosaurs that glow, which would give the animals a fiery appearance. (To ancient people, and some modern third-world people in remote areas, a glow at night could be interpreted as fire.)