A long-standing belief is now cast into doubt. The fiery flying serpent was probably a long-tailed flying creature, perhaps like the ropen. Ropen Fiery Flying Serpent Recent Sightings nonfiction book "Searching for Ropens and Finding God" scientific paper published by David Woetzel
According to Whitcomb’s 2014 non-fiction book Searching for Ropens and Finding God: (Chapter Six): “My associates and I believe that the fiery flying serpent of the Old Testament  was a ‘basal’ pterosaur, perhaps related to the long-tailed ropen of Papua New Guinea. We believe they called it ‘fiery’ because of its glow, which we attribute to bioluminescence. ‘Flying’ is literal, with wings.” (Appendix): “In two chapters of Isaiah, in the Old Testament of the Bible, we find ‘fiery flying serpent.’ The book of Numbers reveals that those creatures caused the death of many of the ancient Israelites, although the King James version does not include the word “flying” here . . .” “Many of those who have searched for modern pterosaurs in Papua New Guinea and elsewhere believe that the Old Testament refers to Rhamphorhynchoid pterosaurs, the type that had long tails. . . . they may have resembled snakes when their wings were folded up, for they had long tails. We believe “fiery’ refers to the bioluminescent glow, still present in at least one species of ropen.” According a scientific paper by David Woetzel, as he quoted John Goertzen: “That Hebrew word, m’opheph Jpvfm, is a polal participle; a form used only by Isaiah when describing the reptilian saraph (14:29 and 30:6). The polal indicates an intensive of the root pvf ooph that means to fly or flutter. BDB, [Brown-Driver-Briggs] then, interprets it as meaning to ‘fly about, to and fro.’ The imperfect form of the polal is found in Gen. 1:20, ‘flying creatures that flutter to and fro…’  The meaning may be best illustrated by a polal infinitive construct in Ez. 32:10 ‘when I cause my sword to fly to and fro’ or ‘when I brandish my sword.’ The rapid back and forth movement of the sword (brandishing) illustrates the emphasis of the polal intensive. The idea of TWOT [Theological Wordbook of the Old Testament] then, that m’opheph Jpvfm could indicate a serpent’s swift bite, will not work since a serpent’s strike is not a back and forth motion. The word indicates an animal with swift back and forth motion, like the flying of a humming bird.”
Nick-named “the Bible of Modern Pterosaurs,” this third edition will take you into the lives of many of the eyewitnesses of the ropen. This is greatly expanded and improved from earlier editions of the book.
The Fiery Flying Serpent
Lake Pung, Umboi Island, where seven natives were terrified by a giant ropen that flew over the surface of the lake, in the middle of the day—that led to interviews between three of those natives and the American explorer Jonathan Whitcomb, during that 2004 expedition in Papua New Guinea.
Duane Hodgkinson, eyewitness of a huge ropen that flew up from a jungle clearing near Finschhafen, New Guinea, in 1944
Near Finschhafen Harbor, Papua New Guinea, near where two soldiers, in 1944,  witnessed a huge “pterodactyl” up close
Searching for Ropens and Finding God
The true-life adventures of those who searched for modern living pterosaurs in Papua New Guinea and in other areas of the planet, and the shocking encounters that ordinary persons had with the unexpected appearances of featherless flying creatures