The Jerome Clark book also recounts several sightings of pterosaurs, pteranodons and pterodactyls, which are flying reptiles, but not feathery birds (P-156).

ALLPLANETS-HOLLOW Cavern Worlds
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People,

Remember the movie The Birds? Bad times are coming, and underground creatures seem to be behind it all.

http://www.holloworbs.com/Thunderbirds!.htm