Dragons of the Air by Harry Seeley

Harry G. Seeley was a student of law, but when attending a lecture bySir Richard Owen, who coined the term "dinosaur" ("Terrible Reptile" or "Fearfully Great Reptile") in the 19th century,on flying reptiles, his interest in paleontology was piqued, and he pursued paleontology for the remainder of his life.
Seeley determined that dinosaurs could be divided into two groups, the lizard-hipped dinosaurs and the bird-hipped dinosaurs. He is also credited with characterizing flying dinosaurs as warm-blooded active flyers rather than cold-blooded passive gliders.
Dragons of the Airis a comprehensive treatise on the structure, classification, and possible evolutionary origins of the Pterosaurs as well as their relationship to birds.
Dragons of the Air was first published in 1901. Audiobook read by Jeffery Smith, running time 7 hours, 50 min. Unabridged full version.