Draconic Taxonomy
Casual observers may initially perceive dragons as reptilian in nature. While it is true that both have scales and hatch from eggs, dragons differ from reptiles in at least one important respect: they are warm-blooded. In the field, the crews of harnessed dragons may seek shelter against their dragon's sides for the warmth given off. Sir Edward Howe notes that "heavier dragons greatly prefer warm environs, where their air sacs can more easily compensate for their great weight," (Howe, 1796) and certainly all dragons enjoy basking in warm locations. However, warmth appears to be a pleasure rather than an absolute necessity for them. Young heavy-weight dragons - including a Regal Copper, one of the largest breeds - have been observed to frolic in the icy waters of [Loch Laggan covert|Loch Laggan] with great enjoyment. The basking behaviour of dragons may thus be compared more closely to that of some mammals (notably, cats) rather than the behaviour of reptiles such as iguanas.
The particular combination of scales and eggs with warm blood is the hallmark of the order Draconia, first described by Carl Linnaeus (1707-1778) in his Systema Naturae. Later researchers in the field of evolutionary theory established by Charles Darwin (1809-1882) have established that both dragons and birds are descended from dinosaurs, specifically from the primarily carnivorous theropods rather than herbivorous sauropodomorphans or ornithischians.
There is a paucity of data concerning members of the order Draconia other than dragons themselves. The one notable exception are the sea-serpents or, more properly, sea-dragons (kiao in Chinese), which are known to live in the Atlantic, Pacific and Indian Oceans, as well as the China Sea.
It remains unclear whether all sapient dragons are members of one species (Draco sapiens) or rather represent different species of the same genus. Sir Edward Howe notes that "the most common French breeds, the Pecheur-Couronne and the Pecheur-Raye, are more closely related to the Widowmaker breed than to the Reapers, in we may judge by wing confirmation and the structure of the breast-bone, which in both breeds is keeled and fused with the clavicle. This anatomical peculiarity renders them both more useful for breeding down into light-combat and courier breeds, rather than into heavy-combat breeds" (Howe, 1796).
It is not clear from Sir Edward's phrasing whether it is simply more practical to breed Pecheurs down or whether in fact Pecheurs (and other breeds with keeled, fused breast-bones, such as Winchesters) are infertile with Reapers and heavier breeds. The defining trait of a species is that its members can not produce fertile offspring - if they produce any offspring at all - when interbred with members of other species.
