The largest and most ferocious modern wyvern, Jugoceras horriblus (Northrop, 1985) lives alongside two dragons, the basal dracolympian Spinodracos dysonii and the bizarre cat mimic, Felimimus paradoxus. By all accounts, Jugoceras does not relish the company, and chance encounters between it and Spinodracos are violent and brutal (Naish, 2005). This great wyvern can grow up to forty feet long, although a large portion of that length is made up of neck and tail, both of which are surprisingly thick and muscular. Aside from its immense size, Jugoceras is notable for several reasons. First, it has a full compliment of five toes, and one is fully reversed. The individual toes are fairly short and terminate in large black claws. The wyvern is heavily armored, with black plates running down its entire ventral side and light brown, keeled plates running from between its shoulderblades to the end of the tail. Both ventral and dorsal plates overlap to provide some flexibility. The keels on the dorsal tail plates are taller than those on the body. The animal's neck is decorated differently on its dorsal surface: The plates are small, retangular, and do not overlap. Their keels are more like spines. Black, conical spines erupt from the skin just to each side of the dorsal cervical plates.
The head is unique among wyverns in that it is short, squared-off, and fairly narrow. Northrop described the teeth as "oversized," comparing the dentition to Ceratosaurus nasicornus. Jugoceras has a very broad range of binocular vision. Its most striking cranial features are what its namesake: Each jugal bone is equipped with an impossibly long and rigid horn. Additionally, a small nasal horn is present just above the external nares. Like many wyverns, Jugoceras is capable of breathing fire. Yates (2001) noted that rather than using its fire breath for attacking prey, Jugoceras "spurted" its fire breath, and seemed to use it primarily for intimidation. Indeed, Naish never mentioned the giant wyvern using its breath weapon during encounters with Spinodracos, where such an offense would be an obvious advantage.
The oddities, however, do not end there. Jugoceras has short arms but long metacarpals and extremely long, but thin, phalanges. Unlike most wyverns, there are five fingers in the wing. The first fingers is short and flexible, and is used for terrestrial movement. The other four fingers end in similarly elongate claws. As they have no use in flight, Northrop concluded that the claws must have a display function. Not surprisingly given its bulk and unusual wing construction, Jugoceras is restricted to the lower, less snowy sections of the Alps and spends a lot of its time clambering about the rocks on all fours. It feeds mainly on ungulates. Juveniles have never been observed, though we can probably assume that they are not as weighed down as their parents and may live a very different lifestyle.
While Jugoceras obviously presents a great many unique derived characters, it also displays some obviously basal ones. The five-toed pes and manus, for instance, make it more primitive than even Eowyvern. It would appear that the wings were once useful for flight, but the creature's lifestyle and enormous bulk preclude such ability. A small, squarish head and overszied teeth may be primitive for the group, as Eowyvern also demonstrates these characters. Mantell (2001) placed Jugoceras in its own family, the Jugoceratidae, and placed it below Eowyvernidae. He cautioned, however, that Eowyvern could represent a basal wyvern that independantly lost many basal features, such as pentadactyly and quadrapedality. In that case, Mantell argued, Eowyvern would likely originate from a more basal clade than Jugoceras, as Jugoceras is more derived in its wing construction and ability to fly.
Northrop, A. (1985). Comments on a gigantic wyvern from the lower Alps. Natura Historia 392: 322-331.
Naish, D. (2005). Jugoceras is unquestionably aggressive toward Spinodracos. Draconium 46(1): 56-58.
Yates, A. (2001). Fire-breathing behaviors among wyverns. European Journal of Draconology 102(3): 294-297.
Mantell, G. (2001). A broad look at wyvern systematics. European Journal of Draconology 102(2): 305-311.