Above are shown the differences between females (top) and males (bottom).
Wyverns in Tergeryz are one of the most diverse clades within Pseudodracomorpha, occupying a wide variety of ecological niches and displaying many shapes and sizes. A family in particular that stands out for their unique morphology is Therovenatoridae, or the giant ground wyverns, the largest and heaviest of the wyvern clade. It is a fairly small family, having only four extant members: the great butcher (Crassionyx ferox), the painted gorecrest (Lythrocephalus vercicolor), the dwarf puruk (Crassionyx minor) and the windchaser (Fulmenura bicrestata bicrestata), along with its subspecies, the bluehills windchaser (Fulmenura bicrestata borealis). Their main characteristic is their complete lack of flight and remarkable size, some being as big as –or bigger than– an adult dragon.
They are primarily carnivorous, with the exception of Crassionyx minor, which feeds almost exclusively on hard shelled nuts. Despite the vestigial appearance of their wings –reduced length of the phalanges of digit IV and of the patagium–, they still have several uses, such as thermoregulation and as display to impress mates or ward off threats. The rest of the digits have a substantial range of movement, particularly digit I.
These giant wyverns are also unique in that the males are larger than the females, something seldom seen in the rest of pseudodracomorphs; this is likely due to the fact that males are often the ones that care for their offspring, and have established territories that they must defend from other males. F. bicrestata and C. minor have a particular way to go about chick rearing, as the latter form monogamous couples that protect one territory, and F. bicrestata males sometimes form long lasting homosexual pairings, increasing the chances of their chicks' survival.
Interspecific competition is rare, as even though they all inhabit the Vast Moor, each species has a preferred biome, meaning their ranges barely overlap. Their enormous size and aggressive, solitary nature make them a considerable threat to dragons, since their claws can easily shred wings and leave a dragon defenseless. Deadly interactions between giant wyverns and dragons increase during the first half of the year, as that is when wyverns are competing for a mate or looking over their eggs and young.
Size comparison between both sexes of all species, a human, and a moor runner.