Wyverns

A wyvern is a type of dragon.

Habitat
Ice wyverns tend to live in the northern part of the world where it is very cold, fitting for their frosty nature. Auroth's current lair is in an abandoned keep at the top of Mt. Gorod in the frigid realm of Icewrack. Another ice wyvern named Karaul Silverwing turned the waypoint between Azura and Whitecap into her nesting ground.

Morphology, physiology, and whatnot
Instead of a typical dragon's total of six limbs (2 arms and 2 legs and a pair of wings), a wyvern has a total of four limbs, consisting of a pair of wings as their sole forelimbs and a pair of legs, very much like a bird or a bat or even a pterosaur.

According to Thesos, a dragon skeleton's bones are strong but light, and seem to be more akin to a bird's bones. This seems to suggest an interesting link between Dragons (perhaps including wyverns) and avian creatures.

Like most dragons, if not all of them, a wyvern stokes their flame breath in their gullet. This is the same organ where they store their swallowed foods, which is gnashed and grinded by the steel or other hard materials that they keep in there. In some wyverns who breathe ice instead of fire, their frosty gullets produce a cold breath that sends victims into a "burning agony"—a paradoxical combination of 2 incompatible elements. An ice wyvern's frozen gullet also has specialized vesicles that slowly produce ice shards for them to launch towards enemies as a projectile attack. As for their fiery counterparts, perhaps their gullets have flameglands (instead of ice-producing vesicles) that generates their fire breath.

It's implied that a wyvern's gullet is somewhere beneath the hide of its breast.

Wyverns may have some of a dragon's usual characteristics, such as having remains that still retain their powers and properties, even in Death: including fiery scales, their hot blood, and volatile dragon drool. The fiery blood and explosive saliva may not apply to ice wyverns, though.

Intelligence
A wyvern has the potential to be an Eldwurm, an old and wise dragon learned in many bodies of knowledge, and are capable of ruminating, casting magic spells and a complex artistic expression. Auroth is a good example of this.

Personality

 * Like most dragons, wyverns may be lordly creatures and thus cruel to lesser beings. They recognize no authority other than themselves, and do whatever they please with impunity and disregard for the power of lesser beings.
 * Also like most dragons, wyverns have a tendency to hoard precious items like gold and magical trinkets. Because of this, they are often wanted for their money.
 * A creature that's confident in their knowledge, wyverns prefer to not have their wisdom questioned.

In Dota: Dragon's Blood
Although dragons in the animated series are mostly classified by their elemental and fundamental power/identity, some dragon types resemble wyverns. Lirrak and her water dragons, including the rogue Auroth, have a wyvern's features. Uldorak and his earth dragons are vestigial wyverns, because they have shortened (hence useless) wings on their arms. The air dragons and their sovereign Aethrak are wyverns too.

Heroes
Auroth the is the most notable example of a wyvern.

Characters
Although most of the Crimson Wyvern's appearance is shown on the equipment forged from its remains, it is hard to tell if it is actually a wyvern, since we don't see the rest of its body, especially the wings which is most important in determining if it's a wyvern. Only its name tells us that it was one.

Karaul Silverwing looks like a wyvern, but the locals call it a dragon or an icewyrm,  not to mention that the lore of her stage calls it an icewyrm.

Hunting
Gastromancer Remi once presented his dish of wyvern filets in order to earn a place amongst the White Orchids, suggesting that wyverns are an exotic delicacy.

wears a suit of armour made from the remains of the Crimson Wyvern. His suit includes shoulder armor made from its scales, a sword made from its talons, and a pair of bracers made from the interlocking scales on top of its spine

Wyvern Riders
According to the lore of the, there exists a faction of merciless wyvern riders.

Romantic interests
Aghanim loves wyverns very much and has had romantic relationships with them in the past, his first course of action upon meeting them being seduction.

Against civilization
According to Auroth, dragons (possibly including wyverns) inflict many detriments on civilization, such as razing entire cities down to the ground, enslaving lesser beings and preying on whomever and whatever they please. Thus they're so feared, that the mere sign of a dragon-strike in an area is enough to make the local people revere the dragon in the hopes that they might be spared. Although Auroth claims to be an artistic dragon, she still can't help being a conventional dragon, as shown when she ate farmer Botfrit's bluehorns.