Order:Saurischia - Suborder:Dragon feet - Infraorder:Armor Shell Wyvern - Superfamily:Flying Wyvern - Family:Rath. One of the most recognized of the true flying wyverns, Rathalos are bipedal creatures that sport a pair of strong wings and long tails that hold a spiked end frequently used as a weapon in combat. Rathalos are easily distinguished by their brightly colored bodies. Like other true flying wyverns, Rathalos are extremely proficient in the use of their fire breath, using it to scorch foes from great distances. They are known for being some of the most intelligent species of flying wyvern, amongst the likes of Berukyurosu and Doragyurosu.
Rathalos of the Old World inhabit the Forest and Hills, Tower, Gorge, Old Swamp, both Volcanoes, and the Highland. New World Rathalos inhabit the Deserted Island, Volcano (3rd), Misty Peaks, and Ancestral Steppe. These creatures can survive in almost any environment, save for environments with extreme cold such as the Snowy Mountains, or Tundra. Their high metabolism means medium sized prey must be relatively abundant, so many Rathalos stick to forested areas where grazing herbivores are plentiful. Rathalos and their mates nest almost exclusively in large, wind-sheltered caves near mountain tops. It is one of the most territorial of true flying wyverns.
Rathalos fear almost nothing else found in their habitat range, except other large predators and Elder Dragons. Rathalos may prey on lesser wyverns, particularly bird wyverns such as Jaggi, Velociprey and their alpha forms or pelagus such as Bullfango. Only certain predators in a Rathalos' territory are strong enough to fight back if a Rathalos is attacking. Foremost among them are other wyverns and large monsters that live in the same habitat. Such predators include Lagiacrus, Tigrex, Gore Magala, Brachydios, Deviljho, Stygian Zinogre, Agnaktor, Lavasioth and the rare Rajang as they are large and powerful enough to threaten and possibly kill an adult Rathalos.
An adept flyer, Rathalos often use fire-balls to attack foes from both land and air. Rathalos have powerful hind legs, making them extremely fast on ground, as well as giving them the capability to launch devastating claw attacks from the air, often severely injuring its target. While in the air, they are also capable of diving to claw foes on the ground. A Rathalos' claws contain a potent toxin that will often kill a hunter if they don't seek immediate treatment after the blow that inflicted the wound. Rathalos, like many others of its kind, have a powerful roar that they use to intimidate rivals and stun prey. Its bright red scales most likely serve the purpose of attracting a mate.
The Rathalos' body build, along with the Rathian's, seems to differ between the Old World and New World. In the New World, Rathalos have a wider wingspan, while in the Old World, their wingspan is less. Their elemental weaknesses have also changed. Some hunters debate whether these changes are because of the different areas the monsters are in. Though some unique Rathalos in the Old World no longer have a weakness to Thunder and Ice.
Some rare individuals in the Old World appear to be older, with a darker red tint, more developed and longer spikes on their back and tail, larger leg muscles and increased flying abilities. It is unknown if this is caused by aging or a mutation.
Like most true flying wyverns, Rathalos possesses the cunning, speed and strength to fell almost any threat or prey they come across in the wild, though they will rarely challenge anything larger than themselves outside of their territory. It also seems that whilst in combat with a significant threat, Rathalos become enraged far more often than most other monsters.
One of Rathalos supporting factor of their successful survival is their intelligence that seems to be beyond of normal Wyvern's (Even Monster's) standard, there are several possible proves of this: in MH opening video, Rathalos claims the kill of a group of Velociprey, it is possible that the Rathalos simply waited for the Velociprey to do their job and then came to snatch the kill. In MH Tri opening video, Rathalos, once again spoiled from other's effort, preys on Aptonoth slowed down by a Jaggi pack. When confronting the Lagiacrus, Rathalos's challenging pose might be just a mere taunt so that the Lagiacrus would try to bite the evasive Rathalos instead of his catch, thus making Rathalos' escape with his prey a success. In MH4 trailer, the Rathalos shoots down the unstable platform to remove his competitor the powerful Tigrex, this was not accidental, because it can be seen clearly that the Rathalos was aiming down to the platform.
Rathalos are especially aggressive during mating season. After mating with a female Rathian, Rathalos will play the role of a protective father, actively patrolling his territory for a significant threat, freeing the Rathian to hunt for food and care for offspring.