BannedLagiacrus

Name: Great Jagras (ドスジャグラス)
Title: Thief Wyvern (賊竜)/Great Glutton
Length: 1109.66cm
Height: 373.28cm
Foot Measurements: 153cm

Order: Saurischia/Wyvern Hip
Suborder: Four-Legged
Superfamily: Thief Wyvern
Family: Jagras
Genus: Jagras

Habitats: Ancient Forest, G. Lands 

A species of fanged wyvern that was first discovered in the New World, the Great Jagras is the leader/alpha male of the Jagras.

Jagras are a fast-moving species of fanged wyvern that often hunt in packs. 

Name: Jagras (ジャグラス)
Length: 437.45cm

Order: Saurischia/Wyvern Hip
Suborder: Four-Legged
Superfamily: Thief Wyvern
Family: Jagras
Genus: Jagras

Habitats: Ancient Forest, Guiding Lands 

These packs are made up of males and females, and while the females remain small, the males continue to grow larger as they age.

When a young male Jagras reaches a certain age, he'll isolate himself from his pack as he further grows. 

Most young males die during this time in their lives, but some of them are able to survive and become a Great Jagras. Once these surviving males reach adulthood, they'll return to familiar territory before attempting to claim a pack of their own. 

Dreadlock-like crests can be found on a Great Jagras's head and chin, and they are used to indicate the age and strength of the individual. They also use these crests and subtympanic shields (The large scales found under their ears) to attract females. 

Only one Great Jagras can rule over a pack of Jagras at a time, which leads to these individuals fighting against each other for control over a pack, particularly during the breeding season. 

During the breeding season, Great Jagras will fight each other in order to mate with several females. A Great Jagras can mate with as many as twenty females, and each female can lay about three to four eggs. 

The females will lay their eggs in a warm area, such as a cave, before leaving them to incubate on their own.

Predators, such as Kulu-Ya-Ku, are known to raid these unprotected nests. https://x.com/BannedDino/status/1249676832301092865 

While the smaller Jagras tend to hide in the trees for protection, a Great Jagras can't due to his larger size. 
Great Jagras tends to patrol his territory from the ground, searching for potential prey. 

Unlike the Jagras, Great Jagras can hunt alone, and this is due to his size and strength.

While the Jagras prey on Shepard Hares and other endemic life, Great Jagras preys on smaller monsters like Kestodon, Aptonoth, and, rarely, other Jagras. 

The Jagras need a pack to hunt for larger prey while Great Jagras doesn't. He'll use his jaws, front limbs, and body weight to take down prey. Once the prey has been slain, he'll swallow his victim whole, which causes him to nearly double in size. https://x.com/monsterhunter/status/877622921086222336

Great Jagras can swallow prey about as large as himself due to the acid in his highly flexible stomach. The stomach of a Great Jagras produces a lot of gastric acid, which he uses to quickly digest his quarry. 

While his stomach is empty, this powerful acid will melt his stomach walls, leading to Great Jagras immediately searching for another victim. Great Jagras doesn't completely digest his prey, he'll often spit bits and pieces of his meal out of his mouth. https://x.com/BannedDino/status/1445048846237773825

To maximize the amount of nutrition he gets from his prey, Great Jagras will continually ingest and partially digest new prey throughout the day. This not only helps him maintain his frame, but it also helps his pack. 

After swallowing a prey item whole, Great Jagras will return to his pack and give them some of his kill. Compared to the endemic life that Jagras feed on, the bits of prey left behind by Great Jagras has higher nutritional value. https://x.com/BannedDino/status/1245064320142245889

The Jagras aren't completely loyal to Great Jagras, often letting him deal with larger threats, but he can gain and keep their loyalty by feeding them some of his prey. If he becomes enraged or is weakened, the Jagras will leap out of the trees and attack his assailant. 

The Jagras will also attack weakened large monsters when given the chance. https://x.com/BannedDino/status/1245176845877870594

Great Jagras will usually use his forelimbs and jaws to dispatch enemies, but, when his stomach is filled up, he'll use his entire body to crush them. While in this "Bloated State," Great Jagras will also hurl chunks of his meat and gastric acid out of his mouth at enemies. 

Great Jagras will usually stay hidden while he is bloated, but he noticeably becomes bolder while slim.

When hungry, Great Jagras will sometimes attack monsters larger than himself, including Anjanath and Rathalos. His hunger is said to rival the hunger of larger monsters. 

Sources
1. Monster Hunter: World
2. Monster Hunter World: The Official Complete Works (DIVE TO MONSTER HUNTER: WORLD モンスターハンター:ワールド 公式設定資料集) - pg. 200 - 205, pg. 394 - 395
3. HAUNTING OF THE SUN モンスターハンターライズ：サンブレイク　公式設定資料集 - pg. 192 