Megabrachio

As the largest terrestrial animal on the planet, Megabrachio is perhaps one of Darcia's most charismatic species. At an average length of 90 feet long fully grown and weights of over 110 tons, only the Great Dappled Wailword is heavier, and only the former wailword and the Long-Tailed Wailword are longer among vertebrates. An ecosystem-shaping animal, the flora and fauna of Northre relies on the presence of these giant reptiles to shape it.

Taxonomy
Megabrachio's placement among Darcia's Archosaurs was, for many years, unclear. While it was clearly an Archosaur, being the only extant herbivorous Archosaur on the planet, and many of its morphological traits being significantly different from other groups showed it was likely only distantly related to them at best.

The discovery of other Megabrachio species such as Megabrachio minutus and Megabrachio giganteus in the fossil record shortly after the initial explorations of Northre indicated that Megabrachio was part of a transcontinental family of reptiles that were well-adapted to browsing on broad-leafed foliage and were all the largest herbivores in their ecosystems- with the exception of the specialized species Megabrachio minutus. The only greater continent that Megabrachio fossils had not been found on was Sirenta. Only a few years after the discovery of other Megabrachio species, a second, closely related genus was discovered from Sirenta- aptly named Sirentasaurus. While closely related, Sirentasaurus had some significant cranial and limb morphology that indicated adaptations more effective for a drier environment dominated by ferns rather than angiosperms. While Sirentasaurus indicated the presence of a more staple clade that had existed for millions of years, it would not be for several decades before the discovery of Pachylophosaurus, also from Sirenta, would solidly place Megabrachio on the Archosaur family tree. Pachylophosaurus, and later its relatives, while not Megabrachids proper, were closely related to the family and placed the order Megabrachia as sister to the Dasplasauria, likely diverging in the early Cretaceous.

This placement has been disputed in the past, originally placing Megabrachio as sister to Darcisuchia, however this is no longer supported, as their relation to Parahadrosaurids such as Pachylophosaurus is quite solid based on limb, vertebral, and cranial morphology, and their relation to Dasplasauria is supported by the presence of the robust and specialized nasal strut found in Dasplasaurus and wailwords in early Megabrachians.

Physiology
Megabrachio superficially resembles a Terran Sauropod, with a long neck, scute-covered skin, long tail, and columnar legs, however, these adaptations are superficial at best, and upon closer examination are only convergent because of similar niches.

Megabrachio's skull measures approximately five feet long, placing it as having one of the largest terrestrial animal skulls on the planet, after Dasplasaurus and the Saber-Tooth Crab Finger. However, despite the massive size of its skull, it is significantly lighter than either's skull, despite the similar skull size. This is because the skull is highly pneumatized and is mostly taken up by the animal's cavernous mouth.

Megabrachio's mouth contains a total of twenty-eight teeth, twelve on the upper jaw, and sixteen on the bottom. In the live animal, the teeth are rarely visible and are all identical, with the exception of the unique fangs found in the upper jaw of the males, which are used for intraspecific combat. The teeth are all replaceable, except for the males' fangs, which are deeply rooted. the antorbital fenestrae in males is actually smaller to make room for this root, and the two sex's skulls can be differentiated without the presence of teeth at all because of this. The other teeth in the skull are small and peg-like, for stripping leaves from branches. These teeth are usually not visible, covered by thick, protective gums.

The neck of Megabrachio is incredibly muscular and relatively long. The vertebra themselves are rather gracile, however they have large spinous and transverse processes that support powerful tendons and muscles. Males can be differentiated from females by the large fat deposit on the underside of the neck, giving it a somewhat thicker appearance, and is derived from a similar feature seen in Terran alligators. In some individuals, the neck features a slight red tinge. The body itself is tall, with the vertebral column held parallel to the ground. Each rib is over twenty feet long, and is heavily built to support the massive weight of the animal's organs.

The tail takes up about half the Megabrachio's body-length, and is where the majority of the animal's fat deposits are located. The tail also controls the musculature of the hind-legs.

All four of Megabrachio's limbs are approximately the same length, with three toes, each with a short, blunt nail. Behind each foot is a fat deposit that helps displace the reptile's immense weight more effectively, and gives the legs a columnar appearance.

In total length, adult Megabrachio average 90 feet long. Males are typically heavier by a few tons, but length-wise their is no discernible difference between the two sexes.

Distribution and Habitat
Megabrachio is found exclusively on the continent of Northre, but is found across the continent except for the most rugged mountainous regions. Megabrachio is responsible for the almost uniform mosaic of Darcian Redwood and fern prairies. While specialized browsers, Megabrachio are too large to actively travel through the forests effectively, and as such, clear the forests as the herd moves, creating new prairie area, while also fertilizing old prairie area, promoting the growth of new forests.

Megabrachio populations are especially prevalent around the three great rivers of Northre- the Verdant River, the Rollili River, and the Kibrian River. The sheer water volume of these rivers can support much larger groups of Megabrachio than elsewhere on the continent, where populations are restricted by water availability.

Behavior
Megabrachio are herd animals, living in small groups of usually unrelated individuals, typically four or five adult females, one or two adult males, and a selection of juveniles and subadults of both sexes. While most of the year males are passive amongst each other, in the fall, they become quite aggressive and enter a state similar to the musth seen in Terran elephants, aggressively biting and slamming into each other's necks and chests. During this state, females will actively avoid males, who will continue to follow the herd in a sexual craze. Males will literally chase the females of the herd to exhaustion to mate with them. Oftentimes, however, the males do not succeed, as they tire themselves out fighting other males. Because of this behavior in the fall, males are typically found on their own throughout the winter, before rejoining a herd in the spring once females disperse to lay their eggs.

Females typically nest deep in the forest, digging a depression six feet deep with their hind legs, before laying down over the depression to lay around a hundred eggs. She then carefully covers them before returning to the plains to rejoin the herd.

Young hatch at about 1.5 feet long, and hatch about three months after being laid- typically in the beginning of summer. These young grow very rapidly, reaching thirty feet long by their first winter. It is after their first winter that they join a herd. During this winter, their growth slows exceptionally, and they will take another fifteen years before they reach the 90 feet of an adult.

Megabrachio are mostly oblivious of other animals, while not actively antagonistic they make no effort to avoid killing them accidentally. The only exceptions to this are the Darcian Kib and the Megamole. While Darcian Kibs are aggressive psuedo-parasites of adults, and predators of juveniles, Megamoles are only predators of first-year individuals, however they are still attacked and chased just the same by adults.