Caesarus

The Caesarus is a saurian creature native to the planet Territorium de Caesarus. As of the No Man's Sky's 2017 update, the species had mysteriously gone extinct.

Biology
It is considered the largest creature to be discovored on record within the No Man's Sky Universe, the "Prime" gender standing at 8.43 meters tall. It is unclear if the Prime gender is indeed the female gender of Caesarus or not, though it's most like female as male Caesarus are more properly identifiable.

The male and prime hold distinct differences between eachother: the Prime gender had an insectoid-like head with two antennae-like sensory organs and stalked eyes resembling a snail or slug. Tails of the prime gender also have feather-like attachments to them.

The males themselves lack most of these details, appearing more like the terrestrial T-rex in overall anatomy, including a slightly shorter face/snout, a V-shaped protrusion from its nose and lacking any feathers of any sort.

Behavior
Upon observation, these giants are sociable creatures and are hardly ever seen all alone. They communicate to eachother in deep bellowing noises, and are known to be fiercely protective of their young.