Though several oviraptorosaur species are known to have developed a full coat of feathers, Gigantoraptor, due to its size, could have lost some of this integument.

In a quarry at Saihangaobi, Iren Dabasu Formation, Erlian basin, Sonid Left Banner (Inner Mongolia), numerous remains of the sauropod Sonidosaurus have been uncovered since 2001.

As he wiped the bone clean, he suddenly realized it was not from a sauropod, but from an unidentified theropod in the size class of Albertosaurus.

[3] In 2015, Takanobu Tsuihiji with team reported a partial—and large—caenagnathid dentary (specimen MPC-D 107/17) from the Bayan Shireh Formation, discovered in 2008 by the Hayashibara Museum of Natural Sciences-Mongolian Paleontological Center Joint Expedition, at the Tsagaan Teg locality.

Despite shared traits between Gigantoraptor and MPC-D 107/17, and their close relationships, Tsuihiji and team regarded it as Caenagnathidae indet.

This element fused into a broad shovel-like shape, indicating that the unknown skull was over half a metre long and also toothless, likely equipped with a rhamphotheca (horny beak).

The angular has a bowed shape and is mainly forwards extended with a large lateral depression that joints with the posterior lower process (bony projection/extension) of the dentary.

[13] Microvenator Gigantoraptor Hagryphus Epichirostenotes Anzu Caenagnathus Caenagnathasia Chirostenotes Leptorhynchos Apatoraptor Elmisaurus Xu and team in 2007 suggested that Gigantoraptor might have been partially "naked" because it is 300 times as heavy as feathered species like Caudipteryx, and large animals tend to rely more on body mass for temperature regulation, leading to the loss of insulating coverings found on their smaller relatives.

However, they suggested that at least arm feathers were probably still present on Gigantoraptor, since their primary functions, such as display behaviour and covering the eggs while brooding, are not related to the regulation of body heat.

The performed histology also suggests that this individual was an adult, as there was extensive development of the secondary osteons, tightly packed LAGs close to the periphery of the bone, and a poorly vascularized layer of lamellar bone in the outer circumferential layer, which indicates a relatively sloppy growth rate.

However, given that the fourth to seventh sets of LAGs were not very tightly packed, Xu and colleagues inferred that the individual reached its young adulthood at the age of 7.

Xu and colleagues pointed out the larger the theropod becomes, the shorter and stockier the legs become in order to withstand the increasing mass.

[1] In 2017, Waisum Ma and colleagues re-examined the preserved jaws of Gigantoraptor and found that it had the deepest beak among caenagnathids and a relatively different diet from other oviraptorosaurs.

This movement aided with the sharp shelves of the dentary may indicate a shearing bite capable of cutting through plants (and potentially meat).

The depth of the lower jaw indicates the presence of a large tongue, which could have assisted the animal in food processing, and possibly improving the feeding efficiency.

[3] As the shape and size of the rostrum in large herbivores is related to dietary habits, the strongly U-shaped dentary of Gigantoraptor may suggest that this oviraptorosaur was a highly non-selective feeder, an adaptation that could have been useful in the variable environmental settings of the Iren Dabasu Formation.

The team could not disregard an occasional carnivorous diet as the strong beak together with a propalinal jaw movement may have allowed meat processing.

The presence of Macroelongatoolithus in North America indicates that gigantic oviraptorosaurs were present there as well, though no fossil skeletal remains have been found.

[14] The 2017 description and naming of Beibeilong—based on an embryonic individual associated with eggs—further supports that Macroelongatoolithus eggs and nests belong to colossal caenagnathid oviraptorosaurs, such as Gigantoraptor.

Their results showed that eggshell porosity indicates that the eggs of almost certainly all oviraptorosaurs were exposed in the nest without an external covering.

Tanaka and colleagues pointed out that this adaption was beneficial to avoid egg-crushing and could have allowed some body contact during incubation in these giant oviraptorosaurs.

The Iren Dabasu Formation had extensive vegetation and foliage, evidenced in the paleosol development, the numerous herbivorous dinosaurs remains that were found in both the river channel and the floodplain sediments.

[19] The dinosaurian fauna of this formation includes the fast-running tyrannosauroid Alectrosaurus, the ornithomimosaur Archaeornithomimus, the therizinosaurids Erliansaurus and Neimongosaurus, the sauropod Sonidosaurus, and hadrosauroids Bactrosaurus and Gilmoreosaurus.