“ Having clever, caring parents can give youngsters an excellent start. And here in the badlands of Asia, there are few more dedicated dinosaur parents than these. A colony of nesting Corythoraptors. ”
Corythoraptor (Helmeted Thief) is a genus of oviraptorid dinosaur that lived in the Nanxiong Formation of the coastal province of Guangdong in South China, 67 - 66 million years ago, during the Maastrichtian stage of the Late Cretaceous Period.
Corythoraptor is named for a structure it has in common with other oviraptorosaurs, a tall, cassowary-esque head crest likely covered in a shell of keratin (in its case, around 2 millimeters or 0.08 inches in thickness), possibly serving as a means of display, a radiator to dissipate heat from the head, a resonator to pick up low-frequency signals from long distances and pinpoint their origin, or a combination of these. Corythoraptor also has other standard oviraptorid traits, namely, a skeleton made lightweight by several air pockets, a powerful, toothless beak, a long neck, sharp claws, a short tail, and a coat of feathers, with longer ones lining the arms and tail to form a pygostyle (tail fan).[1]
Microanalysis of the bones show that Corythoraptor was subject to seasonal growth spurts. With this, the Corythoraptor type specimen is estimated to be a six or seven year-old individual that grew 1.6 meters (5 feet, 3 inches), just as it was about to start growing again, indicating that it hasn't reached its full size yet when it died.[1] Conversely, if the crest serves as a mating display, this would indicate that, even as a young adult, Corythoraptor would have taken part in courtship, competitive mating, and other such activities even though it is yet to fully grow. With all these taken into account, it can be reasonably assumed that, like its famous relative Oviraptor, Corythoraptor grew around 1.6 - 2 meters (5 feet, 3 inches - 6 feet, 7 inches) in length, and weighed approximately 33 - 40 kilograms (73 - 88 pounds),[2] which fits its stated mass of 80 pounds (36.3 kilograms) on the show.[PhP 1]
On Prehistoric Planet, only male Corythoraptors are seen, covered in vivid blue feathers with an underside of white feathers, and sporting a crest in shades of red and bright orange. While these traits imply that its portrayal was inspired by cassowaries (fitting since it is believed that the species lived a cassowary-esque lifestyle), according to Dr. Darren Naish, Prehistoric Planet's lead consultant, Corythoraptor was not originally intended to be blue.[DN 1]
Corythoraptor first appears in the fourth segment of Forests, with a flock of them feasting on fallen gingko nuts during autumn while they themselves get hunted by a female Qianzhousaurus. Corythoraptor is next featured in the third segment of Badlands, with males brooding over their eggs under the hot desert sun, only leaving during the night to feed while some remain behind to guard the nests, which provides an opportunity for a Kuru kulla to eat some eggs and steal one for her chicks to practice on. Footage of Corythoraptor in the third segment of Badlands is also used for the Uncovered segment "Were Dinosaurs Good Parents?", which tackles the different ways in which dinosaurs took care off their eggs, from the costly brooding of the Corythoraptors to the reliance of Isisaurus on the heat of volcanic areas to incubate their eggs for them.
“ This is east Asia. In these mountain forests, autumn arrives early. This is when many trees produce their fruit, and amongst the most highly-prized are the nuts of the gingko tree. ”
Corythoraptor lived 67 - 66 million years ago in the Nanxiong Formation, Guangdong Province, South China, which is depicted on Prehistoric Planet as a series of temperate, deciduous mountain forests. Corythoraptor lived alongside six other oviraptorosaurs in this area (Banji, Ganzhousaurus, Huanansaurus, Jiangxisaurus, Nankangia, and Shixinggia). While the plant life of Late Cretaceous China is poorly known, it is believed that the oviraptorosaurs actually lived in arid environments, and thus fed on xerophytic (drought-resistant) plants, indicating that the Nanxiong Formation had an arid or semi-arid climate.[3]
While not explicitly found in a desert environment, Corythoraptor appears to have been depicted in the third segment of Badlands as living in the Barun Goyot Formation (where Kuru kulla, the other dinosaur it shares that specific segment with, hails from) of the Ömnögovi Province in the northwest of Gobi Desert, a region in south Mongolia. This portrayal may be due speculation that the animal had a greater range than the fossil records show, or, in order to conserve budget and avoid making another dinosaur model, Corythoraptor was simply reused to serve as a stand-in for an oviraptorid species in the Barun Goyot Formation (which has three oviraptorids, Conchoraptor, Heyuannia, and Nemegtomaia).
Feeding Preferences[]
Corythoraptor lived alongside six other oviraptorosaurs in the Nanxiong Formation. In order to avoid competition, all seven animals likely had different food preferences, forming separate niches and preventing competition. While oviraptorosaurs are theorized to feed on xerophytic (drought-resistant) plants,[3] their actual dietary preferences is still a subject of debate. A 2022 study of four oviraptorosaurs (Incisivosaurus, Khaan, Citipati, and Conchoraptor) suggests that oviraptorosaurs had strong bite forces for their size, and thus likely fed on tougher or more types of vegetation than the other herbivores they coexisted with, like ornithomimosaurs and therizinosaurs.[4] On the other hand, it has also been suggested that oviraptorosaurs may have been durophagous, crushing shelled prey like molluscs and crustaceans (though shellfish are unlikely to proliferate in the environment that oviraptorosaurs preferred),[3] and, though it is not likely a primary part of their diet as was once believed to be the case, oviraptorosaurs may have still fed on eggs if it is the easiest meal to obtain given certain circumstances, as they are likely as opportunistic as any other predator. One piece of evidence that may possibly prove that oviraptorosaurs still ate eggs when given the chance can be seen in the oviraptorosaur nest which contains the first known Citipati fossil (an embryo labeled as specimen IGM 100/971). The nest had two skulls that belong to young or embryonic Byronosaurus, a troodontid. Some suggest that the juveniles were attempting to raid the oviraptorosaur nest, or that their eggs were laid their by an adult Byronosaurus (this behavior, known as brood parasitism, can be seen in cuckoos and other birds today). The other idea is that the owner of the nest snatched the Byronosaurus (either newly-hatched or still in its egg) to feed its chicks.[5][6]
To further aid in digestion, oviraptorosaurs swallowed stones to help mash up food in their digestive system. These stones, known as gastroliths, have been found in the small oviraptorosaur Caudipteryx,[7][8] as well as one of the oviraptorosaurs of Ganzhou City, which is close to the Nanxiong Formation.[9] Dinosaurs also consumed stones for nutrition; ostriches (which, being birds, are technically dinosaurs) swallow limestones to supplement their diet with calcium.[10] This practice, known as lithophagy (stone consumption) is related to geophagy (earth consumption), a behavior that has been portrayed earlier in Forests, which shows a small group of Triceratops eating clay in caves to neutralize the toxins of the plants they ate (with mineral consumption given as a secondary reason for this action).[DN 2]
Social Behavior[]
“ These have found a particularly abundant fall of fruit, but such gatherings can attract unwelcome attention. ”
Corythoraptors are shown to congregate to feed on an abundance of food. This unfortunately attracts the attention of a hungry Qianzhousaurus, which manages to sneak up quite close to them before being detected (and by that point, its very individual for themselves, with the oviraptorans running off like ostriches). The second time around, the gloom and the howling of the winds rustling up more leaves causes the Corythoraptors to be even less aware of incoming threats, leading one to get grabbed by the Qianzhousaurus. The Corythoraptors also make use of their flocking behavior to ensure the safety of their eggs.
Parental Habits[]
“ A few days ago, females laid eggs on these circular mounds. But the job of brooding them falls to the males. And that is not easy. Exposed to the midday sun, the eggs would soon cook. But the fathers use their broad tail and fallen feathers to keep the nest shaded... and pay a heavy price, enduring hour after hour in the searing heat. ”
Corythoraptor is an oviraptorosaur, a family of theropod dinosaurs that were mistakenly named "egg thieves" because the type species, Oviraptor philoceratops, was found atop what was assumed to be a Protoceratops nest, only for the eggs to turn out to be its own, showing that the animal was not a stealer of eggs, but rather, a brooding parent that died (likely buried alive by a sandstorm) because it refused to abandon its nest. Following this, discoveries of several nests in Asia showed that oviraptorosaurs laid their eggs two at a time in a circle and covered them all evenly with their feathered arms and the rest of their body.[11] And based off of geochemical analysis, it appears that oviraptorosaurs incubated their eggs within the same temperature range as modern birds, around 35 - 40 degrees Celsius (95 - 104 degrees Fahrenheit).[12] Prehistoric Planet portrays the task of brooding being solely done by the males, though, much like modern birds, it is possible that the parents took turns during the day, or that the exact strategy varies between oviraptorosaur species.
“ At last, in the cool of the evening, the males can step away in search of food. This is where nesting in a colony brings benefits. Instead of all leaving at once, the Corythoraptors take turns, so there's always a neighbor keeping an eye out for danger. But even this neighborhood watch can't guarantee their safety. ”
In a further ironic twist, while the oviraptorosaurs are attentive parents as opposed to being the regular egg stealers popular culture stereotypically portrays them as (though they may have eaten eggs occasionally, it is unlikely their standard food), oviraptorosaurs themselves are known to be victims of true nest raiders, as indicated by the remains of the Chinese alvarezsaurid Qiupanykus being found with some oviraptorid eggshells.[13] Prehistoric Planet depicts this irony in the third segment of Badlands. During the night, when the sun no longer threatens the eggs, the male Corythoraptors can get off their nests, though, once again showing their grouping behavior and its advantages, they do not leave all at once, relying on a few of them staying behind to keep watch over the rest of the nests, and alert the others when an intruder, like the velociraptorine dromaeosaur Kuru kulla, is discovered, prompting the rest of the flock to run the intruder down and attack with their powerful crushing beaks and sharp claws. This means little, however, when the nest raider takes advantage of the Corythoraptors' poorer night vision and overall poorer senses to feed on a few eggs undetected, and is fast enough to get away with one last egg.
