Present on Prehistoric Planet is an unnamed azhdarchid pterosaur that lived in the Nemegt Formation of the Ömnögovi Province, an area in the northwest region of the Gobi Desert in southern Mongolia, 70 million years ago, during the Maastrichtian stage of the Late Cretaceous Period. It is sometimes referred to as the "Gurilin Tsav pterosaur" after the locality it was found in, "Gurilin Tsav" (sometimes spelled as "Guriliin Tsav" or "Gurlin Tsav"),[1] or the "Mongol Giant", though usage of the latter term is discouraged due to its derogatory connotations in the modern day.[3]
“ One of the most interesting - because they are the most bizarre - are the azhdarchid pterosaurs, and to try and describe what an azhdarchid pterosaur is like is very difficult. They stand as tall as giraffes, they've got heads that may have been 2 meters long, wingspans of 10 meters... they're just some of the most bizarre things to have ever evolved on Earth. ”
― Dr. Mark Witton, Paleoartist & Paleontologist
Much like Phosphatodraco from Morocco, this pterosaur, still unnamed as of 2025, is only known from a few neck vertebrae. But from these fragmentary remains, it is believed that the Mongolian azhdarchid is one of the largest pterosaurs known. Comparison of its fossils with those of other azhdarchids imply that it may have been like Hatzegopteryx in terms of proportion, with a wingspan of 10 - 12 meters (33 - 40 feet), as well as a shorter but stockier neck than other azhdarchids.[1][2] Furthermore, assuming that they are indeed similar, then the Mongolian azhdarchid perhaps also had Hatzegopteryx's short but stout, blunt beak as opposed to the slender, spear-like beak seen in other azhdarchids like Quetzalcoatlus, an adaptation that allows stocky azhdarchids to bash prey too big to swallow whole, and thus attack animals that their sleeker relatives would not normally target.[MWDN 1]
Even with these few details known about the animal, Prehistoric Planet does not give the Mongolian azhdarchid an appearance more like the robust physique of Hatzegopteryx, but rather the exact same model as the thin, slender Quetzalcoatlus, down to the tan and bluish-gray pycnofiber coat, though this is mostly obscured and cleverly masked by zoomed-out shots, unclear viewing angles (like shots from within a sauropod carcass), and brief screentime. The newly-hatched azhdarchids shown in the first segment of Swamps (assuming that they are indeed the juveniles of this species) are confirmed to be also based on Quetzalcoatlus.[DN 1]
The Mongolian azhdarchid first appears in the second segment of Deserts, where several of them wait for a pack of Tarbosaurus to leave a sauropod carcass before scavenging it. Some later appear in the fourth segment of the episode, congregating around a temporary oasis along with many other animals. What appears to be their juveniles appear in the first segment of Freshwater, where a trio of Velociraptors sneakily infiltrate their cliffside waterfall stronghold to ambush some of them for a meal. The Mongolian azhdarchid briefly appears by the end of the fourth segment of Badlands, quickly passing over a canyon, while the juveniles reappear in the first segment of Swamps, where several hatchlings fly out of the swamp islands of the Songliao Basin,[PhP 1] away from the Shamosuchus-infested waters and to the forests where they can hide and hunt for food as they grow. The juveniles also make cameo appearances in two Prehistoric Planet: Uncovered segments, "Could Giant Pterosaurs Really Hunt on the Ground?" and "What Else Lived Alongside The Dinosaurs?".
“ For millions of years, the lands of the planet Earth have been carved by water, and the rivers that flow here are still shaping these great canyons. Such places are the home of flying reptiles. Pterosaurs. ”
The Ömnögovi is the largest aimag (province) of Mongolia, found in the south of the country, in the northeast portion of the Gobi Desert. Within this aimag is an area called the Nemegt Basin, known locally as the "Valley of Dragons" due to its rich fossil content. It encompasses three formations showing the states the area underwent throughout the Late Cretaceous, namely, the Djadochta (75 - 71 million years old), Barun Goyot (72 - 71 million years old), and Nemegt (70 million years old) Formations. The Gurilin Tsav azhdarchid lived in the last of the three formations, which showed evidence of a rich, humid environment with large river channels, tidal flats, and forests. However, the Nemegt Formation is also known to have undergone periodic droughts, and there is precedence for arid regions much like the Gobi Desert today existing in Mongolia during those times, thus justifying the depiction of this pterosaur living in or at least traveling through a vast desert environment.
The Songliao Basin in northeast China
“ The vast swamplands of northeast Asia. Within this low-lying, flooded territory, there are countless islands. Each of them is surrounded by slow-moving waters. And that makes them potential sanctuaries for new life. ”
Much like Alcione and Quetzalcoatlus, this Mongolian azhdarchid appears to prefer damp environments to cover their leathery eggs, as implied in the first segment of Swamps, where juvenile azhdarchids are found in islands within the swamplands of the obscure lacustrine Songliao Basin of China,[PhP 1] where they are faced with a challenge, the need to leave this sanctuary to feed within the forests beyond their hatching grounds. While it is not confirmed to be the case by fossils, the presence of this species in China (assuming that the pterosaurs in the first segment of first segment of Swamps are indeed young Mongolian azhdarchids) is not too far-fetched given the relatively short distance between China and Mongolia, and overall knowledge regarding this still-unnamed animal is poor to begin with.
Hunting Tactics and Feeding Preferences[]
“ Pterosaurs would have been an awe-inspiring sight in the sky, but these giants were even more impressive and terrifying on the ground. ”
As discussed in the Uncovered segment "Could Giant Pterosaurs Really Hunt on the Ground?", azhdarchids were not agile enough to pursue airborne prey, and their necks were not strong enough to withstand the stresses of skim-feeding like various fishing birds. For these reasons, azhdarchids were likely terrestrial hunters, with preserved azhdarchid footprints supporting the fact that they were competent enough to walk on all fours. Hence, while their flight capabilities allowed them to survey great distances and search for prey from above, once azhdarchids have found viable targets, they likely preferred to stalk and pursue their prey on the ground.[MWDN 1]
Mongolian Azhdarchids come down to feed on a sauropod carcass
“ The Tarbosaurs move on. And now the pterosaurs can come down and claim a share of the carcass. ”
Like most azhdarchids, the Mongolian pterosaurs were shown to be opportunistic carnivores. When live prey is hard to come by, they are shown here patiently waiting for a carcass to be left to them, for scavenging an already-dead animal requires less effort than hunting. Due to sharing the region with Tarbosaurus, the Mongolian azhdarchids exhibit a degree of caution in the presence of the large tyrannosaurs, wisely keeping their distance while a group of Tarbosauruses are guarding a rotting sauropod, only coming down to feed when the tyrannosaurs have left.
Parental Habits and Juvenile Lifestyle[]
“ A young pterosaur. An azhdarchid just a few hours old. Being on an island means that she's able to take her first tentative steps in safety. Having found her feet, it's time to try out her wings. Getting them to work properly will take some practice. ”
Pterosaurs are believed to lay leathery, soft-shelled eggs like lizards rather than hard-shelled eggs like birds.[4][5] Hence, it is believed that, much like crocodiles and turtles, they buried their eggs (preferably in damp soil, as the Quetzalcoatlus did in the fourth segment of Freshwater, to ensure they didn't dry out). While this allowed for weight-saving adaptations, it limited pterosaurs to laying eggs in specific environments and conditions.
“ Although she's only one foot-tall, she will grow into a giant with a 30-foot wingspan, and to do that will require plenty of food, something this tiny island can't provide. She will have to leave, to feed in the swampy forests that surround her island. ”
These nesting preferences - along with the problems that come with being limited to these choices - are made clear in the first segment of Swamps, where newborn juvenile azhdarchids are found on tiny islands in vast swamplands that served as an ideal nesting ground for the adults. While they were safe within these islands, they needed to leave for the forests past the swamp in order to find sustenance. While traversing the gap between their isolated place of birth and the forests, some proved to be too weak to maintain flight at a decent height, and this can lead to some plummeting to the swamp and getting eaten by predators like Shamosuchus, in line with the process of natural selection, as only those fit - and, to an extent, lucky - enough to fly all the way to their destination get to survive just long enough to prepare for the trials of life still ahead of them.
“ Their wings of skin stretch from finger to ankle. And they can fly for hundreds of miles in a day. ”
A majority of modern-day flying vertebrates are incapable of flight early on in life. Most birds, depending on the species, must be around 10 days to 12 weeks old before being capable of flight. There are, however, exceptions, like megapodes and other galliform birds, which are capable of flight in a few days, or even on the very day they hatch. In a 2021 study by Dr. Darren Naish, Dr. Mark Witton, and Dr. Elizabeth Martin‑Silverstone (all three being involved in the making of Prehistoric Planet, with Dr. Naish serving as the show's lead consultant), pterosaurs are superprecocial, capable of extreme locomotor movements (including flight) shortly after hatching. By wing area to mass ratio, juvenile pterosaurs can out-glide living volant animals, and their wings are more suited for active, sustained flight as opposed to short-distance gliding. Additionally, the humeri (upper arm bones) of juvenile pterosaurs are also thick and robust in proportion to their length, allowing them to withstand great stress and further supporting the idea that they engaged in active flapping early on.[MWDN 2]
“ Each evening, they come to this canyon in huge numbers, to roost on its narrow ledges. There is safety in numbers, and anyway, few land-living hunters venture here... but one does. ”
Several species on Prehistoric Planet are portrayed as being similar to animals today in that even closely-related members of the same clade varied in lifestyle. Pterosaurs were no different, as the variation in their fossil record suggests that there was no single "universal" pterosaur parenting strategy.[MWDN 2] In the first segment of Coasts, the Tethydraco are shown nesting in colonies, taking care of their young on the beaches of Morocco, while young Alcione are more independent, simply left to hatch on an offshore island, a sanctuary they must leave, risking predation and other dangers in order to find food and a more suitable habitat. The Mongolian azhdarchids are shown more like the latter, with the young left to fend for themselves on a temporary sanctuary surrounded by opportunistic hunters. Overall, the show portrays the Mongolian azhdarchid as an r-selected species, an animal that spawns many offspring, and thus does not provide extensive parental care, since most of the juveniles are not expected to reach adulthood, with many dying while many more survive to bring forth the next generation.
