“ Without water, no animal can survive. Yet, this is home to these young Tarchia. They are desert-living ankylosaurs, heavily-armored, with huge, clubbed tails. ”
Tarchia (Brainy One) is a genus of ankylosaurid dinosaur that lived in the Barun Goyot and Nemegt Formations of the Ömnögovi Province, an area in the northwest region of the Gobi Desert in southern Mongolia, 75 - 70 million years ago, from the Campanian to the Maastrichtian stage of the Late Cretaceous Period.
The species that was depicted on Prehistoric Planet could be any of the two species which lived in the Nemegt Formation (T. teresae and T. tumanovae), for the Nemegt Formation is the likely setting of the segments the species appears in (the type species, T. kielanae, lived in the earlier Barun Goyot Formation, and also possesses some differences in skull features).
“ In the end, the Prenocephale are little more than annoying. But an adult Tarchia is another matter, especially one almost twice the youngster's weight. It wields a club weighing almost 50 pounds. ”
A large ankylosaur around 5.8 - 6.7 meters (19 - 22 feet) long and 2.5 - 3 metric tons (2.8 - 3.3 short tons) in total body mass,[1][2]Tarchia is depicted with the standard ankylosaur body, heavily-armored with osteoderms set in thick skin and equipped with a massive tail club, useful for fighting off predators and each other, with evidence being seen on one Tarchia specimen with pelvic and tail injuries as well as an asymmetrically-shaped club, likely worn down by several strikes.[4] On Prehistoric Planet, traces of this can be seen on the adult Tarchia, which has the tip of one of the spikes on his back chipped off, likely due to having gotten involved in such conflict previously. This also serves as proof of his experience, which is crucial for him to know when to press his advantage, and when to call off a fight. This was why he was willing to intimidate and take on a juvenile that trespassed into his domain, and wisely retreated when another juvenile Tarchia came, doubling the threat of getting clobbered by tail clubs.
Ankylosaurid tails, stiffened by bony rods and swung by powerful muscles, can strike with enough force to destroy a car.
“ It's very stiff, it's stiffened by lots of bony rods that run along the length of the tail that would have a lot of force behind it when it was swung from side to side. Some paleontologists have calculated that it could be swung with enough force to devastate a car. ”
― Professor Paul Barrett, Natural History Museum
In 2009, a study about the impact forces of ankylosaur tail clubs was published. The species involved in the paper include Anodontosaurus lambei (with one of the specimens used in the study, AMNH 5245, considered to be a Euoplocephalus by that time), approximately 4 - 5 meters (13 - 16 feet) in length and 2 metric tons (2.2 short tons) in mass,[1][2][PhP 2] and Dyoplosaurus acutosquameus, measuring around 4 - 4.5 meters (13 - 15 feet) in length and 1.2 metric tons (1.32 short tons) in mass.[1][2] Composites of their tail clubs are estimated to weigh around 17 - 20 kilograms (37.5 - 44.1 pounds). Given this mass, the average ankylosaurid club is capable of delivering a bone-shattering impact force of 7,281 - 14,360 newtons or 742 - 1,464 kilograms (1,636 - 3,228 pounds), and an impact stress of 36,400 – 71,810 newtons (3,712 - 7,323 kilograms) per square centimeter (52,800 - 104,152 pounds per square inch), or 364 - 718 megapascals.[3]Tarchia is bigger than either of the two aforementioned ankylosaurs, and, with a tail club that can weigh around 23 kilograms (50 pounds),[PhP 1] it can likely strike with a force that exceeds the calculated results of the study. Even so, the paper clarifies that these tail clubs would not have been hard for the ankylosaurids to wield. The knobs that compose a tail club are predominantly cancellous (spongy and porous bone), and, while the tails have limited vertical flexibility, they can be swung approximately 100 degrees horizontally.[3] This is demonstrated in the fourth segment of Badlands, where the Tarchia have to put slightly more effort in brandishing their tail clubs up and down, but need less windup when swinging their tails from side to side, during which their weapons can be moved with a wider range of freedom.
Desert Life Adaptations[]
The large nose of a Tarchia helps the animal conserve water by condensing their breath with every exhale
“ Dark patches protect the Tarchias' eyes from the glaring sun. And this is the sound of Tarchia's very own air-conditioning system. Their large nose cools the air as it leaves the body, condensing - and so conserving - valuable water with every breath. It allows them to survive long periods without drinking as they search for a meal. ”
Despite all their defensive features, given how these ankylosaurs live in the desert, which could be the biggest enemy of all creatures within it, all this heavy armor isn't enough, hence why they are also shown with adaptations to survive intense heat. It is not really known if Tarchia is a desert specialist, but it is nevertheless depicted with proper adaptations for a lifestyle in such a hostile environment, hence, it is portrayed with dark and pale markings distributed all over its body, fit for constant exposure to high amounts of ultraviolet rays, walking on rocky, rugged terrain, and moisture conservation. One key to its survival is its large, unusually complex nose, considered as "Tarchia's very own air-conditioning system", meant to conserve the water they have whenever they breathe. In the series, it is speculatively portrayed with a convex, shield-like covering with an overhanging scute roof that surrounded the massive bony nostrils, which had mobile edges that can be sealed by a shutter-like flap if needed. This is based on the muscular, mobile nostrils of crocodylians, a feature given to other dinosaurs in the series (though Dr. Darren Naish regretted this choice, as it is likely not the case for most dinosaurs).[DN 1] As for the internal features of its head, Tarchia got its name, "brainy one", since, given how large the base of its skull is, it is presumed to have a larger brain than Saichania, a closely-related ankylosaur that lived in the same area and time, with this difference in brain size believed to be one way to distinguish both ankylosaurs from one another.
As a desert-dwelling species, Tarchia needed all the nutrition it can get. Hence, Prehistoric Planet portrays them subsisting on even low-quality plants in the desert, and, as indicated by the animal's muzzle, broad and rectangular, it engaged in bulk feeding, consuming all that it can.[4]Tarchia also likely relied on hindgut fermentation, primarily processing food in its stomach rather than the mouth (so it may have preferred to feed on succulent plants that do not require complex chewing), and the microwear pits marking its teeth imply that it had to deal with more grit compared to ankylosaurs that lived in tropical environments since it lived in the desert.[5]
Growth[]
An adult Tarchia (left) confronting a juvenile around half his size
The growth cycle of Tarchia is unknown. However, based on Pinacosaurus, an earlier ankylosaur from Mongolia and China, Tarchia may have grown to at least 60% of their adult size without reaching sexual maturity yet. An adult Pinacosaurus is around 5 meters (16 feet) in length, while the holotype specimen is only 3 meters (10 feet) long, still considered a juvenile due to some bones either being fewer in number or still being fused (four of their rear dorsal vertebrae are fused into a "sacral rod").[6] As they grew, the forelimbs of juvenile ankylosaurs become more robust, while their hindlimbs do not become significantly larger relative to the rest of the body.[7] The process of ossification (the formation of bone, as well as the conversion of some preexisting parts into bone) then proceeds from the snout and the neck all the way down to the tail.[8]
On the show, the two juvenile Tarchia are about half the size of the adult they encounter, but they proved themselves to be large and strong enough to intimidate small animals like Prenocephale and, together, even threaten an adult Tarchia, which, having recognized their chances of beating him, promptly backed away from them.
“ Trudging through a scorching desert, two young Tarchia find relief at an oasis and encounter an adult twice their size, ready to lay claim. ”
― The official Apple TV+ episode synopsis for Badlands
Prehistoric Planet depicts Tarchia as being mostly brown, very much like the usual coloring associated with ankylosaurs. This dark coloration is explained on the show as a means of protecting them from the heat of the desert sun. Their armor also comes in the form of prominent spines rather than simple pebbly knobs and studs. According to Dr. Darren Naish, Prehistoric Planet's lead consultant, it was not easy to reconstruct Tarchia because of scarce information regarding it, like the variation between species (hence, it currently cannot be determined if the species shown on Prehistoric Planet is T. teresae or T. tumanovae), or its skull armor. It is unknown if the show's depiction of Tarchia had the correct anatomical details, for although several ankylosaurids found in the Gobi Desert had such features, it cannot be confirmed if Tarchia had the same specific traits. Even so, Dr. Darren Naish initially designed Tarchia based on its possible behavioral and ecological aspects, with the reconstruction then greatly improved by Gabriel N. Ugueto.[DN 2] Because of the standard barrel-shaped body of ankylosaurids, it proved challenging to properly portray Tarchia's gait, as its great width made it difficult to position its legs and feet in accordance with what is known of ankylosaur tracks.[DN 3]
A few Tarchia briefly appear among the numerous animals that visit the temporary oasis in the fourth segment of Deserts. Individuals of this species ended up becoming the main characters of the fourth segment of Badlands, where two young Tarchia journey through the desert and find a small spring in a canyon, running afoul of the canyon's residents, a group of seven Prenocephale and an adult Tarchia twice their size. Tarchia and other club-tailed ankylosaurids also serve as the focus of the Prehistoric Planet: Uncovered segment "How Did Ankylosaurs Use Their Tail?", where it is determined that ankylosaurs used their clubs not only for defense, but also intraspecific combat, with research regarding the ankylosaur Zuul crurivastator being one likely support for the information brought up during that segment.[9] Stock footage of the Mongolian Titan from the fourth segment of Deserts (featuring Tarchia and some of the sauropod's other contemporaries) is also used near the end of the Uncovered segment "How Did Dinosaurs Get So Big?"
A pair of juvenile Tarchia traveling through the Mongolian badlands in search of water
“ The high temperatures here create scouring winds which carve the rocks into extraordinary shapes. But they also strip the ground of soil. Some plants, however, manage to take root in cracks between the rocks. Any meager mouthful is worth competing for. ”
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. Tarchia is known from the latter two formations.
The Barun Goyot Formation showed that, 72 - 71 million years ago, the Gobi Desert was an area of sparse vegetation, sand dunes, and rocks heavily eroded by strong winds. Even so, small, intermittent lakes and seasonal streams can still form in this desolate region. Two million years later, during the time of later Tarchia species, T. teresae and T. tumanovae, the area became an overall more hospitable area, for, based on evidence preserved in the Nemegt Formation, the desert was replaced by a rich, humid environment with large river channels, tidal flats, and forests.
Even so, 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, with the only compensation coming in the form of oases, as seen in the fourth segment of Deserts when a few Tarchia and other animals visit a temporary oasis. This is also shown on the fourth segment of Badlands, when the juvenile Tarchia came across a small spring within a canyon in the middle of the desert.
Paleofauna[]
A juvenile Tarchia arrives to drink from an oasis, to the dismay of seven Prenocephale
Ankylosaurs are believed to have evolved their armor because they are too large to run or hide (though some, like the Early Cretaceous nodosaurid Borealopelta, still had countershaded skin for camouflage),[10][11] yet too small to deter predators the same way sauropods do.[12] Given its size and defenses, an adult Tarchia would have likely never been bothered by small predators like the velociraptorine dromaeosaurs in the Nemegt Formation, the large troodontid Zanabazar, or the sleek tyrannosaur Alioramus, which would have more likely gone after smaller, faster prey.
Despite its armor and bone-shattering tail club able to keep it safe from most hunters, Tarchia was not immune from predation. A Tarchia skull was found with the tooth marks of the tyrannosaurid Tarbosaurus, the apex predator of the Nemegt Formation.[13][14] While it is possible that this was the result of scavenging, it is likely that the tyrannosaur used its bone-crushing bite force in an attempt to kill the ankylosaur.
Navigation[]
A juvenile Tarchia entering a canyon with an oasis
“ Like many nomads, the Tarchia have a mental map of the desert, and can travel across empty landscapes with unerring accuracy. They remember the rare places where there are natural springs. Desert oases, like this one. A life-saver for animals that can find them. ”
As with Prehistoric Planet's depiction of Secernosaurus, Tarchia are portrayed as being able to make their way through the desert via some means. In this case, the juveniles either remember the location of the spring due to a prior memory (indicating that, even as young animals, they are already well-traveled), or are simply able to sense where oases are based on telltale signs of places that can likely have water, like the presence of plants, presence of other animals, or the area itself simply looking like it could retain or even hide water better than others, like an isolated canyon.
Social Behavior[]
In a battle against a juvenile half his mass, the adult Tarchia (left) has the edge, but he is unaware of another youngster coming in to help challenge him
“ If this comes to a fight, the juvenile can't win... but reinforcements are on the way. ”
Generally, adult ankylosaurs are found alone, supporting the idea that they are solitary animals. But occasionally, discoveries are made indicating that at least some species lived gregariously at some point in their lives. Mass death assemblages, bone beds of many animals that died together (usually due to disastrous events like flash floods or failed river crossings) help show an animal's social capabilities if many members of the same species are found on the site. Such cases are well-documented for hadrosaurs, ceratopsians, and sauropods. For ankylosaurs, at least six mass death assemblages are known,[15] with examples involving Gastonia lorriemcwhinneyae of the Cedar Mountain Formation,[16] and three types of nodosaurids (six Hungarosaurus, two Struthiosaurus, and four skeletal remains belonging to indeterminate species) in the Santonian Iharkút vertebrate locality of western Hungary.[17]
A pair of juvenile Tarchia drinking from a small oasis, while some Prenocephale watch them from a distance
Most relevant to Tarchia are the numerous mass-burial sites of Pinacosaurus, an ankylosaurid that lived in Mongolia and China 75 - 71 million years ago, during the Campanian stage of the Late Cretaceous Period. In the Bayan Mandahu Formation of China, several Pinacosaurus are believed to have been buried alive by a sandstorm, with no sign of adults or very young individuals (the smallest ankylosaur in the mass death assemblage is about a meter, or three feet and four inches, in length). And for several years, many juvenile Pinacosaurus (numbering around 30 or more) have been found in close proximity with each other in the Alagteeg Formation of Mongolia, with the individuals believed to have been deposited by a flood, for the site is believed to be a floodplain with braided rivers based on the mudstone beds of the mass-burial sites. In every major locality around the same age as the Djadochta Formation in Mongolia (except for Tögrögiin Shiree), several Pinacosaurus mass-burial sites have been found, strongly supporting the idea that the juveniles of their species were constantly engaging in clustering behavior rather than only gathering together due to certain occasions or unfavorable circumstances.[18]
A pair of juvenile Tarchia standing together against an adult
These mass death assemblages may imply that ankylosaurs may have lived in groups as juveniles, but eventually split up and lived solitary lives as adults, which are more capable of fending for themselves alone. In the fourth segment of Badlands, only two young Tarchia are portrayed traveling together, and, while they occasionally compete for resources like food (showing the disadvantage of herding behavior), in the end, their companionship allowed them to successfully threaten a lone adult Tarchia twice their size, together negating the advantages that the older ankylosaur posed over either of them. This strategy of youngsters traveling together independent of adult care was also demonstrated by various animals depicted throughout the series, from Alcione, Antarctopelta, and Therizinosaurus, to Zalmoxes, Isisaurus, and Nostoceras. Even so, it is possible that, like most dinosaurs, they still maintained connections of sorts even when fully grown.[DN 4]
Tarchia and several other Nemegt Formation animals that normally do not live with each other gather together by a temporary waterhole
However, mass death assemblages do not entirely confirm that the animals involved were social. The numerous Pinacosaurus bone beds, for example, still cannot be considered full, incontrovertible proof that they engage in true herding behavior despite their consistent presence strongly supporting the idea.[18] The alternate theory is that unfavorable circumstances can force even animals with poor social capabilities to come together - and, consequently, die or at least be deposited together - in one place, giving off the illusion of herding behavior. Sudden catastrophes like floods, sandstorms, or forest fires could coerce several solitary individuals to travel in the same direction, and prolonged times of hardship like droughts can cause gregarious and non-gregarious animals alike to meet and linger by precious resources.[15] This is demonstrated in the fourth segment of Deserts, where several animals are seen gathering near a temporary waterhole. There are groups of creatures that were depicted on the show as being social during adulthood, like Barsboldia, Nemegtosaurus, azhdarchids, and massive titanosaurs. However, also present were groups of animals that were otherwise shown to live alone as adults in other segments throughout the series, like Tarchia and Mononykus, as well as solitary adult Therizinosaurus.
A Tarbosaurus drinks from an oasis in the Nemegt Formation, alone and undisturbed by the other animals present
To further support the point, a solitary Tarbosaurus also visits the waterhole in that segment. More peculiar than its logical avoidance of unnecessary conflict (though the other animals wisely keep their distance from the tyrannosaur) is the fact that it is alone, even though the second segment of Deserts and the second segment of Badlands depicts it as a pack hunter. Several explanations can be assumed from this; the Tarbosaurus may have simply temporarily wandered away from its pack (possibly as a scout, or one hunting for the sake of a mate, chicks, or other members of the pack), it may be alone due to sex, season, or age-related factors (none of the individual Tarbosaurus in the series have had their sexes or ages confirmed), or the individual itself chose this peculiar lifestyle in contrast with how the others of its kind lived. Based on this, if individuals of the same species may live in different ways, it is even more reasonable to believe that members of different species (closely related or otherwise) had different social lifestyles, the same way that lions today live in prides while other big cats are mostly solitary outside of certain circumstances like mating and cub-raising, a concept seen among many of the animals on Prehistoric Planet, even ones closely related to each other. The 2021 study that discusses ankylosaur social lifestyles concludes that this likelihood of variation in their social capabilities supports how diverse ankylosaurs can be, with each species socializing to the degree that they deem necessary, all surviving and thriving despite their differences in gregariousness.[15]
Given all this, it remains to be confirmed what sort of lifestyle Tarchia had in terms of intraspecific social interaction. But given its depiction on Prehistoric Planet, it is likely that its social habits were based on that of its Campanian predecessor Pinacosaurus, with the juveniles traveling together to cover up their individual vulnerabilities, while the more capable adults mostly live independently, competing with others of their kind over various reasons (like food, mates, and territory) when they cross paths, except in cases when resources are more plentiful and therefore easier to share.
Competitive Habits and Agonistic Behavior[]
A juvenile Tarchia gets into an altercation with some Prenocephale
“ Tensions often run high around an oasis. But a display of strength can prevent a dangerous battle. ”
Given how resources are limited in the desert, animals may be justifiably greedy and competitive over resources. In the fourth segment of Badlands, one Tarchia refused to share a patch of vegetation with his companion, shoving him away when he tried to get close. Following this, the other juvenile Tarchia intimidated a group of Prenocephale into leaving him alone and letting him have the oasis to himself by slamming his club down on the ground. This story, an idea by Dom Walter, the segment's producer, initially had the Prenocephale try to defend their secluded valley "spa" more aggressively than they did in the final version.[DN 5]
An adult Tarchia (bottom left) reconsiders his chances of winning against two juveniles, each one half his size
“ In theory, ankylosaur tails would have been able to break the legs of predators. But it's possible that they were also using their tail clubs for fighting a rival for a mate, or to be the leader of the pack. ”
― Dr. Susannah Maidment, Natural History Museum
Upon encountering an adult Tarchia almost twice his mass, both the juvenile and the adult fight over the oasis, even though the younger individual is clearly outmatched, though this changed when the other juvenile Tarchia came in, and together, both intimidated the adult into letting them also have a share of the oasis.
Gallery[]
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↑Gallagher W.B., Tumanova T.A., Dodson P., Axel L., 1998, "CT scanning Asian ankylosaurs: paleopathology in a Tarchia skull", Journal of Vertebrate Paleontology18: 44A-45A
