Dreadnoughtus (named after the "dreadnoughts", massive, powerful battleships that dominated the early 20th century, which in turn have a name that means "Fears Nothing")[1] is a genus of titanosaurian sauropod dinosaur that lived in the Cerro Fortaleza Formation, Santa Cruz Province, southwest Argentina, 76 - 70 million years ago, from the Campanian to the Maastrichtian stage of the Late Cretaceous Period.
A male Dreadnoughtus showing off the air sacs on his neck to potential mates
Known from more complete skeletons compared to other massive titanosaurs, Dreadnoughtus stood at least 12 meters (40 feet) tall, spanned 26 meters (85 feet) long, based on the partial remains of two skeletons, with the holotype specimen, MPM-PV 1156, believed to have still been growing by the time of its death, despite already being larger than the other Dreadnoughtus fossil.[1][PhP 1] Initially estimated to weigh around 59.3 metric tons (65.4 short tons),[1] it is now believed to weigh approximately 40 - 50 metric tons (44.1 - 55 short tons).[2][PhP 1] In any case, while huge, Dreadnoughtus is far from being one of the largest sauropods; a slightly larger titanosaur, Puertasaurus (which is itself slightly smaller than Argentinosaurus), is known to live in the same formation as Dreadnoughtus.
A "bachelor herd" of male Dreadnoughtus, packing fat deposits above their hind legs for reserve energy, both for the journey and the arduous trials to come.
One peculiar feature the animal has is a ridge known as a "keel" on the underside of the first vertebra of its tail (among sauropods, only Bonatitan of the Allen Formation has a similar feature, positioned further back),[1] something that can be prominently seen on the show. Following a discussion with the BBC Natural History Unit, the experts of Prehistoric Planet have decided to portray this as the support structure of a fat reservoir,[DN 1][PhP 2] mirroring how big birds, lizards, and crocodiles store fat on top of their pelvis or by the base of their tail (the reptilian equivalent of camels accumulating fat in their back humps), with this being used up as a source of energy where and when food is scarce, which is usually the case in arid conditions like those of deserts. This reserve can also be metabolized for stressful, intense actions and events, like the prolonged defense of mating rights and overall dominance.
Old Dreadnoughtus bull rears up to warn and scare off a potential threat to his dominance
On Prehistoric Planet, both male and female Dreadnoughtus are depicted with a dull greyish-brown color and cream-colored undersides, providing them countershading (which many animals, predator and prey alike, use to enhance their camouflage), though, given their massive sizes, it is likely a design choice left over from their ancestors, or camouflage that helped them as juveniles, and simply stuck until adulthood, where their skin patterns may serve a role in individual identification and mate attraction.
Old Dreadnoughtus bull further intimidates his rival with his air sacs
“ The titanosaurs' immense necks are supported by an ultra-lightweight air-filled skeleton. Their hollow neck bones are connected to a series of bellows that inflate bizarre gular air sacs. Those males with the most impressive displays will attract the most females. ”
For males, portions of their neck and head are highlighted by vibrant patches of red (as opposed to the females, which have simpler gray patches on their heads), and, more notably, they possess inflatable orange air sacs on either side of their necks, impressive displays to intimidate rival males and attract females. Their bodies are bulky and layered with muscle and fat, in contrast with their relatively short legs. Each of their pillar-like front feet have a single dagger-like "thumb" claw, while their back feet are broad and turtle-like with three claws.
Two male Dreadnoughtus assess each other prior to battle
Dreadnoughtus is the main focus of the first segment of Deserts, showing a grueling duel between an old male and a younger challenger during the mating season. Footage of the species and other titanosaurs in the series is used in the Prehistoric Planet: Uncovered segment, "How Did Dinosaurs Get So Big?", which is dedicated to how dinosaurs grew bigger than most land animals in Earth's history. Footage of Dreadnoughtus is also briefly used for another Prehistoric Planet: Uncovered segment, "Were Dinosaurs Good Parents?", though it is only used there because, as a sauropod, it likely laid eggs the same way Isisaurus does, and is overall irrelevant to the topic of the segment since its sole appearance on the show was about the titanosaur's violent nature during the mating season, not parenthood.
Paleoecology[]
Paleoenvironment[]
Dreadnoughtus males visit the desert for their mating season
“ The west of South America, and one of the most desolate places on this Prehistoric Planet. Few animals venture here, yet it is the stage for one of the most extraordinary gatherings on Earth. ”
Dreadnoughtus lived 76 - 70 million years ago in the Cerro Fortaleza Formation, an area that would one day become part of the Santa Cruz Province of Argentina. During its time, the area would have been a fluvial region, with geological formations shaped by the action of rivers and streams. Dreadnoughtus normally resides in "rich forest feeding grounds".[PhP 1] For competition and display, however, they need large, open areas, and the nearby desert, just within walking distance (though a few miles away, the trip seems relatively short enough for the titanosaurs), is the perfect stage for these purposes.[DN 2]
Mating and Intimidation Display[]
Female Dreadnoughtus watch intently as the males display the air sacs on their necks, judging which ones are the most suitable to mate with
“ These are all males, and they're many miles from their rich forest feeding grounds. They come here for only one reason, to fight for the chance to mate. Crowds of females scrutinize the newly-arriving males, assessing their strength and suitability. ”
The exact behavior of Dreadnoughtus is unknown. However, they appear to have customs based on those of elephants, with a bachelor group of males traveling out to impress a group of females. It is unknown if these males regularly live in herds, or otherwise lead solitary lives past the mating season. They mostly rely on their gular air sacs to intimidate rival males and attract females, but should this fail, the males readily move on to physical blows.
Agonistic Behavior[]
The titanosaurs wrestle like monitor lizards
“ This huge bull, white with dust, has held the center stage for two weeks. He weighs nearly 50 tonnes. And his display has, so far, intimidated all challengers. But this newer rival... is not deterred. ”
The fighting style of Dreadnoughtus appears to be based on those of monitor lizards (which rear up and wrestle in an attempt to push their enemy back), giraffes (as shown by the neck swinging) and elephant seals (as shown by how the titanosaurs collide, push, and even attempt to bite each other during battle). The Dreadnoughtus were shown rearing up several times and even slowly walking on two legs (while leaning and pushing against an enemy) because, despite their size, titanosaurs were relatively agile due to features like wide hips to support and spread out their weight, strongly-muscled hind limbs, muscular tails robust enough to serve as a third leg when rearing up, front halves that are deceptively light due to being greatly pneumatized (with this pneumatization also serving another purpose in the show as justification for the orange air sacs used for display), and other such adaptations.[DN 3]
Duels are determined not just by the strength of the individuals, but also how long they can last before expending all their energy
“ Lifting up such a huge body is exhausting. It's a battle of endurance. As the conflict intensifies, each fighter tries to wound the other, stabbing with dagger-like spikes on each thumb, and raking the skin with their teeth. ”
The Dreadnoughtuses were also shown resorting to rougher methods the longer their battle goes, stabbing the enemy with their thumb claws and even attempting to bite each other, for most animals, even herbivores, would eventually resort to using their jaws in fights, even if their teeth and bite forces are not suited for doing so.
The old bull lies on the ground, exhausted and defeated, never to get up again
“ The old bull's rule is finally over. The young victor takes his turn on the center stage. The price of defeat, for some, is very high. ”
While most animals usually stop fighting and submit before they incur serious injuries, some battles with high stakes can motivate rivals to continue battling each other despite the risks, resulting in mortal wounds and fatal outcomes. As proven by musk oxen killing each other during the mating season,[3] as well as several cases of deer continuing to attack their long-dead rivals or getting their antlers stuck with each other (sometimes resulting in the deaths of both combatants),[4][5][6] animals are willing to use lethal force and risk their own lives in the process several times (regardless of whether they are aware of the risks or have their better judgment clouded by testosterone-fueled rage) just to emerge victorious in battles against their own kind. Hence, while not all titanosaur mating duels will reach the same extent as the Dreadnoughtus battle depicted in the first segment of Deserts (which resulted in the death of the older male), evidence and comparison with other animals suggest that, in more intense battles, they would have likely been willing to deliver and sustain grievous, life-threatening injuries in order to win, with any scars that remain serving as solid evidence of an individual's experience as a strong fighter and survivor, making them more intimidating to enemies (predators and rivals of the same species alike) and more attractive to members of the opposite sex.
Gallery[]
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Dreadnoughtus is the only sauropod in the series depicted with air sacs. Dr. Darren Naish, Prehistoric Planet's lead consultant, explained that it could be justified by the idea that none of the other sauropods on the show were closely related to Dreadnoughtus, and thus did not have anything resembling this specific feature that Dreadnoughtus may have inherited from its ancestors. He also revealed that the other sauropods were also supposed to have distinct inflatable structures, but these were toned down, reduced as the series was being made.[DN 4]
