Guest Factoid: Majungasaurus


Image Credit: Jaime A. Headden (User:Qilong), CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

John Michalski is a senior geology major at the University of Wisconsin, Milwaukee. He has been passionate about dinosaurs since he could walk and talk, and loves to discuss and educate others about paleontology and prehistoric life.


An age-old debate that has often sprung up among both professional paleontologists and paleo-enthusiasts is “were some theropod dinosaurs scavengers or active predators?” In truth, no obligate carnivore is purely one or the other (even vultures hunt despite being known for their scavenging habits). The reality for all meat-eaters, dinosaurs or otherwise, is that hunger must be satiated by any and all means. As an apt quote goes, “the tragedy is not to die, but to be wasted.” And in nature, no opportunity for a meal should be passed up, even if it means committing cold hard fratricide. In the Mesozoic era, on the island of Madagascar, one particular dinosaur’s infamy would be bolstered by such behavior recorded in its very bones. The carnivore in question? Majungasaurus crenatissiumus.

The first time I recall seeing this dinosaur was from the premiere episode of Jurassic Fight Club, as I’m sure was the case for many others. At the time, it was referred to by the now abandoned name Majungatholus. Ever since then however, the creature’s notoriety would skyrocket, becoming recognized as the “cannibal dinosaur” and (less frequently) the “Hannibal Lector of the Mesozoic.” But before we get into the macabre details of this dinosaur, some background should be in order.


o Majungasaurus was a medium sized majungasaurine abelisaur from the late Cretaceous of Madagascar. It’s history of discovery goes back all the way to 1895, when fragmentary remains were found in the Maevarano formation. First assigned to the genera Megalosaurus and Dryptosaurus, they were finally assigned to the genus Majungasaurus…only to then be termed Majungatholus atopus in 1979. Back then it was believed to have been a pachycephalosaur (think the dome headed dinosaurs), the very first to have been found in the southern hemisphere. It was in 1993, when the Mahajanga Basin Project was christened, that more material was found, allowing the name Majungasaurus to finally stick, and its place in the dinosaur family tree to be within the abelisaurs, a group of theropods chiefly known from the southern hemisphere.


o Current estimates place Majungasaurus at about 5 to 7 meters in length, and an estimated weight of about 1,100 kilograms. Its fossils have been dated to the late Maastrichtian stage (between 70 and 66 million years ago), right at very end of the age of the dinosaurs. It’s possible that Majungasaurus was among the very last dinosaurs and may have even bore witness to the meteorite’s fateful crashing upon Earth.


o While more famous dinosaurs such as Tyrannosaurus rex, Triceratops, and Ankylosaurus were roaming North America during this time, Majungasaurus lived with a stranger cast of characters. These included the sauropod Rapetosaurus (conventional long necked dinosaur) and the noasaurid Masiakasaurus (small theropod with some really funky teeth), as well as the bizarre carnivorous crocodyliform Mahajangasuchus (round snouted crocodile), the herbivorous chimaerasuchid Simosuchus (pug cross bred with a crocodile), and (no, I’m not making this up) the infamous “devil frog” Beelzebufo. Pretty sure the nickname explains that one.


o As an abelisaur, Majungasaurus was related to dinosaurs like Carnotaurus and Aucasaurus, and shared several important characteristics with them. First and foremost, its skull was short and broad, supported by a strong, robust neck. It has been suggested, though not completely proven, that abelisaurs hunted very differently from other theropod dinosaurs by biting and holding onto prey until it was sufficiently subdued. Powerful neck muscles would’ve allowed for abelisaurs like Majungasaurus to steady their heads against the torsion caused by struggling prey.


o This hunting strategy may have been crucial because like other abelisaurs, Majungasaurus’s arms were surprisingly small, and practically useless. Its humerus (upper arm bone) was short and curved, and its finger bones were fused together, making the hands totally immobile. This made the limbs essentially vestigial. Vestigial characteristics are features that linger on within an animal, but no longer serve any real purpose to the creature in question. Of course, a liver with some fava beans doesn’t necessarily need arms or hands to eat, but that nice chianti’s going to be a bit of a pain to open and drink from.


o An incredibly well-preserved vertebrae series from Majungasaurus has been used to suggest how this dinosaur may have breathed. Cavities found in the ribs and vertebrae, called pneumatic foramina, are thought to have resulted from both lungs and air-sacs similar to modern birds. This would’ve allowed for oxygen-rich air to be inhaled while never mixing with exhaled carbon dioxide, a kind of “flow-through ventilation” type of respiration. For an apex predator such as Majungasaurus, this may have been very efficient while on the move. On a broader note, the presence of these air-sacs in both Majungasaurus and other non-related dinosaurs provides further evidence in their relation to modern day birds.


Now, about its…erm…very interesting recreational activities.


o The first evidence of cannibalism from Majungasaurus came from discoveries published in 2007. Numerous bones of one individual had bite marks identical to those found on sauropod bones from the same localities. There appeared to be no signs of healing, implying that the dinosaur either sustained fatal injuries, was being eaten, or both. These marks did not line up with the teeth of Masiakasaurus, nor Mahajangasuchus. But they were consistent with the spacing, size, and serrations of Majungasaurus teeth. The conclusion was clear: Majungasaurus was a cannibal!


Or at least the first confirmed case of dinosaur cannibalism. While by no means an insignificant find, the truth is that cannibalism among carnivores is not uncommon. Komodo Dragons, Burying Beetles, and even Chimpanzees have been documented as cannibals in the present day. And while evidence of dinosaur cannibalism is rare, it is not exclusive to Majungasaurus. Similarly, unhealed bite marks on bones belonging to Allosaurus and Tyrannosaurus rex that match up with teeth of their own kind, supports the case for cannibalism among other theropod dinosaurs.

But in Majungasaurus’s case, there may have been environmental factors that encouraged cannibalism among its kin. The Maevarano formation has been interpreted as having been a semi-arid ecology, and prone to spells of harsh drought. In such conditions, practically anything that moved, including fellow Majungasaurus, would’ve been possible prey. Of course, it is always possible that one hungry Majungasaurus stumbled across the corpse of one of its own, and decided to satisfy its hunger that way.

Whatever the case may have been, the discovery of cannibalism in Majungasaurus remains an important find in understanding the lives of dinosaurs, and the success of theropods as a family. It serves as a testament to their tenacity and endurance against mother nature, able to exploit any and all opportunities to survive in a world where your next meal is never guaranteed. If nothing else, they indicate that such scars have the power to remind us that the past was very real.


P.S. As for the occasional Hannibal Lecter comparison I’ve seen here and there? Personally, I’d happily pay a fair sum to see Anthony Hopkins or Mads Mikkelsen voice a Majungasaurus in a movie or show of some kind. Both are great actors in their own rights, and excellent Hannibal Lectors in their respective programs. Might not happen in the near future, but one can certainly dream.


References:

Agnolin, F.L., Chiarelli, P. The position of the claws in Noasauridae (Dinosauria: Abelisauroidea) and its implications for abelisauroid manus evolution. Paläontol Z 84, 293–300 (2010). https://doi.org/10.1007/s12542-009-0044-2

Bartlett, J. (1987). Filial cannibalism in burying beetles. Behavioral Ecology and Sociobiology, 21(3), 179-183.


Bygott, J. D. (1972). Cannibalism among wild chimpanzees. Nature, 238(5364), 410-411.


D'Amore, D. C., & Blumenschine, R. J. (2009). Komodo monitor (Varanus komodoensis) feeding behavior and dental function reflected through tooth marks on bone surfaces, and the application to ziphodont paleobiology. Paleobiology, 35(4), 525-552.


Drumheller, S. K., McHugh, J. B., Kane, M., Riedel, A., & D’Amore, D. C. (2020). High frequencies of theropod bite marks provide evidence for feeding, scavenging, and possible cannibalism in a stressed Late Jurassic ecosystem. Plos one, 15(5), e0233115.


Krause, D. W., Sampson, S. D., Carrano, M. T., & O'Connor, P. M. (2007). Overview of the history of discovery, taxonomy, phylogeny, and biogeography of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology, 27(S2), 1-20.


Longrich, N. R., Horner, J. R., Erickson, G. M., & Currie, P. J. (2010). Cannibalism in Tyrannosaurus rex. PLoS One, 5(10), e13419.


O'Connor, P. M., & Claessens, L. P. (2005). Basic avian pulmonary design and flow-through ventilation in non-avian theropod dinosaurs. Nature, 436(7048), 253-256.


Rogers, R. R., Krause, D. W., Rogers, K. C., Rasoamiaramanana, A. H., & Rahantarisoa, L. (2007). Paleoenvironment and paleoecology of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology, 27(S2), 21-31.

Sampson, S. D., & Witmer, L. M. (2007). Craniofacial anatomy of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the late Cretaceous of Madagascar. Journal of Vertebrate Paleontology, 27(S2), 32-104.


Rogers, R. R., Krause, D. W., & Rogers, K. C. (2003). Cannibalism in the Madagascan dinosaur Majungatholus atopus. Nature, 422(6931), 515-518.

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