Mortal combat in the Mesozoic 1

Which dinosaur would win in a fight?

Which dinosaur would win a fight? This is the most common question I get as a paleontologist, particularly from younger paleontology enthusiasts. Although this seems like a simple question, giving it a scientific answer is going to require some digging (forgive the paleontology pun). For clarification, I should note that this article will deal strictly with non-avian, that is, the non-bird dinosaurs. Yes, all birds are dinosaurs, but not all dinosaurs are birds. So far, I have only been asked about fights between the non-avian variety. If I ever get asked about fights between, say, a pigeon and a chicken, I will need to hit the books again (my money is on the chicken). The question of combat between dinosaurs is extremely difficult to answer, as the fossil record rarely preserves behavior. Much of what you see of dinosaur behavior in movies and documentaries are educated guesses, based on the behavior of living animals and, increasingly, biomechanical studies of dinosaurs based on computer reconstructions. For the majority of dinosaurs, we can’t say for certain if the animals fought or even interacted on a regular basis. Remember that a fossil deposit represents rock accumulated over centuries or sometimes even millions of years. Two animals found in the same deposit may never have crossed paths! Consider my home state of rural Michigan, where the bones of recent farm animals, like horses, sheep, and chickens, can get mixed in with the fossilized bones of woolly mammoths. Just because you find two bones in the same layer of rock or dirt does not mean that they lived at the same time or ever interacted. A further challenge is that even animals that live in the same time interval may never interact. 200 million years from now whatever intelligent life form has taken over for humans might ask: “who would win in a fight, a horse or a blue jay?”. This is a nonsensical question for us today, but with information filtered by hundreds of millions of years of time and the ravages of Earth history, it might seem that blue jays and horses interacted in a meaningful way. Deep time has a way of destroying information and context, making it difficult to ask meaningful questions about ecology and evolution in extinct animals.

The circumstances required for evidence of combat between dinosaurs to fossilize are extremely rare. We can think of these circumstances as a scientific checklist, standards that need to be met for us to use a fossil as evidence for combat. For this article, we will consider combat between predators and prey, which is a common question asked for dinosaurian combat. First, to consider one organism as a predator of another, they need to be found in the same place and in the same geologic time interval. Although it is fun to think about a Tyrannosaurus rex fighting a Stegosaurus, they are separated in time by tens of millions of years and thus would have never interacted. Second, we need fossils that preserve the by-product of predation, such as bite marks in the bone. Such marks do not necessarily have to be from teeth. For example, we know ancient humans hunted and ate woolly mammoths because of the marks made by stone tools during butchering. Third, we need damage to the bones and the organism to not be fatal. Non-fatal injuries that fully or partially healed are required to confirm that the injury happened while the animal was alive. Otherwise, there is no way to know for certain if a broken or scratched bone happened before or after death. You can imagine that in the process of fossilization, excavation, and preparation, there are a lot of opportunities for bones to break or get beaten up. Therefore, a partially or fully healed injury, such as a bite mark, is the gold standard for paleontologists wishing to study dinosaur combat. On top of all these requirements (I promise we are getting to the fun part soon), the fossil of a skeletal injury that healed still needs to be fossilized, survive the rigors of geologic time, be found, recognized, and studied by scientists. Therefore, we know relatively little about dinosaurian combat. Thankfully, there are a handful of isolated cases that can give us a window into ancient combat. For all the reasons listed above, the exceptions to the caveats of the fossil record are extraordinarily valuable to scientists. Today, we will dive into those rare instances where we can learn about dinosaur combat.

Being a scientist, I am not supposed to use words like ‘miracle’ to describe fossils. However, the fossil I am going to talk about can only be described as a miracle. On August 3rd, 1971, a joint Polish-Mongolian expedition to the Toogreeg region of the Gobi Desert of Mongolia discovered a fossil that is a scientific miracle. Finding a dinosaur skeleton, rather than an isolated bone or tooth, is a rare occurrence. Finding two dinosaur skeletons locked in an eternal deadly embrace is so unlikely as to border on the supernatural. Thanks to the hard work of an intrepid crew of Polish and Mongolian paleontologists (see list of names at the end), the specimen that would come to be known as the ‘Fighting Dinosaurs’ entered the scientific lexicon. The skeleton of the turkey-sized predatory dinosaur Velociraptor mongoliensis (left) embraces the head and chest of Protoceratops andrewsi (right), a frilled herbivorous dinosaur in an apparent life pose:

Figure 1. A cast of the “Fighting Dinosaurs” on display at the Nagoya City Science Museum in Japan. Photo by Yuya Tamai via Wikipedia Commons.

For the reader who didn’t grow up obsessed with dinosaurs, let’s introduce our fighters. First, both dinosaurs would have had feathers of some kind. Velociraptor most likely was covered in feathers even as an adult, whereas close relatives of Protoceratops primarily had quill-like feathers running down the tail. Although Velociraptor is smaller than the movie animals (which are based on American species like Deinonychus), the preserved individual would have been a deadly, even cat-like predator. Velociraptor is armed with a mouth of teeth that are sharp, recurved, and serrated and three fingered hands with hooked claws. The foot of Velociraptor is armed with the Cretaceous equivalent of a switch-blade, where the second toe is held off the ground, keeping an enlarged, sickle-like claw sharp. Dromaeosaurs, the ‘raptors’ of Jurassic Park fame, are thought to have used the claws of their hands and feet to eviscerate their prey. A key piece of evidence for this hypothesis is the fighting dinosaurs, as the Velociraptor has its left toe-claw extended and embedded in the chest of the Protoceratops. So, on one side we have a small but vicious predator armed to the nines. Let’s meet our other fighter.

Figure 2. My favorite scientific restoration of Velociraptor mongoliensis, showing the feathered body and switch-blade like toe claw in an active pose. Image by Fred Wierum (see sources for more information).

At the size of a large dog (just over 6 feet long), Protoceratops is diminutive compared to its more famous cousin Triceratops, which would have been ~7 feet tall and the shoulder and over 20 feet long. However, Protoceratops is no less fascinating. Ceratopsian dinosaurs lost the bipedal stance that is shared by the earliest dinosaurs, instead evolving to walk primarily on four legs as the head enlarged and the marginal skull elements expanded into a bony frill. It is tempting to think of frills in dinosaurs as being bony shields. They are, after all, vaguely shield-shaped. In larger, geologically younger ceratopsians like Triceratops, the frill does form a solid bone, shield-like structure. In Protoceratops, the bony frill is thin and has holes that, in life, were filled with soft tissue. Pretty crappy shield right? Well, yes. But, we paleontologists think the ceratopsian frill originally served not as a shield, but as an extended anchor for the attachment of massive jaw closing muscles. The jaws of Protoceratops and other ornithiscian dinosaurs are pronounced into a giant, bony, bird-like beak. In life, the bone would have been covered with a sheath of tissue called keratin (which covers our fingernails), giving Protoceratops a parrot-like appearance. Scientists hypothesize that the beak and frill, combined with powerful jaw muscles, would have made Protoceratops a living pair of gardening shears. The beak would have allowed Protoceratops to cut tough, woody plants, which would have been processed by a battery of teeth in muscular cheeks In the fighting dinosaurs, we see that the beak could also serve as a weapon in a life or death struggle, as the Protoceratops is biting the right forearm of the Velociraptor. Here we learn an important lesson in evolutionary biology. Rarely does a structure serve only one function. Even if the beak primarily functioned in snipping plants, it evidently could serve as a weapon in a life or death situation. Now that we know the fighters, let’s look at the box score.

Figure 3. Illustration of the skull Protoceratops andrewsi, showing how the skull bears a pronounced bony “beak” and a frill formed from lengthened cranial bones. Image from Łukasz Czepiński (2020), see sources for more details.

In this case, neither dinosaur won the fight. Although we do not know for certain how, the fighting dinosaurs preserves two animals locked in a mortal struggle. Two combatants stuck in an eternal embrace, preserved forever by geology. Whether the animals were buried alive by a falling sand dune or if they inflicted mortal wounds on each other and died still locked together (and were buried later) is a subject of debate. In either case, the fighting dinosaurs teachers us several important lessons. Combat in nature is not sport. These two animals fought for their lives, not for a prize. In this we see that the conception of herbivorous animals in a lot of media as passive or the ‘good guys’ is wrong. Neither side is good or evil, they are animals fighting literally tooth and claw to survive. The Velociraptor is fighting for a meal, the Protoceratops its life. Rather than being a passive food source, the Protoceratops, similar to a lot of other herbivores, fought to survive. In the end, both of these animals lost their lives in the struggle for survival. So we see that the question of which dinosaur would “win” is flawed. In nature, there is no such thing as losing. In a sport, losing means you play again another day. In nature, when the survival of two organisms is mutually exclusive, the question is not which will win or lose. The question is which will live and which will die. Put another way, in nature there is only victory in survival or death, there is no losing. Being nature and not a game, there is no guarantee that either animal will survive. In this case, both animals died trying to survive. So the next time we consider which dinosaur would “win” in a fight, we would do well to consider that nature isn’t a game. There is no winning and losing and nature, only survival.

Figure 4. Mortal combat in the Mesozoic. Illustration by Raul Martin, from Chiappe L. M. (2003) figure 1.

Sources:

Barsbold, R., 2016. " The Fighting Dinosaurs": The position of their bodies before and after death. Paleontological Journal, 50(12), pp.1412-1418.

Benton, M. J. 2015. Vertebrate Palaeontology. Fourth Edition. Wiley Blackwell.

Bell, P.R., Hendrickx, C., Pittman, M., Kaye, T.G. and Mayr, G., 2022. The exquisitely preserved integument of Psittacosaurus and the scaly skin of ceratopsian dinosaurs. Communications biology, 5(1), p.809.

Brusatte, S.L. 2012. Dinosaur Paleobiology. Wiley Blackwell

Chiappe L. M. 2003. A Field Trip to the Mesozoic. PLoS Biology, 1(2), e40. https://doi.org/10.1371/journal.pbio.0000040

Czepinski, L., 2020. New protoceratopsid specimens improve the age correlation of the Upper Cretaceous Gobi Desert strata. Acta Palaeontologica Polonica, 65(3).

Farke, A.A., 2014. Evaluating combat in ornithischian dinosaurs. Journal of Zoology, 292(4), pp.242-249.

Holtz, T.R. Jr. 2003. Dinosaur predation: Evidence and ecomorphology. Pg. 325-340 in “Predator-Prey Interactions in the Fossil Record” (edited by Patricia H. Kelly, Michal Kowalewski, and Thor A. Hansen). Kluwer Academic/Plenum Publishers, New York.

Kielan-Jaworowska, Z. and Barsbold, R., 1972. Narrative of the Polish–Mongolian palaeontological expeditions 1967–1971. Palaeontologia Polonica, 27, pp.5-13.

Pawłowska, K., 2017. Large mammals affected by hominins: Paleogeography of butchering for the European Early and Middle Pleistocene. Quaternary International, 438, pp.104-115.

Members of the 1971 joint Polish-Mongolian expedition that recovered the fighting dinosaurs:

Polish Group: Mr. ANDRZEJ BALlNSKI, palaeontologist; Mr. JAN BIJAK- doctor and cook; Mr. ANDRZEJ EUŻANOWSKI - student; Dr. TOMASZ JERZYKIEWICZ - geologist; Prof. ZOFIA KIELAN-JAWOROWSKA - palaeontologist, leader of the Polish group; Eng. MACIEJ KUCZYNSKI - technical leader and drive; Mr. CYPRIAN KULlCKI, palaeontologist; Dr. TERESA MARYANSKA - palaeontologist, vice-leader; Mr. EDWARD MIRANOWSKI - driver; Mr. WOJCIECH SKARZYNSKI - technical assistant; Dr. ANDRZEJ SULlMSKI - palaeontologist; Mrs. MARIA ZIEMBINSKA-TwORZYDLO - palaeobotanist.

Mongolian Group: Dr. RINCHEN BARSBOLD, palaeontologist, leader of the Mongolian group; Mr. ALTANGEREL PERU, palaeontologist; Mr. SAMBU- technical assistant.

Images:

Cast of the fighting dinosaurs: Yuya Tamai. License. No changes made. https://www.flickr.com/people/76758469@N00.

Velociraptor reconstruction by Fred Wierum via Wikipedia, no changes made. License.

Protoceratops skull figure from: Czepinski, L., 2020. New protoceratopsid specimens improve the age correlation of the Upper Cretaceous Gobi Desert strata. Acta Palaeontologica Polonica, 65(3). License, no changes made but image cropped.

Fighting dinosaur restoration: Illustration by Raul Martin, appearing in Chiappe L. M. (2003) figure 1.