10 Dinosaur Behaviours That Will Blow Your Mind
Dinosaurs were complicated animals, with complex social lives, fierce parental instincts and, perhaps, a propensity to play...
There’s something fascinating about dinosaurs. Ever since they were first officially described in the early 19th century, they’ve captured the attention of the masses and influenced pop culture in a way that no other group of animals - living or extinct - ever has done. It’s tough to put a finger on why dinosaurs evoke such widespread awe, but it perhaps has something to do with the mystery that surrounds them.
Forgetting birds for a moment, dinosaurs no longer roam our grasslands, jump from tree to tree in our forests, or paddle in the shallows of our seas. They’re long gone and - unless you thought Michael Crichton’s Jurassic Park was a work of non-fiction - they’re not coming back. To learn more about them, particularly how they behaved and interacted with the world around themselves, we have to find their fossilised bones, and they’re not exactly forthcoming.
In what can only be described as a cruel ploy against palaeontologists, Mother Nature put just several pieces of the dinosaur jigsaw puzzle back in its box after she was done playing with it - the rest were lost to time. Those bones we’ve dug up and described across the last two centuries have gone a long way in helping us to lay down a few edge pieces, but vast parts of the interior of our jigsaw are still missing. That said, we don’t necessarily need the missing pieces to fill in our gaps, we can learn more about dinosaurs through studying animals that are alive today.
We live alongside two groups of animals, crocodiles and birds, that share a lot of similarities with dinosaurs. All three of these groups evolved from a common ancestor, with crocodiles branching one way as dinosaurs - which later evolved into birds - went the other. This means that any shared characteristics we see in modern-day crocodiles and modern-day birds can be traced back to this common ancestor, and therefore also attributed to dinosaurs. To put that into an example: since certain species of crocodiles and birds dance to attract mates, it’s likely that certain species of dinosaurs also did the same - more on that later.
That’s not to say that all of our interpretations of dinosaur behaviour come from observing modern-day analogues, though, there’s also a lot to learn from fossils themselves. A dinosaur’s teeth, bones, and the traces it leaves behind in rocks, can give us a lot of clues as to how it may have lived. This combination of hard data and observations of extant animals helps us to paint some pretty realistic pictures of dinosaurs.
Some interpretations are, of course, more speculative than others, based on just tiny fragments of evidence and a lot of ‘maybes’. But even the most bizarre behaviours are perhaps not as far-fetched as you might think. Just look at some examples from our modern world - dolphins wearing sea sponges as hats, horned lizards spraying blood from their eyes, and elephants holding funerals - and you’ll see that animals, us included, are capable of doing some of the craziest things.
Let’s take a look at some of the most bizarre behaviours exhibited by dinosaurs…
Swimming tyrannosaurs
If you didn’t know already, dinosaurs only lived on land. Some may have lived along the water’s edge, but none - that we know of at least - had fully aquatic lifestyles. During the time of the dinosaurs, the Mesozoic, the seas were instead full of ichthyosaurs, plesiosaurs and mosasaurs, marine reptiles which are often mistaken for dinosaurs.
Just because there were no fully aquatic dinosaurs doesn’t mean that they couldn’t swim. In fact, it’s widely agreed amongst the palaeontology community that most dinosaurs could swim, or at least float to some degree. This includes the ‘Tyrant King’ himself, Tyrannosaurus rex. It’s hard to imagine that a 12 m-long, 10-ton monster could even keep itself afloat, yet studies have shown that it would have actually been a very adept swimmer.
Firstly, Tyrannosaurs like T.rex are theropods - a clade of dinosaurs characterised by their hollow bones, bird-like hindlimbs and three-toed feet. The hindlimbs on Tyrannosaurs were enormous and covered in huge muscles, which would have given them a powerful kicking motion when in the water. Their tails were similarly muscly and, crucially, very long, giving them a functional rudder which they could have used to direct themselves.
In 2013, a study led by Chinese palaeontologist Lida Xing described a trackway that featured a series of clawed gouges on an ancient riverbed. These gouges have been interpreted as theropod swim traces, created when these two-legged dinosaurs kicked with their hindlimbs and scraped the riverbed below with their claws. The time period which these swim traces were dated to - the Early Cretaceous (145-100 Ma) - and the area in which they were found - Sichuan, China - means that they weren’t made by T.rex, though they could have been made by an earlier ancestor.
This study has led many to believe that the ‘Tyrant King’ could have swam too. Darren Naish, the lead consultant on BBC’s Prehistoric Planet series, describes T.rex as an “excellent swimmer” and a dinosaur which would have used its talents in the water to “expand its feeding opportunities”. This is a behaviour seen in T.rex’s modern-day ancestors, ostriches and emus. These large, flightless birds are also strong swimmers and have been observed crossing large bodies of water - sometimes in excess of several miles - to find new feeding grounds.
Plant eaters didn’t just eat plants
Contrary to popular belief, there’s no such thing as a pure herbivore or a pure carnivore. In reality, herbivory and carnivory exist on a spectrum - with omnivory lying slap bang in the centre. Herbivores, in particular, supplement their nutrient-poor diets with some occasional hits of protein, whether that be in the form of insects or, shock horror, baby birds.
On the Isle of Rum in Scotland, Red Deer have been seen hanging around the nests of seabirds, waiting for newly-hatched chicks to emerge before pouncing and gobbling them up. This observation has led some to suggest that megaherbivores that lived during the Mesozoic - like Stegosaurus, Triceratops and Iguanodon - may have also occasionally eaten meat.
Again, there’s evidence for this in the fossil record. In 2017, a study published in Scientific Reports found crustacean shells embedded in coprolites (fossilised poo) from what are believed to be Hadrosaurs - large, predominantly plant-eating dinosaurs that lived during the Late Cretaceous. Karen Chin, the lead author of the study, concluded that eating shellfish wasn’t a common behaviour exhibited by Hadrosaurs, and likely more reflective of dietary shifts during breeding seasons. A similar degree of dietary flexibility is also seen in modern-day birds that are deemed mostly herbivorous, like parrots, pigeons and finches.
Of course, the notion that not all plant eaters strictly ate plants has led to some pretty wild suggestions - the most wild being that Triceratops, one of the most recognisable herbivorous dinosaurs, was actually a mean, meat-eating machine.
This fringe theory points to Triceratops’ unique skull as evidence for its meaty diet. The part of its jaws which hold its spade-like teeth are inset into its skull, meaning it probably had huge jaw muscles to power its bite. It also has a huge, curved beak. The typical interpretation of these features is that they’d have helped Triceratops to uproot and chew through some of the period’s toughest plants. This fringe theory doesn’t deny that, but it does add that they would have also used their powerful jaws to chow down on small animals, just like omnivorous boars do today.
Dinosaur dancefloors
Whatever compels us to take to the dancefloor on a Friday night and throw some provocative shapes in an attempt to woo a potential partner, also compelled the dinosaurs. Granted, their dancefloors didn’t lie in the basements of dank nightclubs choked by a smelly cocktail of booze and sweat, rather open expanses of sand or dirt under romantic starlight, but they’d have served the same purpose nonetheless. You see, sex is something that drives all animals, and those who are good at dancing typically get the most of it.
As mentioned earlier, since flirtatious dancing behaviour has been observed in extant crocodiles and birds, we’re pretty sure that dinosaurs must have done it too. Birds - dinosaurs’ closest living relatives - are actually some of the best dancers around today, known for their dazzling displays of colours and acrobatics. It’s unclear whether birds have refined this behaviour over time or whether it was passed onto them by their non-avian relatives, but with almost complete certainty we can say that dinosaurs danced to some degree. I personally like to picture Deinonychus ‘moonwalking’, just like red-capped manakins do during breeding seasons.
Finding evidence of dinosaurs having a boogie is tough. While we may leave behind a lot of evidence from our booze-fueled nights out, half-empty bottles, stamped-out cigarette buts and empty pizza boxes, dinosaurs didn’t. Instead, we have to look for traces they may have made in rocks while dancing. Thankfully, some sites - nicknamed ‘dinosaur dancefloors’ - have been preserved. In 2016, a team led by Martin Lockley described an incredible site from western Colorado where more than 50, 2m-long scrape marks were found on a single sandstone surface measuring ~750m².
The site is around 100 million years old and, according to Lockley and his colleagues, documents signs of “dinosaur foreplay”. The scrapes are found in irregular groupings and are apparently consistent with those seen in the display arenas of extant ground-nesting birds. It’s unclear exactly which dinosaur these ‘dancing feet’ can be attributed to, but the chief suspect is Acrocanthosaurus - a huge, ridge-backed theropod that was just a bit smaller than a T.rex.
Work hard, rest harder
Our perceptions of dinosaurs, particularly the meat-eating kind, have been massively warped by famous movies like Jurassic Park, King Kong and The Land Before Time. These movies painted predators as killing machines which spent almost every second of their lives hunting. Sure, there’d have been a lot of bloody battles during a predator’s life, but they wouldn’t have happened daily - if they did, many wouldn’t have lived long enough to become adults.
Believe it or not, hypercarnivores spend the majority of their time either resting or sleeping. Some, like lions, spend as much as 20 hours per day asleep, and only tend to hunt every three or four days. Even predators which don’t live in social groups, like grizzly bears, spend a lot of time resting. A 2017 study of Alaskan grizzlies found that resting was the most common activity that they engaged in, followed by travelling. Hunting, on the other hand, was only observed during 1% of the time in which they were awake. There’s no reason to believe that life would have been any different for the hypercarnivores of the Mesozoic. Perhaps during times of scarcity they’d have spent more time hunting and less time resting, but during times of plenty there’d have been a lot of lounging around.
For megaherbivores the reserve is true. These types of animals typically consume nutrient-poor foods, so they need to eat vast quantities of it and to do that they need to graze for long periods. In a 2020 study conducted on zebras living in the Majete Wildlife Preserve in Malawi, researchers found that they typically spend 42% of their daylight hours grazing and just 19% resting. Some types of cattle, like cows, sheep and goats, can spend upwards of 10 hours a day grazing - clearly domestication has some benefits…
A common scene depicted by the films mentioned above is one of a grazing herd of herbivores suddenly ambushed by a huge, bloodthirsty T.rex. In reality the scene was likely very different, with T.rex perhaps lying on the brow of a grassy hill, dozing off as it counted Edmontosaurus on the pastures below.
Herds of harmonious honkers
There was no shortage of weapons during the Mesozoic, most dinosaurs had something they could use to either subdue prey or beat off a would-be predator. Stegosaurus was blessed with huge, metre-long spikes at the end of its muscular tail, Triceratops with three pointy protrusions, two above its eyes and one on its nose, and Deinonychus with two razor-sharp, sickle-shaped claws on its inner toes. But what about the humble Hadrosaurs, what did they have?
These herbivorous ornithischians, which lived alongside T.rex and Triceratops in North America during the Late Cretaceous, were some of the most populous, large-bodied dinosaurs of their time, often described as “the sheep of the Mesozoic”. They were relatively unremarkable dinosaurs whose main form of defence was the fact that they lived together in large herds, perhaps thousands strong. As individuals they did have one trick up their scaly sleeves, though, a superpower other dinosaurs didn’t possess - they honked.
It’s thought that most species of Hadrosaur could honk, thanks to their expanded nasal cavities which reverberated with deep, resonating sounds as they expelled air. Of 40 known species, it’s Parasaurolophus which holds the crown as the family’s best honker - the tubas amongst the wider Hadrosaur brass band. These 10m-long giants looked a lot like others of their kin, that is until you got to their heads which were adorned with long, arching crests that resembled snorkels. This crest was full of winding passages which, when air was blasted through, created a unique sound.
In 1981, David Weishampel and his colleagues made a model of a Parasaurolophus’ skull, including the crest, and blew into it. The resulting noise sounded like that made by a crumhorn, a Renaissance-aged wind instrument known largely from Germany. It’s a unique honk indeed, and one that sounds like it’s announcing the imminent arrival of a mediaeval cavalry charge. This sense of danger, evoked by such a deep, foreboding honk, is almost definitely something that Parasaurolophus could have weaponised. An individual honking may have been enough to deter a hungry T.rex. A herd of them honking, on the other hand, could have driven the ferocious predator from its hunting grounds entirely.
Love bites
It’s relatively common to find large theropod skulls pitted with puncture marks around their snouts. Many of these holes demonstrate signs of healing, meaning the animal survived whatever - or whoever - made these injuries. Typically, these holes match the teeth of other large theropods, and often the same species as the victim in question. In nature it’s very rare to see animals of the same species actively hunt and kill one another, so the obvious inference here is that these holes show evidence of intraspecies aggression - signs of ritualised combat rather than mortal struggle.
A 2022 study took a close look at these facial blemishes, particularly in Tyrannosaurs, and found that they were absent in juveniles - they only started appearing in immature adults. Of the adult specimens studied, ~60% showed signs of intraspecies aggression. This ontogenetic distribution of puncture marks, with the number of marks increasing with age, seems to be associated with the onset of sexual maturity.
Caleb Brown, the lead author of the study, noted that most puncture marks were inflicted by males on other males, likely in contests for food, mates or territory once they reached adulthood. But not all marks were made equal, and those that were found on females have been interpreted as signs of courtship behaviour, or rather: 66-million-year-old love bites.
This kind of sexual aggression has been observed in modern-day crocodiles but, interestingly, not in modern-day birds. Brown and his colleagues suggest that this biting behaviour likely disappeared as theropods became more feathered and, to put it simply, bird-like. When you’ve nothing more than a head full of teeth it’s understandable that you’d use them to get your way. But when you’re covered head-to-toe in vibrant feathers you tend to let those do the talking instead.
Big burrowers
Burrowing is a behaviour often associated with mammals and other small critters, but some pretty sizeable dinosaurs did it too. The first ever burrowing dinosaur was discovered back in 2007, when a fossilised burrow containing three partial skeletons was found in mid-Cretaceous-aged rocks in southwest Montana, USA.
The remains, which came from an adult and two juveniles, were assigned to a brand-new genus - Oryctodromeus, or ‘digging runner’. It may have been small compared to other dinosaurs which shared its habitat, but relative to us and burrowing animals that are alive today it was quite large, at 2.1 m in length and ~35 kg in weight.
The burrow that the three Oryctodromeus were found in closely fits the proportions of the adult, suggesting that it dug out its own home rather than squatted in that of another. A close examination of the burrow revealed that it had a pronounced s-bend, which researchers believe Oryctodromeus dug to make it harder for predators to enter. The fact that an adult was found alongside two juveniles also suggests a degree of parental care and that the burrow was perhaps used to protect and rear offspring.
This grand discovery of a burrowing dinosaur completely changed what researchers thought they knew about this long-extinct group. “It was generally assumed that dinosaurs wouldn’t dig - they tend to be either runners or very large. This [Oryctodromeus] is quite a departure,” said Paul Barrett, researcher at London’s Natural History Museum, in a conversation with Nature at the time of the discovery. For a long time, the inability to burrow was proposed as one of the reasons why non-avian dinosaurs didn’t survive the asteroid impact which ended their reign on Earth. If dinosaurs could dig, then they may have survived the initial impact and weathered the ensuing nuclear winter, just like several small mammals did.
It’s an interesting thought, that some non-avian dinosaurs may have survived past the end-Cretaceous extinction event, but there’s no physical evidence to suggest that it actually happened. Sure, the existence of burrowing dinosaurs challenges the argument, but they’re yet to be found in the latest rocks from the Cretaceous. No non-avian dinosaurs have been found in Paleocene-aged rocks either (the Paleocene is the period of time which followed the Cretaceous).
Clash of the titans
As a huge dinosaur fan, it’s impossible to sit down and watch a dinosaur movie without pointing out clichés to everyone else in the room. Perhaps the biggest cliché perpetuated by these movies is that sauropods - the biggest dinosaurs, and by quite a large margin - were gentle giants. These were, and probably forever will be, the largest animals to walk on land. The biggest amongst them were the Titanosaurs and the Apatosaurines, growing over 30 m in length, 20 m in height and weighing in at around 75 tons.
These behemoths didn’t eat meat, instead they gorged on massive amounts of plant material. This idea that they were placid herbivores isn’t quite accurate, though. Like megaherbivores that live today - elephants, hippos and rhinos to name a few - they’ll have been prone to fits of aggression, specifically during breeding seasons and disputes over territory.
In 2015, a team led by the University of Bristol’s Mike Taylor closely examined the incredibly thick and robust necks of Apatosaurines. They noted several novel features, including displaced cervical ribs which strengthened neck movements, a ventral trough which provided soft-tissue protection for the trachea, and knobs on vertebrae which may have served as bony clubs. This suite of adaptations begged an interesting question: why would these animals evolve necks that were biologically expensive to build, maintain and operate?
A common answer to this question is that adaptations are driven by sexual selection - in the case of the Apatosaurines, those with the biggest, fattest necks were considered the fittest (in both meanings of the word) by the opposite sex. But this isn’t thought to be the primary reason why Apatosaurines evolved such robust necks. Instead, Taylor and his colleagues believe that combat drove evolution in the case of these dinosaurs.
Looking at the nature of their adaptations, it has been suggested that Apatosaurines would have crashed their necks down or sideways into the neck of an opponent. This differs from the way in which giraffes fight. They use their horned heads as weapons, rather than their comparatively weak necks. A bout between two Apatosaurus would have no doubt shook the ground beneath them, with each clash of their necks sending loud, thunderous claps over the surrounding hills and beyond.
One big happy family
It’s perhaps a little arrogant to think that we, humans, make the best parents. Yes, we may look after and nurture our children for decades, but we’re not the only ones who invest so much in the next generation. The practice of parenting is observed in many groups of animals: fish, amphibians, reptiles (including crocodiles), birds, and mammals.
Again, the fact that crocodiles and birds have been observed nurturing their young suggests that dinosaurs must have done it too. It’s not too hard to imagine dinosaurs as parents; after all, anyone who has seen The Land Before Time can attest to the ‘exceptional’ parenting skills of a mother Brontosaurus. But the way in which some dinosaurs looked after their young may surprise you.
Maiasaura, a large Hadrosaur that lived in North America during the Late Cretaceous, is perhaps one of the best dinosaur parents that we know of. Its prowess as a parent is even reflected in its name, which means ‘Good Mother’. In 1977, Marion Brandvold - owner of “The Rock Shop” in Bynum, Montana - discovered a huge Maiasaura nesting ground, which was later nicknamed ‘Egg Mountain’. This site preserved 14 closely-packed nests, each containing 30-40 eggs in circular clutches. There were also remains of hatchlings, juveniles and adults found at the site, suggesting that Maiasaura of all ages lived together in one giant herd.
Maiasaura’s proficiency as a parent went beyond just living alongside their young, though. The hatchlings discovered at the site were found to have immature leg muscles and undeveloped teeth, which would have made them incredibly reliant on their parents. Based on this, it’s believed that Maiasaura would bring food back to their nests and care for their hatchlings until they were old enough to fend for themselves - which, if you think about it, is no different to our parents making us sandwiches up to the point at which we found out how to butter bread ourselves.
Not all dinosaurs were as good a mother as Maiasaura, however. The long-necked sauropods are thought to have been amongst the worst, laying dozens of eggs in long trenches before burying them and walking away, leaving their young to fend for themselves after hatching. This isn’t quite how The Land Before Time depicted it, in the original 1988 film Littlefoot’s mother sacrifices herself in order to save her son from a hungry T.rex. But we can’t be too harsh on these giants, it would have been near impossible for an animal of their size to even see one of its newly-hatched, 30 cm-long babies, let alone care for it.
Never too big to play
In a scientific sense, play is defined as: a repeated behaviour which lacks an obvious function and is initiated voluntarily when the animal isn’t stressed. We do this all the time, but so do many animals. It’s not too hard to picture our mammalian cousins playing, we’ve all seen dolphins bobbing balls on their noses, cats chasing laser pens, and dogs rolling in mud, but it’s a lot harder to picture other groups of animals doing it. Yet, many do - birds drop and catch objects in midair, iguanas play fetch, and some fish, particularly cichlids, knock small pebbles around their aquariums.
With this in mind, it’d be rather foolish to suggest that dinosaurs didn’t play, and that their lives were instead consumed by just three core activities - eating, reproducing, and trying not to get killed. As explained above, dinosaurs, particularly the meat-eating kind, would have had a lot of free time. Most of this time would have been spent resting, but it could have also been spent playing and engaging in activities that enhanced the development of certain skills.
How dinosaurs played is somewhat of a mystery - that kind of behaviour, surprise surprise, doesn’t readily show itself in the fossil record. That said, some T.rex tooth marks found on Ceratopsians have been interpreted as signs of play. These marks, noted by the University of Kansas’ Bruce Rothschild in a 2015 study, were noticeably different to marks made during feeding. They were also found on parts of Ceratopsians where there’d have been a large, ball-shaped bone and little meat. These observations led Rothschild to conclude that some T.rex may have, quite literally, played with their food, although there’s little consensus on this.
We’ll never know exactly how dinosaurs played, though given how widespread the behaviour is amongst their living ancestors we can say, with a degree of confidence, that they did play. It’s unlikely that they’ll have thrown frisbees to one another or played hide-and-seek, but it’s relatively easy to imagine that they would have wrestled, chased one another, and engaged in playful nipping and biting - similar to how many animals play today.
It’s also possible that some species of dinosaurs may have engaged in object play, a behaviour observed in extant crocodiles and birds. Just picture it now: a juvenile theropod - let’s say a Gorgosaurus - happens across a fallen branch in a clearing at the edge of a forest. With its mother and siblings away from view and out of earshot, it scurries over, picks the branch up in its jaws and tosses it several metres. There’s a loud, satisfying thud as it makes contact with the hard-packed ground, and the teenage Gorgosaurus grins from ear to ear.
References
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* Thumbnail image adapted from original artwork by Steveoc 86. CC BY-SA 3.0, available here.
