Prehistoric animal behaviour discussion

[Tyto_Theropod]

Firstly: Plot twist! I'M NOT DEAD!

Okay, so my idea for this thread was for questions, discussions and friendly debates about how dinosaurs and other prehistoric life forms behaved. How they lived, fed, reproduced, interacted and perceived the world around them. Of course it's very pretty much impossible to scientifically observe and test such things when all we have is fossils, but it's fun to speculate and perhaps come to logical conclusions based on what we see in modern animals.

To start us off, I was thinking about how to portray sociality in Maniraptorans (specifically Dromaeosauridae) in a story idea I had. We've discussed the idea that Dromaeosaurs might have lived in mated pairs, but what if they had some kind of polygamous structure similar to ratites? In cassowaries, females defend territories encompassing those of several males, with whom they breed. Cassowaries are browsers, but AFAIK tigers have a very similar system (only the sexes are reversed). Rheas move in flocks most of the time, but in the breeding season males establish territories and mate with several females. This could work for an animal in a seasonal environment where they'd have to keep moving in order to find food. In both these birds, males largely or wholly responsible care of the nest, which would fit with the evidence we have from fossils of brooding/nest guarding Maniraptorans.

As such, I'm interested to hear what kinds of social and reproductive strategies people on here would think more likely for different Maniraptoran groups/diets/environments. Given what I know about sociality in other dinosaurs, we could definitely extend the conversation to cover them as well, but from the point of view of my idea I'm especially interested in the Djadochta Maniraptorans. Anyway, what are your thoughts?

ADMIN: We've probably had similar sorts of threads in the past, so the mods can merge this if they feel it necessary.

[Brocc21]

Perhaps they shared nesting duty. One would sit on the eggs while the other would defend the territory and hunt. And then after a given amount of time they'd switch.

[Papi-Anon]

I could see dromaeosaurs sharing nesting duties, too. Behaviorally I also think mated pairs of different species and genera of maniraptorans would be as common as the seasonal-pairs that may or may not ever get back together after the chicks hatch. Whether mom or dad took care of the kids, more than likely it was the mother I think with that being the norm in the animal kingdom as a whole.

One thing that interests me is the behaviors of non-maniraptoran therapods. Endocasts have shown that Allosaurus had a brain shaped more like modern crocodilians than birds. Due to this shape the general consensus has been that Allosaurus probably was more instinct than reason in its behavior, but recent findings have shown crocodilian intelligence to be greater than we've long given them credit for. Certain modern crocs can be trained to come on command (and by responding to a specific name given to them at that!), and some like the Nile Crocodile are crafty enough to place sticks on their snouts while floating in the water to fool birds into coming over to grab the twigs to make a nest (only to be gulped by the croc). Makes me wonder how intelligent therapods like the allosauroids could have been in life.

[Brontozaurus]

I could see dromaeosaurs sharing nesting duties, too. Behaviorally I also think mated pairs of different species and genera of maniraptorans would be as common as the seasonal-pairs that may or may not ever get back together after the chicks hatch. Whether mom or dad took care of the kids, more than likely it was the mother I think with that being the norm in the animal kingdom as a whole.

One thing that interests me is the behaviors of non-maniraptoran therapods. Endocasts have shown that Allosaurus had a brain shaped more like modern crocodilians than birds. Due to this shape the general consensus has been that Allosaurus probably was more instinct than reason in its behavior, but recent findings have shown crocodilian intelligence to be greater than we've long given them credit for. Certain modern crocs can be trained to come on command (and by responding to a specific name given to them at that!), and some like the Nile Crocodile are crafty enough to place sticks on their snouts while floating in the water to fool birds into coming over to grab the twigs to make a nest (only to be gulped by the croc). Makes me wonder how intelligent therapods like the allosauroids could have been in life.

I feel like as a species we've been hung up on brain size as a measure of intelligence for far too long. If simply having bigger brains meant higher intelligence, blue whales would have taken over the world by now.

[Brocc21]

Good point

[Papi-Anon]

I feel like as a species we've been hung up on brain size as a measure of intelligence for far too long. If simply having bigger brains meant higher intelligence, blue whales would have taken over the world by now.

It isn't absolute size, though. Last I recall, it's about how much brain mass is needed to operate the body and its functions versus how much the animal actually has. In Chordates the spinal cord plays a role in brain power too for the more instinctive body reactions (partly why a freshly beheaded chicken will run around and flap about for several seconds before falling down for good). Most animals (especially invertebrates) have encephalization quotients below 1.0, and based on endocasts it seems few non-avian dinosaurs were close to Paleocene mammalian EQ's.

But to play devil's advocate, we as a species are across the board getting lower EQ's ever since the end of the last ice age, with earlier anatomically-modern humans having greater EQ's than us. Despite that we're more intellectually advanced (if given the right education and upbringing) than our stone age ancestors.

[stargatedalek]

As a point of reference, even the smartest evidence from extinct dinosaurs display what could be considered almost basal in comparison to modern birds. Even derived maniraptorans were likely at a level equivalent to finches.

[HD-man]

Okay, so my idea for this thread was for questions, discussions and friendly debates about how dinosaurs and other prehistoric life forms behaved. How they lived, fed, reproduced, interacted and perceived the world around them. Of course it's very pretty much impossible to scientifically observe and test such things when all we have is fossils, but it's fun to speculate and perhaps come to logical conclusions based on what we see in modern animals.

I was thinking more-or-less the same thing (specifically, maniraptoriformes), but haven't had time to post about it. I'll have to get back to you about it.

To start us off, I was thinking about how to portray sociality in Maniraptorans (specifically Dromaeosauridae) in a story idea I had.

If we're talking about eudromaeosaurs, then like this for reasons discussed therein: http://dinotoyblog.com/forum/index.php?topic=6116.0

To add to the above, "Vicious Velociraptor : tales of a turkey-sized dinosaur" basically sums up what we currently know about Velociraptor. The David Button quotes are of particular interest ("I think it's quite useful to think of Velociraptor like a land eagle as they're very similar to eagles in many ways and it's reasonable to expect they would have behaved similarly as well...It wouldn't have been particularly nice to meet - I wouldn't want to meet a grounded eagle, let alone one that's used to being on the ground...Velociraptor was not smart like a chimp, or even a parrot or crow. But it was smart like an average bird - a hawk or something like that"): http://www.nhm.ac.uk/discover/velociraptor-facts.html

We've discussed the idea that Dromaeosaurs might have lived in mated pairs, but what if they had some kind of polygamous structure similar to ratites?

Probably not. As previously mentioned, eudromaeosaurs were raptorial predators, not omnivorous grazers (See the Bakker quote, which also explains why tigers are a bad analogy in this case, AWA the highlighted paragraph in this link: https://books.google.com/books?id=hTTUBAAAQBAJ&pg=PA6&dq=%22stork-like+than+raptorial%22&hl=en&sa=X&ved=0ahUKEwiz4LzOtbDWAhUGOiYKHSyHD5MQ6AEIKDAA#v=onepage&q=%22stork-like%20than%20raptorial%22&f=false ).

Quoting Bakker (See Raptor Red):

Female dominance is a powerful piece of evidence that permits us to reconstruct the private lives of Cretaceous predatory dinosaurs. A family structure built around a large female is rare in meat-eating reptiles and mammals today, but it's the rule for one category of predatory species...carnivorous birds. Owls, hawks, and eagles have societies organized around female dominance, and we can think of tyrannosaurs and raptors as giant, ground-running eagles.

[Tyto_Theropod]

Thanks for this, HD-man. I really appreciate a comprehensive and well-grounded argument! Those links are very insightful and there are some I doubt I'd have found on my own. I like how you've made a conclusion based on niche and diet. It's much more logical than my rather slipshod phylogenetic bracketing approach. Regardless, it does make me wonder whether one might have found ratite-like breeding models in foraging herbivorous and omnivorous dinosaurs.

Perhaps they shared nesting duty. One would sit on the eggs while the other would defend the territory and hunt. And then after a given amount of time they'd switch.

On the subject of predatory dinosaurs sharing nesting duties, I've always seen this as a possibility. However, in most modern birds (and in virtually all birds of prey), one parent tends to invest way more in brooding eggs and young chicks while the other fetches food for everyone else. Older chicks tend to get left on their own while both parents hunt/forage. Off the top of my head, taking turns only tends to happen when the parents must travel a very long distance (e.g. several miles out to sea) from the nest site to find food.

I feel like as a species we've been hung up on brain size as a measure of intelligence for far too long. If simply having bigger brains meant higher intelligence, blue whales would have taken over the world by now.

It isn't absolute size, though. Last I recall, it's about how much brain mass is needed to operate the body and its functions versus how much the animal actually has. In Chordates the spinal cord plays a role in brain power too for the more instinctive body reactions (partly why a freshly beheaded chicken will run around and flap about for several seconds before falling down for good). Most animals (especially invertebrates) have encephalization quotients below 1.0, and based on endocasts it seems few non-avian dinosaurs were close to Paleocene mammalian EQ's.

But to play devil's advocate, we as a species are across the board getting lower EQ's ever since the end of the last ice age, with earlier anatomically-modern humans having greater EQ's than us. Despite that we're more intellectually advanced (if given the right education and upbringing) than our stone age ancestors.

I'm also going to play devil's advocate and point out that crows and parrots have relatively small brains and are at least as intelligent as human toddlers. Having said which, these birds have greater EQs than non-avian dinosaurs. It's interesting that they seem to have achieved their advanced intelligence/EQ through the same pathway as humans - namely through selection for neotenic traits (i.e. adults retaining features of their ancestors' juvenile forms - in this case large heads in proportion to their bodies).

[Lizerd]

Intlligence is a pretty hard thing to measure. While Eq is pretty good and gives a decent estimate n how intelligent an animal is it isn't perfect. Predatory dinosaurs would very likely guard eggs like their modern relatives birds do, simply put as it makes sense and they would invest more care into an infant than other animals did.

On the subject of relative intelligence it can be fascinating. To compare take me and my lizard. Hands down in terms of social skills and interpretation I'm the smarter being. In fact he attacks his own reflection on a regular basis. However in say running away he has me completely outclassed. He has been able to wriggle out of my grip several times and uses things to his advantage like my attention span. Simply put, judging an animal by a skill it does not need like interpretation or self awareness doesn't make sense, it doesn't need them.

[Jose S.M.]

Something about behavior that always makes me think it's the social structure in herading dinosaurs, since they are tipically thought to be less intelligent than extant mammals so I don't know if abny comnparison with those has validity, I wonder how herds moved and how the animals behave within the heards.

[Neosodon]

I think dinosaurs considered to be less intelligent such as Stegosaurus would still have had complex behavior. Allot of insects have an incredible range of survival and social behaviors despite being dumber than the dumbest dinosaurs. Intelligence has its role in adaptibility and ingenuity but complicated behaviors and abilities can be maintained instinctivley with little brain power.

[Jose S.M.]

That's right, complex behavior such as a social structure is seen in lots of groups with different brain capacities, what I wonder is which extant groups are the better for comparison to something like a big Maiasaura herd or something like that. Dinosaur documentaries tend to present those herds behaving in a similar manner than a zebra or wildeebest herd and some people think that mammals are not the best to compare dinosaurs with in some aspects.

[Papi-Anon]

That's right, complex behavior such as a social structure is seen in lots of groups with different brain capacities, what I wonder is which extant groups are the better for comparison to something like a big Maiasaura herd or something like that. Dinosaur documentaries tend to present those herds behaving in a similar manner than a zebra or wildeebest herd and some people think that mammals are not the best to compare dinosaurs with in some aspects.

I forget which species of modern, desert-dwelling lizards that do this, but I remember reading about one species that has a quasi-herd social-structure. They have no problems with one another since they prey on small arthropods. but in the congregations of their kind there's usually a few sentries in the group looking out for predators and signal by raising one of their front legs or bobbing their heads (something to that extent). Now, when danger does come they scatter with an 'every lizard for itself' mentality.

[Lizerd]

It's probably more accurate to compare them to a flock of birds. They hangout together but when they see a foe they will do any number of things, such as running, mobbing it, or in a few bizarre cases, unleashing the poopy bombs. Probably different from massive herds of things like wildebeests.

[Tyto_Theropod]

It's probably more accurate to compare them to a flock of birds. They hangout together but when they see a foe they will do any number of things, such as running, mobbing it, or in a few bizarre cases, unleashing the poopy bombs. Probably different from massive herds of things like wildebeests.

That's a very good analogy. With the way that birds are, I can imagine that such flocks would be deafeningly noisy!

This discussion actually made me recall the huge flock of greylag geese I saw grazing in a field yesterday. According to Wikipedia, these modern examples of flocking, herbivorous dinosaurs have a lot of behaviours in common with herding mammals, as well as with what we know about dinosaurs:

The chicks are precocial and able to leave the nest soon after hatching. Both parents are involved in their care and they soon learn to peck at food and become fully-fledged at eight or nine weeks.

[...]

Greylag geese are gregarious birds and form flocks. This has the advantage for the birds that the vigilance of some individuals in the group allows the rest to feed without having to constantly be alert to the approach of predators. After the eggs hatch, some grouping of families occur, enabling the geese to defend their young by their joint actions, such as mobbing or attacking predators. After driving off a predator, a gander will return to its mate and give a "triumph call", a resonant honk followed by a low-pitched cackle, uttered with neck extended forward parallel with the ground. The mate and even unfledged young reciprocate in kind.

Young greylags stay with their parents as a family group, migrating with them in a larger flock, and only dispersing when the adults drive them away from their newly established breeding territory the following year. At least in Europe, patterns of migration are well understood and follow traditional routes with known staging sites and wintering sites. The young learn these locations from their parents which normally stay together for life.

It's interesting to imagine Hadrosaurs, especially species that may also have been migratory (e.g. Parasaurolophus) behaving in a similar way. Personally, though, I've always imagined such species as lekking rather than mating for life. Of course, we're unlikely ever to know for sure what kind of reproductive behaviours they had...

[Jose S.M.]

That's very interesting about those geese behavior. And I can see herding dinosaurs behaving similarly.

[HD-man]

Thanks for this, HD-man.

Anytime. Glad I could help.

Regardless, it does make me wonder whether one might have found ratite-like breeding models in foraging herbivorous and omnivorous dinosaurs.

Probably ornithomimosaurs, for obvious reasons

On the subject of predatory dinosaurs sharing nesting duties, I've always seen this as a possibility. However, in most modern birds (and in virtually all birds of prey), one parent tends to invest way more in brooding eggs and young chicks while the other fetches food for everyone else. Older chicks tend to get left on their own while both parents hunt/forage. Off the top of my head, taking turns only tends to happen when the parents must travel a very long distance (e.g. several miles out to sea) from the nest site to find food.

That reminds me of this this article AWA the Woodward quote below: https://web.stanford.edu/group/stanfordbirds/text/essays/Size_and_Sex.html

Quoting Woodward (See DK's The Dinosaur Book):

TOOTHED EAGLE
When the first fossils of Velociraptor were found in Mongolia in the 1920s, it was imagined as a scaly, lizardlike animal. But fossils of a closely related dinosaur discovered in nearby China show that Velociraptor would have looked more like a bird. A row of bumps on one of its forearm bones also shows that its arms carried long feathers very like those of a bird's wing.
Even the behavior of Velociraptor was probably birdlike. Related dinosaurs laid their eggs in nests and sat on the eggs to keep them warm, using their "wings" to shelter them. Velociraptor almost certainly nested like this, perhaps in pairs, and while one of the pair brooded the eggs, the other would go hunting. Recent research into how Velociraptor hunted suggests that it ran after its prey and pounced on them like a flightless eagle, pinning animals to the ground with the special, enlarged claws on its feet. The hunter would then tear into its unlucky victim with its sharp-edged, serrated teeth, ripping it to pieces. It may even have taken some of the meat back to the nest for its mate.

I think dinosaurs considered to be less intelligent such as Stegosaurus would still have had complex behavior.

That reminds me of this doc (which shows how similar green iguana behavior is to how experts think some herbivorous dinos behaved): https://www.youtube.com/watch?v=1CPf8wm8ins

That's right, complex behavior such as a social structure is seen in lots of groups with different brain capacities, what I wonder is which extant groups are the better for comparison to something like a big Maiasaura herd or something like that.

That reminds me of this this article AWA the Gardom/Milner quote below: https://www.popsci.com/can-first-known-dinosaur-brain-fossil-tell-us-anything-about-dinosaur-intelligence

Quoting Gardom/Milner (See The Natural History Museum Book of Dinosaurs):

These dinosaurs must have had some kind of homing instinct, like swallows or pigeons, that guided them back to the same breeding ground year after year. Nest construction must have been instinctive knowledge, but the ability to construct a complex colony in co-operation with others suggests quite high degrees of communication skills. And once the Maiasaura young were moving about, the parents must have had some means of recognizing their own babies from among the many others in the breeding colony. Did they do this by smell? By special sounds? By distinguishing marks or colours? These questions are probably unanswerable, but they do show how socially advanced scientists now believe some dinosaurs to have been.

[Lizerd]

Actually here is something to toy with in our thoughts, what if hadrosaurs, seemingly pretty chill dinosaurs, acted like geese? While it may seem kinda wack at first, if you think about it, it would make sense. They are fairly large and like geese seem to lack much weaponry. At first. They could do something similar to a t.rex, where if it got to close to a member of the herd they would run towards, honking and shoving it. Like geese this would lead to minor injuries but would do an excellent job deterring predators.