Welcome Guest [Log In] [Register]






Shoot a firework rocket ~ Winners!
Make a forum zoo!

Welcome to The Round Table. We hope you enjoy your visit.


You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free.


Join our community!


If you're already a member please log in to your account to access all of our features:

Username:   Password:
Add Reply
Extinct Animal Questions
Topic Started: Nov 26 2013, 10:24 PM (193,222 Views)
stargatedalek
Member Avatar
I'm not slow! That's just my moe!

54godamora
Jun 6 2018, 04:17 PM
question: did dromaeosaurs hunt in packs or was it more like mobbing behavior?
More like neither.
Offline Profile Quote Post Goto Top
 
54godamora
Member Avatar


don't some birds alive today hunt in packs and don't some reptiles use mobbing behavior, like komodo dragons?
Offline Profile Quote Post Goto Top
 
Komodo
Member Avatar
Varanus komodoensis

54godamora
Jun 6 2018, 06:59 PM
don't some birds alive today hunt in packs and don't some reptiles use mobbing behavior, like komodo dragons?
Archosaurs hunting in packs is more an exception than a rule. Among predatory birds, the Harris's Hawk is the odd one of its family regarding cooperative hunting, and that's because it's believed to be smarter than the average raptor. Dromaeosaurids, though relatively smart for dinosaurs, were still in the middle range of the spectrum if you take all vertebrates into consideration, and definitely not as smart as modern birds and mammals. It's still plausible some species could travel or even capture prey and feed together, but don't expect complex hunting strategies like those of lions or wolves.

Komodo dragons don't rely completely on mobbing behavior/kleptoparasitism to feed, that occurs mostly when many dragons gather around a prey, and larger specimens make their way to eat first. Still, like most predators, dromaeosaurids probably were opportunistic hunters if they needed to, seizing any chance of securing a safe meal, so eating carrion, robbing food and harassing smaller carnivores on some ocassions, can't be fully ruled out.
Offline Profile Quote Post Goto Top
 
stargatedalek
Member Avatar
I'm not slow! That's just my moe!

Most Dromaeosaurs were also nocturnal to the point where we see specialized adaptations in the diurnal species rather than the nocturnal ones.

Most birds that hunt cooperatively are not birds of prey, and of them only ground hornbills are even vaguely relatable to Dromaeosaurs (as most are piscivorous).

It's very unlikely that Dromaeosaurs hunted in packs or mobs, though this is based on their anatomy and what we know of their diets, not on intellect. Intelligence is not particularly relevant to an animals ability to hunt in coordination.
Offline Profile Quote Post Goto Top
 
Incinerox
Member Avatar
Āeksiot Zaldrīzoti

This wasn't meant to be as long a text wall as it turned out to be. Whoops.

stargatedalek
Jun 7 2018, 12:23 AM
Most Dromaeosaurs were also nocturnal to the point where we see specialized adaptations in the diurnal species rather than the nocturnal ones.
I'd like more detail on this. Partly because the last I heard about nocturnality in dromaeosaurs was that they tested a few sclerotic rings from dromaeosaurs against other animals with similar structures, only to find that the correlation was loose at best or something. But also because there seems to be an implication here that nocturnal living and social groups are mutually exclusive, which I hope to God is just me misinterpreting the context of this point.

Most birds that hunt cooperatively are not birds of prey, and of them only ground hornbills are even vaguely relatable to Dromaeosaurs (as most are piscivorous).

A fair point. But even then, the comparison between a wolf or even bear sized dromaeosaur and any living archosaur is a stretch no matter what you do with it.

It's very unlikely that Dromaeosaurs hunted in packs or mobs, though this is based on their anatomy and what we know of their diets, not on intellect. Intelligence is not particularly relevant to an animals ability to hunt in coordination.
The first half of this is worth challenging. We do have trackways from multiple locations (such as the Chinese Achillobator sized Dromaeopodus shangdongensis and its 6 trackways, and African Deinonychus sized Paravipus didactyloides with a pair of trackways; both instances of multiple animals moving in the same direction at the same time), the Utahraptor death pit and its 6 individuals ranging from large adults to a teeny tiny baby, and indeed the fossils that started it all, the infamous Deinonychus and Tenontosaurus fossil associations. So what we "know" based on morphology (which is moot anyway, I'll get to that in a minute), and diets (again, fairly moot since we know that diet doesn't exactly determine how social an animal was), are put to the test when weighed against the fact that we actually do have evidence for dromaeosaurids at least finding themselves in close proximity to each other. Whether that's deliberate or coincidental on their part is the question.

But that part about morphology being something that can demonstrate group living, I actually question how this works. Because there are several instances of clades of predatory animals with similar morphologies that demonstrate both solitary and group living. Notably the infamous comparisons for dromaeosaurids, big cats and wolves. Morphology tells us nothing. We can't even make inferences on extinct pantherine group living based on morphology alone, and we have living ones for comparison.

That second point, however, is valid and is nowhere near thought about enough in this particular debate. Bear with me because I'm about to make comparisons involving mammals, but they're worth thinking about anyway. To start, lions are generally thought to be the "dumbest" of the big cats. Compared to other big cats, their brains are proportionally quite small, and their problem solving skills aren't the best. Solitary tigers by comparison, have the largest brain to body size ratio of the lot. Yet lions are the ones that form the largest social groups among the entire cat family. Cheetahs as well aren't considered especially smart for cats in general, but they're still far more social than a leopard or tiger would be.

Then when you consider wolves. Their pack hunting behaviour is overestimated - it's literally just an alpha pair with their offspring from multiple generations. We see many birds as well that live in families that consist of parents, and their offspring sticking around to help rear their younger siblings until they're fully grown. It's not all that big a step from basic parental care really. But then you have domestic dogs. Selectively bred for thousands of years by humans to be tamer, friendlier and dumber than wolves, to make them easier to manage.

Yet in populations of stray dogs, they'll have to socialise with totally unrelated dogs, and have been observed in many cities worldwide exploiting human public transport for daily "commutes" to and from feeding or social areas. I don't imagine a wolf would be able to figure out public transport.

Of course, we all know that the pinnacle of animal intellect, as demonstrated by its social groups of literally millions, is the ant. Or perhaps termites.

But there have been far more complex behaviours observed in far less brainy animals than gregarious archosaurs. Like, properly weird things. Shingleback lizards, which pair for life, demonstrate what can be interpreted as grief when one of the pair dies for whatever reason, for instance. Something otherwise reserved for only the most intelligent species we know of. Food for thought.

Point being, intelligence doesn't seem to factor in as much as people assume it does when it comes to social groups, and that does not come up anywhere near enough in the debate at hand. Do we even have good dromaeosaur brain scans publicly available?
I think the thing that's most interesting to me about the whole subject is the fact we have multiple occasions where groups as large as 6 individuals are observed in particularly large dromaeosaur species from the Early Cretaceous. Say what you want about other dromaeosaurs, but this, to me, is more than coincidence.

I guess overall, my absolute honest opinion (and I do stress the word "opinion" here) on the subject is that whether or not dromaeosaurids lived in groups or not is entirely variable between species. Some just did, some just didn't. No either/or for the whole clade (which people tend to actually end up doing). And I think that distinction may simply be the result of environmental factors. You can't just "tell" either way by looking at the bones.
Edited by Incinerox, Jun 7 2018, 07:16 AM.
Offline Profile Quote Post Goto Top
 
54godamora
Member Avatar


I apologize if I started a nasty debate
Offline Profile Quote Post Goto Top
 
Furka
Member Avatar


Truth to be told, the Utahraptor pit doesn't convince me much about their social nature.
IIRC there was one (maybe two?) adult, and all the others were youngs or juveniles.
To me it could be the case of the one adult dominant animal(s ?) resident in that area and the younger ones which are allowed into its territory because they pose no threat or competition for either food or mating (if anything they could be seen as food aswell). No other adults because you already have one that would keep the others away from the area.
Sorta like how Golden Eagle pairs are very territorial towards other adults and especially rival nesting pairs, but will usually let young animals enter their space (especially since youngs are more vagrant and wouldn't remain in one place for long).
Offline Profile Quote Post Goto Top
 
stargatedalek
Member Avatar
I'm not slow! That's just my moe!

I'm having trouble relocating my sources on the nocturnal evidence, I'll have to get back to you on that. That was in reference to Komodo speculating they were generalist predators, which is also not impossible for nocturnal animals though considerably less common than specialization (in large animals anyway). Not in reference to cooperative hunting.

When I said anatomy I meant that in reference to methods of killing. Adaptations for raptor-like prey restraint are seen almost universally among dromaeosaurs and it's not something that lends itself well to cooperative hunting. That doesn't rule out potentially tracking or chasing prey as a group, though we see these RPR adaptations in the same large dromaeosaurs we find preserved together so they presumably still killed in the same "one at a time" way.

The reason dromaeosaur morphology gives us anything to go by for group hunting is only because it's so specific to their methods of killing. It wouldn't hold water with practically any other group of animals.

Living in a cohesive, even amicable group is different from hunting as one, we see this distinction quite often in seabirds. Those that do not aggressively compete for nest space or resources will often interact peacefully or even defend their immediate neighbors nests from predators, regardless of whether they hunt together at all let alone cooperatively.

It's also worth noting some large dromaeosaurs have rather extreme anatomical differences between adults and young, such as flight capable young Deinonychus. While there are a number of different ways this could be taken; vestigial traits from a flying ancestor, juveniles living on their own and behaving differently, or juveniles living with adults and so needing these adaptations to stay out of harms way, are the most commonly presumed answers.
Offline Profile Quote Post Goto Top
 
Posted Image Flish
Member Avatar


I actually have put extensive investigation into this myself, and while there is no correlation between group living in ambush predators (like most Dromaeosaurs), there IS some correlation in morphology. We only ever see any signs of group behavior in large Dromaeosaurs. If anything, Velociraptorines and Unelagiines show adaptations specifically for hunting prey too small for multiple animals to feed on- fish and small game. This leaves Dromaeosaurines (and Deinonychus, depending on where you place it), which we see actual evidence of group behavior in (trackways and the Utah grouping)

on the subject of morphology not indicating group behavior, this is simply not true. We do not see any animal alive today that is both an endurance predator and hunts alone. Sailfish, dholes, wolves, hyenas, humans, orcas, etc. all are endurance hunters and pack hunters. This is why we can say with very little doubt Ceratosaurus and Dilophosaurus were both group animals (I mean, the Dilophosaurus holotype was found with two other individuals, too, so)

As for nocturnality in Dromaeosaurs and their braincases, megafaunal ambush predators are almost always nocturnal. It makes it much, much easier to hunt, and while it's not always the case in ambush predators (cheetahs are diurnal, but should be taken as an exception as this is almost certainly directly to avoid competition with larger, more dangerous predators) it's a pretty safe rule to live by, and from what I heard (though I never saw any paper) there was a study on Dromaeosaur braincases that indicates they had a massive olfactory bulge, and extreme senses of smell, eyesight, or hearing all indicate nocturnal behavior.
Offline Profile Quote Post Goto Top
 
54godamora
Member Avatar


what kind of islands where the ones like at the solnhofen limestone? i know that based on the fauna, it was islands with large bodies of water like lagoons and reefs but what were the islands like? were they arid or tropical?
Offline Profile Quote Post Goto Top
 
Komodo
Member Avatar
Varanus komodoensis

They seem to have been covered in sub-tropical dry forests and scrublands, with most of the vegetation comprised of shrubs, cycads and small trees. The climate was likely seasonal, with droughts being longer than rainy times.
Edited by Komodo, Jun 11 2018, 04:53 PM.
Offline Profile Quote Post Goto Top
 
54godamora
Member Avatar


define small trees. small like 3 meters tall or 3 feet tall?
Offline Profile Quote Post Goto Top
 
Komodo
Member Avatar
Varanus komodoensis

Closer to 3 meters tall, according to wikipedia.
Offline Profile Quote Post Goto Top
 
54godamora
Member Avatar


ok next fossil formation, cedar mt 126 mya.

my Princeton field guide of dinosaurs reads as:
"short wet season, otherwise semiarid with floodplain prairies and open woodlands, and riverine forests"

any additional info?
Offline Profile Quote Post Goto Top
 
Incinerox
Member Avatar
Āeksiot Zaldrīzoti

I think most of your questions can be solved with literally 5 minutes of googling.
Offline Profile Quote Post Goto Top
 
2 users reading this topic (2 Guests and 0 Anonymous)
Go to Next Page
« Previous Topic · Extinct Animals & Evolution · Next Topic »
Add Reply