Dinosaurs and other prehistoric creatures

[Xenodog]

For dinosaur, T-Rex cause it's the motherf**king T-Rex, in all seriousness though it's big, looks cool, and has a lot of sharp teeth.

As for prehistoric mammal, it's a tie between a Cave Bear and Basilosaurus. Both are bigger and more badass versions of animals that still exist, and Cave Bears are basically giant bears, that's f**king awesome no matter how you put it.

If you like Cave Bears, are you aware of the giant Short Faced Bear? 

[DoomRulz]

No one else?...

In that case, favourite dinosaur & prehistoric mammal and why, anyone?

T.Rex, always. I grew up with it as the ultimate carnivore and that has stuck with me since I was a kid. Mammal...it's a tie between a mammoth and Basilosaurus. I grew up knowing about mammoths and that term has become synonymous with anything large in life, plus I love whales so that's why I took to Basilosaurus.

[Gilfryd]

Pterosaur myths busted
http://pterosauria.tumblr.com/post/64864790579/image-pteranodon-by-larry-felder-pterosaur

[King Rathalos]

For dinosaur, T-Rex cause it's the motherf**king T-Rex, in all seriousness though it's big, looks cool, and has a lot of sharp teeth.

As for prehistoric mammal, it's a tie between a Cave Bear and Basilosaurus. Both are bigger and more badass versions of animals that still exist, and Cave Bears are basically giant bears, that's f**king awesome no matter how you put it.

If you like Cave Bears, are you aware of the giant Short Faced Bear? 

Absolutely.

[Vertigo]

Pterosaur myths busted
http://pterosauria.tumblr.com/post/64864790579/image-pteranodon-by-larry-felder-pterosaur

I've been reading through Mark Witton's book on pterosaurs while on holiday, I'd strongly recommend it to anyone here. It's obviously written by a scientist rather than an author, as he frequently gets bogged down in details and research trivia. So it doesn't exactly bring pterosaurs to life, but it's extremely comprehensive and shows you the complete picture, detailing the competing theories and strength of evidence for each major issue.
It's pretty academic, but as Witton explains most of the terminology, it's rarely a difficult read. I think any adult with an interest in the subject will be able to enjoy it.

[Vertigo]

Just answering these posts from the Crynosaurs thread in somewhere more on-topic.

A bit off topic, but what do you think about the scientific thought that dinosaurs were literally so far from reptiles that modern birds are now considered survivors of the Dinosaur era?

It's pretty much unanimously accepted at this point that birds are dinosaurs. They evolved from coelurosaur theropods during the late Jurassic. They're a bit deeper into the group than Compsognathus and Tyrannosaurus, putting them in the subdivision Maniraptora along with the closely-related therizinosaurs, alvarezsaurs, oviraptorosaurs, dromaeosaurs (inc. Velociraptor) and troodontids. Birds are most closely related to the latter two.

The most compelling evidence of this comes from recent fossil discoveries in China, with creatures like Epidexipteryx and Anchiornis which are unmistakably dinosaurs yet are evolving traits that appear in 'first bird' Archaeopteryx. They blur the line to such a degree that it's hard to decide whether they should be classed as a bird or a dinosaur.

We've also discovered tiny amounts of dinosaur biological material, and they've proven to be closer to birds than anything else alive today.
Finally, we see bird traits in many dinosaur groups, such as feathery insulation, calcified eggs and skeletal air sacs. Not to mention, as alluded to in Jurassic Park, the similarities are striking even if you just look at the skeletons - scientists suggested the connection as long ago as the 19th century.


Anyway, that 'reptile' name. 'Reptilia' isn't actually a cladistic term, it's more of a descriptor - anything cold-blooded, scaly, sprawling and laying squishy eggs. It's a term used for thoroughly unrelated creatures - lizards (along with snakes, plesiosaurs etc), crocodiles and our ancestors the synapsids are all referred to as 'reptiles' yet each is separated by vast gulfs of time and evolution.
However. It's almost certain that no dinosaur was strictly cold-blooded (though some early species may have required additional thermoregulation from their environment). Many theropods were feathery rather than scaly, and there's a chance that every small or cold-weather dinosaur may have had some form of bristly insulation. Every dinosaur had an upright, active stance like birds and mammals do. And every dinosaur egg we've ever found has been a hard structure similar to a bird's.
Even if you discount the birds, there isn't really any 'reptile' feature that applies to every dinosaur group. Though if you take the Wikipedia definition of Reptilia as "any amniote that isn't a mammal or bird" then maybe I'm being unnecessarily pedantic.

I believe it. Most people think about T-Rexes shrinking down because of evolution, though. That's probably the wrong way to look at it. The big dinos are the ones that probably died out, and the small ones evolved and started to develop feathers and wings at some point.

Tyrannosaurs kept getting bigger as time went on! Rexy itself was the apex of the family - the largest by a considerable margin, and the last one before the mass-extinction event. This is a trend that happened in several other dinosaur groups immediately before the extinction, particularly in North America, and we're not sure why. It was terrible timing, as on land only small animals survived the apocalypse.

The birds had actually evolved a hundred million years before the extinction, though most of the bird groups were annihilated at the end of the Cretaceous too. Their ancestors were indeed all small dinosaurs, as you suggest - they did shrink on the way to becoming birds, but not by an order of magnitude.

[xeno-kaname]

Just answering these posts from the Crynosaurs thread in somewhere more on-topic.

I believe it. Most people think about T-Rexes shrinking down because of evolution, though. That's probably the wrong way to look at it. The big dinos are the ones that probably died out, and the small ones evolved and started to develop feathers and wings at some point.

Tyrannosaurs kept getting bigger as time went on! Rexy itself was the apex of the family - the largest by a considerable margin, and the last one before the mass-extinction event. This is a trend that happened in several other dinosaur groups immediately before the extinction, particularly in North America, and we're not sure why. It was terrible timing, as on land only small animals survived the apocalypse.

The birds had actually evolved a hundred million years before the extinction, though most of the bird groups were annihilated at the end of the Cretaceous too. Their ancestors were indeed all small dinosaurs, as you suggest - they did shrink on the way to becoming birds, but not by an order of magnitude.

Ah, I'm glad I seem to be right on that one, at lest to some degree  I was mentioning how people scoff at this particular theory because of that misconception. They're imagining huge dinosaurs shrinking down to the birds we see today. I guess it's not impossible, but improbable. It's just that when the theory is usually talked about in articles or publications, they rarely specify which dinosaurs evolved. So we get skeptics (mostly overly religious ones, in my experience) mocking the thought of Rexes shrinking down to modern day birds  Once I mention small dinosaurs, it gets easier to imagine.

[DoomRulz]

Every dinosaur had an upright, active stance like birds and mammals do.

I'm not sure the quadrupedal herbivores would fit that description.

I believe it. Most people think about T-Rexes shrinking down because of evolution, though. That's probably the wrong way to look at it. The big dinos are the ones that probably died out, and the small ones evolved and started to develop feathers and wings at some point.

Tyrannosaurs kept getting bigger as time went on! Rexy itself was the apex of the family - the largest by a considerable margin, and the last one before the mass-extinction event. This is a trend that happened in several other dinosaur groups immediately before the extinction, particularly in North America, and we're not sure why. It was terrible timing, as on land only small animals survived the apocalypse.

I think T.Rex in particular had to grow as large as it did in response to the prey items of the day. When you're going after creatures like Triceratops, Ankylosaurus, Alamosaurus, and Edmontosaurus, size will come in handy.

[Xenodog]

Every dinosaur had an upright, active stance like birds and mammals do.

I'm not sure the quadrupedal herbivores would fit that description.

I believe it. Most people think about T-Rexes shrinking down because of evolution, though. That's probably the wrong way to look at it. The big dinos are the ones that probably died out, and the small ones evolved and started to develop feathers and wings at some point.

Tyrannosaurs kept getting bigger as time went on! Rexy itself was the apex of the family - the largest by a considerable margin, and the last one before the mass-extinction event. This is a trend that happened in several other dinosaur groups immediately before the extinction, particularly in North America, and we're not sure why. It was terrible timing, as on land only small animals survived the apocalypse.

I think T.Rex in particular had to grow as large as it did in response to the prey items of the day. When you're going after creatures like Triceratops, Ankylosaurus, Alamosaurus, and Edmontosaurus, size will come in handy.

Ankylosaurus predation sounds pretty ambitious!
I think ankylosaur ecology is pretty interesting in regards to predation though. If Ankylosaurus lived at low densities (suggested by the fossil record compared to Triceratops and Edmontosaurus) this would presumably keep oppurtunistic rex predation very low solely due to abundance. But if they layed egg clutches then maybe the species had a high infant mortality - I think I read somewhere it had been suggested ankylosaur armour was softer and more spongey in early life?

[DoomRulz]

I think that T.Rex would have avoided Ankylosaurus as it's a prey item that is more trouble than it's worth but in times of desperation would go for it.

[Xenodog]

Yeah that's most likely I.M.O. I also wonder if certain individual dinosaurs in a species, despite their more primitive brains, had the ability to specialise in certain prey items that were unusual or dangerous like some modern predators.

[Greedo]

Anyone image what Dinosaurs could have done if they had camo ? *__*

[DoomRulz]

Yeah that's most likely I.M.O. I also wonder if certain individual dinosaurs in a species, despite their more primitive brains, had the ability to specialise in certain prey items that were unusual or dangerous like some modern predators.

Yes, I would say so but I couldn't comment on their mental capacity in this case. From a physical perspective however, I say it's a definitive yes. I think the reason T.Rex grew the super-strong jaws it had was because it was going after large, bulky prey like ceratopsians and hardosaurids and such raw power would have helped tremendously. I also think the same of carnosaurs like Allosaurus or Mapusaurus. They had longer arms, one extra claw (three vs. two), and serrated teeth designed for slicing because if you're tackling large sauropods, you aren't going to stand your ground and fight tooth and nail. It's easier to take nips here and there and wait for it to bleed out.

[Requiem28]

I think that T.Rex would have avoided Ankylosaurus as it's a prey item that is more trouble than it's worth but in times of desperation would go for it.

Once it got him on his back, though......game over for Ank.

[Vertigo]

Every dinosaur had an upright, active stance like birds and mammals do.

I'm not sure the quadrupedal herbivores would fit that description.

By 'upright' I mean they held their legs directly beneath their bodies in a pillar-like manner, rather than the side-sprawled manner of reptiles. I was trying to avoid saying 'erect' as this makes me imagine them walking along on a set of giant penises.
The advantage of a sprawled posture is that it allows an animal to go from sitting to running almost immediately, essential for a cold-blooded animal that spends most of its time resting.
The downsides are that it's a drain on energy as it uses more muscle power to move quickly, and as the locomotion compresses the torso, it limits (or even negates) their ability to breathe while running. Warm-blooded animals gain far more of their energy from breathing than cold-blooded ones do, so they need an upright posture to achieve peak performance.

All dinosaurs had this upright leg configuration, and aside from my point about this differentiating them from the classic definition of 'reptile', it marks them out as a very active group of animals. You can pick out an outdated piece of palaeo-art very easily, as they often depicted the quadrupeds with a sprawled leg posture to match the sluggish, cold-blooded lifestyle they were assumed to lead at the time.

Spoiler

I believe it. Most people think about T-Rexes shrinking down because of evolution, though. That's probably the wrong way to look at it. The big dinos are the ones that probably died out, and the small ones evolved and started to develop feathers and wings at some point.

Tyrannosaurs kept getting bigger as time went on! Rexy itself was the apex of the family - the largest by a considerable margin, and the last one before the mass-extinction event. This is a trend that happened in several other dinosaur groups immediately before the extinction, particularly in North America, and we're not sure why. It was terrible timing, as on land only small animals survived the apocalypse.

[close]

I think T.Rex in particular had to grow as large as it did in response to the prey items of the day. When you're going after creatures like Triceratops, Ankylosaurus, Alamosaurus, and Edmontosaurus, size will come in handy.

Certainly true, predators tend to evolve in response to their prey (herbivores are less tied to their predators' evolution, as generally the percentage taken by predation isn't large. Then again, most herbivores in history haven't had to contend with Tyrannosaurus rex...). The question is why the herbivores needed to grow so huge, and why many smaller animals became marginalised or extinct in the last age of the Cretaceous (the Maastrichtian).
My guess is that it had something to do with their diet. I know certain types of grasses appeared at some point in the Cretaceous, but am not sure exactly when. A larger stomach aids digestion, so if the Maastrichtian herbivores were needing to cope with a wider variety of food, or just tougher stuff, then it might explain the growth spurt.

Yeah that's most likely I.M.O. I also wonder if certain individual dinosaurs in a species, despite their more primitive brains, had the ability to specialise in certain prey items that were unusual or dangerous like some modern predators.

Dinosaur intelligence is an incredibly tricky subject, I ranted about it a little while ago. Probably fair to assume that any dinosaur with a lower EQ than a crocodile wasn't terribly bright, and many of the groups may be comparable to each other, but other than that, the only accurate assumption is that we don't really have a clear impression of what they could do. My two-minute bout of googling suggests that avian intelligence is governed by a region of the brain called the nidopallium caudolaterale, and I've never seen a study of this in dinosaurs.
But no dinosaur brain is entirely comparable to that of a bird, and they probably aren't comparable to crocodiles either, so until we put a Compsognathus through a maze to find some cheese, I wouldn't put faith in any assessment of dinosaur intelligence.

Intelligence aside though, it's true that the modern avian brain structure was constantly developing throughout Coelurosauria and well into the early birds, so the 'primitive' label is indeed accurate as a comparator to their descendants. I seem to have lost my notes, but I dimly remember that a tyrannosaur brain is around 5% of the way from reptile brain structure to bird.
It's important to make the distinction that this doesn't necessarily have anything to do with intelligence though, some reptiles can be surprisingly smart. I remember reading a study in which a heated-up tortoise was put around the same maze as a rat, and it solved it more efficiently - whereas it fared poorly in rooms below its peak operating temperature, the state that all previous reptillian studies had been performed.

Anyway. Specialisation is a result of learned behaviour, so I suppose a lot of it depends on how long theropods were raised by their parents. Aside from this resulting in parental teaching of hunting techniques, animals with extended rearing periods tend to have more flexible behaviour, less programmed by instinct (this is just me speculating based on animals I'm familiar with, so feel free to call bullshit on that one). But I see learned specialisation in animals as disparate as great white sharks, lions, orcas and harris hawks, so it wouldn't surprise me to see it in dinosaurs.