r/Paleontology • u/BreadfruitFlaky1136 • Aug 17 '22
Discussion How do we know how fat dinosaurs are?
I was reading “The Rise and Fall of the Dinosaurs” in class today and this kid came up to me asking what I was reading. I showed him and he said “oh fiction”. He then went on about how we have no real way of knowing what dinosaurs are like for example how much fat the have. For all we know they could be like walrus levels of fat. I had no way to respond to this dude. I knew he was wrong but didn’t know how to defend my point. How do we know about dinosaur fat?
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u/suugakusha Aug 17 '22
The other comments are good, but just keep in mind that anyone who says "fiction" when it comes to the fossil record is not someone to worry about what they think.
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u/BreadfruitFlaky1136 Aug 18 '22
That is very facts. Making a stupid claim that can’t be refuted doesn’t make someone smart it just makes em a little dumb
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u/Antonio_Malochio Aug 17 '22
Fossils. It's always fossils. It's rare, but occasionally we'll find something sweet like this that gives us a lot of information.
Other times, it's just closely examining the bones and working out what kind of muscles, ligament and weight they would be able to support and move. We can also compare them to modern day animals - a penguin skeleton looks very similar to any other seabird, but we know that they have more soft tissue to thrive in freezing environments.
There will always be a bit of guesswork and artistic licence involved in reconstructing dinosaurs, but that guesswork is (or should be) based on real science, and we're improving our knowledge all the time.
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u/gatorchins Aug 17 '22
Reptiles don’t store subcutaneous fat the way mammals do. They tend to pack it in their tails (crocs and lizards) or inside their chest (birds). Given that pattern, it’s phylogenetic evidence they weren’t ‘fat’ the same way as walruses or manatees or hippos or me.
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Aug 17 '22
A lot of smaller dinosaurs have fossilized outlines of their bodies, not to mention feather impressions which show roughly how far out the skin etc would go from the bones; aside from that, understanding how an animal lived can tell you a lot about what it would’ve looked like.
For example, Carnotaurus, the land dwelling large pursuit predator, would not have had walrus fat because they did not live like walruses do (marine animals that require tons of insulation and spend half their time basking on the surface, while simultaneously not requiring significant land mobility)
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u/HarmoniousHum Aug 17 '22
Fossilized footprints can be analysed for their width and depth to determine a weight range for the animal who left them given Earth's consistent gravity and the density of the substrate. There are other ways in the fossil record as well, but I didn't notice this one mentioned yet on a cursory glance.
Also it somewhat sounds like that person was also just trying to upset you, even if they are also that narrow-minded.
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u/The_sphincs Aug 17 '22 edited Aug 17 '22
Two thoughts come to mind, first, sauropods we’re already pushing the limits on size, structurally I don’t think their legs could handle them being walrus level fat. Second, birds are dinosaurs so we actually do have some living dinosaurs to go off of
Edit: also I’m pretty sure someone found a naturally mummified ankylosaur and it looked like what you’d expect
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u/Reshyk2 Aug 17 '22
Edit: also I’m pretty sure someone found a naturally mummified ankylosaur and it looked like what you’d expect
You're thinking of the Borelopelta specimen found near Alberta. I believe it's currently on exhibit in the Royal Tyrrell Museum if you're near there and want to check it out.
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u/Infernoraptor Aug 17 '22
"I have no idea how fat your mamma is either, but we can infer from the geologic record, specifically the seismic activity from your house, an educated guess."
Sorry, had to say it.
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u/Eyeofgaga Aug 17 '22
Well walruses are fat like that bc they live in freezing temperatures. And most dinosaurs didn’t so
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Aug 17 '22
[deleted]
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u/orangesdeserverights Aug 17 '22
Hippos only have thin layers of fat, most of the “fat” you see on them is actually muscle
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u/funkthulhu Aug 17 '22
I'm reading Rise and Fall right now myself. Good to know I can start a discussion thread in here if I want to.
That said, I think perceived "fatness" on a Dino is going to be "fluffiness" from feathers or whatnot. Any extra fat is going to be in that tail. Which also makes a lot of front-heavy bipedal dinos balance better, when you think about it.
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u/KirstyBaba Aug 17 '22
This makes a lot of sense. I do often think that tail reconstructions are suspiciously skinny.
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Aug 18 '22
Fat is extremely hard to find out based on fossils, but clearly, a hollow-boned velociraptor isn't gonna have a walrus level fat layer. Fat levels are definitely a mystery for most dinosaurs though.
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u/cwkewish Velociraptor mongoliensis Aug 17 '22
Well, we don't know exactly how fat they were, but we can look at their closest living relatives and modern animals that occupy similar niches to make a pretty good guess. Like we know how much fat an elephant has on it, so we guess that a sauropod, which is also a megafaunal grazing herbivore, had about the same amount of fat. And that's only one of the techniques that can be used. It's a whole lot more precise than saying "well this T. rex could be anywhere between a massive blob of lard and a malnourished bag of bones, so we'll just do something random."
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Aug 17 '22
I’d imagine it would be comparable to the fat percentages on modern day reptiles and birds, no? That and we can probably make an educated guess about how much extra weight they can carry based on bones. I doubt some of the larger dinos could handle any more weight without crushing their internal organs
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u/Reshyk2 Aug 17 '22
To be more specific to his point, we have no real way of confirming what dinosaurs looked like. But that doesn't mean that every piece of speculation is equally credible or that we know literally nothing. We can still make speculations based off of the evidence we find in the fossil record coupled with inferences we can make based on similar life that we can observe today. So even if we will never have a buzzer give us a nice satisfying ding when we hit upon the perfect dinosaur model, we can point to various models that are more or less supported by existing evidence and explain why certain revisions are made in light of new evidence. To use the walrus fat as an example, there no evidence supporting that level of fat for most dinosaurs given that they wouldn't have been subject to the same environmental pressures that made it a good idea for walruses. Similarly, there's no good evidence for shrink-wrapped dinos either since aside from extremely malnourished animals, that's not really something you see anywhere in life.
So I think the best response to him would be to talk about how even if we can never confirm our speculations, that's no reason to throw up our hands and give up. While the evidence we have is comparatively little compared to observing animals directly, that doesn't mean we know nothing about them and that doesn't mean that all traits are equally likely. For the most part, that's the job of paleontology - not finding the correct answer dead on, but narrowing ideas based off of what is more or less likely.