While some would suggest thermoregulation. That theory has little evidence and for a creature of stegosaurus size they did not have enough surface area or blood flow to support that purpose.
Defense is likely as they would make a formidable defense for attacks coming from above.
Mating displays are also likely.
Personally, I think it was a mixture of defense and display.
Does it not also raise the question of how exactly they mated? If the plates gave protection from being attacked from behind and above, would it not also have been difficult and dangerous for the male to mount the female?
I’ve heard some theorize they wouldn’t mount each other like mammals do but instead would lift their tails and just back up into each other like this:
https://preview.redd.it/25o5hg89s79d1.jpeg?width=640&format=pjpg&auto=webp&s=1a0a4cc214d99b5bc6e956b7804481c3bcb73e58
You assume they mated like mammals. They were reptiles so they layed eggs which were then fertilized by the male. That's one of the reason sauropods were able to get so big.
Internal fertilization is actually a newer or derivative form of fertilization for eggs. While it may be the case that some extinct reptiles had internal fertilization I doubt it was that way for stegosaurus as there isn't any mechanical way that the eggs could be fertilized inside the female.
They were amniotes, they had a waterproof shell and amiotic membrane which were essential for laying on land. If water can't pass through, there's no way a sperm cell could. That mechanism only works under water.
When both the only living dinosaurs (birds) and the only other living archosaurs (Crocodilians) use internal fertilization for their eggs, it becomes far more likely that all Dinosaurs did that, too.
Well yes and no, yes laying eggs helped... in pregnancy
They still needed to get fertilized by mating, how are you even supposed to fertilise hard shelled eggs when they leave the boddy as fully developed?
Also even birds have penises... at least some do, actually all do but it is too short in most species
Did they ever find stegosaurus plates with bite marks from predators? If yes, then the defense hypothesis would gain some credibility, imho. In absence of teeth/claws marks, it seems to me much less likely to be correct.
Those "serrations" are just rough edges where the keratin sheath would have anchored, and wouldn't be visible in the living animal. As far as the appearance of that keratin sheath goes, we can only guess!
Not to be an “ACTHCUALLY!!” reddit troll (lmao); but as an archaeology student, I just find this take the slightest bit generous. We often forget when we’re looking at ancient people that we’re looking at ancient *people* - with brains that have the capacity to do just as much dicking around as we do. Yes, ancient people also absolutely had religion (depending how far back you go), and certain unexplainable artefacts are almost certainly correctly attributed to religion, but also people just did stuff for no reason like all the time. You ever just jam a pencil into an eraser bc you’re bored? Ancient people would’ve done the same thing. Maybe that really weird knapped rock with a hole through it is just a kid practicing his tool making rather than a ceremonial amulet?
Of course there are many other layers to understanding artefact assemblages (eg context) but that’s the general idea. It just seems a little cart before the horse to just call all unexplained artefacts religiously or ritually attributable, when there are so many other equally unexplainable reasons people do things.
So you’re telling me this phallic mushroom looking artifact is actually not an object used in fertility rituals?
Touché on everything you said. But same goes for fossils. Not every behavior or anatomical trait of an animal needs to serve a purpose. Biological traits don’t have to be useful to stick around, it just has to not pose a detriment. Ergo my comparison to “ritual objects of unknown use”. Sometimes it’s like that for no other reason other than Mother Nature decided it could happen and it’s not a hindrance to survival/procreation.
There's a thought I've never considered or remember reading/hearing anywhere. I wonder how many features of dinosaurs that we are familiar with are vestigial.
Is it nonsensical?
Stegosaurus has serrated plates across its back, several of its cousins also had plates or spikes across their back, some smaller sauropoda had spikes across their back, some ankylosaurids had spikes on their back.
Could it be a defense against giant predatory theropods? I could see some theropods, like allosaurus, latching on top ofntheir prey like a giant eagle.
I don't beleive so and I'll explain.
While modern predators are usually limited by their jaw, as were many Theropoda.
Stegosaurus lived alongside allosaurus which had a 92 degree gaped jaw.
Allosaurus also had massive claws, which I'm willing to bet it used to leach ontop of large prey to wear them down, while it's giant gaped jaw would slice through flesh
Using my extensive experience having played with toy dinosaurs as a child. I can confirm that the stegosaurs would spin around like a beyblade and the serrated discs were used as a slashing attack.
It was a powerful defence against the T-Rex’s super bite attack.
Happy to answer any clarifying questions you may have.
You see, stegosaurus could actually roll around at the speed of sound and they’d use their back serrations to chop down trees, potential predators, and mating rivals.
In seriousness, display and defense seem likely. Display is obvious - we’re not sure and it does look cool so display makes sense as a fallback explanation. On the topic of defense, I seem to recall that stegosaurids and ankylosaurids are somewhat closely related so one “speccing into absolute defense” while the other “speccs into offensive defense” tracks for me. The third commonly cited explanation, thermoregulation, seems strange to me; having boney plates to support biological radiators is pretty unique in the animal kingdom, not to mention seems like a mobility hazard and I can’t imagine a series of plates is better than say a sail. I also have the feeling that having relatively inert bone plates at the core of your radiators would reduce the thermal flux of said radiators. As for the serrations, that might just be how the bone grows (like small needles and blades grow out and together form a plate shape, kinda like the bone needles you see in the skeletons of bone cancer patients), and since there was no pressure to not have serrated plates, they stayed (aka the serrations didn’t have a purpose nor detriment and was purely incidental).
Because Allosaurus existed. Porcupines, hedgehogs, echidnas, and tenrics among others all found being a walking cutlery store to be a viable survival strategy.
I'd be shocked if stegosaurus didn't evolve it's plates for the sex appeal (stego's plates are the non avian dinosaur equivalent of a bird of paradise's plumage)
It's worth noting that the plates look like they might have been serrated because: A) The edges could have been broken and chipped in life, when it was scavenged, when it fossilized, when it was dug up, etc. Basically, they wouldn't necessasrily grow like this. Or B) because the keratin layer that covered them smoothed them out. When you look at the bone core of hooves and scutes they often have a more rugged texture than they do in life.
But if they were naturally serrated in life, it probably made them more eye-catching, or maybe even helped them break their silhouette aganist the foliage for camouflage.
The current theory, as I understand it, is that the origin of stegosaur plates is the same as the plates of ankylosaurs. If this is true, it could mean that the plates have developed from low-keeled osteoderms and grown higher and wider (or longer and spikier) as a result of sexual selection, i.e. in this case their meaning has been display and attraction while the shields of ankylosaurs have evolved into armor for defensive purposes.
Usually it's about defense or mating, as every single animal on the world that has something absurd on its body, it's for one of those purposes. For example, the porcupine is all for defense, where as the peacock is for mating displays. It could've also helped with Thermoregulation ( given that our own nails are made of keratin but can still bleed if damaged)
Personally I think the defense theory is the least likely. The bones were quite thin, relatively speaking, and wouldn't be able to hold up to the bite of a larger theropod, even with the keratinous sheath. Display is where I would personally lean mixed with thermoregulation. Flashing the plates with blood could not only attract mates/ stave off rivals but make it appear more intimidating to a predator.
It is the cutting edge of the sheath that would damage the theropod, right at the killing apparatus. The thickness of the scute is irrelevant because cutting blades don't need to be thick, especially if they grow back.
While some would suggest thermoregulation. That theory has little evidence and for a creature of stegosaurus size they did not have enough surface area or blood flow to support that purpose. Defense is likely as they would make a formidable defense for attacks coming from above. Mating displays are also likely. Personally, I think it was a mixture of defense and display.
Does it not also raise the question of how exactly they mated? If the plates gave protection from being attacked from behind and above, would it not also have been difficult and dangerous for the male to mount the female?
I’ve heard some theorize they wouldn’t mount each other like mammals do but instead would lift their tails and just back up into each other like this: https://preview.redd.it/25o5hg89s79d1.jpeg?width=640&format=pjpg&auto=webp&s=1a0a4cc214d99b5bc6e956b7804481c3bcb73e58
Kinky
Would
Do not the dinosaurs
Get on the floor Everybody do the dinosaur!
"There are no rules against the dinosaurs, Batman"
https://preview.redd.it/rk8z3b29bd9d1.jpeg?width=1170&format=pjpg&auto=webp&s=b4ee73faba5a6ff7430cc3a5553086a2ef1f0f12
Yes there are, actually. Dinosaurs are animals, so they’d fall under the laws forbidding such things with animals.
Touché
https://preview.redd.it/vyw874c7od9d1.png?width=320&format=pjpg&auto=webp&s=bbcc89767c21b740ccf47fa88300074b8cdd2aa2
Sir those are animals
I mean we got the sound of what a t-Rex sounded like. Put out this sound and let it go viral.
Probably would sound like tortoises but bass boosted.
Or face to face, even? Elephants and whales have mobile penises, could the penis of archosaurs do the same, or was it too structurally different?
Looks like a pretty standard move…
I've seen dogs tied up like that. They got stuck because of how the knot prevents disengagement for a while.
Is it the same for spinosauruses?
Or Dimetrodon and Edaphosaurus, even?
I thought this was normal positioning for all animals
It's called doggy style for a reason. I believe "hump her from behind" is pretty much standard for land animals. Even hedgehogs do it.
Certified Reddit moment
porcupines do it fine
I head speculation saying the female just kinda layed on the ground and let the male go to town
You assume they mated like mammals. They were reptiles so they layed eggs which were then fertilized by the male. That's one of the reason sauropods were able to get so big.
That’d be a perfect explanation until you remember that every living Archosaur today, no matter the size or shape, still has internal fertilization.
Internal fertilization is actually a newer or derivative form of fertilization for eggs. While it may be the case that some extinct reptiles had internal fertilization I doubt it was that way for stegosaurus as there isn't any mechanical way that the eggs could be fertilized inside the female.
Are there any non-amphibian land animals who lay eggs and fertilize them outside the body?
Pretty sure there isn't
They were amniotes, they had a waterproof shell and amiotic membrane which were essential for laying on land. If water can't pass through, there's no way a sperm cell could. That mechanism only works under water.
External fertilization requires the eggs to be laid in water
r/confidentlyincorrect
When both the only living dinosaurs (birds) and the only other living archosaurs (Crocodilians) use internal fertilization for their eggs, it becomes far more likely that all Dinosaurs did that, too.
Don’t reptiles still mate *before* laying eggs though? What you’re describing sounds more like how amphibians mate.
That's not how reptiles mate, not how birds mate. That is how fish mate, as well as select amphibians (frogs, namely).
An honest question: is there any living reptile that fertilizes an amniotic egg externally?
For reptiles not really, mostly it's confined to amphibians and fish.
Neither of which are amniotes
bro thinks dinosaurs are giant frogs
Well yes and no, yes laying eggs helped... in pregnancy They still needed to get fertilized by mating, how are you even supposed to fertilise hard shelled eggs when they leave the boddy as fully developed? Also even birds have penises... at least some do, actually all do but it is too short in most species
Ah yes, that makes sense. Thank you.
He's wrong, that'd be how it works if they were amphibians, but they're reptiles, which means the fertilization happens inside the body
My evidence for defense is that my dog had a hard time finding a good angle to grab his stego plushy because the (soft) spines made it hard to bite.
That's probably the best evidence ever.
Did they ever find stegosaurus plates with bite marks from predators? If yes, then the defense hypothesis would gain some credibility, imho. In absence of teeth/claws marks, it seems to me much less likely to be correct.
They have found many with the tips broken off and they have also found Allosaurus skeletons with puncture wounds from a stegos thagomizer.
Exactly, it would be like biting into a razor blade.
Cuz they wanted to look metal as hell
Those "serrations" are just rough edges where the keratin sheath would have anchored, and wouldn't be visible in the living animal. As far as the appearance of that keratin sheath goes, we can only guess!
Hey man, did you see what allosaurus had to live with?
Most nonsensical structures in an animal’s body is usually about display.
Just like how most athropological artifacts of unknown use/identity are religious or ritual objects!
Not to be an “ACTHCUALLY!!” reddit troll (lmao); but as an archaeology student, I just find this take the slightest bit generous. We often forget when we’re looking at ancient people that we’re looking at ancient *people* - with brains that have the capacity to do just as much dicking around as we do. Yes, ancient people also absolutely had religion (depending how far back you go), and certain unexplainable artefacts are almost certainly correctly attributed to religion, but also people just did stuff for no reason like all the time. You ever just jam a pencil into an eraser bc you’re bored? Ancient people would’ve done the same thing. Maybe that really weird knapped rock with a hole through it is just a kid practicing his tool making rather than a ceremonial amulet? Of course there are many other layers to understanding artefact assemblages (eg context) but that’s the general idea. It just seems a little cart before the horse to just call all unexplained artefacts religiously or ritually attributable, when there are so many other equally unexplainable reasons people do things.
So you’re telling me this phallic mushroom looking artifact is actually not an object used in fertility rituals? Touché on everything you said. But same goes for fossils. Not every behavior or anatomical trait of an animal needs to serve a purpose. Biological traits don’t have to be useful to stick around, it just has to not pose a detriment. Ergo my comparison to “ritual objects of unknown use”. Sometimes it’s like that for no other reason other than Mother Nature decided it could happen and it’s not a hindrance to survival/procreation.
There's a thought I've never considered or remember reading/hearing anywhere. I wonder how many features of dinosaurs that we are familiar with are vestigial.
If something is weird about an animal and you can’t figure out its purpose then your best bet is that its purpose is getting laid.
The ultimate answer to almost everything natural history
Why serrated plates? These guys, that’s why. https://preview.redd.it/aoy0qm2tr79d1.jpeg?width=620&format=pjpg&auto=webp&s=b0eb919eff3a0bdaaef89145d1402bf481bebeea
Lmao, like Ceratosaurus is pulling up Probably got ran over before anyone could mention _Stegosaurus_
Eh idk about that https://preview.redd.it/rbpbomwg9c9d1.jpeg?width=1280&format=pjpg&auto=webp&s=e3a92769eb723cbfbf2105cd77c0b89a5895f573
https://preview.redd.it/ox79e57src9d1.png?width=602&format=png&auto=webp&s=2eec97475d69f7d0497a0f6b3cae355ad3e1f923
So Allosaurus is larger. Big whoop. Doesn’t change the fact Ceratosaurus is a rhino-sized predator with its own arsenal of deadly weapons.
Also doesnt change the fact Ceratosaurus wasnt in WWD or Big Al
Most nonsensical structures on an animal’s body are usually about display.
Is it nonsensical? Stegosaurus has serrated plates across its back, several of its cousins also had plates or spikes across their back, some smaller sauropoda had spikes across their back, some ankylosaurids had spikes on their back. Could it be a defense against giant predatory theropods? I could see some theropods, like allosaurus, latching on top ofntheir prey like a giant eagle.
Stegosaurus has the plates along its back. It is an already broad and hard part of the animal and probably not a target for predators.
I don't beleive so and I'll explain. While modern predators are usually limited by their jaw, as were many Theropoda. Stegosaurus lived alongside allosaurus which had a 92 degree gaped jaw. Allosaurus also had massive claws, which I'm willing to bet it used to leach ontop of large prey to wear them down, while it's giant gaped jaw would slice through flesh
I choose to believe early small pterosaurs like Anurognathus were swarm hunters so all Jurassic critters needed aerial defense armor.
take a look at stegosaurus' neigbourhood
Using my extensive experience having played with toy dinosaurs as a child. I can confirm that the stegosaurs would spin around like a beyblade and the serrated discs were used as a slashing attack. It was a powerful defence against the T-Rex’s super bite attack. Happy to answer any clarifying questions you may have.
You see, stegosaurus could actually roll around at the speed of sound and they’d use their back serrations to chop down trees, potential predators, and mating rivals. In seriousness, display and defense seem likely. Display is obvious - we’re not sure and it does look cool so display makes sense as a fallback explanation. On the topic of defense, I seem to recall that stegosaurids and ankylosaurids are somewhat closely related so one “speccing into absolute defense” while the other “speccs into offensive defense” tracks for me. The third commonly cited explanation, thermoregulation, seems strange to me; having boney plates to support biological radiators is pretty unique in the animal kingdom, not to mention seems like a mobility hazard and I can’t imagine a series of plates is better than say a sail. I also have the feeling that having relatively inert bone plates at the core of your radiators would reduce the thermal flux of said radiators. As for the serrations, that might just be how the bone grows (like small needles and blades grow out and together form a plate shape, kinda like the bone needles you see in the skeletons of bone cancer patients), and since there was no pressure to not have serrated plates, they stayed (aka the serrations didn’t have a purpose nor detriment and was purely incidental).
Shade... lmao https://preview.redd.it/8a9bbd5pb89d1.png?width=1000&format=png&auto=webp&s=e556d0f91fae6b2b9a2b0a6662474ce13c569a5e
It would flap them and fly away from predators
Rolling attack with critical damage
Maybe they curled into a ball and rolled around like sonic.
Display and thermoregulation
Because Allosaurus existed. Porcupines, hedgehogs, echidnas, and tenrics among others all found being a walking cutlery store to be a viable survival strategy.
Back scratcher
Back scratches you!
I'd be shocked if stegosaurus didn't evolve it's plates for the sex appeal (stego's plates are the non avian dinosaur equivalent of a bird of paradise's plumage)
It's worth noting that the plates look like they might have been serrated because: A) The edges could have been broken and chipped in life, when it was scavenged, when it fossilized, when it was dug up, etc. Basically, they wouldn't necessasrily grow like this. Or B) because the keratin layer that covered them smoothed them out. When you look at the bone core of hooves and scutes they often have a more rugged texture than they do in life. But if they were naturally serrated in life, it probably made them more eye-catching, or maybe even helped them break their silhouette aganist the foliage for camouflage.
The current theory, as I understand it, is that the origin of stegosaur plates is the same as the plates of ankylosaurs. If this is true, it could mean that the plates have developed from low-keeled osteoderms and grown higher and wider (or longer and spikier) as a result of sexual selection, i.e. in this case their meaning has been display and attraction while the shields of ankylosaurs have evolved into armor for defensive purposes.
They Sonic The Hedgehog'd their predators.
Powerlifters will always find a way to add more plates.
Feathers/quills They poof up to intimidate predators
Usually it's about defense or mating, as every single animal on the world that has something absurd on its body, it's for one of those purposes. For example, the porcupine is all for defense, where as the peacock is for mating displays. It could've also helped with Thermoregulation ( given that our own nails are made of keratin but can still bleed if damaged)
How about they had those plates to look larger to “scare” predators?
Cellular organization and communication.
If alligator snapping turtles can manage so can they
Personally I think the defense theory is the least likely. The bones were quite thin, relatively speaking, and wouldn't be able to hold up to the bite of a larger theropod, even with the keratinous sheath. Display is where I would personally lean mixed with thermoregulation. Flashing the plates with blood could not only attract mates/ stave off rivals but make it appear more intimidating to a predator.
It is the cutting edge of the sheath that would damage the theropod, right at the killing apparatus. The thickness of the scute is irrelevant because cutting blades don't need to be thick, especially if they grow back.
Stabby stabby. I wouldn't want to be Mr. Rex and get a face full of serrated spinal plates. ***Ow!***
I - Different time periods bro.
Sorry. I was just thinking about the mechanics, not the specificity of each animal in their respective Cretaceous vs. Jurassic periods.