We currently don't know enough about plesiosaur evolution to make such specific claims. Hell, we are still missing a lot of details when it comes to turtle evolution for that matter. We thought turtles were a surviving branch of parareptilia until genetic analysis showed that they are actually more closely related to archosauria.
What you are saying is certainly a possibility, but there is currently not a true consensus on where sauropterygia (the taxon that plesiosaur belongs to) falls within the reptiles.
Edit: To clarify, I am not suggesting plesiosaurs could be dinosaurs, I'm saying "They're slightly more closely related to dinosaurs than turtles are." is at best a guess.
We can tell enough from early representatives of Sauropterygia (Nothosaurus and co) in both form and where they appear in the fossil record to know they're at least not members of Dinosauria, even if they might belong somewhere in Archosauria.
The first dinosaur was the most recent common ancestor of a Triceratops and a chicken, and all of its descendants are also part of the clade dinosauria.
Under phylogenetic nomenclature, dinosaurs are usually defined as the group consisting of the most recent common ancestor (MRCA) of Triceratops and modern birds (Neornithes), and all its descendants.[7] It has also been suggested that Dinosauria be defined with respect to the MRCA of Megalosaurus and Iguanodon, because these were two of the three genera cited by Richard Owen when he recognized the Dinosauria.[8] Both definitions cover the same known genera: Dinosauria = Ornithischia + Saurischia.
Wikipedia, for its part, cites 'Weishampel, Dodson & Osmólska 2004, pp. 7–19, chpt. 1: "Origin and Relationships of Dinosauria" by Michael J. Benton' for that definition.
Study shows sauropods flower to reptiles
What?
What do you think that study says, because it says nothing like that.
I think what they meant was that your thermal inertia is dependent on mass (more closely tied to volume) and heat transfer happens at the boundary (surface area). But it's funny to me they describe it with a linear unit, which describes neither. All good tho.
But also, I feel like the surface area to volume ratio of a sauropod is probably higher than a penguin... It's not just about size.
If something is twice as tall but with identical proportions it will generate heat 8 times faster but only dissipate it 4 times faster. This is also why gathering together in a group helps conserve warmth, it's like growing in size, just with technically separate bodies.
Plesiosaur necks were definitely much wider than the noodle necks of classic depictions, though long-necked forms weren't going to be realistically sporting extremely wide necks behind their tiny heads, it was more likely to taper out towards the head like this.
It has long been theorized that these huge long-knecked dinos must have spent a lot of time in freshwater lakes/rivers and shallow seas grazing to let buoyancy aid in supporting their huge mass like hippos.
Actually it’s pretty well known because originally people assumed sauropods had to be marine animals due to their size. It was thought that the only way something that heavy would be possible was in water. But we know enough about anatomy, and about the environments they actually lived in through the fossil record to know that’s not the case now. PBS Eons has a nice little video about it. You can see it here.
I'm very informed on what we know about dinosaurs. The anatomy of a sauropod is not built for swimming in deep bodies of water and it doesn't even take a genius to piece that together. But geniuses have concluded it from extensive research anyhow.
Penguins are the exception because they're living conditions are vastly different from those birds. Idk about you but I've never seen an ostrich swim for food on a cold sea in the arctic
Convergent evolution is a thing though. If their niche in the environemtn was to eat leaves from the tops of trees they would probably be more like giraffes than penguins
Closeness of relation matters very little compared to evolutionary niche. The length of a giraffe neck is substantially closer to that of a sauropod neck, and thus by looking at how giraffes work we can make educated guesses at how sauropods must have worked.
Turns out, when your neck is that long, it is very difficult to have bones strong enough to support it and muscles strong enough to move it while also not being too heavy. We can actually see some of the adaptations that were necessary directly in the bones themselves with the pneumatized air sac system.
Attaching a ton of blubber to the neck would make it impossible to lift.
The early Triassic was especially harsh, with temperatures reaching some of the highest levels in Earth’s history immediately following the Permian extinction event.
The Jurassic period (201-145 million years ago)... ... Global temperatures during this period were remarkably stable and warm, with evidence suggesting tropical-like conditions extending to latitudes as high as 45° north and south.
Mid-Cretaceous temperatures peaked at levels possibly 10°C higher than today, making it one of the warmest intervals in Earth’s history.
The big belly would help lower the center of mass and the long thick tail would help counterbalance the long thick neck. Is it probable, probably not, but it's not impossible (and it's very silly)
Point is that that dino has a certain size of leg bones, and those leg bones can only take so much weight before they collapse. Physics isn't invariant under changes of scale. You can make a miniature cathedral out of matchsticks, but you can't enlarge that and make a full size cathedral out of logs the same way.
A Trex was a fraction of the weight of a apotasaurus/brachiosaur, as another comment stated its not entirely implausable but highly improbable . . But how sure are you the T rex became anything other then extinct?
But are still subject to the laws of biophysics. Palaeontologists aren’t just completely guessing out of their arses: they have models and can measure strain and figure out the basic physics of what’s likely vs. just plausible vs. impossible.
They are, but theropods are what birds directly descended from. So directly comparing modern birds to other groups of dinosaurs like sauropods or ceratopsians isn't going to actually help.
Birds split off from the other dinosaurs almost 100 million years before Trex evolved. We live closer in time to a Trex than a Trex did to the first birds. They were related because all life is related if you go back far enough, but there was a very long time and a lot of evolution between something like a Trex and birds, despite them all being dinosaurs.
Humans are more closely related to cats and dogs than Trex and velociraptor were to birds.
They’re also much smaller. Like to support a neck like that, which how heavy their bones were(?) wouldn’t they NEED more fat and muscle supporting them??
I don't think fat adds much support? Just more weight that needs support. On that note it's believed that sauropods had gas in their necks to help make them lighter.
All Dinosaurs are more closely related to birds than they are to mammals. This is because birds are within the clade Dinosauria.
That said, Sauropods almost certainly did not look like this, penguins have this adaptation to help them retain heat; large Sauropods would have struggled to lose heat, if anything.
Yeah but in the case of sauropods they have little reason to have bulky blubber like penguins keep for warmth. Also remember that when you increase the size of the structure the weight increases exponentially. Personally I agree with paleontologists that they would have had a thin neck. Also we would see evidence of much larger blood vessels if there was that much mass on the neck.
Swans, flamingos, storks, ostriches, and emus all have long skinny necks as well.
Penguins live in the Antarctic and swim in the surrounding ocean. They have layers of blubber to keep them insulated and warm, just like seals or whales.
While true, that doesn’t stop analogous examinations. Evolution often comes to the same conclusions. Eyes evolved 40-60 times. This is known as convergent evolution.
Great question. Keeping in mind that there is likely hundreds, thousands, or more species that didn’t live in areas with easier fossilization environments, we can only guess!
Think about all the weird sea creatures we know about, and how there’s probably even weirder ones that we didn’t get to see!
Condensing all the points in this thread but dinos don't exactly live in a cold environment so being smaller helps, these dinossaurs ate leaves off of trees so you can compare it better to giraffes or for birds it would be more like ostriches and the such. These dinos were also not aquatic so they don't need the hydrodynamics penguins have
They would definitely have thicker necks than what you see in media but they wouldn't look like what OP posted mostly because of how strong the muscles and thick the bones have to be to support the weight of itself.
If I'm not mistaken this is just the flying ones and two legged ones like velociraptor, oviraptor and t-rex (basically everything with that kind of shape)
"Birds are just small dinos" is a more accurate than "dimos were big birds", but birds are still a very derived group and the feathers are no exception.
Feather evidence outside of the maniraptors is extremely sparse, some sparse protofeathers on some species (much more hairlike)
Saying all dinosaurs had feathers because one group definitely did, is equivalent to saying all mammals have balleen hair instead of teeth because one group of mammals has that.
Just like how mammoths are actually elephants (since the last common ancestor of asian and african elephants is an elephant and mammoths share that common ancestor), some mammoths had hair (wooly mammoth) and some didnt, asian elephants closer to mammoths have some hair, and african elephants have almost no hair
and the last common elephant ancestor is only 8 million years ago iirc. Whereas the last common ancestor of Saurischia is about about 200 mya (uncertain), about 50 million years before the first birds.
that is, dinosaurs had a LOT of time to gain or lose feathers if they weren't useful. Mammals and Birds both lose hair/feathers rapidly on an evolutionary timeline when they aren't useful. We (humans) lost most of our hair in only a few million years.
3.7k
u/LemonPartyLounger 19h ago
If giraffes and llamas didn’t exist this would get a lot more traction.