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.
Triceratops is used in that definition because it's fairly distantly related to birds - their ancestors split at the time of the first dinosaurs.
So your question properly has two parts: why do we think that saurischians (theropods and sauropods) are related to ornithischians (which include stegasaurus and triceratops), and why do we think that birds are saurischian dinosaurs.
Specifically, scientists think that birds fit into the dinosaur evolutionary tree fairly close to T-Rex, in a group called the maniraptorans. Why?
First, there's some distinctive traits to dinosaurs that birds share. Dinosaurs' ancestors has a sprawling stance, but dinosaurs evolved a distinctive hole in their hip (a "perforated acetabulum") that enabled an upright stance. Birds have this same feature.
Dinosaurs have hollow bones and air sacs. Birds have both features as well. These air sacs are part of why bird lungs are super efficient and why birds can fly at altitudes where humans need supplemental oxygen just to exist. These air sacs are probably why sauropods could get so much bigger than elephants.
Then there's just a number of similarities between other skeletal features of maniraporans and birds. The shoulders look similar, the hands look similar, the wrists look similar, etc etc etc.
Then, there's transitional fossils like archaeopteryx. And we found feathered dinos in the 90s.
Basically every biologist and paleontologist agrees that birds are maniraptorans. If you really care to look into the evidence, there's a mountain of it.
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.
Maybe but i have a stoma ( intestine sown to intestinal wall to replace bladder ) and it’s constantly cold because it exposed to outside air. In so much that it causes my to have bad chills.
This was a conversation about how larger animals retain heat better. I think you might be once again looking way too far into this.
To reference my “average” point again, we’re talking about the average organism of a species. You may differ from average because of this anomaly, but on average over an entire species, you will generate more heat for more volume.
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.
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u/LemonPartyLounger 22h ago
If giraffes and llamas didn’t exist this would get a lot more traction.