I also believe this to be true. Too many times I've read that such and such dinosaur was warm blooded and hunted in packs and gave live birth and what they ate and how they lived. Then I see that the only fossils are like a couple vertebrae. I don't see how you can see this and not know that they are just making shit up.
Nobody can call them out on their bullshit except other paleontologists and they aren't going to call their colleague a liar because they are going to do the same thing when they find a couple of bones.
I feel the same way about space discoveries. "I discovered a new planet. It is made of diamonds and it rains lava and the volcanoes spew out ice. Also I'm pretty sure there could be life." You look up an image of this new planet and it's just a dot. The scientists can tell all that by just looking at a dot, ok. "James Webb is so powerful that it can see the beginning of the universe." Does anyone ask them to prove it? No, we just believe them.
Probably I'm just retarded though.
A lot of it is speculation or deduced by assuming a similarity with modern day equivalents, but some other stuff is actually genuine, as crazy as it may seem. I have a few examples coming from paleobotany. First of all, basic morphology of the leaves is already a good indicator for a lot of things. If they are small and scale-like, or stubby and chubby, then it's very likely that the plant was adapted to very hot climates, making it xerophytic. If they have an extended leaf tip (a "drip-tip"), then they lived under high rainfall. If the leaves are often found in dense accumulations representing leaf mats, and if the leaves are entire (not too weathered), then they may have been shed naturally, making the plant deciduous.
Other organs can also give plenty of details on the plants, such as how they reproduced, how tall they were, what kind of other organisms they interacted with, etc... Sometimes you can even have exceptional finds like an entire plant (
Antarcticycas) or an accumulation of a single taxon in certain areas, indicating large monotypic communities (
Equisetum columnare, a shit of Sphenopsids)
It's generally a similar process with animals. There's a lot of unique finds that often allow the knowledge of X or Y animal to go further than "small quadruped herbivore" or "planktonic organism", ranging from small dinosaurs preserved inside of their former burrows to small aquatic nodosaurs with fishes inside of their stomachs as well as fossil embryos still in their eggs, ichthyosaurs giving live birth and mass accumulations of coprolites from a single species.
A lot of informations like this are generally well-detailed in the papers describing the species, and you can get a solid grasp of why the paleontologist think like this, but since most paleontology "fans" are NIGGERS that only have a surface-level understanding of science, they read about it in Wikipedia or on some blog and take it as gospel without attempting to understand what it means.
On top of that, a lot of the fucking redditors you see out there are massive fans of speculation and will take every single new theory (credible or not) as fact to get the chance of going "GUYS do you know that X may have been XXXXX ? WOW so interesting i can't believe that !". Just look at when some dudes announced a proposal to split Tyrannosaurus rex into several species ; that paper's conclusions were not followed by anyone and it was pretty much moot but for several weeks you had every redditor screaming about it.
TL ; DR : don't be a redditor that assumes every theory as fact and read the OG papers, they may be chonky but they explain fairly well the reasoning behind certain theories
