>Marine reptiles in the Mesozoic swam in a way not shared by any animal alive today.>Sabertooth predators existed all throughout prehistory and just happened to die out right as the modern age arrived.This shits so cool, normally when studying extinct animals you can look at living ones for reference, but that's not possible here. Paleontologists have to start from square one to figure out what the fuck these animals were doing. Any other examples of this?
>>5169851The Ancycloceratina were a large family of externally shelled squids that were just the weirdest fuckers ever. The one major thing that unifies this group is that their shells are bafflingly strange. Knotted, extremely long and thin and looping around on themselves, forming long screw shapes, etc. Why they would ever evolve to look like this and it somehow propagate for millions of years is totally unknown. If it is sexual selection, it makes peacocks look restrained.
>>5169863>If the Nautilus didn't survive we'd have zero extant references for shelled cephalopods which were prevalent in virtually every era of prehistory's oceans.Our understanding of ammonites and such would probably be drastically different if we didn't have them.
>>5169851Would the general theropod body plan count? we don't have any bipedal animals that stand horizontally and have arms and long tails
>>5169868I would say they pass the bar. Locomotion wise they are similar to terrestrial birds, but even birds differ in some aspects, like not having tails. They can have counter balancing tail feathers, like pic related, but will never truly have important tail muscles like the caudofemoralis.
>>5169863how do we know theyre just not fucked up phenotypes, like something bad happened during the formation of the shell and it grew in the wrong direction, because dont those shells grow from the opening and layers are added that way
>>5169880We got a lot of them.
>>5169883I wonder if they had lots of algae that draped on them or something
>>5169863desu it is funny how sexual selection is so random at times. like both humans and blue footed boobys will sexually select females based on their feet.
Unless I'm mistaken, ceratopsids were the only animals to have ever evolved bony frills. Other animals have evolved elaborate horns and crests, like living bovids for the former and hadrosaurs for the latter, but the frills seen in ceratopsids are completely unique to them. The sheer number of ceratopsids known from Laramidia made them ubiquitous like bovids in Africa or birds of paradise in Papua New Guinea as well, which makes it even stranger that this adaptation has only evolved once. You would expect other animals to have convergently evolved bony frills at some point.>>5169851>Sabertooth predators existed all throughout prehistory and just happened to die out right as the modern age arrived.Glyptodonts like Doedicurus and meiiolanid stem-turtles both were also the last animals to have evolved clubbed tails for defense and they died out just a few thousand years ago after encountering humans. They converged on the same body plan as ankylosaurs during the Jurassic and the Cretaceous, not just with the clubbed tails but the body armor as well.
>>5169907On the topic of dinosaurs with lost anatomical traits, stegosaurs stand out as especially strange since nothing else evolved dorsal plates like them. There's nothing alive today that can be compared to a giant herbivore with plates on its back and a spiked tail that it swings at predators, which shows how different the terrestrial ecosystems of the Jurassic and Early Cretaceous were since stegosaurs lived were widespread throughout the world.
No living animals have an euryapsid skull. it's similar to synapsids (one postorbital fenestra), but it was located higher on the skull between different skull bones.It was found in ichtyosaurs, plesiosaurs, and placodonts
>>5169851Whatever Helicoprion was doing with that weird pizza cutter mouth
>>5169851Sabertoothed animals appear to be a Synapsid-line staple.Whenever sabertoothed animals appear, they are calling back to their Permian ancestors, the first sabertooths. It's in their DNA.It's kino.
>>5169907>>5169908Why were dinosaurs like that anyway? i swear every other dinosaurs is full of horns, spikes or armor. It's why people get the impression that hadrosaurs and sauropods were fodder, because they compared to other dinosaurs they look defenseless (even though they weren't)
>>5170008Well if you weren’t huge like Sauropods or fast (relatively) like Hadrosaurs and had to deal with the uniquely gigantic predators that lived at that time the best option is armor, weapons, or both.
>>5169907There probably was some sort of weird therapsid or other permian goober with the bony frill feature. Those creatures looked really diverse
>>5169851That one herbivorous archosaur with HORNS PROTRUDING OUT OF ITS SHOULDERS
>>5169907Ceratopsians were pressured by evolution to develop the crests since you get one-shotted by a bite from any of the predators of its time.
>>5170008Since dinosaurs died off the worst thing any prey animal has had to face would be a lion basically. What was the biggest cat ever? Did they even reach a ton? Plus they’re a “sprint up to you and try to choke you out” type predator. So the animals we see (deer, bison, etc.) don’t have to have tails with spikes and armor and shit, a herd of bison with thick furry coats can repel most lion attacks.In a dinosaur ecosystem, now you have t-rex and other shit like it as the main threats to your survival. Thick furry coats aren’t going to cut it here against something that can run up and bite you in half or rip your head off, if you’re an animal in that ecosystem you need armor and spikes and all that.
Sails pretty much died with the dinosaurs. There are still some reptiles that technically have them but they're meme tier compared to pic related.
>>5170008Other anons have mentioned anti-predator defenses but I think sexual selection or visual intimidation could've been a factor as well. Spicomellus was covered in overkill spikes despite later ankylosaurs having much more conservative armor while living alongside bigger theropods like allosauroids and tyrannosaurs. I was thinking about this after posting last night but even the predators often had elaborate crests and display structures, a trend seen across theropods. You don't really see mammalian carnivores with head crests or sails since they tend to have more sleek and conservative body plans. Birds can see ultraviolet colors and this trait was potentially present in other dinosaurs, which lines up with how common elaborate displays structures evolved multiple times across unrelated lineages. You see the same thing in pterosaurs as well, multiple lineages evolved large head crests. Mammals have more limited color version because of the nocturnal bottleneck and are generally less reliant on sight compared to smell and hearing. The Mesozoic could've been a more visually extravagant world than today since visual competition within species was more of a factor than today.
>>5169906Talking about yourself weirdo
