![]() Tangasaurids were a weird group of end-Permian to earliest Triassic animals, with some adapted for aquatic life in freshwater and lake environments, and other living life on land like other reptiles. They would have been superficially lizard-like - again - but very different, and they had ridiculously long tails and toes, making them powerful movers. They were as big as living monitors, and they had less kinetic (mobile) skulls than living reptiles. Younginids are reptiles from right around the End-Permian extinction, basically only living in the latest Permian and earliest Triassic. I will go through each group, but just know all we know is that these groups fall outside the next big chunk - Sauria - but within Diapsids. Lots of different groups diverged here very quickly. Parareptiles may actually go here, or only some of them. Unfortunately, we’re now at the part of the tree where evolutionary relationships are a mess. That said, they probably lived similarly to them, though some members may have been adapted for climbing, and others for swimming. In fact, they had more slender limbs, longer tails, and less specialized heads than lizards. I cannot stress enough that nothing so far has been an actual lizard. Our first group of Diapsids are the Araeoscelidans, which - again - were SUPERFICIALLY lizard like. In fact, they seemed to have been adapted for climbing trees, making them among the earliest known animals to do so! All remaining reptiles are Diapsids, characterized by having two holes (postorbital fenestrae) behind the eye socket. They were small, superficially lizard-like animals, but their limbs were a lot more slender and long than lizards, as were their bodies and heads. Next to branch off are the Protorothyridids, which lived only in the latest Carboniferous. Living from 300 to 252 million years ago, they started out as small carnivores, and eventually evolved to be large herbivores! Protorothyridids The next group to branch off are the Captorhinids, a group of interesting little reptiles with shorter tails, sprawling limbs, and weirdly boxy heads. ![]() So, skulls like living reptiles! Captorhinids Yay science! All the rest of reptiles are in Eureptilia, which have smaller bones in the lower back of the skull that no longer connect to the roof of the skull. Unless their evolutionary relationships change. Most Parareptiles were Procolophonomorphs, and included everything from the bipedal Eudibamus to the huge Pareiasaurs that were major megafaunal herbivores during most of the Permian period.Īll Parareptiles, as far as we can tell, are extinct today. The next group to branch off were Millerettids, which were small insectivores with superficially lizard-like apperances. The earliest members to branch off were the Mesosaurs, a small group of aquatic reptiles! They were long and slender, and quite small compared to later aquatic reptile groups. ![]() They also had swollen, thick vertebrae, and stout upper limb bones. While early members of the group had long tails, over time, the bodies of parareptiles became more stout with shorter tails. Many of them look superficially like lizards, in that they’re quadrupedal animals with limbs splayed out to the sides, but they were *nothing* like lizards. They also had very robust and broad skulls. They had robust bodies that were low to the ground, with legs *usually* sprawled out on either side. These were weird mfers, living from around 310 million years ago until 200 million years ago. for now, we’re going to go with them as the earliest branching group and assume they’re a single thing, even though that is probably going to be very wrong in the next few years). (Note: Their evolutionary history is in flux and it’s possible they’re actually further down on the reptile tree, or not even a natural group. ![]() So now we go through our groups of reptiles based on their evolutionary/familial relationships, and the first group to branch off from other reptiles were the Parareptiles. ![]() The First Reptile Group to Branch Off: Parareptiles Turns out, this includes birds, but I’ll get to that. ![]()
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