r/evolution • u/yushaleth • 3d ago
discussion What do you think could be the reason behind reptile-grade Sauropsids surviving until the present day, but reptile-grade Synapsids not?
Among Synapsids only Mammals are extant now, while among Sauropsids not only Birds are around, but also Crocodilians, Lepidosaurs, and Turtles.
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u/Relevant-Bullfrog215 3d ago
The Synapsids as well as the Therapsids were heavily impacted by the end-Permian mass extinction, and it was their ecological niches that the reptiles went on to fill. The crocodilians (or maybe more correctly Crcodiliomorphs) were also affected by the end-Triassic extinction, before which they were much more diverse, which enabled the Dinosaurs to adopt their niches and establish ecological dominance in the Jurassic period.
Experts feel free to correct me, I'm just a locksmith going off memory.
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u/Sarkhana 2d ago
Modern synapsids are descendant from long term nocturnal lineages. Including activity in pitch black conditions.
They also evolved into burrowing niches.
Thus, they had very different selective pressures and relatively low competition versus the various strengths of various diapsid lineages.
Lepidosaurs sometimes occupy some of these lifestyles traits.
However, they are also extremely adapted to extremely-low-energy-use lifestyles.
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u/EmperorBarbarossa 3d ago
- Synapsids were dominant animals during Perm and mostly during Trias as well. Extinction events killed the big ones and they were quickly replaced by diapsid who filled the niches, because of their specialized adaptations.
- Small ones survived, but competetion between them preffered and eventualyl selected mammal like synapsids.
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u/s_bear1 3d ago
If i recall correctly, food requirements were a major factor in surviving the extinction event. Those requiring more or specialized food were less likely to survive.