Arctic ice and the ecological rise of the dinosaurs

[GojiraGuy1954]

https://www.science.org/doi/10.1126/sciadv.abo6342

Major one right here. If this is true, and i'm interpreting the text correctly, this gives a lot of credence to the idea that feathers / filaments are basal to Dinosauria.

"Empirical evidence of L-IRD in strata associated with dinosaur footprints shows that these insulated archosaurs lived in areas and in times with freezing conditions since their inception in the Late Triassic. In contrast, the tropical large terrestrial archosauromorphs of the Triassic, including phytosaurs and pseudosuchians, lacked insulation and presumably could not tolerate prolonged cold, let alone persistent freezing. Thus, large-bodied (>1 m) terrestrial archosauromorphs went extinct during the initial CAMP eruptions at the ETE."

This right here says that Dinosaurs were able to more easily survive the end-triassic extinction (hypothesized here to have been caused by global cooling) because they were insulated by feather coating, unlike many of the dominant animals of the day, such as the Dicynodonts and Pseudosuchians.

[Faelrin]

Interesting. I guess this means @Doug Watson Coelophysis was ahead of the curve then (or maybe it was in line with the evidence at the time)? I also wonder what this means for pterosaurs as well. It would make sense for them to evolve filaments for insulation purposes as well. Granted I'm not well versed on pterosaurs as it is, so it's possible this is already common knowledge I just lack.

I wonder if this also helps to explain why small ornithischians like Kulindadromeus, Tianyulong, and Psittacosaurus all had filaments to some degree (though in Psittacosaurus case, it used them as display structures)?

Wasn't there also a study involving crocodilians showing they had the genes to create filaments, but just weren't activated? Or am I misremembering it? I know there's been a lot of stuff suggesting filaments have been there at the start of archosauria or somewhere along the line for a while now though.

[Halichoeres]

This is definitely an interesting addition to the body of evidence suggesting feathers or something like them were present way down the bird stem-group.

@Faelrin Holthaus et al. 2018 found that birds and crocs share "epidermal differentiation genes," but that doesn't necessarily mean that crocs could have ever made feathers, just that the different integuments of birds and crocs share some genomic architecture.

[Faelrin]

@Halichoeres That's what it was that I was thinking of. Thanks for the correction, and info on that study. Been a while, so no longer I couldn't remember the details quite right, with my poor memory these days.