A feathered T-Rex? Why not? (Image from Safari Ltd.)
A recent paper by Olsen et al. appeared on "Science Advances". It discussed the fauna and the climate of the Earth of Late Triassic, just before and during one more of the great mass extinctions of its long history.
The authors claim that "The Late Triassic and earliest Jurassic are characterized as one of the very few times in Earth history in which there is no evidence of polar glacial ice sheets," which I am not so sure about. Anyway, this Late Triassic Iceless age is interesting for us because it is where we may end as the result of the current burst of fossil carbon combustion, deforestation, and marine desertification. It is another example of ice-free earth, probably similar to the Eocene epoch, some 30-50 million years ago.It seems that the Late Triassic was not so hot, despite the high CO2 concentrations (maybe 1000-6000 ppm). In the high latitude regions, the temperature was cold enough that ice would form in winter, likely not perennial. Dinosaurs lived in the Northern and Southern areas of the Pangea, and they already had "filamentous integumentary cover" -- beautiful term! -- that is protofeathers, clearly used for thermal insulation. In the equatorial regions, instead, the heat made life easier for cold-blooded animals, the pseudosuchia -- which indicates crocodile-like creatures. Apparently, it was too hot for dinosaurs there.
Does this have some relevance to the current climate? Everything is correlated, although it must be said that the conditions of the earth some 200 million years ago were quite different. The fact that there was ice at the poles, despite a very high CO2 concentration, is no proof that CO2 is not the greenhouse gas we know it is. Among many other things, the solar insulation at that time probably around 2% lower than it is today.
Today, if we were to go back to those CO2 concentrations, crocodiles may still have a good time, but they will probably invade a much larger share of latitude. On this point, this is a paleontological study, so they don't mention modeling the climate of those times. They tend to attribute the low temperature to volcanic ashes. They seem to say that the mass extinction was caused by cooling, unlike the later K-Pg event. That despite the fact that the CO2 concentration was so high. Their main conclusion is that dinosaurs were adapted to cold temperatures, and they were mostly feathered. Which means that the creatures seen in "Jurassic Park" are all wrong!
They also report this interesting graph with the CO2 concentrations over 300 million years. It is stuffed with acronyms, apparently well known by paleontologists, but not so much by us, mortals. Anyway, "EPE" stands for "End Permian Extinction" (the huge one) "ETE" stands for "End Triassic Extinction" (less well-known, but it was not a joke). "T-OAE" stands for "Torcian Oceanic Anoxic Event" (quite an event, it must have been). The "K-Pg-E" is an acronym of acronyms, but you know what it stands for: it is the end of the dinosaur age -- the big asteroid falling on Earth (maybe) or/and the Deccan giant igneous province (more likely). Finally, the PETM is the "Paleocene-Eocene Thermal Maximum", quite a maximum in temperatures, but it didn't do as much damage as one would have expected.
They also report this interesting graph with the CO2 concentrations over 300 million years. It is stuffed with acronyms, apparently well known by paleontologists, but not so much by us, mortals. Anyway, "EPE" stands for "End Permian Extinction" (the huge one) "ETE" stands for "End Triassic Extinction" (less well-known, but it was not a joke). "T-OAE" stands for "Torcian Oceanic Anoxic Event" (quite an event, it must have been). The "K-Pg-E" is an acronym of acronyms, but you know what it stands for: it is the end of the dinosaur age -- the big asteroid falling on Earth (maybe) or/and the Deccan giant igneous province (more likely). Finally, the PETM is the "Paleocene-Eocene Thermal Maximum", quite a maximum in temperatures, but it didn't do as much damage as one would have expected.
