Geological Timing Differences:
There are some serious differences between the timeline of the XenoPermian and our own. In the stages of geology alone happens to be one such. We're going to highlight a few here with the help of the above graphic. You will note that it is similar to the USGS graphic of the geological periods. However, the differences are glaring too.
Starting from the deepest geological time period, the divergences began with the Permian Period. The PT Extinction never happened in this tour de force. Rather than ending the Permian at 251 MYA, witht he eruptions of the Siberian Traps, the traps erupted over a much longer period that lasted from the Guadelupean Extinction to 245 MYA. Their effect was tolerated a lot more by the biosphere and the Permian - now XenoPermian - extends all the way up with its evolving Paleozoic ecosystems until 199.6 MYA. This is marked by the XenoPermian-Jurassic Extinctions. This marked the end of the Paleozoic and the start of the Mesozoic.
Obviously, the Mesozoic has been curtailed since the Triassic has simply ceased to exist under the Xenopermian TL. However, through a fluke of orbital mechanics, the Cretaceous and by extension the Mesozoic was extended to 55.8 MYA. The rock that ended the Mesozoic instead of landing in Chicxulub, Mexico on the Yucatan Peninsula, the great splat hit what would have been Bristol, England and caused a slightly milder mass extinction. The Cretaceous is now divided up into the Upper, Middle and Lower Epochs.
The Allozoic picks up where the Mesozoic left off and there is a distinct difference between the Allozoic and the Cenozoic. The Paleocene is history and the Paleogene and Tertiary is also circumscribed.
Next up, Paleoenvironmental differences between our Permian & Triassic and the XenoPermian. This will actually be in the next week.
For previous XenoPermian posts look here.
Starting from the deepest geological time period, the divergences began with the Permian Period. The PT Extinction never happened in this tour de force. Rather than ending the Permian at 251 MYA, witht he eruptions of the Siberian Traps, the traps erupted over a much longer period that lasted from the Guadelupean Extinction to 245 MYA. Their effect was tolerated a lot more by the biosphere and the Permian - now XenoPermian - extends all the way up with its evolving Paleozoic ecosystems until 199.6 MYA. This is marked by the XenoPermian-Jurassic Extinctions. This marked the end of the Paleozoic and the start of the Mesozoic.
Obviously, the Mesozoic has been curtailed since the Triassic has simply ceased to exist under the Xenopermian TL. However, through a fluke of orbital mechanics, the Cretaceous and by extension the Mesozoic was extended to 55.8 MYA. The rock that ended the Mesozoic instead of landing in Chicxulub, Mexico on the Yucatan Peninsula, the great splat hit what would have been Bristol, England and caused a slightly milder mass extinction. The Cretaceous is now divided up into the Upper, Middle and Lower Epochs.
The Allozoic picks up where the Mesozoic left off and there is a distinct difference between the Allozoic and the Cenozoic. The Paleocene is history and the Paleogene and Tertiary is also circumscribed.
Next up, Paleoenvironmental differences between our Permian & Triassic and the XenoPermian. This will actually be in the next week.
For previous XenoPermian posts look here.
2 comments:
Woohoo, the return of the Xenopermian! I can't wait for more posts.
Incidentally, regarding the Xenosuchus is an archosaur/not-an-archosaur debate, is it possible that Xenosuchus could be an late-surviving anthracosaur closely related to Archeria? I've heard that fragmentary anthracosaur fossils have been found in the Late Permian, and Jenny Clack in her book gaining ground illustrates Archeria and its kin with the same kind of ridges on the skull. And Archeria seems to have a very similar skull to Xenosuchus.
The ridging is presence, iirc, of lateral line sensoria.
The trematosaurs, iirc, have pretty similar skulls.
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