|Tiktaalik, what were you thinking?! Zina Deretsky, NSF.|
Urban legend has it that Tiktaalik lived in a late Devonian paradise. The climate was mild. Stream banks, swamps, and other places where water met land were lush with delicious nutritious plants. Life was good. There was no reason to go back to the sea, at least not yet.
But life wasn't perfect. These early tretrapods most likely were stumblers rather than walkers. It probably took them all day to find enough food, and they could not escape predators. But as one paleontologist pointed out, Tiktaalik and its brethren were not burdened with self-awareness. “Everyone is, like, only barely conscious of the idea that they’re alive.” (Ben Otoo, U. Chicago grad student)Now the Earth is occupied by creatures greatly burdened with self-awareness. Memers rage that Tiktaalik should have stayed in the ocean, thereby saving us all. Maybe those folks should return to the Paleozoic sea themselves. That's what I plan to do.
|In the "desert ranges which lie to the west as far as longitude 117° 30' there is no considerable mountain body without its exposure of Palaeozoic strata" (geologist Clarence King, 1878).|
Driving across northern Utah and Nevada, you can't miss the remains of that great sea. Most mountain ranges include or are even dominated by Paleozoic strata. Guidebooks make clear that this is not a monotonous stack of rock. There are nearshore carbonates in the east, and deep water siliceous rocks to the west. Quartzites tell of massive sand floods, beds of dolomite force us to confront the mysterious "dolomite problem", and there are fossils galore.
|House Range in western Utah, a monstrous tilted stack of Cambrian rock; view from west, October 2021.|
|Lone Mountain near Eureka, Nevada, May 2021. Click to view Eureka quartzite (arrow), product of sand floods; other strata include limestone, dolomite, and shale (DeCourten & Biggar 2017).|
|Steeply-tilted Permian conglomerate at Tyron Gap; sediments were eroded off the now-gone Antler highland. Sulphur Springs Range, Nevada, May 2021.|
|Limestone and dolomite from late Devonian time, when Tiktaalik was venturing ashore; Devils Gate west of Eureka, Nevada, May, 2021.|
DeCourten, F. 2003. The Broken Land: adventures in Great Basin geology. U. Utah Press.
DeCourten, F, and Biggar, N. 2017. Roadside Geology of Nevada. Mountain Press.
Imbler, S. 2022 (Apr 29). "Started Out as a Fish. How Did It End Up Like This?" New York Times.
King, C. 1878. Systematic geology. Report of the geological exploration of the fortieth parallel, v. II. GPO.
Great write-up! Geological and philosophical all rolled into one. But don't blame it on Tiktallik. Earlier Devonian sarcopterygian osteichthyans like Panderichthys and Eusthenopteron set the stage for terrestrial acquisition that Tiktaalik couldn't resist. Miss you! JackReplyDelete
Hello Jack! Great to hear from you and I miss you too, hope you're well. Ahh ... so not T's fault after all ;)Delete
Fault? No. Evolutionary destiny.Delete
lovely post. I dream of resting on the Tethyan too :)ReplyDelete
Thanks, Suvrat. Best wishes with that! :)Delete
Looking forward to reading about your trip! Thanks for all the botany, geology and past ages of the earth...ReplyDelete
thank you, ingridcc ... for sharing the joy :)Delete