Distinctly Montana Magazine

56 D I S T I N C T LY M O N TA N A M A G A Z I N E • S P R I N G 2 0 2 3 Three Snapshots Three Snapshots of an Underwater Montana Underwater Montana Long before anything resembling a dinosaur left any tracks through our state, most of Montana was under the sea, either deep and dark or shallow and swamp-like. It remained that way for millions and millions of years. There were, however, some mountain rang- es just beginning to form, like the ancestral Rockies and the Appalachians, far to the east. Vast swaths of Pangea, the continent on which we would be standing even as it collides, in geologic slow motion, with the ur-continent of Gondwana, are flat, shallow seas covered in swamps. A world of oceans speckled with dots of damp, green land, the planet is largely tem- perate, averaging in the mid-sixties degrees Fahrenheit. Nothing competes for the skies but stars and clouds, but now and then, an insect, or even a few kinds of fish, can take to the air for a moment and soar a few feet over the ground for their exertions. If we were to step out of a time machine and into that Mon- tana, we would recognize almost nothing of our world except for water, sky, and green plants. And if a creature from the Carboniferous Era were taken from oceanic Montana and dropped in our own lakes and streams, there would be little to remind it of home—not even the water, which now contains significantly less oxygen. A prehistoric fish might well choke to death on our thin water. You or I would gasp at the richness of the air, which contained 80% more oxygen than it does now. We could take in a great deal more oxygen with each breath, although the smell of all the flora and fauna might well have been overpowering. Oh, and we can't neglect to mention that all that oxygen has had a curious side effect on the insects of the period, which sometimes resemble monstrously large funhouse versions of our own bugs, an entomophobe's fever nightmare. Relatives of the dragonfly called the Meganeura grew to have 2.5-foot wing- spans, and you would likely have been able to hear the tell-tale zipping sound that announced its flight as it stalked smaller in- sects and amphibians. Decidedly not smaller, and therefore not at risk, at least from the dragonflies, were the eight-foot-long millipedes which crawled along the floor of what ground there was, eating whatever a titanic arthropod ate. You might also watch out for the two-foot-long scorpions. Yet predominantly, it was fish that ruled Mon- tana in this epoch. Sharks had just appeared, blooming into a startling profusion of creatures much stranger than our relatively narrow vari- etals. Most of those branches of the modern shark's family tree are long extinct, pruned by time. Even sharks had to fear some bigger predators, like the Rhizodus hibberti, a fish-like creature that grew to over 20 feet in length. The apex predator of the early Carboniferous, they were able to make a dinner out of nearly any- thing that walked or swam. You might reel as you took it all in, hands protecting your head from the dog-sized insects, hearing the alien calls of a hundred strange creatures you've never seen before, all provided you were lucky enough to find a patch of land. There are also plants everywhere, mostly seed ferns with small, intricate leaves that flutter when disturbed by the breeze. Perhaps some unrecogniz- able fruit hangs in strands like colored pearls, but there are no flowers in sight, and there won't be for 150 million years or so. In the vast shallows, forests of crinoids wave in the water as fish dart in and out of their feathery arms. For sheer biomass, in some places, as near Lew- istown, crinoids were so numerous that their fos- silized remains later left blankets of limestone fossils, the compressed remnants of a billion simple, ancient lives. The sky turns slate as thick, bil- lowing clouds gather darkly in the east, blowing in from the Pan- thalassic Sea. The insects hush, suddenly, moments before sheets of warm rain begin to fall, dappling the leaves and disturbing the surface of the waters. 300 MILLION YEARS AGO, N THE CARBONIFEROUS ERA by NICK MITCHELL A map showing the location of Montana within Pangea

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