perspectives is BACK babey! Check out #perspectives on my blog as we keep going forwards in time!
"See? Snake!"
Palaeophis/Presbyornis/Striatolamia/Myliobatis/Pseudamia/Eutrichiurides
Paleogene, 49 million years ago, Margaret Formation
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For millions of years, the Earth has existed in a hothouse age.
Water evaporates and rains down, increasing the amount of freshwater flowing through Earth's rivers. As they drain into the enclosed Arctic Ocean, a non-salty layer of water emerges at the top.
Right now, the arctic is warm. It's practically entirely free of ice, even during the long polar darkness. Alligators lurk in the lakes under the midnight sun. And today, in the ocean, so does an enormous, almost-twenty-foot snake, coming up for air and startling a gaggle of Presbyornis in the process. Large even for her kind, she made her way through the ancient North Sea to bask in the polar summer. Warm-blooded, she is more resistant to changing temperatures than your average snake, and the bounty of food has encouraged her to remain here for the time being. With the ability to drink from freshwater on the ocean's surface, this Palaeophis toliapicus thrives in an environment where this is the norm. As the sun sets over the next few weeks, she will swim back the way she came, and repeat the journey every year.
Bizarrely, the Eocene arctic possesses relatively low diversity in marine life. It appears to be dominated by scores and scores of shed teeth belonging to relatives of sand tiger sharks and eagle rays. Aside from that, we see hairtail, smelts, and potentially bowfin. With the mingling of fresh and salt water, this ocean can potentially accomodate species from both environments.
Also notable is the presence of a dense plant carpeting the sea surface: Azolla. They capture carbon dioxide from the air, and as they die, sink to the seafloor, locking it away from the atmosphere. It is these plants that will send the planet spiralling into a cooling climate, culminating in the famous ice ages. Lush forests will slowly but surely be replaced by hardier fare, and then by sprawling glaciers. The arctic will freeze over, and the area will be rendered unrecognizable until a strange species of hairless apes dig up a plethora of shark's teeth in the Margaret Formation millions of years later.
But today, there's no need to worry about that. Today, a visitor arrives, takes a breath of that fresh, fresh air, and submerges herself in the water again, swimming off into the blue, as she has done for much of her life.
Palaeophis is a "sea snake" (actually related to the adorable elephant trunk snake) the size of a python. The toliapicus species is part of a clade of more flattened species with distinct oceangoing adaptations. I like to think that maybe they drank rainwater from the ocean's surface much like modern sea snakes, but that's speculation. It's possible the tropical climate of the time was what allowed them to grow to such massive sizes, and we have another species, colossaeus, from Mali that grew longer than an anaconda. We have no evidence of them ever going this far north, but I think it's possible.
Presbyornis is a bird that looked as if one stretched a duck into the proportions of a flamingo, that was common during the Eocene. Its lineage has a long and storied history dating back to the latest Cretaceous, though none of its kind exists today.
Striatolamia and Myliobatis are known from teeth! Teeth everywhere! Unlike modern sand tigers and eagle rays, they are fully acclimated to brackish water. They make up much of the fossils in the area, indicating a surprisingly low-diversity environment.
