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About Chimneyrock2003

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    Earth science

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  1. Sometime between the Paleocene and Eocene epochs, there was a mysterious, sudden, dramatic rise in global temperature. This moment in time was known as the "Paleocene-Eocene Thermal Maximum", shortened into "PETM". In just 20 to 50 millennia, the temperature rose by five to eight degrees Celsius, and this heatweave persisted for another 200 millennia (that's just the mean estimate.) While its impact on terrestrial plant and animal life is well-known, the focus of the thread is on how the PETM impacted the aquatic ecosystems. The warmer the water's temperature, the less oxygen it can hold, resulting in ocean anoxia. And since water has a low albedo, it absorbs carbon dioxide rather than reflects it. And in an episode as CO2-rich as the PETM, the oceans absorbed so much of the greenhouse gas that they had become acidifed. That, in turn, depleted the supply of carbonates, which many animals relied on to build shells and other structures. Indeed, fossil remains of coral reefs dating from the PETM to several million years afterwards were rare, and anywhere between one-third and half of all the deep-sea species of foraminifera (tiny, planktonic lifeforms) went extinct. Finally, the warmer waters also affected the arrangement of a particular layer called the lysocline: Link The point of departure is this--The Paleocene-Eocene Thermal Maximum did happen at the same time as OTL and at the same speed, but it lasted three to four times longer. With that in mind, questions follow: Would a longer PETM lift the lysocline closer to the surface? Based on our knowledge of shark and ray species that were around to witness the PETM, would any of them survive the longer period of warmer, more acidic oceans? And were there any freshwater species at the time? Would a longer PETM destroy the coral reefs (as is my primary target), and if yes, how would that affect the other invertebrates and the fish that relied on the reefs for food, shelter and breeding? Would life in brackish and fresh water fare better than in seawater? Could pelagic (open-ocean) species have a chance of surviving a longer PETM? And if they colonized the shallow water ecosystems, could they evolve to grow smaller?
  2. Perissodactyla is an order of mammals consisting currently of the seventeen species of horses, rhinoceroses and tapirs. Usually, any clade is connected by a coupling of genetics and physical morphology. The ancestors of all perissodactyls, even the extinct brontos and indriks, were the rodent-like hyopsodontids. They were likely swift and nimble, living in burrows and perhaps hunting with echolocation like some species of moles still do today. The hyopsodontid family did not last long--living from the early Paleocene to the Eocene. But what if they held on a little bit longer, long enough to assume a larger, more otter-like form and taking on an evolutionary path similar to the archaeocetes, the earliest of the true whales? Back home, whales are confirmed to be artiodactyls, with their closest living relations being hippopotamuses. But in this alternate Earth, a clade parallel to whales--let's call them "illhveli", for discussion's sake--are perissodactyls. Using modern perissodactyls as reference, what sorts of anatomical, skeletal or other kinds of morphological differences should I watch out for in an odd-toed cetacean ("illhveli") in comparison to our even-toed cetacean ("whale", "dolphin", "porpoise")?
  3. 55 million years ago, the world was literally a jungle. With such high temperatures, rainfall and humidity, life could proliferate. But 49 million years ago, something drastic happened: The Azolla Event, where ice was forming at the poles. The culprit? A kind of plant called Azolla. Within 800,000 years, photosynthesis and carbon sequestration from those plants reduced the atmospheric quantity of carbon dioxide from more than 3000 parts per million to 650. [figure from Atmospheric carbon dioxide concentrations over the past 60 million years] But the real question here is--did the cooling caused by the Azolla Event create a major extinction event of plant and animal species?
  4. It's a blueprint to some stories I'm thinking about writing.
  5. Hello, my name is John Dailey, and I had taken Earth Science classes at the University of South Dakota in Vermillion. At that time, what I had learned in those classes had inspired me to create an alternate Earth, with geographic and geological features different from Earth's but still inspired by them. The problem I have is that I know only the Cause--i.e. the changing of the geography--and not the Effect (how the changes in geography influence landscape, climate and weather). I have the whole description written down, but before I show you the description, if it is not too much trouble, would you be willing to help me with feedback and advice on the changes I had made? Thank you for your time.
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