Elaine Meinel Supkis
Once again, scientists would like to find just one cause of some great geological/evolutionary/climate event, this time the incredible Ecocene warming that came 10 million years after the end of the dinosaurs. The truth of the matter is, many things contribute to these epic periods: the sun's energy, interstellar objects, volcanic activity caused by plate tectonics and of course plants and animals interacting with each other and the oceans, changing the chemistry of the atmosphere and the waters of this planet.
An extraordinary burst of global warming that occurred around 55 million years ago dramatically reversed Earth's pattern of ocean currents, a finding that strengthens modern-day concern about climate change, a study says.
The big event, the Palaeocene/Eocene Thermal Maximum (PETM), saw the planet's surface temperature rise by between five and eight degrees C (nine and 16.2 F) in a very short time, unleashing climate shifts that endured tens of thousands of years.
The warm event lasted from the age of the dinosaurs until 40 million years ago when it began its long, long decline. A host of huge changes in our flora, fauna and the sun occured this last 60 million years. The chief thing that changed was the colonization of the lands as well as the seas by totally different creatures and plants.
The flowering plants and grasses took over the lands. Feathered and furred animals took over much of the land's niches. And the sun grew much older and moved into new parts of the great Milky Way galaxy that had sucked in the small mini-galaxy that was the womb of this insignificant, old, yellow star. As the star burns its fuel of hydrogen and increases its helium content, the core of the star becomes increasingly destabilized. But we dare not think about that, right?
We can control our pollution but we cannot control the sun at all, not even slightly.
From the article:
With a painstaking reconstruction, Nunes and Norris found that the world's ocean current system did a U-turn during the PETM -- and then, ultimately, reversed itself.
Before the PETM, deep water upwelled in the southern hemisphere; over about 40,000 years, the source of this upwelling shifted to the northern hemisphere; it took another 100,000 years before recovering completely.
What unleashed the PETM is unclear. Most fingers of blame point to volcanic eruptions that disgorged gigatonnes of carbon dioxide, or coastal reservoirs of methane gas, sealed by icy soil, that were breached by warmer temperatures or receding seas.
Let's travel back in time: it is right after asteroids slammed into the earth when the sun passed through some of the dust trails that this galaxy is sucking in, that black stuff that hided the brilliant heart of this galaxy, its gigantic black hole, from us. When some of these asteroids slammed into the earth's oceans, it caused tremendous floods, tsunamis and rain, lots and lots of rain.
The many tiny furred or feathered creatures clinging to the frondy trees and forest understories survived this degradation of the climate. Oh, how they huddled as the hours between stormy onslaughts would pause enough to let some of the sun in and then the rain would pound down again! There is tremendous erosion as plants are swept away.
This map from Ohio University shows where the angiosperms, the flowering trees and plants, radiated out from: the greatest rift valley in the history of geology: the point where Africa and South America seperated.
This is where the Congo and the Amazon rivers, two of the earth's greatest drainage basins co-joined and flowed into the growing Atlantic Ocean. The fact that all trees and flowers that survived the destructive rains grew in this zone is very interesting. For this is where the lemur-like ancestors of ourselves lived. And it is where many mammalian creatures survived the destruction of their environment. None were larger than a large cat or small dog. This tells us how terrible things were for all the large land therapsids died.
Back to the storms post-asteroid hit: the Atlantic Ocean which had already begun to enlarge between North America and Africa (Europe still being attached at the top of the globe), the salinity level must have not been very great and these rains fed even more purified water. For when the asteroid slammed into the ocean, a lot of salt water ended up on land and this killed most of the dominant plant species.
The volcanic eruptions that created Iceland might also have triggered one of the most catastrophic episodes of global warming ever seen on Earth, a new study suggests.
Michael Storey at Roskilde University in Denmark and colleagues have found evidence that a huge volcanic eruption, 55 million years ago, unleashed so much greenhouse gas into the atmosphere that world temperatures rose by as much as 8°C – with the Arctic ocean reaching a toasty 25°C.
"It was already a warm Earth, and it got a lot warmer," says Storey. The climatic turmoil that ensued was disastrous for most life, he says, killing off many deep-sea species.
Ancient ocean sediments that record this episode, called the Palaeocene-Eocene Temperature Maximum (PETM), also contain an unusually small amount of the heavier isotope of carbon, carbon-13. The sediments point to a sudden influx of available carbon dioxide or methane – which would explain the sudden warming – from some source with reduced carbon-13 levels.
OK: when the Atlantic came pouring into what was hither-to, a rift valley with swamps filled with dinosaurian creatures and giant crocodiles, etc, suddenly became ocean. And the space between the continents was spreading which meant, there was a lot of underwater volcanic action going on, I would suggest this break-up of the continents was like opening the door to hell: it being the core of the planet. This released energy into the upper systems of this planet, heating them up from below. Namely, the Atlantic, which was much shallower than the Pacific, was easily warmed this way. The fissure in the earth's crust runs the entire length of the planet, after all!
And we know that huge amounts of very hot lava poured out of this fissure. Warm oceans breed big storms. So the climate wasn't like the earlier one with a lot of moisture but not huge storms with high winds, I bet. After all, a major problem being a gigantic dinosaur would be lightning. Indeed! Despite all the movies showing Tyrannosaurs running wild in lightning storms, this is impossible. They would be struck by lightning bolts and killed pretty fast!
I know this for a fact. In bad lightning storms, I would rush out into the pastures to gather up Chip and Dale, my huge ox team. No way would I leave them out there with their big horns and broad backs with lightning seeking targets! I never worried about the sheep who were small and low to the ground.
So, this new climate had lightning bolts a-plenty. And the small mammals probably shivered and shrieked as lightning storms bore down on them! And the gases released by the huge fissure that opened up right in the center of where the survivors of the asteroid hid probably changed the ocean's chemistry since the Atlantic was more like the Mediterranean at this time. I suppose, when the temperatures rose, the salinity of this new ocean was intensified as evaporation competed with the incoming rain waters.
And the slender, new ocean between Africa and South America must have gotten very saline as the northern waters flowed in this hot channel that had lots and lots of lava activity. Probably the switch in direction of these waters was due to changes in salinity and temperature as the ocean grew wider and wider.
The Eocene Epoch (55-38 million years ago)
By the beginning of the Eocene, Gondwana had almost split apart, but Australia, Antarctica and South America remained joined. The Antarctic portion of Gondwana straddled the South Pole but because the global climate was warmer it was free of ice and snow. A forested corridor linked Australia and South America.
Because Antarctica was ice-free, this means the oceans had to be much warmer than today. Did the hot waters from the Atlantic kitchen heat up the Pacific? There was yet another tectonic plate event over there: India shot nortwards at an amazing speed and slammed into Asia. It passed over a hot spot in the ocean that caused a huge lava event, the Deccan Traps. This changed the atmosphere's chemistry in a big way as well as this hot spot probably heated up the ocean between Antarctica and India.
Based on new findings on the PETM, increasing amounts of greenhouse gasses in the atmosphere will also have dramatic impacts on land ecosystems. Research released last week in Science reports that a rapidly warming climate 55 million years ago caused significant changes in forest composition and distribution.
“It indicates that should we have a period of rapid global warming on that scale today, we might expect very dramatic changes to the biota of the planet, not just the mammals and other vertebrates, but forests also completely changing,” said Jonathan Bloch, a University of Florida vertebrate paleontologist and member of the research team for the Science paper.
After an initial period of increasing aridity in northern latitudes like the study site of Bighorn Basin in northwestern Wyoming, it appears that plants species migrated towards higher latitudes and forests transitioned towards warm tropical ecosystems with closely spaced trees, ideal for the evolution of primates. Further, global warming allowed mammals -- including rhinos and the earliest known horse -- to emigrate across northern land bridges to expand into new habitats.
55 million years ago, mammals were finally radiating out of their rift valley. They started out small, clinging to trees for the most part. The previous era featured gigantic animals that ate much of the plants that grew then. But now the flowering plants took over rapidly and eventually covered all the lands and few cropped them down. Next came the insects and following them, the bedraggled tree dwelling ancestors of ours, insect eaters exploiting this new, abundant niche.
On land, many new types of mammals appear in a dramatic evolutionary radiation, filling the ecological roles vacated by the dinosaurs. But compared to the majestic Cretaceous megafauna, these animals were puny. No Paleocene mammal exceeded the size of a small modern bear, and most were a lot smaller. They were all short-legged and plantigrade (walking on the soles of their feet), and they had five toes on each foot, a primitive feature. Most or all have fourty-four low crowned teeth, another primitive feature. Almost all of them had slim heads with narrow muzzles and small brain cavities. In terms of brain to body weight ratios they were well below late Cenozoic mammals. A number of typical Paleocene mammals are shown in the following sketch by Dr Bob Bakker.
When plants dominate the environment, they release a lot of oxygen and change the chemistry of the soil, the air and water. So the gases they released during the 2-3 million years of few eaters of plants after the extinctions, the atmosphere would heat up and not go down again even as the insect and animal population takes off and starts making a dent in the abundant plant life.
From the article above:
A 400-metre-long core of sediment recovered near the North Pole shows the region was subtropical about 55 million years ago.
Scientists consider the Arctic to be a bellwether for climate change, but until recently, they've had to rely on samples collected thousands of kilometres away from the Pole.
First, the Arctic Ocean went through a warm period with temperatures of 23 C, like a tepid bath. Then, about 49 million years ago, freshwater was released into the Arctic, cooling it to about 10 C.
At the time, the salinity was dilute enough for freshwater ferns to cover much of the surface in the summer, the team said.
The fast-growing greenery likely absorbed carbon dioxide, helping to cool the Arctic, theorized Henk Brinkhuis of Utrecht University, a co-author of one of the papers. Pebbles carried to the middle of the Arctic basin, dropped by icebergs, suggest ice started to form about 45 million years ago, the start of the region's current "icehouse" conditions.
Now that, I find most interesting. The fresh water sat on top of the salty water and cooled it down but not enough for ice, enough for ferns like we see in the lakes here in the Northeast. Namely, winter doesn't bother them, the snow and ice melts and the ferns grow like crazy.
Still, looking at the chart at the top here, one can see that the global cooling was gradual until 35 million years ago when it suddenly plunged, becoming significantly cooler. And this was the dawn of the Grazing Era--hoofed eaters of grasses evolved rapidly in size and numbers, growing to massive size in some cases, radiating outwards as they took over the ecosystems of all the continents except for Australia.
The Paleocene carnivorous mammals of Laurasia had to share their world with giant flightless birds of prey like Diatryma and it's cousins (order Diatrymiformes), which appear suddenly during the late Paleocene and continue through to the Middle Eocene. Standing 2 meters or more in height and weighing in at around 200 kg, these large-beaked birds were the biggest and fiercest animals on land for some five or ten million years. In South America similar giant predatory birds, the Phorusrhacids, are known from the Eocene but most probably likewise evolved during the Paleocene. These great birds were the last successors of the mighty theropod dinosaurs of the Mesozoic.
Due to their mobility, birds spread into every niche faster than mammals. It is amusing that a giant bird evolved so swiftly. Vultures, turkeys and penguins can be quite large today but not the gigantic size from this age where almost all the mammals were still quite small.
There is one thing we have to consider when picking and choosing causes of climate change and that is, not all living things go through the same extinction cycles at the same time, indeed, plants run on a different schedule, it seems.
d) Only 2 tracheophyte extinctions coincide with a "minor" vertebrate mass extinction, none coincide with marine invertebrates-->environmental and other catastrophes have drastically variable effects on different organism groups
And this means anyone who suggests that this thing or that process caused vast climate changes could be mistaken. Namely, it is a confluence of forces building up over time. Oceans forming or closing off, cracks or hot spots causing massive lava events, volcanic gasses or volcanic dust, solar activity or inactivity, the solar system passing through dirty parts of the galaxy versus relatively clean sectors, and the density and type of life forms: all these together, move the environment and the weather.
This lost landscape, where hunter-gatherer communities once lived, was swallowed by rising water levels at the end of the last ice age.
University of Birmingham researchers are heralding "stunning" findings as they map the "best-preserved prehistoric landscape in Europe".
This large plain disappeared below the water more than 8,000 years ago.
The Birmingham researchers have been using oil exploration technology to build a map of the once-inhabited area that now lies below the North Sea - stretching from the east coast of Britain up to the Shetland Islands and across to Scandinavia.
The world's shorelines have changed frequently as the oceans rise or fall depending on where ocens are forming or being closed off as well as thickness of ice sheets or if ice sheets can even form. The continental shelves probably hold a treasure trove of fossils which can't be dug up yet due to difficulties. Mostly, core samples are drilled. But this is really a hit or miss thing and I would expect we would find many wonderous fossils there if we could.
Maybe if there is another Ice Age, perhaps.