Whales evolved from wolf sized land animals that roamed the planet around 50 million years ago. Presently, there actually are some wolfs on Vancouver Island in Canada that might be starting a similar evolution. They hunt fish for a majority of their food, swim most of the day, and even have developed webbing between their toes.
There is a fern that has such a high level of atmospheric carbon sequestration that it caused an ice age 49 million years ago. Azolla thrived because of the perfect conditions it found to grow in the North Pole. Large amounts of this fern kept growing and falling to the bottom of some sea without being able to decompose for 800,000 years. It reduced the CO2 levels in the atmosphere so much that it became a threat to its own survivability.
23Messinian Salinity Crisis
Messinian salinity crisis was an event that occurred more than 5 million years ago during which the entire Mediterranean Sea evaporated and dried out after the closure of the Strait of Gibraltar. This event caused the Mediterranean to become far saltier than the Atlantic Ocean. When the strait opened up again it refilled somewhat rapidly in the event that is known as the Zanclean Flood.
We are presently still in the ice age that began 2.6 million years ago at the start of the Pleistocene epoch, because the Greenland, Arctic, and Antarctic ice sheets still exist. Even less well understood are the cycles of comparative balminess between ice ages, known as interglacials. It is mildly unnerving to reflect that the whole of meaningful history - the development of farming, the creation of towns, the rise of math and writing and science and all the rest - has taken place within an atypical patch of fair weather. While many interglacials seemed to last as little as 8000 years ours has reached 10000 currently.
Scientists have recently found evidence that suggests that a supernova explosion that occurred 2.6 million years ago and 160 light-years away from the earth directly led to extinctions of many marine megafauna species on earth because of exposure to the supernova’s deadly muon radiation. Interestingly hominids and land megafauna survived this extinction event.
Humans were once an endangered species. About 1.2 million years ago, at a time when our ancestors were spreading through Africa, Europe, and Asia, there were probably only around 18,500 individuals capable of breeding. Humans faced another population bottleneck where the human population was reduced to less than 1000 people total around 70,000 years ago due to a supervolcano explosion in Indonesia that triggered a nuclear winter.
The Earth's magnetic poles move. About 780,000 years ago the Earth's magnetic poles flipped and we could be in the early stages of another. The magnetic North Pole moves in loops of up to 50 miles per day. It is slowly moving west and in the last 150 years, the pole has wandered a total of about 685 miles.
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The mammoth steppe was the Earth’s most extensive biome. It spanned from Spain eastwards across Eurasia to Canada and from the arctic islands southwards to China. It thrived for approximately 100,000 years without major changes and then suddenly became all but extinct about 12,000 years ago. Vegetation was dominated by high-productivity grasses, herbs and willow shrubs and the animal biomass was dominated by bison, horses, and the woolly mammoth.
A wobble of Earth’s axis causes the Sahara to cycle between desert and grassland every 23,000 years. The last cycle started 7,000 – 10,000 years ago and Sahara will turn back into vast grassland in around 16,000 years. These are known as Milankovitch cycles, which are caused by variation in orbit and tilt of the Earth. These cycles have a great effect on the earth’s climate and are a leading cause of periodic ice ages.
The Younger Dryas was a time period occurring about 12,000 years ago when the Earth’s temperature dropped 2 to 6 degrees Celsius within decades, which is amazingly fast in geological terms. It is debated to have been caused by asteroid impacts and volcanic eruptions. Humans developed light skin as a balance between vitamin D production and UV protection, likely in response to the Big Freeze that followed.