Probably the most well known of all major extinction events is the Cretaceous-Paleogene, also called the K-Pg, extinction event which happened about 66 million years ago. About 80% of all species were eliminated. Image
Nearly all dinosaurs and many marine invertebrates went extinct during this time. In fact, the only lines of archosaurs (the group that contains dinos, birds, and crocodilians) that survived were those that led to modern birds and crocodilians
Since the 1980s the leading theory for the main cause of the K-Pg extinction is that of the famous ‘asteroid theory’…
Tektites (fractured sand grains from meteorite impacts) and iridium (vanishingly rare in the Earth’s crust, but found in meteorites) are found in the fossil record associated with the extinction to support this theory.
A crater some 180km across was found buried near the Yucatan peninsula in Mexico, this was confirmed as an impact associated with the K-Pg event in 2016 following drilling below the sea floor to bring up rock samples.
Like with the other 4 mass extinction events we’ve looked at this week, the K-Pg event was likely caused by several factors. Some say there were multiple asteroids that made impact with the Earth, and others cite…
…the outpouring of lava from the Deccan Traps in modern-day India which caused a massive release of CO2 into the atmosphere that greatly warmed the planet…
…and still others associate the die-off with the continued rearrangement of the world’s landmasses which would have gradually changed the habitats favoured by the dinosaurs and other animals living at the time.
A combination of the above theories is still likely, with a gradual deterioration of ecosystems ending with a massive asteroid impact which would have sent debris and sulphur into the atmosphere,…
….blocking light, stopping plants from photosynthesising, as well as causing tsunamis and wildfires, and perhaps even causing the eruptions at Deccan lavas.
Many well-known creatures from the towering T. rex to the humble ammonites disappeared from the planet. Pictured here is the skull of Triceratops horridus, which weighed twice as much as an African elephant Image

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More from @morethanadodo

14 Oct
Partula dentifera & Partula hebe

There were once many native species of Polynesian tree snails found across the French Polynesian islands, but now species like P. dentifera and P. hebe are Extinct in the Wild. Image
Extinct in the wild means that there are no, or no significant, wild populations remaining, but the species lives on in captive breeding programmes. In 1986 an international conservation initiative started to try to save this snail genus.
In 1967 the French Polynesian government allowed the import of giant African land snails to be used as a food source on the islands. However, some snails escaped and bred, quickly growing an invasive population. Image
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13 Oct
Did your parents always tell you not to play with your food? Well, at our special #MeatTheFuture Late Night event, you’ll have the chance to do just that!

Checkout these fun food-themed games in the thread below! Image
Join us for talks, drinks, snacks, and activities that will give you some ‘food for thought’ about the impacts of animal agriculture and meat consumption on people and the planet.

oumnh.ox.ac.uk/event/late-nig…
Fancy walking in the shoes of a dairy farmer with a daring game of skill and chance? You’ll have the opportunity to play ‘Grade Up To Elite Cow’ with @TheMERL at our Late Night Event. Image
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13 Oct
Pangolins are the most internationally traded non-human animal on the planet. There are eight species of pangolin found in Asia and Africa and all are threatened with extinction. This is a Sunda pangolin which is found across SE Asia. Image
Pangolins are hunted both for their meat and for their scales which are used in traditional Chinese medicine. Pangolin scales are made of keratin, the same as our hair and nails, and have no medicinal qualities. Image
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Read 5 tweets
8 Oct
About 201 million years ago the Triassic-Jurrasic extinction event (also called the end-Triassic) took place and some 76% of all species (marine and terrestrial) went extinct and about 20% of all existing taxonomic families were lost. Image
The extinctions that took place during this period really paved the way for the rise of the dinosaurs. It is hypothesized that climate change and rising sea levels are largely to blame for this mass extinction event.
Some studies have estimated that the rifting (coming apart) of the supercontinent Pangea may have released up to 100,000 gigatons of CO2 which could have raised the average air temperature by 10-15 ºC and acidified the world’s oceans.
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6 Oct
About 252 million years ago the largest known extinction events occurred, the Permian-Trassic. Also known as the ‘Great Dying’ an estimated 96% of all species went extinct during this period. Image
Ecosystems on land were dominated by a group of animals called Therapsids. It included many of the first megaherbivores and carnivores as well as smaller creatures
One you might recognise from the Museum is the Diictodon. This burrowing creature was the size of a small dog and its fossil remains have been found in what is now South Africa, and Zambia. Image
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5 Oct
Some more #MassExtinction chatter today:

The Late Devonian not only suffered from a protracted extinction event, but was marked by low speciation (meaning that fewer new species were evolving at this time than average). Image
About 375 to 360 million years ago the Devonian period experienced elevated rates of extinction that lasted as long as 20 million years. Evidence has suggested that this rise in extinction rates was caused by a dramatic decrease…
…in stratospheric ozone and a warming climate. When the ozone layer was striped away, possibly by a nearby supernova which would have accelerated cosmic rays and delivered ionizing radiation to the Earth’s surface.
Read 14 tweets

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