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WITH DEATH COMES LIFE (Cretaceous-Paleogene Extinction Event) ((66.0 MYA))

#paleoart #palaeontology #K-pg #mass extinction

i don't think we mention how fucking horrifying that extinction was in popular media enough. like funny asteroid go brrrrr but that's really fucking sad to me. they were here for hundreds of millions of years and just got fucking obliterated by a big enough rock.

like it was ONE DAY

ONE

most mass extinctions take millions of years

but the world literally went from

"look at this lovely biosphere, all these wonderful animals and plants and fungi and microbes, look at them doing their thing"

(Prehistoric Planet)

and then

BOOM

everything over 25 kg? dead

Anything under? Better hide from the

GLOBAL WILDFIRES

TSUNAMIS

SHOCK WAVES

and IMPACT WINTER

and hope you can find food for the next few millennia while the SUN IS BLOTTED OUT

this is *trauma*. the BIGGEST TRAUMA our biosphere has possibly EVER HAD

(there's one impact event that was bigger, 2billion years ago, but this was before life really became complex - so who knows how that affected the life at the time)

ONE DAY

change isn't supposed to fucking happen that fast

never mind such DEVASTATING change

and like, the Jurassic + Cretaceous is the longest period of relatively stable terrestrial environments on earth. The Paleozoic through the Triassic is just a lot of awkwardness, complex life stretching its metaphorical legs and figuring things out

but the J+C was a fairly stable series of succeeding ecosystems with gradual change and a few minor mass extinctions that they got through

like,,,,,,,,,,,,,,,,,,,,

WHAT

#end cretaceous extinction #k-pg #mass extinctions #history of life #palaeoblr

The worst singular day in the history of life on Earth.

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#palaeoblr #paleoart #hell creek #dinosaurs #k-pg #north america #plains #cretaceous

The Mesozoic concludes as we explore the Cretaceous, and the most famous mass extinction in Earth's history.

This Fossil Friday we continue our Time Tour, unlocking the past on The Cretaceous Period! How did the reptiles continue to dominate life on earth, and how did our mammal ancestors fair, and what happened in the most famous mass extinction of all time?

#paleo #palaeo #Palaeoart #palaeoblr #Mesozoic #fossils #t rex #triceratops #plants #mammals #mass extinction #Cretaceous period #k-pg #Argentinosaurus #time tour #blog #article #palaeontology #paleontology

The boundary clay

One of the distinct features of the boundary between the Cretaceous and the Tertiary (paleogene) in the geologic record is found in this photo. Sandwiched in the middle of this section, you see what is called the “boundary clay” layer.

66 million years ago at the end of the Cretaceous, a rocky asteroid hit the Earth off the shore of the Yucatan peninsula. Near the site of the impact, rocks were tossed around by enormous waves creating tsunami-caused deposits several meters thick in places like Cuba.

Away from the impact site, a variety of other things happened. The ash from that impact blotted out the sun and took years to rain out, causing rapid and catastrophic shifts in the climate. The change in climate caused changes in rock types that appear and then, in some places, suddenly disappear, as you see here. Many things died in the time window represented by that small layer, but after the catastrophe was over, sedimentation returned to mostly what it was doing pre-impact.

This rock comes from an exposure of the boundary in Wyoming. One of the distinct characteristics of this extinction is that the boundary clay is enriched in elements that aren’t abundant in the Earth’s crust. When the Earth formed, many elements sank along with iron metal and sulfide into the Earth’s core, depleting the surface layers of those elements. One of those elements, Iridium, is enriched by a factor of 1000x in that layer relative to the rocks around it; measurement of that iridium anomaly was the key step in realizing that these global boundary clay layers had to be caused by an impact.

There are many mass extinctions in Earth’s history and the Cretaceous is not the biggest. However, it is the only one we can tie fairly directly to an impact. The end-Permian extinction was bigger; many more species died and life took ~10 million years to recover from that calamity, but so far there is little to no evidence of a similar “boundary clay” layer or similar chemical fingerprints of an asteroid impact associated with any other extinction. The K-Pg boundary extinction thus may be a unique event in Earth’s history, at least over the last 500 million years.

-JBB

Image credit: Wikimedia Commons http://en.wikipedia.org/wiki/File:K-T-boundary.JPG

#Geology #boundary clay #k-pg #K-T #science #wyoming #sediment #asteroid #bolice #cretaceous #dinosaur #extinção #ion #the earth story

Are Mass Extinctions Periodic, And Are We Due For One?

“If we start looking at the craters we find on Earth and the geological composition of the sedimentary rock, however, the idea falls apart completely. Of all the impacts that occur on Earth, less than one quarter of them come from objects originating from the Oort cloud. Even worse, of the boundaries between geological timescales (Triassic/Jurassic, Jurassic/Cretaceous, or the Cretaceous/Paleogene boundary), and the geological records that correspond to extinction events, only the event from 65 million years ago shows the characteristic ash-and-dust layer that we associate with a major impact.”

65 million years ago, a catastrophic impact from outer space caused the last great mass extinction on Earth, destroying 30% of the species that lived on our world at the time. These mass extinction events happened many times in Earth’s past, and the Solar System also passes through denser stellar regions of space periodically, as determined by the orbit of the Sun and stars in the Milky Way. It’s a combination of facts that might make you wonder whether the extinction events are also periodic, and if so, whether periodic impacts are predictable. If so, then shouldn’t we be aware of whether we’re living in a time of increased risk, and prepare ourselves for that possibility accordingly? After all, the dinosaurs didn’t have a space program or the capability of deflecting a dangerous object like the one that wiped them out.

But before we go that route, we should take a good look at what the data shows. Are mass extinctions periodic? Are we due? Let’s find out!