Відео

I got the impression that you're saying the movement of the continents caused extinction events, with hardly any mention of vulcanism. The Siberian Traps caused massive extinctions ~250 Ma, the Indian Traps wiped out life ~35 Ma, and the Atlantic Rift between NA, Europe and Africa caused a lot of extinctions. I'm sure the continental masses and their location on the globe had an effect on life. But I think vulcanism affected it more.

You are kidding yourself if you think for a second that human over-hunting had even "restricted" any of the megafauna species during the younger dryas.

That dendrochronology had me stumped ...

We get a large temperature maximum every 25k years--called a glacial maximum. Is that a mass extinction? The sea level was rising 3X as fast as now about 5000 years ago.

Cocos Plate, not couscous plate ... though that sounds delicious!

i have a carbonaceous meteorite i wanna do isotope oxygen ,can u help for finding where to do it thx ,

I love the colipso music granny makes in Europe

its a psy op

I've encountered people who seriously say that radiometric dating is unreliable, because - you don't know what the rock started with - you don't know the decay rate is constant They basically argue that the laws of physics were drastically different in the past so we can never get absolute dates They want the laws of physics to vary over time so they can reject our dates for rocks because, in case you didn't guess, they are young earth creationists. They think the earth is only 6000 yrs old Yes these people exist, and yes it's frustrating to talk to them

I remember learning that greater air pressure increases the boiling point of a substance. So when solar winds got rid of Mars’s atmosphere, air pressure would’ve dropped significantly, allowing for there to be more water vapor due to a lowered boiling point, which would’ve then been blown off by solar winds. The only caveat to this might be that if greenhouse gases were removed during atmospheric destruction, that would’ve led to colder temperatures, making it less likely for water to vaporize despite the lowered boiling point. So maybe that’s why there’s still ice left over? 😅

Your videos were helpful to clear iit jam geology exam, so thank you

The dire wolves in 'Game of Thrones' look like big wolves, whereas real dire wolves, iirc, were reddish in colour and had differently shaped heads. Four of those fictional dire wolves behave like dogs but two exhibit wolf-like behaviours.

I would love to do lots of field work especially if it has something to do with exploration. Would you recommend me to study geoscience or plain geology? I live in Germany btw

Ur is a play on words with one of the oldest cities in history Ur in Mesopotamia (according to the Bible also Abraham's birthplace), and the German syllable Ur meaning "origin" as in "Urkontinent" (paleocontinent) or "Urmensch" (early hominid). So I would pronounce it like "oor".

Your videos are always very enlightening for me (and I'm sure many others) and help my understanding a LOT, not a little. As always a BIG thank you!

You really deepened my understanding of the supercontinents and the mass extinctions around them. I still don't have knowledge of every detail but I have a better foundation to draw on in my readings. Thaks a bunch!

😊

Love this. I have a Ph.D in geology, but my topic didn’t cover a lot of earth’s history. I appreciate that you don’t glaze over details that a wonk like me requires. :-)

So are your videos part of your teaching curriculum, Rachael?

Boring 3.4 billion.

I found some of those Crinoid stems in a rock wall outside a motel parking lot in El Paso Tx about 20 years ago. I was having a smoke outside the motel room and noticed the Crinoid stems embedded in the rock in the wall. I had thought they were prehistoric worm segments at the time. They were around the thickness of a woman's pinky finger.

I’m in my mid-late 20s but I’d really love to go back to school and be involved in this field

Thanks , I spent the whole video thinking will she talk about the future. Well now I have even more reason to wait on the next episode!

Another boring about definition if or not a super-continent. The importance of big landmass is * they are so big so have a fully locked inside area without rain * there mein position like equator or pole, to trigger another world wide climate. Over this definition discussion we forget over the important impacts of size and position.

Thank you....

I think this video was good, but it misses a lot. It only covers a tiny fraction of the megafaunal losses, mainly the famous American taxa. Even that is a small sampling of the American extinctions. The diversity of life we lost is truly staggering, from "wombat-lions" to club-tailed horned turtles to giant "ostrich-ducks" to beavers the size of bears, and literally dozens and dozens if not hundreds of other unique examples. I read about this stuff a lot and I still regularly come across bizarre, fantastical beasts I never knew existed, but which humans encountered once upon a time. This gets into the second point: these extinctions were extremely global, affecting literally every single continental landmass and large island in the world excluding Antarctica, and took place across tens of thousands of years (the earliest starting perhaps 100,000 years ago, although 80,000 is a more robustly demonstrable date). The Younger Dryas only attempts to explain one of these events, though it was a big one, involving the Americas. It does even that poorly: it wasn't anything special whatsoever, and climatic fluctuations on par with this or even more intense occurred regularly and never wiped out American megafauna, or had any discernible impact at all, really. The fact that humans arrived exactly coincident with the start of the decline is the smoking gun. It not only happened here, but on literally every single landmass where megafauna went extinct. Every last one of them, without a sole exception, coincides exactly with local human arrival. This isn't a coincidence, as I've said for many years, and in the past few years many very high-quality studies have entirely put this question to rest, with studies looking at both local and global extinctions confirming the "sufficient and necessary" role of humans. None of the other "Big Five" extinctions is thought to have been caused by mild, local climatic fluctuations, though they were similar in scale to this current one. I like that you said that the human hypothesis is not just about hunting. I personally am not sure hunting was even a very important factor, given the sheer scales involved. Humans are more effective at altering habitats, spreading diseases, etc, which are some of the things you mention. I think it is a tragedy that the human hypothesis gets reduced to just "overhunting on steroids", because there is a lot more involved here. Really though, it doesn't matter all that much how they did it. Humans gonna human, and it is very clear from the patterns what the impact of that has been, continuously from 80,000 years ago right up to this day. Otherwise, a few nitpicks: there are a few animals whose babies are actually megafaunal, by the 45kg/100lb definition. Elephants can have newborns weighing over 200lbs, and rhino babies can be over 100lbs. Whale babies are much bigger. I like your overview of proboscidean evolution, but when you say "and finally modern elephants", it makes it seem as though modern elephants are more recently-evolved than mammoths or mastodons (or _Paleoloxodon_, gomphotheres, other recently extinct proboscideans). This is not the case; they are all exactly equally modern. Tens of thousands of years is a blink of an eye evolutionarily. The ones that survived are the lucky ones, but they haven't changed, and if these extinct guys were still around, they'd look and act the same as they did. This applies to all the Late Pleistocene and later extinctions. Giant short-faced bears (_Arctodus_) were probably omnivores, or even primarily herbivorous. The only living tremarctine bear, the spectacled bear, is the second most herbivorous living bear (over 90% of the diet). In fact, all living bears besides the polar bear are omnivorous, and most have at least some populations, at least seasonally, which are very herbivorous. Studies on _Arctodus_ suggest variability, with some bears being very carnivorous and others very herbivorous, very similar to modern brown bears. But I would bet they were more herbivorous overall, as some researchers suggest.

@Geo Girl. I have now seen all your extinction videos, and appreciate your well-constructed information provided along with your clear and concise reasoning. My question for you is "based off the geography of the Earth, how could the Earth go from a Unicellular organism to the Cambrian Explosion of complex multicellular diversity?" What was the cause and condition to transform to such an incredible state for life when the last Billion years had relatively no change? Thank you for any insight you can provide!

Blew my mind when I discovered direwolves were real. Though I guess it (kind of) makes sense, what with Game of Thrones being set in what appears to be a pre-medieval or very early medieval era...

Thanks for another great video. I'm from the West of UK in the area called Avalon (Avalonia) but at the moment I am in Agadir Morocco, just where the CAMP break up was located. It's really old rock here. Think it's called the West African Craton (WAC) There are fossils in the garden here and this is where the Atlas mountains drop down to the sea. Looks like the mountains just got cut up with a big knife! Thanks for the wonderful channel.

Always brightening up my day 🌻

That was really good. I finally understand it

Wow, look at some of those weird early life forms. I wonder what they could have evolved into if they survived.

Why is Afro-Eurasia not considered a supercontinent?

Great presentation. The only problem now is that our current warming is at a magnitude unprecedented in geological time and 100% caused by us. The other problem we have is that nearly half the world's human population have far smaller brains than the dinosaurs, who I'm sure would never have contemplated voting for the Donald.

Geological mapping has nothing in particular to .............geology ?

Nom nom nom

Thanks for making this really informative video!!! Can you please make a video about Vaalbara, Ur, Kenorland, Arctica (?) and Columbia/Nana? I've looked for more information about these first contents but i haven't been able to find much info (as you have mention). Maybe you could discuss the evidence for these continents, and alternative theories? Also, in the past when reading about these early continents, i have assumed that they were created by plate tectonics, but thats really interesting that they formed before plate tectonics started (you video with Steve was super interesting btw! ). One thing im wondering now is why would these first continents form all together instead of all of the lighter continental material raising to the surface through differentiation equally across the early earth? Please make a video about this, it would be super interesting 😀

Boring billion is really stupid name :) There was a lot of evolution then, but evolution was on molecular and cellular levels, but also the basis for multicellularity was developed in many groups (red algae, animals, fungi, etc). Most eukaryotic groups were formed during this time.

Fun fact: the Caspian Sea, while considered a "lake" since its landlocked, it's actually the last remnant of the Tethis Sea, as Eurasia closed in around it. It's bottom is oceanic crust, rather than continental crust, like other true lakes

Wow! I never knew that giant armadillos existed. I always thought armadillos were small burrowing creatures. It's amazing to think about all the giant creatures that roamed the Earth during the Pleistocene Epoch. I wonder what other creatures we don't know about?

Rhodophyta (red algae) were probably first multicellular organisms. They appeared before 1.0-1.2 Ba (billion years ago), it is possible that they might be already at 1.6 Ba. On other side, animals, fungi, green algae (including ancestors of plants) maybe had advantage in Snowball Earth conditions. In addition, everchanging conditions (glaciation, no ice, glaciation) might also speed up evolution, by forcing organisms to adapt to new conditions. It might be interesting to you that the last common ancestor of Opisthokonts (Animals, Fungi, and related organisms) lived approx. 1.1-1.3 Ba.

Your pronunciation of Latin names is not correct. You are pronouncing them like English words, whereas they are Latin. For example, your pronunciation of "Cnidaria" is example of that, you are should also pronounce first letter (as "k"); they word should be pronounced: k-n-i-d-a-r-i-a, not 'naideria'.

Reunite Pangea!

THANK YOU! I've wondered about how continental drift affects life for a few years, and you summed it up very nicely. What hypotheses do we have for WHY the continents drift the way they do? Why wasn't continental drift occurring for the first billion years or whatever of Earth's history? What drives them together, and then apart again? Does the mantle have a 250 million year cycle of sloshing back and forth somehow? I look forward to future vids!

Ur looks like a diving penguin. Such a cool name too, Ur!