How Mammals Survived the Asteroid Impact that Wiped Out Dinosaurs | GEO GIRL

Ever wonder why mammals survived the asteroid impact at the KPg boundary, 66 million years ago, while the non-avian dinosaurs went extinct? In this video, I cover the major factors that allow mammals to survive the KPg mass extinction event over dinosaurs. Hope you enjoy!

0:00 Intro & Why We Care
1:53 The KPg Extinction Took Out Dinos
2:31 But Mammals Survived then Radiated
4:40 Leading up to the KPg Event
6:22 Mammals Were Hit HARD
7:11 Mammals vs Other Mammals
9:04 Mammal vs Dino Size
11:37 Mammal vs Dino Diet
11:59 Mammal vs Dino Niche
12:42 Dinos Already Declining?
13:40 Mammal vs Dino Stability
15:45 Mammal vs Dino Metabolism
16:22 Extinctions of Other Mammals
17:02 Post-Extinction Rise of Mammals

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[GEOGIRL]

The video I linked at the end about birds vs dinos (avian vs non-avian dinos) is currently a member-only video (meaning you have to be a channel member to watch it), but don't worry, it will be out for everyone in a couple weeks! ;)

[toastyburger]

Delightfully presented! Hard to believe only 23 mammal species survived the KPg extinction. I never realized how close mammals came to going extinct along with the dinos.

[persimmontea]

mammal burrowing might have been a big factor ... picture regions where many mammals were in hibernation during the worst of the impact winter. Also, high valleys ... similar to Lake Tahoe today ... might have acted as refuges with the air clearing much sooner than lower elevation regions so that a high wetland that was frozen over and in hibernation during the impact awoke months later after the high elevation air was relatively clear as the heavier particles had settled out. Also, one can imagine a lot of flies and cockroaches for awhile after the mass death and these insects would have favored small mammals and birds as a food source.

[sjoer]

I always enjoy listening to you ramble in the background while I'm cooking dinner for myself <3

[joecanales]

Howdy Rachel, extinction events are so interesting. What we can piece together always makes an interesting story. I especially like the paleo-reconstruction of tectonic maps, something useful in my previous career studying paleo-environments. They seem to get more detailed since I retired.
Thanks, your topics are always interesting.

[terenzo]

Adaptability is pretty doggone important. Life throws curveballs.

[sjzara]

A great video. Personally I find find the “mammals vs dinosaurs” angle helpful, because some dinosaurs survived, presumably for the same reasons that some mammals survived, and presumably many mammals went extinct as well. Also, there are more dinosaur species alive today than mammal species.

[noitalfed]

Thanks! First congrats Dr.Geo Girl for completing and successfully defending your thesis. Let me vote for more videos like this. What could be more interesting than learning the story of us. Our distant but essential ancestors who made it thru bottleneck allowing us to be here now. With regard to your unnamed species. I think they will make thru the current trouble. As a species because of their adaptability, yes, but probably not technology based industrial capitalist civilization. Thats going down. See Collapse by Jared Diamond.

[michaeleisenberg]

Rachel 🪃,
Very well put together. Thank 🙏 you.
👏👏👏👏

[francoislacombe]

The birds made a bid for dominance before mammals could get started. There are, after all, a lot more bird species than mammalian ones. However, because birds were specialized for flight, they had built in limitations that held them back long enough for the mammals to get the upper hand.

[uncleanunicorn]

9:27 I never thought about it that way before, Dinosaurs prevented mammals from becoming large, but mammals prevented dinosaurs from becoming tiny. For the same reason; mammals already dominated the tiny animal niche.

[SandhillCrane]

"I'm very specialized for this ecological role, but unfortunately there is no ecosystem. I guess I'll just die."
–The Dinosaurs

[donaldbrizzolara]

Rachel: I think a more in depth discussion of the relationship between birds and dinosaurs would be fascinating. Are birds the successor of the dinosaur line (especially the theropods)?

[alexeyvlasenko]

So, it's more like "small animals survived, large ones did not" - and the small ones were (some) mammals and avian dinosaurs, but not larger mammals and dinosaurs. Afterwards, these surviving groups diversified again and evolved large size, but it was predominantly mammals that became large this time (though there are / have been a few large birds as well)

[SiqueScarface]

We have to consider that most birds also died out after the KT event. The sole survivors were bird with no teeth, but sharp beaks. This points to the diet of those birds: seeds and detritus eating insects, worms and other arthropoda. After the KT event, Earth was experiencing a strong winter, and most plants were either dying or at least not thriving. Every animal that relied on green plants for survival, or on predating on animals which eat green plants, was having a hard time. But seeds can survive a winter, and thus also feed animals during a winter - and with some luck, a few of them also during a very long winter. In the same way, animals feeding on dead plants were having a good time, as enough plants were dying. Thus insects and worms and millipedes were surviving, and with them the birds preying on them.

[sciencecompliance]

I've said this before, but I would love to see a mini-series like Prehistoric Planet follow the events from the day of the asteroid impact to basically the end of the asteroid's/comet's influence on the environment when photosynthesis was back in full swing again. It would be pretty bleak until the end, but it's a pretty damn important epoch (in the colloquial sense of the word) in our evolutionary history.

[frankb]

Hi Rachel, I enjoy your videos although my own interest has been mostly physics and mathematics although I also grew to love biology while at university. Like you I did a PhD and did two postdocs before becoming a lecturer. Academic work can be very rewarding but also doesn't pay the best. Lots of nice videos to watch on all things geological, it'll be fun. Many thanks, Frank.

[calinradu]

Dinosaurs were losing their diversity leading up to the K-Pg extinction event and some mammals were filling niches and increasing in diversity but the species of dinosaurs extant in the latest Cretaceous were more wide spread, had more numerous individuals than those before and were in dominant positions in the trophic cycle that no mammals back than could even be close to so it would be false to assume that the dinos were in decline and the asteroid just speeded up their inevitable doom as some have argued. However it is true that having less diversity means being more exposed to major extinction events. The asteroid impact was a real game changer for life on Earth and undoubtedly animal life would have been significantly different back then had that not occurred. Rachel I am more interested in natural history than geology and geochemistry but in order to better understand the previous you definitely need to know some of the latter so I think your channel is an intelligent composite!🙂

[ronkirk]

I didn't realize that so few mammal species (~7%) survived the extinction event, which makes it a close call for us as well. I wonder if many insect species survived? They could have been a good high protein food source for those surviving mammals.

[stanengle]

I gotta subscribe to support someone with a local connection to my hometown university, even though I graduated up the street at NMSU. Anyway, it was a very informative video. Thanks Dr. GEO Girl.