How Avian Dinosaurs (Birds) Survived the Asteroid Impact that Killed Non-Avian Dinosaurs | GEO GIRL
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- čas přidán 30. 05. 2024
- Ever wonder why birds 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 avian dinosaurs, or birds, to survive the KPg mass extinction event over non-avian dinosaurs. Hope you enjoy! ;)
0:00 Why We Care
0.52 Non-Avian Dinos Went Extinct at KPg
1:19 But Avian Dinos (Birds) Survived…
2:09 Avian Extinctions Played a Role
4;04 Bird Advantage #1 (flight)
5:55 Bird Advantage #2 (size)
7:34 Bird Advantage #3 (niche)
8:55 Bird Advantage #4 (brooding)
9:44 Bird Advantage #5 (rapid reproduction)
10:02 Bird Advantage #6 (feathers)
11:57 Bird Advantage #7 (dino decline)
12:28 Bird Advantage #8 (brains)
13:40 Bird Advantage #9 (beaks)
14:40 How Birds Survived The KPg Extinction
References:
Longrich et al., 2011: doi.org/10.1073/pnas.1110395108
Feduccia, 2014: doi.org/10.1016/j.cretres.201...
Sakamoto et al. 2016: doi.org/10.1038/s41467-021-23...
Torres et al., 2021: doi.org/10.1126/sciadv.abg7099
Earth System History: amzn.to/3v1Iy0G
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Somewhere along the way, the toothed birds lost the ability to brush and floss.
The shock of getting that dino dental bill likely killed a few.
The fluoride in their drinking water also reduced their fertility rates.
True story
My 10 year and I watch your videos together. I get to spend time with my son while we learn. He loves it and looks forward to your new videos. Thanks for that.
That's so lovely!
Just a fun side note. As a geologist I’ve been very fortunate to have taken part in two partial dinosaur fossil recoveries. During the excavation process I became intimately familiar with the morphology of the various skeletal elements. I highly recommend volunteering to assist in such projects as it is very rewarding. In contrast, at our home we have Canadian geese on our property nearly year around. Frequently they fall prey to fox, coyotes and, occasionally, cougar. At those times when I’ve chanced upon their skeletal remains I’ve marveled at the striking similarity in structure and probable functionality between both bird and dinosaur…and now when I see a grouping of geese tromping about our meadows I can’t help but think that a wandering herd of hadrosaurids or a hunting band of theropods must have moved about in a similar fashion. Excellent discussion, Rachel, on this fascinating topic.
That is so cool! Where I live, there are wild turkeys that travel in packs, and I like to think about them as dinosaurs. If I see tracks, I'll say STOP.... look....raptors!
Neat!
We have Sandhill Cranes here. Their throaty calls are reminiscent of how small to mid sized Dinosaurs must have called.
cats were not around yet. That's how.
I was always pondering about this point. And I always used to say and write even in exams that only non-avian dinosaurs lost the race of survival at the closure of Cretaceous.
Plus I live and study in Pune, India which is all Deccan Volcanic province so this is really impressive to know again 😅😊.
As always I loved the concept and content of this video also. Keep making these contents.
At the end I must say you are beautiful and smart at the same time 😊❤ and I love that thing about you 😊
I would put money on the idea that some species survived the KT extinction, but then went extinct during or relatively shortly after the resulting several thousand years of climate upset. A sort of 'almost made it, but not quite'.
Thank you for leaving the articles you use as sources for your videos, I like reading the scholarly dino articles
Hey, I just want to point out a little error on the slide at 13:48, the picture of the seabirds on the left that depicts a bird with teeth actually isn't showing toothed birds from prior to the K-Pg extinction as I feel like you were trying to imply here with the toothed birds point, only one of the birds in the picture is 'Toothed' but its actually very strange. The bird in question is Pelagornis, this is actually a much more modern bird, its probably even a Neognath, so its ancestrally toothless, and its part of a family of 'Bony toothed birds' that only went extinct about 2 million years ago. Basically these birds, in lieu of having real teeth, just evolved projections from their jawbone directly that have the same functionality, hence the term 'Bony toothed' used to describe them. They are very interesting, they generally had a lifestyle and appearance most similar to albatrosses, but in addition to the weird fake bone teeth they were also distinguished in being absolutely massive, Pelagornis here had a wingspan of something like 6 or 7 metres, at least twice the width of the wandering albatross, comparable to some large pterosaurs like Pteranodon. The fact that tooth like structures evolved again in them suggests that there was a very strong environmental pressure to do so, they probably would have just used regular teeth if they still had them so went for this weird solution since they were long lost millions of years previously. The image is showing it alongside some other ancient seabirds, including more familiar things like penguins and gulls, all of these evolved post K-Pg extinction.
Its a weird story, I can see that the image is one of the first things that shows up when you google search 'Toothed birds', but it undermines the overall point being made since its not really got anything to do with the extinction event, and the teeth in question are not real teeth. A bird like Hesperornis, which did have true teeth, and also predated (and likely died out during) the K-Pg extinction probably would have been a better choice for this segment.
Thank you for sharing your knowledge ❤
Excellent and informative video! If I hadn't already known how things turned out, I would have been worried about the birds' survival chances following the K-Pg event. One of their DIS-advantages would have been their homeothermy (warm-blooded thermoregulation) and its requirement for additional energy needs and food supply, versus the overall mesothermic characteristics of most other dinosaurs (we think, for now!). There must have been a significant scarcity of food, which wouldn't have affected poikilotherms like reptiles nearly as much, which allowed many of them to survive. I suppose that all the advantages you listed for the birds added up to overcome this thermoregulation disadvantage, while the mesothermic dinosaurs got caught in the middle - needing more energy than reptiles, but unable to make use of flight, brooding, rapid reproduction, etc. that the birds used!
Yea, exactly! I think it was just enough advantages to allow them to scrape by and make it to the Cenozoic and from there of course their diversification was practically inevitable! :)
Great video GeoGirl. The understanding of deep history and its flora and fauna has expanded so much in the last 50 years or so. When I was a kid in the 1970s, the asteroid impact at the KPg boundary hadn't been found or even suggested, and the mass extinction at that time was a complete mystery. It has been thrilling to see the expansion of knowledge that has happened since then.
Bicentennial baby, 80’s school kid here. They was teaching the asteroid ☄️ impact but where wasn’t published till the 90’s high school. The oil companies definitely knew since they found it The Yucatán region is definitely a beautiful to visit. The food, culture, the old Mayan culture, nature …well I had a great time exploring in my youth right after high school.
The interesting thing is that now they aren’t sure how much of the extinction was the asteroid and how much was caused by crazy volcanic activity. I mean, either way, the asteroid impact caused insane damage. But it might have just been a final nail in the coffin type of thing. That’s still an open question, as far as I understand it
Thanks Rachel, I learned much about the birds. I had thought their small size helped, but brooding and beaks were new ideas. You always put together an excellent presentation.
The dinosaur's rebranding as birds is common for major enterprises when they become unpopular. Everybody loves birds! 🌺♥️🦢🦚🦜🐓🐧🐦🦃🦅🦆🦉🪶
Dinosaurs, avian and otherwise, are always exciting. 😊🐦🦖🦕
A few items of interest: 1) Asteriornis maastrichtensis is a latest Cretaceous goose, a highly derived taxon of toothless bird in trait analysis. 2) African secretary birds (Sagittarius) are ancestral to South American terror birds in trait analysis, which means they had cross the South Atlantic in the Cretaceous before the Atlantic widened too far for them to fly. 3) We know of Paleocene penguins from near Antarctic New Zealand. These are derived from Arctic birds that fly and swim: murres, aka guillemots.
These few examples indicate that many, if not most extant bird clades survived the asteroid, despite a dismal fossil record. What killed their look-alikes with teeth is a good question.
Lacking these examples, Latest Cretaceous Vegavis, from then warmer safe haven of Antarctica, might have served as a last common ancestor candidate because it is close to the base of all extant birds
Pterosaurs. We know of small flying pterosaurs (an embryo ctenochasmatid from the last day of the Cretaceous site in North Dakota), so flying was not what saved the smallish ancestors of extant birds.
Thank you for your presentation. Certain birds must have survived in small pockets here and there, perhaps closer to the poles and outside of the circulating patterns of fire, debris, clouds and sun-obscuring dust.
As GeoGirl said: teeth vs. beaks is a question of diet. Toothed birds were probably either preying on vertebrae like fishes, newts, reptiles and mammals, or eating green plant parts like leaves. Beaked birds were preying on insects and other non-vertebrae, or on seeds. After a prolonged period of minimal plant growth due to the impact winter, any bird feeding on green leaves probably had a hard time finding food. So was the case for birds preying on plant eaters. But seeds are sturdy. Being a dormant state of a plant, they survive a long winter, and even if they might lose with time their ability to grew into a new plant, they are still edible. Same with a lot of insects and other non-vertebrae. Many of them are feeding on detritus, and are not relaying on freshly sprouted plants. And they also have one or more dormant states, as egg, or as larvae. So they can survive longer periods of less food.
It makes sense that beaked birds had a better chance of survival than toothed ones.
@@SiqueScarface toothless birds evolved several times during the Cretaceous. e.g. Confuciusornis sanctus
@@DAVIDPETERS12CBut only one of the groups, today called Neornithes, survived the K/T boundary. Some of them, like the Confuciusornis sanctis you mentioned, even died out long before the K/T boundary.
@@SiqueScarface when there is a definitive answer, someone will let you know.
@@DAVIDPETERS12CYou know how you get definitive answers on the Internet? Post anything wrong, and someone will angrily correct you and point to all the evidence that his answer is right.
Dear Rachael, thanks for a very entertaining video talking about why the Avian Dinosaurs descendants survived whilst the Non-Avian Dinosaurs became extinct. There was statement about inverse size giving an advantage to different sized creatures that I have to take exception to. I’d like to present an argument to the contrary, that bigger is better, in some respects at least. Here’s the science or maths, depending on your perspective.
For any given body, the heat loss is through the surface of the organism and this is proportionate to the surface area. Metabolic heat generation relates to the amount of biochemical processing that the organism has. This relates to the volume of the organism. Now let’s say we have an organism with dimensions L x L x L. {Yes, it’s a box}. If L, the dimension of our smaller organism is 1 unit then it’s volume is 1 unit cubed. It’s surface area is made up of six sides, 1 unit squared - therefore 6 square units. Its surface area to volume ratio is 6.
Now, let’s say that we have a moderate sized organism with dimensions of 2 units {Double that of the small organism}. It’s surface area, the part that allows for heat loss is 2 x 2 x 6 = 24 sq units. Its volume, the part that generates heat is 2 x 2 x 2 = 8 cubic units. The surface area to volume ratio is 3. The potential to generate heat, or survive cold has gone up by 100% or 2x by the dimension change. This has given the organism some more wriggle room compared to its tiny counterpart.
Now, lets say that we are a large creature with dimensions of 4 units. It’s surface area is 4 x 4 x 6 = 96 sq units. Its volume is 4 x 4 x 4 = 64 cubic units. This much larger creature has a surface area to volume ratio of 1.5 which means that it can better regulate its temperature under temperate cold conditions.
Now go to whale size with dimensions 10 units. Surface area = 10 x 10 x 6 = 600 sq units. Volume is 10 x 10 x 10 = 1000. SA/Vol = 0.6. This gives the creature wriggle room to survive in extremes such as snow and ice or the deep oceans.
All this explains why a woolly mammoth could have survived in the cold arctic but a canary could not.
Excellent video. I have been fascinated by this. I hadn’t heard of the significance of brain size.
Thank you Rachel, very informative, always enjoying watching your content! Have you ever thought about adding a summary section outlining key points in the end of the video? I often feel overloaded towards the end of the videos and having a simple but informative summary, touching on key ideas/factors would be awesome.
I would add that likely some avian species were already adapted to mountain environments, and thus would have been
1. The safest during the impact event itself
2. Some mountain ranges would be above the cloud layers in the following years, letting photosynthesis continue and maintaining the ecosystem
3. The mountain areas would likely have recovered 1st as clouds thinned and more sunlight started reaching lower altitudes.
🖖🐰👍
(Also makes the kind of place for small rodents to hang out comfortably as well 😉)
Thanks. Small correction. In minute 7, you get it back to front: it is large creatures that are the more energetically efficient, which accounts for Bergmann's rule, that animals in cold climates tend to be larger.
I think what she means is that small animals can survive when the food supply is limited. You are right that proportional to body weight small animals need more food.
Another amazing video! Which always raises another question. So why did feathers evolve? Why would flightless animals produce something needed for flight (like the dinosaur depicted on the right at 0:14 at the start of the video)?
@TreyRuiz Feathers evolved BEFORE flying birds for insulation and sexual display. They made subsequent evolution of flight in birds easier to accomplish. True flight has evolved independently four times. Insects, pterosaurs, birds, bats. Flightless birds dropped flight inherited from their ancestors. Watch her vid on mammals returning to the sea, which happened several times independently. Which begs the question, why evolve limbs? Following your logic. Also look up how many times turtles went from land to water to land... back to water... back to land...
There is NO goal or purpose the evolution follows. No guide or playbook. Evolution is a RESPONSE to environmental change, If the response is too slow, extinction is the result.
Feathers developed first and some dinosaurs with feathers evolved the ability to fly. The early feathers were quite simple and not that different from fur. They were most probably evolved for thermoregulation but also other contributing factors could have played a role. For example birds use feathers also for display. It needs also to be noted that modern birds still have different types of feathers that serve different purposes, like for example down feathers.
@rickkwitkoski1976
(I encourage you to use "raises the question" unless you are referring to circukar reasoning.)
Hi there Geo Girl : ) Another cool presentation - Thank you. Eons ago, I watched a show featuring Robert Bakker (I think it was on NOVA.) where he spoke of the major influence of John Ostrum regarding modern perceptions of dinosaurs, including their relation to birds.
Rachel 🛵, Fascinating video 🎙️! Thank you🙏.
👏👏👏👏👏
Thanks for the interesting, informative, and beautifully illustrated video in the Geo Girl style that has been so much fun to watch over the past couple years. Please make more like these rather than last week's Dr. Doom video.
I was curious about SA:volume area idea that you mentioned favored survival of the avian dinosaurs. I would have thought their larger surface area relative to their volume would put the avian diinos at a disadvantage when it comes to sudden T fluctuations. As endotherms, wouldn't their smaller size mean they needed to eat more to survive colder temperatures?
@olecranon gotta get my head around that one too. Look at hummingbirds. They have to EAT almost continuously. Otherwise they starve to death.
Dear Olecranon, you are absolutely correct and Rachael was incorrect with her statement about inverse size giving an advantage to different sized creatures. Here’s the science or maths, depending on your perspective.
For any given body, the heat loss is through the surface of the organism and this is proportionate to the surface area. Metabolic heat generation relates to the amount of biochemical processing that the organism has. This relates to the volume of the organism. Now let’s say we have an organism with dimensions L x L x L. {Yes, it’s a box}. If L, the dimension of our smaller organism is 1 unit then it’s volume is 1 unit cubed. It’s surface area is also 1 unit squared.
Now, let’s say that we have a moderate sized organism with dimensions of 2 units {Double that of the small organism}. It’s surface area, the part that allows for heat loss is 2 x 2 = 4 sq units. Its volume, the part that generates heat is 2 x 2 x 2 = 8 cubic units. The surface area to volume ratio is 2. The potential to generate heat, or survive cold has gone up by 100% or 2x by the dimension change. This has given the organism some more wriggle room compared to its tiny counterpart.
Now, lets say that we are a large creature with dimensions of 4 units. It’s surface area is 4 x 4 = 16 sq units. Its volume is 4 x 4 x 4 = 64 cubic units. This much larger creature has a surface area to volume ratio of 16 which means that it can regulate its temperature under extreme cold conditions such as snow and ice or the deep oceans.
All this explains why a woolly mammoth could have survived in the cold arctic but a canary could not.
Oh I just looked in your description and see references to Knoll, and Shubin. I love those guys! Im rereading Your Inner Fish right now.
Yes Rachel!! Publish some book reviews please!!!!
I've only just discovered your channel (Why did it take me so long?), subscribed!
Thanks! Hope you enjoy the rest of my content! ;D
I wish I had taken Geology course in college. Molecular biology and biochemistry were interesting but there is sooooo much I don't know. Thank you, Geo Girl.;
Lovely video Rachel thanks❤
thank you. helped answer some of my questions.
Excellent presentation -- thanks Doc!
Thank you doctor! So nice to learn from you. My great pleasure to share in the enthusiasm of an expert such as yourself.
12:00 - In regards to most non-Avian Dinosaurs in decline leading up to the KT extinction event, Rachel, no doubt the Deccan traps flood-basalt eruptions played a role.
Another great one. I so look forward to your cheery enthusiasm.
Another knowledge video, thanks geo girl for sharing amazing knowledge ❤❤❤
Excellent DR GEO GIRL thanks
I just loved loved loved this video, it was so well explained 😊
My grandparents lived where the impact of the second mass extinction event took place. It’s a very scenic beautiful place.
Love your essays
Great video! Well done GeoGirl👍
For 130 million years the archosaurs kept is underground, and forced us through the nocturnal bottleneck. Now we eat fried chicken out of buckets, but we still cannot see UV.
Let us never forget what the evil diapsids stole from us, Dr Phillips. ❤
Wow, so educative ❤
Very interesting video, thank you.
Cheers, and great video!❤
Could you to a video on early human tools/artifacts, during prehistory? Its alright if that's not your specialty :)
If you are interested in extinct apes and hominids, you may also want to explore Gutsick Gibbon's channel.
I've been confused for a long time now on the taxonomy of dinosaurs. When I was a kid, I thought they were reptiles. Later, I somehow got the impression they were a distinct thing on the same level as mammals, reptiles, birds, amphibians, etc. But these days since everybody is saying that birds are the descendants of some dinosaurs, I wonder where they would fit in if they were still around today. Would we say "dinosaur" was on the same level as mammal and reptile, and birds were just a sub-group within "dinosaur"? Or would we consider dinosaurs and birds the same things? Or is "dinosaur" just a catch-all phrase, and there are both reptiles and birds that fall under "dinosaur"?
dinosaurs are reptiles, though reptiles are not a group defined by evolutionary relationships (phylogenetics). Otherwise, birds would be reptiles because they (and dinosaurs as a whole) are more closely related to crocodiles and turtles than they are to squamata (lizards and snakes). Dinosaurs are their own group and birds are one group within that. So yeah, dinosaurs are on the "same level" as mammals and amphibians, but birds are a group that's a part of dinosaurs (like marsupials are part of mammals), whereas "reptile" is a different way of categorization altogether from evolutionary groupings.
Is there evidence that birds already had big brains at the time? Brains require a lot of resources. In mammals there was actually a decline in brain vs body size following the extinction event, for a few million years.
One thing you didn't mention is that some creatures thrive in dead matter. And creatures that feed on those (maggots, worms, insects) had a lot of food
Viewer #1000. 👍😉
Glad you mentioned beaks. That is a key thing isn't it. You can dig out grubs with it and so on. It's a more useful tool for a bird. As Darwin showed with his finches, the beak shape and size can rapidly adapt over just a few generations.
Thank you, Geogirl.
Enjoyed the video. Perhaps you covered this in another video (you have so many!) but what distinguishes an avian dinosaur from a non avian one? How many avian dinosaur species went extinct, and how many survived?
Thanks for expanding on a subject I should have but never considered. New insights were: - Only flighted, only small. only toothless, good brains. :-)
With all the dead wood, fungi thrived and surely would have become important in the food chain. Would birds that could feed on mycophagous insects and beetles have had an advantage?
Keep up the great work! Your intelligence is obvious. Your presentation is great.
And you’re cute too! (Is it okay to say that?)
at 7:10 in... Please correct me if I am wrong but larger animals are more efficient with energy. Smaller animals do however need less energy...
Lots of large dinosaurs that died would be major breeding ground for insects. Birds and small mammals would feed off of the massive amounts of insects. Some birds and small mammals would thrive off of this and breed with no predation. When they pass the insects would utilize their carcass and the offspring could then feed off of those insects.
Super cool video. Are you familiar with Michael J. Benton?
You talk about the advantages of diverse eating, particularly among the small mammals and birds. How did insects and bugs in general contribute to this as a food source, and how well did they do through this event? Thanks, Ronn
Ask Keith Richards...
What makes you say that a small size, hence high surface area to volume ratio, makes you more energy efficient?
A high surface area to volume ratio means you lose (relatively) a lot of heat (through that large area) compared to the small amount that you generate (in that small volume). If you are trying to maintain warm-blooded body temperature, it is less efficient.
LUV, Loren
6:09 Many sources show the opposite-that larger animals are more energy efficient than smaller animals. This is because, for instance, with a sphere a 2x (3x) increase in radius gives a 4x (9x) increase in surface area and an 8x (27x) increase in volume (That is r, r^2, r^3--and those ratios translate to any animal that maintains its shape proportions). Therefore, the volume increases more rapidly than the surface area increases providing greater heat retention for larger sizes.
It's a pity none of the toothed birds survived, Rachel.
Thank you for this. Can you, or anyone in the know, comment on the ecosystems the surviving avian dinosaurs came from? I mean, didn't birds living in forests much more thoroughly die out than those living in grasslands? (because the forests more thoroughly burned and recovered more slowly than grasslands?)
Also, something I haven't found addressed directly, were all forests all around the world really burned? Forests in central Asia were also completely burned in the few days after Chicxulub?
Finally, outside of the area nearest the impact site, were survivors equally represented? Did any life survive better in central Asia and Africa than in distant North and South America, for example?
The entire world was enveloped in red hot rock spherules, dust, HEAT! The impact area was annihilated but the entire globe was covered in death. It is thought that burrowing animals: mammals, birds, reptiles; and aquatic species survived the initial impact days best.
Can't wait for the terror birds video 😈
My wife has an African Grey parrot - he is pretty darned smart - looking at his claws and feet I am thinking Jurassic Park - fortunately for us we are way bigger :).
I would like to ask you a question: What do you think of the non avian dinosaur fossils found in the Ojo Alamo Formation (New Mexico), which have been claimed to come from a layer dated after the creaceous-Paleogene extinction event? Do you think, this is a hint that some species of non anvian dinosaurs survived into the Cenozoic?
I am not sure about that exact fossils you are referring to, but yes, absolutely, I think whenever we refer to extinction events, it is most common that groups that go extinct may have a couple species that straggle on into the next period before finally dying out. I talk about this in one of my videos but I cant remember which one anymore haha! But anyway, yes, I think we can only say so much given the fraction of preserved species the fossil record actually saves, so we always typically assume that there may have been stragglers passed the given extinction event, but in most cases when these are found for groups that went were hit really hard during the event, they are only found in the years directly after the event and not for very long into the next period or era :)
@@GEOGIRL Thank you for your quick answer. Surfing the net I came across an article:Fassett, J.E., Zielinski, R.A., and Budahn, J.R. 2002. Dinosaurs that did not die: Evidence for Paleocene dinosaurs in the Ojo Alamo Sandstone, San Juan Basin, New Mexico, p. 307-336. In Koerble, C. and McLeod, K.G. (eds.), Catastrophic Events and Mass Extinctions: Impacts and Beyond. GSA Special Paper 35.They found a hadrosaur femur in the Ojo-Alamo formation. Using palynology the sandstone of the finding spot was dated up to one million years after the cretaceous-paleocene boundary. This way some other dinosaur fossils were also redated to the paleocene. Fassett et al. concluded that there was still a dinosaur fauna in the early cenozoic. However, this dating was disputed saying that the bones came from the cretaceous and were later reworked.
I can not assess who is correct about this because I am not a scientist. Perhaps the dinosaurs died out more gradually than it is generally assumed.
Loved the "grad school presentation" style.
The course links on your website seem to be broken. Looking for where to start on your channel as this video was at times hard for me to follow just from not knowing all the terms.
Oh no! Thanks for letting me know, I had no idea they were broken, I will fix them right away ;)
Try it now! I think I have fixed them all ;) Sorry about that!
Thanks!@@GEOGIRL
Why does the surface area to volume ratio determine how much energy they need?
I just watched a Kurzgesagt video about the Deccan eruptions over the course of thousands of years. Would be interesting to see a deep dive of what exactly happened and if the extinction of the dinosaur would have been inevitable, considering how long it lasted and how the oceans was become toxic around India when it was a continent. Would it have been similar to the Siberian Traps 200 million years ago
Excellent video. I look forward to the one on terror birds! 🐥🫨
There must haven heaps of insects available for them after the extinction event, for a while anyway, with the countless corpses rotting away.
It isn’t obvious to me why high SA/V is better than larger in a catastrophic event. If it got a lot colder, then high SA/V would suck a lot.
I think it has something to do with thermal regulation and endothermy (producing heat inside the body) vs. exothermy (reliant on environmental heat). A high SA/V in an endothermic animal means there is less volume to keep warm than in a bigger animal. Exothermic animals were likely at a disadvantage, because they couldn't produce their own body heat.
@toughenupfluffy7294
(I agree with Adam Ellison)
My understanding is that high SA/V means that the animal loses heat more quickly in the cold because of relatively little volume producing heat but lots of surface area radiating it away. Which seems like the opposite of what would help while the atmospheric dust kept the planet cool.
I know!! (Raises hand enthusiastically!) Just as the big rock impacted, fhe birds just flew up to avoid it and then flew down when the dust settled! 🎉 Petrie!!
In regards to Terror Birds, Rachel, what did you think of their portrayal in the first episode of "Walking with Beasts" in the form of Diatryma?
I've been troubled by the issue of "Why did NO non-avian dinosaurs survive?" Reptiles much like our idea of dinosaurs did, so why did no dinosaurs survive except birds? Did some actually survive, but we (layman) include them in the KP extinction when they did survive the "extinction event" but died out later because they were outcompeted by mammals, birds, et al? So a bias that says if you didn't survive the last 66 million years you didn't survive the KP extinction...
That's a good question, and we can't definitely rule out that one or a few species of non-avian dinosaurs survived for many generations after the K-PG event. Fossilization happens by chance, and uncovering fossils as well.
But no non-avian dinosaur specimen was found above the K-PG boundary, so sudden extinction within a few generations is a likely explanation. Yet not entirely impossible that some survived for a while in places which aren't the best environment for fossilization to happen & be uncovered.
I guess some of those non-avian dinosaurs decided to put all their eggs in one tarpit...heh..heh...cause fossils... :S
Perhaps the ability to stay small and survive in hard times saved crocs along with their guarding of eggs.
Beaked Avion-Dinos.
Bats. A large fraction of all mammal species is a bat. When did they radiate? ..flying seems a great survival feature, also in the age of humans.
You do realise, anyone who is going to watch your excellent videos already know Avian Dinosaurs are Birds.
Literally the next comment I see is someone who doesn't understand this. Never assume.
High surface area to volume ratios are an advantage over high volume to surface area ratios only if you are able to find your weight in food on a daily basis, and for very small birds many times your weight per day. Small in and off itself is not an energy efficient strategy. Small and very mobile and/or very fast can be, including being able to find (small) shelters. The same can be said for the mammals that survived the post impact world.
A PPT presentation where I didn’t doze off 👍
There is a factor that might have had influence as well and that is warmbloodedness (is that english?). I would love if you could dive into that aspect.
Were there different species of dinosaurs that survived, or was it just one, or a few very closely related species that survived?
I believe it was just a few species of bird. The number I heard was 7, but I don't know if that is true.
Some days in the morning when the black bird sit on my roof and roars into the morning sky I remember: this is a dinosaur... 😆
One subject not covered: Why did birds survive when pterosaurs didn’t?
Because pterosaurs by this time were nowhere near their peak diversity. They were huge and specialized and this isn't a good thing to be when the ecosystem gets ripped out from under you.
😎
Some creatures have survived every extinction event. The KT extinction killed about 60 percent of species. Birds happened to be in the surviving 40 percent. Their small size was doubtlessly a factor.
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Yep, that up/down inflections whining singsong delivery is here too.
Guess all these vids are going to irritate me. Great topics. Info I'm interested in. Offputting singsong Over EMPhasized syllABles.
Yet there is something strange with the kpg extinction. I mean: dinosaurs lived everywhere, in all sizes, in all niches and climates. Somewhere there must have been dino’s that were kind of protected: under water in tropical seas far from the impact, or small dino’s. Sometimes I think: might the impact and its effects have had as result the flourishing of some microbes, bacteria or virusses that non avian or cold blooded dinosaurs had no defense against because of their DNA but flying warm blooded birds and mammals were genetically different and somehow didn’t all die. It is just hard to imagine that ALL dinosaurs went extinct- all sizes, niches and climates - but an epidemic of virusses/microbes attacking specific typical dino biology could do such a thing.
Fascinating idea!
Have avian dinosaurs gotten larger or smaller, in general, over the last 65 million years?
Imagine everything is DEAD and all you have to eat are old seeds. That's how birds survived. Not even the tiniest of tiny pterodactyls could fly away to a place where fish and insects and worms were in abundance. Fish and insects were hit hard too, and almost went exctinct themselves. If you could not eat old, burnt, moldy seeds, you had to die.
After further research by noaa it was agw
"So survial of fitest cannit apply to you if you wing as a species,," ( before wayching vid)😉
13:20 "non-avian bird" is confusing and contradictory as I thought to be avian is to be a bird. I think for this visual, "stem-bird" or "proto-bird" would've been better.
I do think the consensus now is that Archeopteryx is not actually considered a bird anymore.
Love this sort of stuff, but of course birds and mammals aren't all that made it through. We have to deal with the fact that crocs (not particularly smart); sharks (ditto); turtles; snakes; fish in general (some totally unchanged but air-breathing water-going dinos, dead with the rest). Insects of all sorts, many unchanged from pre-dino times, made it through.
Like dinosaurs, all the survivors had evolved through all sorts of changes in climate and had come to fill all sorts of niches for millions of years. Most were arguably no more or less smart than most critters today judging by their success. A dragonfly? Successful, yes; bright, no. Nothing in and of itself suggests dinosaurs were worse than their peers at surviving bad weather. Penguins are dino descendants, after all, and they have Antarctica pretty much to themselves.
Crocs and turtles have blood which is effectively antiseptic, so they can survive wounds while living in a swamp. Might this have helped? Birds can migrate quickly and form remote populations. This must have been an advantage. Perhaps birds prospered post impact. Crocs, turtles, and even sharks all eat birds.
Interestingly, we, and other mammals get the flu. And so do birds. But neither of us always all die from it - at least usually not to a last breeding pair. But we share the bug with birds. My bird and I run a fever; usually we shake it off. Could the flightless dinosaurs? I would put it out there that only one type of thing can come through the house and kill the dog, but not you; kill you, but not the dog; kill the cat but not the dog....And these types of things are always part of the microscopic world that actually runs life on our world - and quite possibly others. And, of course, the evidence they leave of their comings and goings is not as easily found as dinosaur bones (which aren't the least bit easy to find).
So there's still a lot yet to be found out about this interesting subject. Yes, there was an asteroid impact and,yes, the dinosaurs eventually died out around that time, over time. It seems to me a good mechanism of death is still missing from the argument. The asteroid didn't konk every dinosaur on the head and miss crocs, turtles, birds, sharks, fish, insects etc. . It killed air-breathing water critters but less so those who breathed water. Until we have a more satisfactory understanding of the mechanism of death, IMHO any explanation could just be a post hoc ergo propter hoc fallacy. Could the Earth have been hit with a dirty viral snowball? Did the collision gouge up swamp bacteria and distribute them everywhere?
Algore saved them ! Thank God for michael mann and him lol
That only leaves 1 question: why didn't Pterosaurs make it?
Body size & diet = The smallest Maastrichtian pterosaurs were vastly larger than the biggest Maastrichtian birds. Nearly all pterosaurs were predators, a few may have been frugivores.
@@Ozraptor4 that's a fair assumption
Ate bugs and seeds