Spec Evo Trope Talk: The Bigger they are the Harder they Fall

[@DragonsoftheCenozoic]

If you're annoyed by the audioquality, feel free to read the written version on my substack paleogene.substack.com/p/trope-talk-the-bigger-they-mammals Sources: Scientific Papers: The multicausal twilight of South American native mammalian predators (Metatheria, Sparassodonta) www.ncbi.nlm.nih.gov/pmc/articles/PMC8786871/ A biomechanical constraint on body mass in terrestrial mammalian predators www.researchgate.net/publication/227999071_A_biomechanical_constraint_on_body_mass_in_terrestrial_mammalian_predators The Structure of the Mammalian Predator Guild in the Santa Cruz Formation (Late Early Miocene) www.researchgate.net/publication/257656003_The_Structure_of_the_Mammalian_Predator_Guild_in_the_Santa_Cruz_Formation_Late_Early_Miocene Themophysiology and Biology of Giganotosaurs: Comparison with Tyrannosaurus palaeo-electronica.org/content/2-2-giganotosaurs-and-tyrannosaurus Absolute abundance and preservation rate of Tyrannosaurus rex onlinelibrary.wiley.com/doi/full/10.1111/pala.12648 -- Books: Agnolín, Federico L. History of Cenozoic mammals from South America: A new model. Cham: Springer, 2024. Croft, Darin A., and Velizar Simeonovski. Horned Armadillos and rafting monkeys: The fascinating fossil mammals of South America. Bloomington, IN: Indiana University Press, 2016. Defler, Thomas Richard. History of terrestrial mammals in South America: How South American mammalian fauna changed from the Mesozoic to recent times. Cham: Springer, 2019. PREVOSTI, FRANCISCO J.. FORASIEPI, ANALIA M. Evolution of South American mammalian predators during the Cenozoic: Paleobiogeographic and... Paleoenvironmental Contingencies. S.l.: SPRINGER INTERNATIONAL PU, 2019.

[@beastmaster0934]

Mammals aren’t superior to dinosaurs, nor are dinosaurs superior to mammals. By trying to right a wrong made in the past, we’ve gone too far in the other direction, replacing one wrong with another.

[@brandonshmandon1799]

Fantastic video! Glad to see a very nuanced take on the mammals vs archosaur debate. Personally my issue with the whole dropping large Cenozoic mammals into the Mesozoic and thriving is that it seems flora doesn’t typically seen being taken into the account when it’s a such an important aspect of these animals lives. For example, a herd of African Elephants or Colombian Mammoth would struggle in an environment where open areas are dominated by ferns rather than grass.

[@DragonsoftheCenozoic]

Yeah, flora rather than fauna would likely prove to be one of the biggest (if not the biggest) obstical to any Cenozoic transplants sent prior to the Angiosperm Terrestrial Revolution). Browsers like Parasaratherium and Mastadon, and mixed feeders like Notiomastodon and Paleoloxadon would probably be able to adapt, but grazers would struggle unless they were deposited in an area where grass historically existed, like Maastrichtian India and South America.

[@taiko1237]

@@DragonsoftheCenozoic Grasslands as a biome, if I recall correctly, didn't develop at all until the Paleocene or even later. While grass was present in Maastrichtian India and South America, it wasn't in particularly significant quantities - probably not enough for grazers to adapt, in my opinion.

[@UdinJibral]

I'm currently working on the idea with the asteroid hitting the moon, starting a global cooling reaching its high in the Paleogene-Eocene Thermal minimum. It's so cold Neosuchian went extinct and was replaced by predatory Notosuchian, and snake only exist in Australia and Southeast Asia (Mattsoids being the only surviving snake lineage, the main reasoning is the extinction of other snake)

[@AncientWildTV]

What kind of adaptations do you think Notosuchians would have developed in response to the cooler climate?

[@crimsonhero1729]

​@AncientWildTV Maybe a higer metabolism?

[@juanleuschner7457]

Love to see another upload. I agree with pretty much everything in this video. I just want to mention a few things about the study of T.rex population you mentioned. The study that suggested that there was an average of 20 000 T.rexes at any given time is probably underestimating it. This paper is doubted by many modern paleontologists and even the authors say it's lower than what should be expected. The higher range of 328 000 provided in the paper probably being closer to reality (with around 100 000 and 200 000 being likely). Henry the Paleoguy has a video discussing the paper (called "How many Tyrannosaurus Existed at Once and Overall) (sorry I don't know how to link in comments). They would still have a lot lower numbers than prey (both prehistoric and the historic population of modern animals). But maybe not this low. Still love the channel and project. Keep up the good work

[@robertfaucher3750]

I've always felt that when people consider these things, they don't consider behavior as important a factor.

[@idle_speculation]

I think a major edge that would allow certain theropods to outcompete larger carnivorous mammals is their ontogeny. By the end of the Cretaceous a lot of smaller theropods had been ousted themselves by tyrannosaurs, which competed with carnivores of every weight class as they grew, shifting from leggy pursuit predators to hefty bone-crushers over the course of their lives.

[@SonLucasX]

You opened my mind with this video, I always thought about these questions, but I had never stopped to think that perhaps theropod dinosaurs could coexist with large herbivorous mammals without necessarily wiping out their entire population

[@gadielgonzalez2755]

I was pleasantly surprised by the topic since I just got done watching another video by wolfpack astrobiology on a different trope in spec evo media. I love it.

[@DragonsoftheCenozoic]

Loved Wolfpack's recent video about the whale Sea Bird trope.

[@Chordus_Gaius]

Honey! Dragons of the Cenozoic dropped

[@hugobellet4950]

I think my favorite example of a work of fiction where Cenozoic mammals live with dinosaurs is the comic book series ''Frnk''. Not only because it's objectively a good comics, but also because the dinosaur-mammal relationship is quite similar to what was described in this video. The context contains a bit of spoiler (especially for volumes 8 and 9 which have not yet been translated into English) so if you are interested, I advise you to not read further (although I will not address important elements for the story such as the story of the characters). First of all, you should know that this story contains time travel, to be more precise there is a spatio-temporal breach that opens every time the pressure of the local volcano's magma chamber increases (note that it is not always followed by a real explosion) and sends everyone who crosses it to the end of the dinosaur era... And this also includes Pleistocene animals (and prehistoric humans). The ecological relationship between dinosaurs and mammals in this fictional prehistory seems to be quite simple: the former occupy the role of predators and the latter are herbivores (mammals can occupy this role because the vegetation seems to be quite modern with the presence of chestnut trees, banana trees, flowering plants and grass, at least around the volcano). But there are exceptions such as sauropods and ceratopcians how take on the role of herbivorous dinosaurs, and sabertooth cats and wolves (and humans too) how take on the role of predatory mammals … and to that we can also add rabbits which are a bit both predator and herbivore (by that I don't mean omnivorous ... you have to read volume two to understand), the giant predatory birds that occupy a role similar to the Haast's eagle, the huge freshwater fish and the carnivorous plants (which have the particularity of spitting out their prey when they are watered). In addition, the animal species of the Pleistocene seem to have arrived in the age of the dinosaurs before humans and seem to have evolved to adapt to the new environment, the best example being the mammoths which are the size of a Paleoloxodont (probably to protect themselves from predators and/or to access food more easily), have huge ears to cope with the heat (but keep their fur, probably for extra protection against predators and the cold, the region where the story takes place being temperate), they are adapted to a diet more based on branches and fruits, and the males seem to live in the same herds as the females, thus having a social hierarchy more similar to killer whales than to elephants (this last point is a speculation of my own, because some mammoths are draw with a second pair of small tusks at the lower jaw, except for one individual who is confirmed to be a female, I therefore assume that the ''four tusks'' mammoths are males).

[@Zebulun-lg7us]

It probably depends on the mammal group. South America and Australian mammalian megafauna had evolved alongside large reptilian predators and had time to adapt while let’s say Proboscideans were suddenly thrown into a ecosystem with large theropod predators like in a interchange they would be initially surprised but could adapt later on.

[@DragonsoftheCenozoic]

Given that Deinotheres, Stegodonts, and Gomphotheres have all dealt with near peer preditors (giant Hyainailourines for Deinotheres and Gomphotheres, and giant varanids for Stegodon) I think that Proboscideans who face adversity at the beginning, but quickly evolve social and cultural behaviors that would help them survive.

[@thedarkmasterthedarkmaster]

I agree this trope is strange. But man I feel most sad for the tetrapod groups that are neither synapsid or archosaur

[@DragonsoftheCenozoic]

would love to see a project which follows the stem reptiliomorphs like the Seymouriamorphs and Diadectomorphs

[@thedarkmasterthedarkmaster]

@@DragonsoftheCenozoic There was The Great Thriving... Or so I've heard. Kaimere's first dynasty kinda asks the question of if these stem groups got a second chance

[@chasingcheetahs5017]

rhynchocephalians: nobody remembers them even though they were once super diverse and still live as the awesomely weird tuatara

[@chasingcheetahs5017]

@@DragonsoftheCenozoic Some studies suggest that diadectamorphs were synapsids (or the most close relatives to synapsids), but the jury is still out there, and nevertheless, they would be the most basal synapsids and would therefore be like comparing tuatara (the plural would be tuatara due to the Māori origin of the word) to lizards among lepidosaurs.

[@laurentiuvladutmanea3622]

Well, great video. I am sorry for all the bad things that happened. Hope things get better. Yeah, in real life, relationships are pretty complicated. But speaking of the topic of dinosaur and mammal interaction, I do expect them to affect the diversity quite a lot in a timeline where some survived. For example, while I do still expect mammals to have plenty of diversity in the South America of your timelie, I do expect that not only will medium and large Ground Sloths never develop, I expect that their niches will be occupied by Ornithischian descendents(thanks to some of them convergently evolving towards Therizinosaur like body plan and niche), while in Australia I expect that theropods will replace the marsupial medium and large sized predators, thanks to being slightly better at dealing with arid environments. Still, great video.

[@DragonsoftheCenozoic]

Oh absolutely. Basically none of the charismatic iconic mammals of South America and Antarctica will exist in ways we are familiar with, but there will still be megafaunal mammals in both continents. As for Australia, the fossil record is incredibly sparse, but from what is there, Varanids and Mekosuchines seem to have occupied the top order Carnivore niches above the marspial predators. I think these two groups will suffer the most from competition with therapods.

[@JacksonDemetrios-Formella]

Hey bro, first wanted to say amazing video but I want to ask something. Do you have any tips for me because I have a spec Evo project where a small landmass somehow was able to De attach from Pangaea and brought along with it mammal like reptiles and some other prehistoric creatures but since the series takes place in modern day, the Eastland has had small connections with continents to where some small species could cross it small species of dinosaur which was able to get on the Eastland before the mass extinction and a small species of mammal was able to also get to the continent after the mass extinction one it reconnected for a short period of time

[@TheGBZard]

I applaud you for persisting with youtube despite everything which happened. I can't even begin to imagine how tough things have been for you, and I hope you get any help you need.

[@11Legorex]

Great video, while I love your content I don’t expect it out at a fast pace. 1. Because you probably don’t get ad revenue or have a bigger patreon and 2. Because I have huge gaps in releases for my project too lol so don’t want to be a hypocrite. I’m excited to see where your goes and hope you continue to enjoy your work

[@SonLucasX]

Could you make a video talking about how theropods would interact with mammalian predators? Whether current or extinct from the Cenozoic

[@joaovictorburgosfernandes6274]

Loved this video!

[@KiraiKatsuji]

Mic quality isn't the best but it and the voice are not distratracting after a minute so i don't care because quality of the content is Good

[@malekahmed7960]

OH MY GOD A NEW DRAGONS OF THE CENOZOIC VIDEO

[@cro-magnoncarol4017]

Yeah, I'm pretty sure an Elephant is more capable of defending itself from a Tyrannosaur than a Astrapothere was able to defend itself from a large Sebecosuchian...

[@insectilluminatigetshrekt5574]

How often would parasites jump between mammals and dinosaurs?

[@jll682]

Question, any reason why dinosaurs won't be in Africa, I can understand South America and Australia but why not Africa, ancestors of new world monkeys made it from Africa can't the same apply from either South America or Antarctica to Africa for small dinosaurs. If it's a writing choice then just don't mind me then.

[@shingtiong9425]

Because of the ocean and wind currents. It goes from Africa to South America not the other way around so if they were on a draft. The wind and ocean would blow and push it back to South America.

[@jll682]

@@shingtiong9425 ok thank you.

[@davebowman-i2o]

Ok see you in 200 years

[@ashiqurrahman8830]

vividen has a lot of explaining to do.😅

[@Rome....d]

... I'm not mad, just disappointed edit: I am so fucking sorry, I had no idea that was what you were going through

[@Rome....d]

about your upload schedule, the vid was goated

[@Dom_Loves_Dinos]

Couldn't one argue that mammalian herbivores who have not evolved alongside archosaur predators would be vulnerable to a newly introduced one? Mammoths, for example, never had the same pressure of encountering a peer sized predator and thus would have never have evolved anti-predator defenses to deal with such large predators in the same way South American herbivores almost definitely did

[@sobekapep8320]

I mean, their defences should still work against archosaurs. Like, sure, they would be caught off guard at first but it shouldn't be too much of a trouble to adapt to. Mammoths, for example, had large tusks made of ivory(tougher than bone), muscular trunks, elastic and thick skin, were more intelligent than any dinosaur and highly social animals. Not to mention Mammoths still outweight most predatory archosaurs and do have experience fighting similar-sized opponents from members of their own species.

[@brandonshmandon1799]

It would really depend on context. If this is a scenario under which large predatory theropods are dropped into the Cenozoic they may initially cause issue for huge mammals not used to those kind of pressures, but it would unlikely they’d drive them into extinction. After all no huge mammals leaves nothing for them to eat. On the other hand if it’s the reverse and giant herbivorous mammals are dropped into the Mesozoic there bigger issue is the native dinosaur herbivores(assuming that these mammals have enough angiosperms to eat) as animals like say a hadrosaur are on par for size, if not larger compared to most of the largest mammalian herbivores, as the native dinosaurs are already used to both the predatory pressures and have a wider diet than the invading mammals.

[@DragonsoftheCenozoic]

While a mammoth never would have had a near peer predator before, they absolutely had anti-predator defenses to protect their young from animals like homotherium which could be translated to adult defense and Proboscideans did have near peer predators at various times in their time on earth. The mini-stegodon of Timor had to deal with the Timor dragon, a Megalania relative, and while they were smaller in size (at only half a ton) these stegodon still had very long periods of gestation like all mini-Proboscideans. Similarly, smaller deinotheres like D.bozasi had to deal with near peer predators like Megistitherium which were proboscidean and rhino specialist. Not all anti-predator defenses have to be biologically evolved, many can simply be learned cultural behavior, which given the intelligence and sociality of many megafaunal mammals are very likely to be transmitted easily. For instance. Cape Buffalo herds that are hunted by lions do not behave the same way that Cape Buffalo herds which aren't. They don't have a biological difference from those that aren't but their behavioral changes have allowed them to not only cope with predation, but have made it so that they are the leading cause of death among lion prides which specialize in buffalo.

[@LacTose90]

Don't forget mammoths had thick hide and fur akin to armor

[@AncientWildTV]

@@brandonshmandon1799 Would we see new adaptations emerging in response to competition, or might it lead to niche differentiation?

[@din0k865]

🦖👍

[@shafqatishan437]

P4P, most mammals are definitely superior to dinosaurs. It's common sense really.

[@laurentiuvladutmanea3622]

1. To quote Lincoln Barnet in his commentary on the works of Einstein, „Common Sense Is Nothing More Than a Deposit of Prejudices Laid Down in the Mind Before Age Eighteen” 2. Concepts like „superiority” dont quite apply in nature. There is advantages and disadvantages for occupying a certain environment, or for occuping a certain niche first. That is all. What is supperior in one scenario, is inferior on another. 3. Dude. Even today, avian dinosaurs are still highly succesful, with even flightless birds surviving just fine, and coexisting with mammals, while Phorusrhacids(commonly known as terror birds), coexisted with large mammals and did just fine, with Titanis coexisting with placental mammals just fine in North America, up until climate change negatively affected them. South America also shows the example of the Sebecids, which while NOT dinosaurs, do share several traits, like the highly efficient, unidirectional respiratory system. And the Sebecids where the top order carnivores of South America for tens of millions of years.

[@TroyTheCatFish]

Great Video 😄😃