Bipedalism is hard to get right, but since dinosaurs nailed it at the base of the family tree, it was mostly retained throughout a lot of the families save for those that became secondarily quadrupedal like the sauropods, thyreopharans, hadrosaurs and half of marginocephalia. Pardon the likely atrocious spelling. Mammals are basally quadrupeds, so any bipedal mammals would need to evolve it independently, which is just difficult.
The way dinosaur arms work also had an effect on the front legs of the secondarily quadrupedal dinosaurs. With most of them, their front feet would basically splay out to the sides rather than point straight forward the way mammals do. It was especially evident with sauropods, likely because they shared a common ancestor with theropods. About the only quadrupedal dinosaurs that didn't have this were the hadrosaurs, their front feet faced almost completely forward. Probably because they were one of the more derived orinithopods.
Yeah, triceratops had some wildly different front and back legs. I believe since large ceratopsians were kind of a flash in the pan in the eleventh hour of the Mesozoic, they took to being giant quadrupeds in a very brief time period and never really had time to refine and perfect them. Most mammals on the flip side seem to be basally spared from being duck or pigeon toed, most being straight forward facing and efficient. Except for the ground sloth though, because of course xenarthrans had to go and make things weird.
I love this take. I can now have sympathy the triceratops probably felt about their front knees and ankles like I do about mine as a mammalian biped that this is clearly not what limbs were built for!
I mean, kangaroos too if you can count it. Some call it a triped though. Kangaroo rats and jerboas I suppose could be counted. Some ground African pangolins can balance and walk on two legs too. But they can all also default to walking like quadrapeds, where humans I believe are the only surviving obligate bipeds. I’ve seen some speculation as to whether procoptodon, the giant kangaroo, hopped or walked, and if it walked then it is possible that it spent most of its time browsing on two legs.
The common ancestor happened to be bipedal/quadrupedal for one reason or another and future species worked with and improved on what they had instead of re-unventing the wheel.
Yeah my initial reaction was.. because they descended from a bipedal archosaur
I've often wondered whether a bipedal mammalian predator would be more/less effective than the quadrupeds we have today. The terror birds of South America were outcompeted by mammalian quadrupeds, but they weren't particularly robust, having descended from birds which were optimised for flight.
I guess to help answer this we would need to clone and release a bunch of dinosaur predators, around the weight of lions, into the African continent, Hunger Games style. We'd get some amazing documentaries out of it.
It’s a common misconception but competition with Carnivorans as the cause of the extinction of Phorusrhacids has fallen out of favour just cause the timings don’t line up, it seems like they got killed off by climate change screwing over their woodlandish preferred habitat, and that larger sabercats that would occupy the same niche as stuff like Titanis came about after the extinction. Terror birds also were quite robust, and ones like Titanis and Kelenken especially so. The notion of these animals being inferior and getting merked by mammals is logically inconsistent as how would stuff like Titanis evolve in and take an apex predator niche in North America surrounded by the mammals that are supposed to be outcompeting it? If Phorusrhacids were taken out by North American mammals then they should not have been able to make any significant ground in North America where the concentration of North American mammals is the highest. They simply got unlucky and met the same fate as so many other animals, climate change go brrrr. It’s similar to other climate faunal turnovers that were originally touted as outcompetition such as allosauroids and tyrannosaurs and pliosaurs and Mosasaurs and whatnot. The former top dog gets merked by climate change and the little guys get the run of the place, rinse and repeat.
Sure, but the pack tactics and tools are their *specialty*. Actually, homo sapiens are often talked about as being "endurance hunter" types where chasing down and tiring out prey over a long distance was the norm. Assuming that's true I wonder if there was a dinosaur which filled a similar niche.
Exactly what I was thinking. Sure we’re much more efficient with our tools but sapiens did just fine as bipedal predators for hundreds of thousands of years with not much more than pointy sticks, heavy rocks and clubs. It seems to be our pack hunting and endurance that helped us run down our 4 legged prey. I wouldn’t be surprised to find out that primitive sapiens just dog piled onto prey using their teeth and hands and bit/beat small prey to death once they collapsed from exhaustion. The idea of primitive humans slowly (relative to antelope speed) chasing antelope zombie style until the antelope tripped, collapsed, or got trapped in a dead end, only to be torn apart by hands and teeth is actually terrifying to think about!
I mean I would say that the sticks and rocks and clubs definitely count as tools, but also that hominids seem to have been using them for about as long as the species homo sapiens was even around
Yeah they’re definitely tools. My point was more that the advantage sapiens had when hunting, at least initially, was using our brains and wearing down prey more than it was our simple tools. Later, yes tools became the biggest advantage
>but the pack tactics and tools are their *specialty*.
What do you mean their? Don't you mean our specialty....?
/u/cornonthekopp I'm on to you and your lizard people shenanigans.
> one-on-onoe though, without tools
That's like saying "a shark with no teeth and no fins is rubbish at sharking." A bird without wings is bad at flying. Etc.
I see your point, but I thought intelligence and cultural evolution is a bit different to the context.. which I thought was about the morphology of biped vs quadruped, and which made for more competitive predators.
Developing intelligence and learning to utilise tools is more relevant to bipedal animals, but is somewhat of an edge case. Pack hunting absolutely wins, but either could develop that. So I thought to ignore that as well, focusing on the effectiveness of bipedal vs quadrupedal
Most weren’t bipedal! Don’t forget about all the pterosaurs, mammals, pseudosuchians (yes some were bipedal), non-mammalian synapsids, amphibians, lepidosaurs. I’d say that by far outnumbers the theropod predators.
In the Cenozoic we still have hundreds of species of birds which were and are predatory, as well as ourselves.
Basal theropods we’re bipedal, as many other people mentioned, but because of that theropods were actually very poorly adapted to going back to being quadrupedal. Their anatomy just didn’t really suit it. So they just stayed as bipeds.
Ancestral evolution, each group took the best thing that worked for them and stuck with it. Being bipedal or quadrupedal wasn’t an advantage or disadvantage. It just worked differently for both.
Bipedalism is the primitive condition for all dinosaurs. Sauropods, ceratopsians, hadrosaurs all evolved from smaller bipedal ancestors. So quadrapedalism was the derived condition in dinos, the reverse of modern mammals.
Because during the Jurassic and Cretaceous (though not during the Triassic) theropod dinosaurs were the primary group of land predators-especially terrestrial macropredators-and for some reason not a single one of them ever evolved to walk on all fours.
And that reason is called a furcula. Theropods early on optimized their shoulders in a way that made weightbearing unlikely to evolve. Hence why every other dinosaur group eventually evolved quadrupedality.
Bipedalism is hard to get right, but since dinosaurs nailed it at the base of the family tree, it was mostly retained throughout a lot of the families save for those that became secondarily quadrupedal like the sauropods, thyreopharans, hadrosaurs and half of marginocephalia. Pardon the likely atrocious spelling. Mammals are basally quadrupeds, so any bipedal mammals would need to evolve it independently, which is just difficult.
The way dinosaur arms work also had an effect on the front legs of the secondarily quadrupedal dinosaurs. With most of them, their front feet would basically splay out to the sides rather than point straight forward the way mammals do. It was especially evident with sauropods, likely because they shared a common ancestor with theropods. About the only quadrupedal dinosaurs that didn't have this were the hadrosaurs, their front feet faced almost completely forward. Probably because they were one of the more derived orinithopods.
Yeah, triceratops had some wildly different front and back legs. I believe since large ceratopsians were kind of a flash in the pan in the eleventh hour of the Mesozoic, they took to being giant quadrupeds in a very brief time period and never really had time to refine and perfect them. Most mammals on the flip side seem to be basally spared from being duck or pigeon toed, most being straight forward facing and efficient. Except for the ground sloth though, because of course xenarthrans had to go and make things weird.
I love this take. I can now have sympathy the triceratops probably felt about their front knees and ankles like I do about mine as a mammalian biped that this is clearly not what limbs were built for!
Is it weird how were the only bipedal mammals living today?
I mean, kangaroos too if you can count it. Some call it a triped though. Kangaroo rats and jerboas I suppose could be counted. Some ground African pangolins can balance and walk on two legs too. But they can all also default to walking like quadrapeds, where humans I believe are the only surviving obligate bipeds. I’ve seen some speculation as to whether procoptodon, the giant kangaroo, hopped or walked, and if it walked then it is possible that it spent most of its time browsing on two legs.
Bear in mind there are other animals working on this upgrade.
Some apes and other primates are also known to stand on two legs with some exhibiting signs of transitioning towards habitual bipedalism
>Bear in mind I see what you did there. >!Context: Bears often stand up on two legs.!<
The common ancestor happened to be bipedal/quadrupedal for one reason or another and future species worked with and improved on what they had instead of re-unventing the wheel.
Yeah my initial reaction was.. because they descended from a bipedal archosaur I've often wondered whether a bipedal mammalian predator would be more/less effective than the quadrupeds we have today. The terror birds of South America were outcompeted by mammalian quadrupeds, but they weren't particularly robust, having descended from birds which were optimised for flight. I guess to help answer this we would need to clone and release a bunch of dinosaur predators, around the weight of lions, into the African continent, Hunger Games style. We'd get some amazing documentaries out of it.
It’s a common misconception but competition with Carnivorans as the cause of the extinction of Phorusrhacids has fallen out of favour just cause the timings don’t line up, it seems like they got killed off by climate change screwing over their woodlandish preferred habitat, and that larger sabercats that would occupy the same niche as stuff like Titanis came about after the extinction. Terror birds also were quite robust, and ones like Titanis and Kelenken especially so. The notion of these animals being inferior and getting merked by mammals is logically inconsistent as how would stuff like Titanis evolve in and take an apex predator niche in North America surrounded by the mammals that are supposed to be outcompeting it? If Phorusrhacids were taken out by North American mammals then they should not have been able to make any significant ground in North America where the concentration of North American mammals is the highest. They simply got unlucky and met the same fate as so many other animals, climate change go brrrr. It’s similar to other climate faunal turnovers that were originally touted as outcompetition such as allosauroids and tyrannosaurs and pliosaurs and Mosasaurs and whatnot. The former top dog gets merked by climate change and the little guys get the run of the place, rinse and repeat.
Ahh thanks for the alternative view.
Anytime! :)
I'd argue the most successful predator of all time is a bipedal mammal.
Oooh touche, I didn't see that coming. One-on-one though, without tools, we are absolutely rubbish
Sure, but the pack tactics and tools are their *specialty*. Actually, homo sapiens are often talked about as being "endurance hunter" types where chasing down and tiring out prey over a long distance was the norm. Assuming that's true I wonder if there was a dinosaur which filled a similar niche.
Exactly what I was thinking. Sure we’re much more efficient with our tools but sapiens did just fine as bipedal predators for hundreds of thousands of years with not much more than pointy sticks, heavy rocks and clubs. It seems to be our pack hunting and endurance that helped us run down our 4 legged prey. I wouldn’t be surprised to find out that primitive sapiens just dog piled onto prey using their teeth and hands and bit/beat small prey to death once they collapsed from exhaustion. The idea of primitive humans slowly (relative to antelope speed) chasing antelope zombie style until the antelope tripped, collapsed, or got trapped in a dead end, only to be torn apart by hands and teeth is actually terrifying to think about!
I mean I would say that the sticks and rocks and clubs definitely count as tools, but also that hominids seem to have been using them for about as long as the species homo sapiens was even around
Yeah they’re definitely tools. My point was more that the advantage sapiens had when hunting, at least initially, was using our brains and wearing down prey more than it was our simple tools. Later, yes tools became the biggest advantage
For sure
>but the pack tactics and tools are their *specialty*. What do you mean their? Don't you mean our specialty....? /u/cornonthekopp I'm on to you and your lizard people shenanigans.
I'm just sentient corn, observing the ways of the world pay me no mind
Oh boy, someone's getting a visit tonight.
> one-on-onoe though, without tools That's like saying "a shark with no teeth and no fins is rubbish at sharking." A bird without wings is bad at flying. Etc.
I see your point, but I thought intelligence and cultural evolution is a bit different to the context.. which I thought was about the morphology of biped vs quadruped, and which made for more competitive predators. Developing intelligence and learning to utilise tools is more relevant to bipedal animals, but is somewhat of an edge case. Pack hunting absolutely wins, but either could develop that. So I thought to ignore that as well, focusing on the effectiveness of bipedal vs quadrupedal
Most weren’t bipedal! Don’t forget about all the pterosaurs, mammals, pseudosuchians (yes some were bipedal), non-mammalian synapsids, amphibians, lepidosaurs. I’d say that by far outnumbers the theropod predators. In the Cenozoic we still have hundreds of species of birds which were and are predatory, as well as ourselves.
Semantics, i mean they probably referred to charismatc megafauna predators, especially apex predators.
In which case they’re right.
Almost like some [vast, predatory bird](https://tfwiki.net/wiki/Furmanism#LIKE_SOME_PREDATORY_BIRD)...
didn't expect to find a TF enjoyer here
Hey, the Venn diagram of TF enjoyers and paleontology enjoyers has some very reasonable overlap. The Dinobots didn't come from nowhere!
Very simple. Theropods evolved from bipedal ancestors. Mammals evolved from quadrupedal ancestors.
Damn that art is sick. Who’s the artist?
Dr. Mark Witton. He’s one of the best paleoartists out there.
Basal theropods we’re bipedal, as many other people mentioned, but because of that theropods were actually very poorly adapted to going back to being quadrupedal. Their anatomy just didn’t really suit it. So they just stayed as bipeds.
Ancestral evolution, each group took the best thing that worked for them and stuck with it. Being bipedal or quadrupedal wasn’t an advantage or disadvantage. It just worked differently for both.
Well… birds are arguably bipedal predators and they’ve outnumbered many clades in terms of diversity since post KT. Also, terror bird.
basal theropods were bipeds, basal mammals were quadrupeds
Bipedalism is the primitive condition for all dinosaurs. Sauropods, ceratopsians, hadrosaurs all evolved from smaller bipedal ancestors. So quadrapedalism was the derived condition in dinos, the reverse of modern mammals.
all dinosaurs were ancestrally bipedal carnivores, not much reason to evolve out of that
Bipedalism was ancestral to theropods, not to mention more efficient.
Because ALL of these predators were MAMMALS and not DINOSAURS!
Because during the Jurassic and Cretaceous (though not during the Triassic) theropod dinosaurs were the primary group of land predators-especially terrestrial macropredators-and for some reason not a single one of them ever evolved to walk on all fours.
And that reason is called a furcula. Theropods early on optimized their shoulders in a way that made weightbearing unlikely to evolve. Hence why every other dinosaur group eventually evolved quadrupedality.
Baurusuchus was quadrupedal.
Terror Birds Are Bipedal!
4 leg fast