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Strange dinosaur adaptations; Who thinks these are plausible?
Topic Started: Feb 12 2010, 08:59 AM (8,958 Views)
Margaret Pye
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So, as I said on the introduction thread, I haz a maniraptoran sophont. I've been fleshing out a world for them to live in. And I've been violating the phylogenetic bracket appallingly - in ways that strike me as plausible, but I've been doing it a lot and I wanted some second opinions on the plausibility of some of my critters.

I've put fur on a lot of ornithopods, but that doesn't violate the phylogenetic bracket since Tianyulong. (I was writing furry ornithopods before Tianyulong, mind you - how else would Leaellynasaura have avoided freezing into a little hypsilophodont icypole? Especially since it didn't have growth rings in its bones, and therefore probably didn't hibernate.)

Things I want criticism and suggestions on, mostly dinosaur-related:

Opposable digits. I've been handing out opposable digits like candy, and with blithe disregard for phylogeny (I figured they could evolve repeatedly and independently.) Bipedal browsers get opposable digits with which to hold browse. Most of my small-game hunting coelurosaurs have hands like three-fingered hawk claws. Most of my grazers evolved from browsers, and most of my big-game hunters evolved from small-game hunters.

Direct brooding by a lot of ornithopods (I don't know what the ceratopsians and ankylosaurs do, I'll have to figure that out: I think sauropods are extinct, perhaps very recently as a result of sophont activity, and coelurosaurs are the only surviving theropods). No, there's no fossil evidence for it. But it seems enough of an improvement on the megapode model that I'd assume, given enough time, it could evolve. Is this stupid? (The obvious way to get round "It's too heavy to sit on eggs!" is to have them lie next to the eggs rather than on top.)

Pouches. I've given a lot of random dinosaurs (again, it seemed a simple enough and useful enough adaptation to evolve repeatedly and independently) some kind of skin pouch in which to incubate their eggs. A lot of the bipeds, including the sophonts, have "saddlebags" either side of the ribcage.

Venom. I have a clade of venomous coelurosaurs. In most of them, the venom is quite weak: it's the slashing sharklike teeth that do the real damage, and the vasodilator, anticoagulant venom just makes the wound bleed more so that the prey collapses faster. (Yep, idea stolen direct from Komodo dragon.) I'm thinking about creating some with more powerful venom, and possibly with a fancier venom delivery system than "it's in the spit so it gets all over the teeth." In particular, I was thinking about cheetahs, and I came up with a concept for a Coelophysis-shaped creature adapted for camouflage, stalking and incredible sprinting abilities. Except when it caught up with its prey, instead of wrestling it, it'd bite it once and let go - and the prey would run for another minute or so, then drop dead.

External ears. Yes, on dinosaurs. Specifically, on troodonts. Troodonts seem to have had very sensitive hearing, and asymmetrical ears like owls, so it seems reasonable to give them an external sound-focussing device. And yes, I could just give them an owly facial disc of vaned feathers, but external ears didn't seem that improbable. They aren't complex. They're strategically placed flaps of skin, plus a bit of cartilage stiffening and, if you're feeling fancy, some muscle.

Asymmetrical external ears, obviously. One pointing up, one sideways.

And a non-dinosaurian issue: I want to replace rabbits and hares with bipedal saltorial versions. Do you think I'm better off with wallabies, or with very large jerboas?

(I also want some saltorial-biped mammalian predators and omnivores, most of them under 5 kg: they don't have to be related to the kangabunnies, and I don't know whether they're marsupials or rodents either.)
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Holben
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Rumbo a la Victoria

(Crocodilians gather and force fish into each other's mouths. Some monitors have ganged up on prey. Dinosaurs had quite a few packs)

Well, the things stopping it from hypothetically evolving are metabolism, competition and necessity.

Now birds can be very intelligent, raptors and corvids show intelligence only thought present in mammals. But they aren't as intelligent as a dolphin, wolf, or monkey.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Ook
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i always think that the most intelligent birds are more intelligent than carnivores
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Carlos
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Dinosaurs had quite a few packs


There's actually no evidence of pack hunting in theropods; the group of Deinonychus found together has been more recently interpreted as a loose flock of scavengers
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Spinosaurus Rex
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Intelligent life can arise given the correct circumstances. There isn't anything that prevents an organism from circumventing an inherent flaw to survive a situation which demands it. (Holy shit, that was a long sentence.)

^But it's still a very likely possiblity, given the prevalence of pack-hunting in modern species.
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The Dodo
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Holbenilord
Jun 13 2010, 02:56 AM
(Crocodilians gather and force fish into each other's mouths. Some monitors have ganged up on prey. Dinosaurs had quite a few packs)

Well, the things stopping it from hypothetically evolving are metabolism, competition and necessity.

Now birds can be very intelligent, raptors and corvids show intelligence only thought present in mammals. But they aren't as intelligent as a dolphin, wolf, or monkey.
Some corvids are now though to be as intelligent as dogs and sometimes even great apes.
I think a tyrannosaur can become much more intelligent if it needs to.
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Spinosaurus Rex
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Some crows (Some Pacific Island variety) can make tools out of never-before-seen materials. Chimpanzees struggle with similar innovation tests.
The Dreaded AOL Dial-Up has left me afraid to spend more than 5 minutes posting at risk of losing it all. Arghhh.

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The Dodo
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Yes, the New Caledonian crow made a hook out of a metal wire.
http://www.youtube.com/watch?v=lcvbgq2SSyc
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Spinosaurus Rex
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Ah. That was the name.
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Margaret Pye
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"Crocodilians gather and force fish into each other's mouths. Some monitors have ganged up on prey."
Interesting - do you have references?

"Dinosaurs had quite a few packs"
There's some evidence for social behaviour in various species, but there's no reliable evidence for cooperative hunting. The famous Deinonychus/Tenontosaurus specimen makes much more sense as evidence of scavenging (apart from anything else, it'd be very odd for human-sized predators - any number of them - to attack an animal weighing well over a ton.)

"Well, the things stopping it from hypothetically evolving are metabolism, competition and necessity."
I'm assuming a general increase in intelligence, across many clades, due to pressures for more complex behaviour. Not inevitable by any means, but it could happen.

"Metabolism?" You've lost me there. Evidence is fairly solid that tyrannosaurs had much the same metabolism as a raven. The metabolism debate continues, but not over tyrannosaurs.

I think you're confused about animal intelligence. Raptors really aren't known for their problem-solving ability. Lovely charismatic creatures, but most of them have the intellect of a chook. Wolves? They're all right as mammals go, but they're not capable of particularly sophisticated problem-solving, and they have fairly simple dominance hierarchies with no reciprocal altruism. Whereas some parrots and corvids definitely belong in the same general ballpark as baboons or dolphins. It's hard to make precise comparisons, and the birds are often more intellectually specialised, but saying "no bird has the intellect of a dolphin or monkey" is overly strong. (After all, what's the world's second-best species at toolmaking?)

Now, I confess that I'm deliberately trying to make this world as hyperBakkerian as is defensible, because that's what I think is fun. But why isn't it defensible for tyrannosaurs to develop mammalian level intelligence? (Makes more sense than dromaeosaurs inventing FTL spaceships...)
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Holben
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Rumbo a la Victoria

Margaret Pye
Jun 13 2010, 04:07 AM
"Crocodilians gather and force fish into each other's mouths. Some monitors have ganged up on prey."
Interesting - do you have references?

"Dinosaurs had quite a few packs"
There's some evidence for social behaviour in various species, but there's no reliable evidence for cooperative hunting. The famous Deinonychus/Tenontosaurus specimen makes much more sense as evidence of scavenging (apart from anything else, it'd be very odd for human-sized predators - any number of them - to attack an animal weighing well over a ton.)

"Well, the things stopping it from hypothetically evolving are metabolism, competition and necessity."
I'm assuming a general increase in intelligence, across many clades, due to pressures for more complex behaviour. Not inevitable by any means, but it could happen.

"Metabolism?" You've lost me there. Evidence is fairly solid that tyrannosaurs had much the same metabolism as a raven. The metabolism debate continues, but not over tyrannosaurs.

I think you're confused about animal intelligence. Raptors really aren't known for their problem-solving ability. Lovely charismatic creatures, but most of them have the intellect of a chook. Wolves? They're all right as mammals go, but they're not capable of particularly sophisticated problem-solving, and they have fairly simple dominance hierarchies with no reciprocal altruism. Whereas some parrots and corvids definitely belong in the same general ballpark as baboons or dolphins. It's hard to make precise comparisons, and the birds are often more intellectually specialised, but saying "no bird has the intellect of a dolphin or monkey" is overly strong. (After all, what's the world's second-best species at toolmaking?)

Now, I confess that I'm deliberately trying to make this world as hyperBakkerian as is defensible, because that's what I think is fun. But why isn't it defensible for tyrannosaurs to develop mammalian level intelligence? (Makes more sense than dromaeosaurs inventing FTL spaceships...)
Life in Cold Blood, a BBC serious presented by David Attenborough. It's a rare event though.
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Varanid lizards are very intelligent, and some species can even count.[7] Careful studies feeding V. albigularis at the San Diego Zoo varying numbers of snails showed that they can distinguish numbers up to six.[7][8] V. niloticus have been observed to cooperate when foraging.[7] One varanid lures the female crocodile away from her nest while the other opens the nest to feed on the eggs
wikipedia

Well, herds are less disputed. And many scavenegers display pack behaviour.

Well then 'could' is the key word.

We don't categorically know the specific -thermy of any dinosaur, (by specific -thermy a crocodile is more able to maintain body temperature than a caecilian) unless you can give references.


Wolves have much more advanced pack systems then any other animal excepting humans. We don't even fully understand them yet. Problem-solving? Well, they can judge fairness and if you know just how clever a dog is, think cleverer. They can do problem solving, picking the right lever etc., which way to press it, the right series of postures to get a reward, etc.

The world's second best species at toolmaking is not necessarily the world's second most intelligent animal.

Well, picking tyrannosaurs especially aside, they have lower chances of developing sapience than maniraptorans, and i don't see them evolving it.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Margaret Pye
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Yes, the problem with this discussion is the subjectivity of what intelligence means. Behavioural flexibility? Complex politics?

I wasn't suggesting that tyrannosaurs could develop civilisation (um, manipulators?) I was just pointing out that it's a much smaller step from real tyrannosaur to average-mammalian-predator-type intellect, than from real dromaeosaur (not that much larger-brained than the tyrannosaurs) to human-level intellect, and so I found it odd that the tyrannosaurs annoyed you but the dromaeosaurs didn't.

Wolves lack reciprocal altruism, which spotted hyaenas have. Wolves don't take specialised roles in hunting, unlike dholes and lycaons. (And some populations of chimpanzees hunt in packs for monkeys, setting up elaborate ambushes - technically that should win the prize for complex nonhuman hunting, although it's not a big part of their lifestyle). I'm not saying they're stupid, but they don't belong in the same sentence as baboons and dolphins.

Regarding tyrannosaur metabolism, I can give you an exact reference! I don't have the date, but Reese Barrick's popular review The Thermodynamics of Dinosaurs, published in Scientific American, mentions a study using oxygen isotopes in bone that showed a high and constant core temperature for large adult tyrannosaurs (and a slightly lower and more variable temperature in their extremities.) The lack of turbinates is suspicious, but is softer evidence (and on the subject of soft evidence, the giant forms apparently reached full size in 20-25 years, which is a much faster growth rate than any known ectotherm. Also, there are Chinese fossils appearing to be juvenile or miniature tyrannosaurids that have a coat of protofeathers.)

Not solid evidence, admittedly, but nearly all the evidence stacks up on one side - really the only evidence for ectothermy I know of is the lack of bony turbinates. (It's unusual, but perfectly possible, for endotherms to lack turbinates. There's also the possibility of cartilaginous ones.)

...Or if you don't like that, they hey, the abrachids evolved a faster metabolism than their ancestors. They've had time.
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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Margaret Pye
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Is anyone going to comment on the complete lack of arms?
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Cephylus
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I read that biomechanical analysis proved that tyrannosaur front limbs were probably used to hold fast to a struggling prey. Or it could have been used to grab a mate. The powerful arm musculature shows that they were not vestigial and they clearly had some use. So maybe the complete lack of arms may prove a disadvantage to tyrannosaurs unless they evolved some other way to replace the function of arms.
The gourmand from the new dinosaurs completely lack limbs, but they are complete scavengers and therefore no need to hold down anything. Spec tyrannosaurs have arms, and although spec abelisaurs completely lack arms, but they hack off a chunk of flesh and wait for the prey to bleed to death, so again no need to hold down anything.
Edited by Cephylus, Jun 14 2010, 02:44 AM.
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Carlos
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I'm not saying they're stupid, but they don't belong in the same sentence as baboons and dolphins.


Sadly, many people are stupid enough to consider wolves as intelligent as them, when in real life they are stupider than hyenas. Wolves are nothing special really.

As for tyrannosaur arms, they might have been used to carry small carcasses and maybe in holding the prey while the jaws worked, but they seemed to have progressively become less useful. In fact, Cretaceous and post-Cretaceous theropods that were not noasaurids, ornithomimids, therizinosaurs, dromeosaurs or oviraptors seem to have been evolving in a way to use less their arms; tyrannosaurs, abelisaurs, alvarezsaurids, troodontids, unenlagiines and flightless birds (sans penguins and other diving forms that used their arms) all had proportionally small arms, suggesting they were begining to loose their function.

In the case of troodontids and unenlagiines, they, much like birds, probably just relied on their jaws to catch prey, their arms basically being wings (having evolved from gliding/flying stock), though their arms were usually still proportionally big enough that they wouldn't be lost for quite some time, and sentience could emerge and found new use for the arms. For birds, tyrannosaurs, alvarezsaurids and abelisaurs, however, it would be too late.
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Margaret Pye
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Troodonts? Secondarily flightless?

"Stupider than hyaenas" isn't that serious an insult, given hyaenas' complex social politics.
My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.
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