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[Exalt]

I see. So are rhinos simply highly aggressive? I don't blame them considering their neighbors.

It's honestly weird how the sheer lasting power of Dinosauria manages to be underrated, at least in my experience. I rarely see it come up except to compare us to humans, which seems unfair, because that is a comparison of many, many species vs one, even if it's a decent intro to how long the history of the Earth is.

[Infinity Blade]

Well, rhino aggression is overblown from what I've read. For one thing, the white rhino has a reputation for being much less aggressive than the black rhino. And in general, rhinos just want to be left alone. Obviously they'll attack if you get too close and they feel that you startled or disturbed them. But when they don't feel that way (more obvious in captivity), zookeepers have even gone as far as to describe rhinos as "armored puppies".

twpark.com/blog/rhinoceros-are-extinct/

[Exalt]

How were mesozoic reptiles and cenozoic whales able to get a hold of much of the giant aquatic niche space instead of fish?

This question may not come off as very scientific.

[Infinity Blade]

The fact that tetrapods evolved into marine niches, including giant ones, multiple times in spite of the existence of fish suggests to me that there's a niche to be had in the marine realm that fish don't occupy. Remember that an ecosystem doesn't necessarily have to have every single specific niche/ecology filled. In Pleistocene North America, for instance, there was no specialized bone-cracker to the extent of modern hyenas. In pre-human New Zealand, there were no large terrestrial carnivores (only a flying one).

Also remember that the way reptiles and mammals evolve to become fully marine is via land animals increasingly and gradually becoming more acquainted with aquatic resources/life, not from animals already living in the sea becoming large out of nowhere (competition with animals that are already large would prevent that). In that sense, marine tetrapods are outside context invaders.

[Exalt]

I'm going to have to ask about both of those sections.

What niche are you suggesting that fish don't or can't fill?

The latter part just outright confuses me. Are you suggesting that things like whales or mosasaurs became large before they were fully aquatic? Because that's not how I've heard it.

[Infinity Blade]

The latter part just outright confuses me. Are you suggesting that things like whales or mosasaurs became large before they were fully aquatic? Because that's not how I've heard it.

No I'm saying that they accumulated their aquatic adaptations outside of the marine realm (built themselves up, if you will) until they finally became fully marine animals. If the immediate ancestors of Mesozoic marine reptiles or Cenozoic marine mammals were living with the giant fish of the oceans, then yeah, it would be hard for them to evolve into large-bodied niches (similar to how mammals living with dinosaurs weren't able to become truly large until after the latter were nuked). But because they were on land and probably venturing out into non-marine bodies of water (like streams, rivers, or lakes) at first, they had an opportunity to become aquatically adapted without having to compete with already large marine animals from the get-go.

Forgive the fanciful scenario, but it's sort of more like if you scooped up a bunch of tiny Mesozoic mammals onto a spaceship, genetically engineered them into mega-mammals (they're not living with big dinosaurs here), and then plopped those mega-mammals back down to Earth (so that now they're competing with the big dinosaurs). Consequences be damned (whether they outcompete some dinosaurs to carve out a living, find certain niches that dinosaurs may not be filling in any given ecosystem, or get outcompeted themselves).

What niche are you suggesting that fish don't or can't fill?

I don't really know, it's just an idea I put out there. I don't know what that exact niche entails, but if nothing else, it's definitely/evidently a space in the marine realm that tetrapods can carve out for themselves.

[Exalt]

I think my remaining confusion would need a timetable on how some group of dominant secondarily aquatic species came to be, otherwise, I think you've made it clearer.

[Infinity Blade]

Jan 3, 2024 5:02:59 GMT 5 Exalt said:

I think my remaining confusion would need a timetable on how some group of dominant secondarily aquatic species came to be, otherwise, I think you've made it clearer.

>50 mya: Pakicetus walking into water to eat fish and scavenging on dead fish on river or lake bed; shark in sea does its thing

>48 mya: Ambulocetus swimming in bay to eat fish; shark in sea does its thing

>47 mya: Rodhocetus in salt water; shark notices but still does its thing

>43 mya: Basilosaurus; shark commences sweating like a sinner in church because it now has to do its thing with giant whale breathing on where its head connects to its backbone (I'd say "neck", but sharks have no neck)


Something like this. And of course sharks still occupied giant predator niches even in the face of cetaceans.

[Exalt]

I wasn't expecting you to give me one, and figured I'd try to grasp it on my own. But thank you.

This also segues into another worthwhile question: how did the rise of whales occur so quickly, by evolutionary standards?

[Infinity Blade]

Jan 3, 2024 8:41:47 GMT 5 Exalt said:

I wasn't expecting you to give me one, and figured I'd try to grasp it on my own. But thank you.

This also segues into another worthwhile question: how did the rise of whales occur so quickly, by evolutionary standards?

True, it only took 8 million years for whales to go from being terrestrial to fully aquatic. Evolution can be rapid if the processes driving it are intense. So if, for example, there was a serious need for terrestrial ancestral whales to look to aquatic resources for food because their typical food resources on land were in really short supply (I can't say that this is the reason why, I'm just giving an example), that could drive rapid evolution.

However, I'm not sure anyone knows why it was so rapid. That is, what environmental factor was so intense that it drove some animals from living on land to entirely in the sea in just 8 million years.

[Exalt]

How might Pelagornis or a similarly built bird have landed? I have been informed that this can be a difficulty for albatrosses, and the aforementioned has an even broader wingspan.

[Infinity Blade]

Jan 8, 2024 21:38:28 GMT 5 Exalt said:

How might Pelagornis or a similarly built bird have landed? I have been informed that this can be a difficulty for albatrosses, and the aforementioned has an even broader wingspan.

Albatrosses prefer to land either on water or, if they must settle on land, when it's relatively windy. I presume that's because something is helping them move, allowing them better control while landing at slow speeds.

If they can't manage that, albatrosses do often stumble. According to the Cornell Lab, though, albatrosses are accustomed to awkward landings and are sturdy birds. Their bodies and bills are said to typically be sturdy in build (link->).

So I suppose Pelagornis would've been the same. Settle on water, settle when it's windy, or just...stumble and take it like a champ.

[Exalt]

I am getting the impression that some comical scenes must have occurred, especially in the case of Pelagornis as it otherwise may have been quite an intimidating animal.

[Exalt]

Do we have any thoughts on if Varanus Priscus was venomous or not?

[Infinity Blade]

I see no reason to doubt it if extant varanids are also venomous, as they have venom glands.

Whether this venom is actually useful for hunting, however, is a different matter. I've posted information before that showed that varanids kill most large prey quicker than venom could act, their killing method is not consistent with a reliance on venom, and they can kill prey with wounds that venom obviously can't cause (e.g. disembowelment). As far as killing prey goes, it is pretty clear that they don't actually need venom to kill prey; their sharp teeth and powerful muscles are enough.

theworldofanimals.proboards.com/post/63426