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[tyrannasorus]

Which land based predator to our current understanding has the most damaging bite? purely in terms of mechanical damage it can inflict

Mostly between mammals and theropods respectively

[Exalt]

Why don't Odontocetes seem to view us as prey? Cetaceans in general seem to be weirdly tolerant of us, but I don't have any stats here.

[Exalt]

Could terrorbirds, moas, and elephant birds sit on their eggs?

[Infinity Blade]

Oct 22, 2023 9:05:16 GMT 5 Exalt said:

Could terrorbirds, moas, and elephant birds sit on their eggs?

Probably not straight up sit on them, especially moas (which turned out to have thinner, more fragile eggshells). I think curling around the eggs and nest is more likely (one author says so as well, at least in a news article).

A more recent study found that the maximum theoretical body mass for contact incubation in birds was ~2 tonnes. But they note that this only accounts for whether or not the egg is strong enough to support the parent’s weight, and also doesn’t account for the hatching process (a thicker egg is harder to break out of).

www.pnas.org/doi/full/10.1073/pnas.0914096107

mdpi-res.com/d_attachment/biology/biology-10-00738/article_deploy/biology-10-00738-v2.pdf?version=1629369425

[Exalt]

Are there any models for how the positioning might look? This is kind of a specific thing so I won't be surprised if not.

EDIT: I looked up how Ostriches do it for a point of comparison and they don't seem to be on the eggs...how do they stay warm? Does this work because of the relative heat of the Serengeti, or?

EDIT 2: Another moa question. What would be filling the scavenger niche? I would think that Haast's eagle would be wasting a lot of meat, as there's no way a 30 pound eagle is putting away a whole moa before it goes bad, right?

[Infinity Blade]

Oct 22, 2023 19:39:17 GMT 5 Exalt said:

Are there any models for how the positioning might look? This is kind of a specific thing so I won't be surprised if not.

EDIT: I looked up how Ostriches do it for a point of comparison and they don't seem to be on the eggs...how do they stay warm? Does this work because of the relative heat of the Serengeti, or?

EDIT 2: Another moa question. What would be filling the scavenger niche? I would think that Haast's eagle would be wasting a lot of meat, as there's no way a 30 pound eagle is putting away a whole moa before it goes bad, right?

Confusingly, the one reconstruction that was shown in a news article reporting the 2010 study has the moa still being on top of the eggs, even though the researchers considered it unlikely even males could contact-incubate eggs. Go figure.


The graphical abstract of the 2021 study also seems to imply that reverse sexual dimorphism (i.e. females larger than males) is one possible strategy to allow for contact incubation so long as it's the smaller sex, the male, doing it.


I think what the 2021 study (and an earlier study from 2009->) implies is that maybe giant moas could still contact incubate if it's the male doing the incubating, although the risk of fracture is still greater than in other moa species and elephant birds without reverse sexual dimorphism.


As for the scavenging niche on Pleistocene/Holocene New Zealand, there wasn't any specialized scavenger there to my knowledge, even though I'm sure something like a vulture would have felt more than at home there. So scavengers would've probably just been any animal (mainly birds, probably) that could process flesh from a large carcass, really. That means kea, raptors (i.e. Haast's eagle, Eyles' harrier), ravens, and adzebills.

[Exalt]

Any ideas on how beavers got started using wood to build structures, and perhaps how they learned about the concept of damming?

We are apparently the only species that modifies our environment more than they do.

[Exalt]

This one might justify it's own thread, but are there any ideas about the invertebrate/fish split? I know we've discussed the caveat with the term "fish", but the main things I have in mind are:

1. How the earliest backbones developed.

2. What sort of invertebrate lineage/s do fish descend from?

We're talking about a profoundly long time ago by our standards, so I could certainly understand if this hasn't been put together yet.

[Infinity Blade]

I'm not sure it's fair to think of it as a "split". Invertebrates aren't an actual clade, and "invertebrate" is really just an umbrella term for literally any animal that doesn't have a backbone. There are animals we'd call invertebrates that are actually closer to us vertebrates than they are to other so-called invertebrates. Tunicates, for instance (and we know they're closely related to vertebrates because they have a notochord in their larval stage).

ocean.si.edu/ocean-life/invertebrates/tunicates-not-so-spineless-invertebrates

Tying into your first question, backbones must have developed from the notochord. I'm not an expert on the subject, but there seems to be evidence that the notochord has a role in the formation of the vertebral column.

pubmed.ncbi.nlm.nih.gov/11523820/

[Exalt]

I still need to get in and actually read those, but another question before I forget it:

Why does paleotwitter seem to hate co-operative hunting? Is it just that it's representation in carnivorous non-avian dinosaurs far outpaces evidence for it?

This seems particularly odd when such a behavior is linked to intelligence, and we want to quash notions that prehistoric animals were inherently less intelligent. I have trouble believing that lions and wolves (and possibly Homotherium, that seems to be the only extinct one that people don't fight over, unless we want to emphasize that dire wolves aren't true wolves) are that unique.

Also, there's been complaints about the Triceratops in loop galloping? How would it actually have moved?

[Exalt]

So the concept of extinction due to being outcompeted has been getting discussed a fair bit recently. (You likely know why.)

How did such narratives come to be to begin with? Is it because we have wiped out species?

[Infinity Blade]

If something appears in a fossil record right when another disappears, you have what appears to be a correlation. If those two species seem to share a niche, you might think at first glance that one outcompeted the other (as it appears/becomes more common at the expense of the other). The problem, though, is that you need a lot more data for outcompetition to be solidly supported. Like for example, do the dates actually line up?

[Exalt]

Was this idea formulated before the realization that most hunts fail, btw?

[Exalt]

Paleobotany question this time:

So we've established by now (I think that even Jurassic Park briefly touched on this subject) that grass, a highly common species now, has not always been present.

But what plants would actually line the ground in different parts of the past?

[Infinity Blade]

Oct 29, 2023 19:18:09 GMT 5 Exalt said:

Paleobotany question this time:

So we've established by now (I think that even Jurassic Park briefly touched on this subject) that grass, a highly common species now, has not always been present.

But what plants would actually line the ground in different parts of the past?

So here's Hell Creek as an example (image source->).


3-8 is the stuff that would be undergrowth. You got magnolias, pawpaws, buckthorns, hazels, etc.

Now, Hell Creek dates to the end of the Cretaceous, by which point angiosperms had already become widespread. In the Morrison Formation (Late Jurassic, before conclusive fossil evidence of angiosperms exists), you instead have stuff like ferns, cycads, and horsetails covering the ground, like these (image source->).

Oct 29, 2023 5:41:50 GMT 5 Exalt said:

Was this idea formulated before the realization that most hunts fail, btw?

I don't know, I don't imagine the two ideas are very related tbh.