[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: New Cretaceous bird and other papers



> 99.9999%?!?!?! 100%?!?!?!? *That* is the definition of "stretch".

Which is why I wrote "assume". BTW, you typed even one more 9 than I did :-)

> Dude, one look at the data from the most extensively sampled and
best-known
> K/T boundary sites in the world (Hell Creek-->Tullock, Lance-->whatever)
> should tell you that these numbers are, um, slightly inflated. In the
> Puercan, we find animals not only in the same genera, but often a sister
> species, if not the same one! These are mostly mammals and "lower"
> vertebrates. Birds are very rarely found either before or after the K/T so
> it's tough to draw any conclusions.

But we don't find any non-neornithine dinosaur anywhere in the world
afterwards. I do think that tells something.

> But what's a scenario where survival of
> so many groups of amphibians, lepidosaurs, crocodiles, and mammals of all
> stripes approaches 100% at the "generic" level,

I thought 30 % of all lepidosaurs in the above sites died out? And that
metatherians were hit hard (Stagodontidae, Pediomyidae), for example?
All NA freshwater sharks died out. Later in the Paleocene others came back,
so apparently they didn't just shift their ranges with the regression.

> but every single bird in the
> same area is summarily wiped out?

It's _conceivable_ in the newest impact scenarios such as
http://www.dinosauria.com/jdp/impact/impact.htm. Burrowing may help, also in
times of acid rain.

> Q: Why do multituberculates scoot through a huge extinction event
virtually
> untouched, then peter off for seemingly no reason in the middle of the
> Oligocene?
>
> Point is, we really don't know what happened yet.

We certainly don't really know what happened at the Eocene-Oligocene
boundary. Some rather new sources do say that multis were did in then and
don't mention the Oligocene fossils (maybe they assume they're reworked, no
idea). In this extinction the causes are much less known than for others.
        Procolophonids sailed through the P-Tr pretty untouched, but were
wiped out at the Tr-J. Much may depend on where the impact happens.
Apparently there's a good amount of random involved in impact-induced mass
extinctions.