Re: DINOSAUR digest 3384

[David Marjanovic <david.marjanovic@gmx.at>]

----- Original Message -----
From: "K and T Dykes" <ktdykes@arcor.de>
Sent: Friday, November 11, 2005 5:52 PM

> <<They accept that sheltering in water would protect large animal. Even 
> animal submerging with legs touching bottom would dissipate heat. They try 
> to defend it surprisingly: "no evidence exists that (...) non-avain 
> dinosaurs could (...) swim or dive (...)".  It exists.>>
>
> I think the quotation is a bit wrong, Jerzy, as they don't quite say that. 
> Page 764 contains: "No evidence has been offered that late Maastrichtian 
> pterosaurs or nonavian dinosaurs could burrow, swim, or dive (Padian, 
> 1983)."

To be precise, none has been offered that they burrowed or swam for a 
living. This means that the probability was very low that any of them 
happened to be in a burrow or in the water _when the heat came_.

> <<They cannot explain why birds survived, which mostly don't shelter - 
> including ratites, numerous waterbirds, shorebirds etc.>>

Most birds, it seems, didn't survive.

> They furthermore explicitely address ratites

This wasn't necessary. Based on the current knowledge of the fossil record, 
palaeognaths as a whole need to have survived, but ratites may be entirely 
Cenozoic. The only evidence to the contrary (so far) comes from molecular 
dates with... unconvincing calibration.

> On page 766, they mention the burrowing habits of a living ratite, namely 
> the kiwi.

That's probably really derived.

> They're actually somewhat puzzled about why some of the toothy ones 
> didn't, seeing as the divers should've been well-qualified.

The heat pulse alone can't explain that. But the collapse of the plankton, 
caused by darkness* and acid rain, probably can.

* Not so much from the ejecta, but from the soot of the fires, and the 
clouds that must have formed from the water vapor and sulfuric acid of the 
impact, and from the nitrogen dioxide (which is deep reddish brown).