K/T event and amphibians, birds

[Nick Longrich <longrich@alumni.princeton.edu>]

Frog Baseball-
	How good is our evidence of amphibians, anyway? I haven't 
spent much time looking over K/T vertebrate collections but the 
published things i've seen make the small vertebrate fauna look 
pretty poor- e.g. a single pubis+ischium for an alvarezsaur, or a 
partial lower jaw for a putative psittaciforme from the Hell Creek. 
The Late Cretaceous stuff I've seen for Alberta is pretty similar- 
handfulls of small, isolated elements, occasional good ones which can 
be IDed as some interesting family or order. Are the amphibs much 
better than this? If not, I'd be skeptical of having genus-level ID 
on either side of the boundary to where you could say that all the 
genera survived.
	That being said, genus-level survival doesn't equal no 
extinction.  There's an idea that surviving the K/T is equivalent to 
coming through without a scratch. But "Surviving" the K/T may have 
meant getting almost, but not quite, totally annihilated down to the 
last animal.  You could wipe out every species in a genus except for 
one, and every population of the species except for one, and most of 
that population to where only a few thousand individuals remain- and 
in a complete absence of any competition, they'd rapidly expand in 
population and start moving into vacant niches and you'd probably 
have a large number of incipient species and subspecies forming 
within just a few thousands of years. The genus would be thriving 
before a mass extinction, thriving after. The question is, would 
frogs (or anything besides abundant microfossils) offer enough 
resolution to test this hypothesis?
	One thing that struck me in a documentary on Mount Saint 
Helens is that frogs survived through the blast- apparently there 
were eggs buried under snow, or something.

Regionalization of Bird Faunas?
	Re: paleogeography- yes, birds have dispersal barriers but it 
seems to me they are far less influenced by them than any other 
tetrapod. Hawaii had a massive radiation of finches and endemic 
species of crows, recall- both passerine "landbirds" (i don't like 
these terms... what's the Northwestern Crow, then, which commonly 
flies over water and likes to hunt in the tidepools). The ranges of 
most orders, many subgroups, a fair number of genera, and even some 
species are best described as "vast" or "global".
	Globally distributed (by "global" I mean all continents 
except Antarctica) orders include Procellariformes(the waters 
surrounding all land masses, anyway), Podicipediformes, 
Falconiformes, Anseriformes, Galliformes, Gruiformes, 
Charadriiformes, Columbiformes, Psittaciformes (although largely 
confined to the tropcs and subtropics) Cuculiformes, Strigiformes, 
Caprimulgiformes, Apodiformes, Coraciiformes, Passeriformes. 
Piciformes are in five continents, not having been established in 
Australia. Among the Passeriformes, the swallows, finches, and 
corvids are some of the subgroups which have achieved a global 
distribution. Some species have extraordinarily broad distributions 
as well-  the Golden Eagle ranges across the northern hemisphere and 
is found in places like Mexico, Alaska, and North Africa. The Glossy 
Ibis is reported to live in temperate and tropical Eurasia, 
Indonesia, Australia, Africa, the West Indies and Caribbean. The 
American Golden Plover's range is listed as N. America, Asia; winters 
in South America, Hawaii and other Pacific Islands, Australia, New 
Zealand. (this data is just taken from a couple of popular animal 
reference books). I was once having dinner at some friends' house and 
a duck was served which had been shot wearing a GPS transmitter. The 
transmitter had been tracking the bird when it was killed on Kodiak 
Island; before it had been up on the North Slope (and some of its 
fellow anatids had been as far as Siberia), they had originally been 
tagged in Northern California. So even a single individual can have a 
vast range. And just in the past century, cowbirds blown across the 
Atlantic Ocean from Africa during storms have taken up residence in 
deforested areas of Central America. Birds- and to a degree this is 
true whether you're talking about orders, families, species, 
individuals- get around.
	So I'm  skeptical of nice neat patterns like "enantiornithes 
north, ornithurines south", it doesn't make sense in light of modern 
bird distribution. Sure there were Late Cretaceous ornithurines in 
the North, I've seen them while rummaging through collections looking 
for misidentified theropod bones. The null hypothesis- the hypothesis 
to beat- should be that these birds had global distributions, because 
that's what we see today, and there's no reason to believe that by 
the Late Cretaceous these things weren't capable fliers. I don't 
think we can say positively this was the case, but I really wonder if 
we have the data to argue otherwise at this point.

Nick