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

Re: K/T extinction (forams and birds)



>       Forams were not wiped out.  Class Foraminiferea actually came
through
> K/T almost unscathed in terms of ordinal diversity.  Order Involuntinida
> (which made it through the Permian extinction) apparently did not make it
> through K/T (but who knows, it may be found in the early Paleozoic
someday).
>       But most Cretaceous foram orders made it through and are still with
us
> today:  Monothalamida, Allogromiida, Astrorhizida, Haplophragmiida,
> Spirillinida, Miliolida, Lagenida, Robertinida, Globigerinida, Buliminida,
> Cassidulinida, Nonionida, Plaorbulinia, Asterigerinida, Discorbida, and
> Rotaliida.    Sadly, Order Orbitoidida made it through K/T, but only made
it
> to the Eocene.

How many species of these orders survived? 1? 2? 100?

Still not a single crown-group placental has turned up from the LK AFAIK,
which might mean that only one species survived (casts additional doubt on
NA marsupials being outcompeted by invading placentals). From biogeographic
and phylogenetic considerations, 3 species at minimum must probably have
survived (the ancestors of Xenarthra, Afrotheria and "Boreoeutheria" [ = the
rest]). (If we don't accept the molecular clock estimates, that is; I
don't.) However, this is surely a minimum because even in NA alone more
species of marsupials and multituberculates survived.

> (disaster doesn't seem like strong enough
> word for K/T--- a ghastly time to have been alive, especially on land).

It was even worse, IMHO. More tomorrow.