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Another possible explanation for the survival of neornithine birds across the
K-T boundary occurs in the
recent NAPC abstracts. Here's the URL for the abstract,
by Judd Case.
Dr. Case notes that
the Antarctic record of Maastrichtian birds appears to consist exclusively of
neornithines, in contrast to other sites in Gondwana, where
enantiornithines occur. I'm speculating
wildly here, but perhaps the geographic distance of
Antarctica from the K-T impact site provided enough of a
"buffer" to muffle the full effects of the impact,
allowing some neornithine lineages to survive the K-T event.
These survivors
could then disperse to other areas where the impact effects were more
severe. This could
provide a possible selection mechanism for the survival of
neornithines vs. enantiornithines across the K-T
boundary. Neornithines survived because they happened to
live in Antarctica, while no enantiornithines survived
because they didn't. The neornithines could have been in the
right place at the right time,
an explanation Steven Jay Gould might find intriguing... ;-)
Guy Leahy |