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Re: BADD BCF



In a message dated 95-12-02 15:19:43 EST, ornstn@inforamp.net (Ronald
Orenstein) writes:

>I'm not sure I accept this.  First of all there is no evidence that
>ostriches (which may have evolved in Central Asia as Feduccia describes in
>"The Age of Birds"), rheas, or emus (not to mention phorusrhacids,
>diatrymids and dromornithids among non-ratites) evolved anywhere but on
>continental land-masses with extant large terrestrial predators - do you
>have any evidence that these areas were "predator-scarce"?  Also we
>certainly have enough material of phorusrhacids, dromornithids and (if we
>accept Feduccia's scenario) ostriches to show at least some evolutionary
>trends such as increasing size etc.  Of course in the first case we even
>have living volant survivors (or at least close relatives) in the form of
>the seriemas (Cariamidae).
>
>

Islands often occur _within_ continental land masses as well as offshore. The
formation of an island could isolate a bird population from the rest of the
continent, then, after the island rejoins the main land mass, the resulting
flightless bird population would be released onto the mainland. I'm not
saying this happened in every instance of evolution of large, flightless
predatory birds, but it is at least plausible and may have operated in some
instances.

My guess is that extant seriemas closely resemble the volant ancestors of the
South American flightless-bird predators.