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RE: On the subject of mysterious absences...The Answer

David Marjanovic wrote:

>>  wonder if Pterodaustro is the first known filter feeder to have evolved?
> Among reasonably big vertebrates, you mean? Leedsichthys is older (Middle 
> Jurassic and later). 

_Pseudocetorhinus_ is even older (Triassic).  It was an elasmobranch (maybe a 

Dan Varner wrote:

> << Briefly: if you want to filter feed without gills, you need to take in a
> large amount of water and then somehow stop it going down your gullet before
> you spit it out past filtering surfaces such as baleen . Only mammals can do
> this, as only they have seals that shut off the back of the throat (such as
> you use when you gargle) -- probably evolved in association with suckling.">>
> See: http://dml.cmnh.org/2008Feb/msg00330.html



(The filter-feeding croc _Stomatosuchus_ has already been mentioned.)



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