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Re: Ichthyornis ancestors



> What do the very early ichthyornithiforms and hesperorniforms look like?
I do
> remember talk (from HP Marjanovic, actually) about volant hesperorns, but
aside
> from that, I am ignorant.

Oh, er... sorry if I sounded like I knew more than I do. :-] The only
reasonably known ichthyornithiform is *Ichthyornis*. Maybe *Ambiortus* is
related, but AFAIK no skull is known of that form, despite all feather
impressions. It is hypothesized that the basalmost hesperornithiforms were
flyers, mostly because a) flightlessness must have evolved at some point, b)
the humeri of *Pasquiaornis* are similar to those of flying birds, according
to www.dinosauria.com/dml/names/aves.htm and c) the quadrate called
*Potamornis*, which appears to be a basal hesperornithiform (tarsometatarsi
that might belong to it are also known), was small and lived far inland
(name = river bird). Loads of fossils remain to be found (let's hope so at
least).