[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
> >I've seen often stated, I think even in this mailing list, that there
> >were no aquatic dinos, yet some exist even today (penguins). ...
> Traditionally, my understanding was that "dinosaurs" were extinct
> Archosaurian Diapsids, which would include Thecodonts, Pterosaurs,
> Saurischians, and Ornithischians, (and Placodonts?), excluding only the
Strictly speaking the term applies to the Ornithiscia and Saurischia
only. This *excludes* thecodonts and pterosaurs as well as crocodilians.
> But am I to understand that birds, or more accurately,
> animals in the class Aves, are also members of dinosauria?
Under the *cladistic* definition of Saurischia they must be included
in the group, and thus in the dinosaurs.
This is because the under cladistic taxonomy a taxon must include
ALL descendents of the most recent common ancestor, and birds are
almost certainly derived from theropod dinosaurs (and thus ARE
theropod dinosaurs to a cladist).
Of course if you allow that a taxonomic group can exclude some
descendent groups, then birds need not be considered dinosaurs.
The peace of God be with you.