Re: another dumb question: Terror Birds are not dinosaurs?

["T. Michael Keesey" <keesey@gmail.com>]

In 6/29/07, Paula Goodman <paulawilder@mac.com> wrote:
> With all this talk about birds-are-dinosaurs, I'm curious to know what,
> if anything, distinguishes the bird status of Phorusrhacidae from that
> of the recently discovered Gigantoraptor, for example. Why do we call
> one a big bird fossil, and the other a dinosaur fossil?

The word "bird" is a bit vague. Most researchers would probably not
extend it to _Gigantoraptor_, although that may not speak for
everyone. It's not as close to avians (crown group) as, e.g.,
dromaeosaurids are, and those are usually not thought of as "birds".

Tradition is a big part of the reason we don't often refer to
phorusrhacids as dinosaur fossils. But, apart from that, I think it
has to do with levels of specificity and the groups most people are
familiar with. For example, _Homo floresiensis_ wasn't generally
referred to as "a new species of mammal" because we have a more
specific group we can refer to, one that everyone is familiar with:
"human".

When communicating about a fossil taxon to lay people, I think it's
generally best to use the most specific grouping that is widely known.
Given that, it makes sense to refer to _Gigantoraptor_ as a dinosaur
and _Phorusrhacus_ (sp?) as a bird. It's certainly not wrong to say
that _Phorusrhacus_ is a dinosaur, but you communicate more to by
saying that it's a bird. (It's also not wrong to say that it's a
neoavian neognath, but then you've lost the lay audience....)

--
Mike Keesey