Re: Dinosaur Books and Movies

["T. Mike Keesey" <tmk@dinosauricon.com>]

On Fri, 23 Mar 2001, Adam Britton wrote:

> > No, since we're not descended from chimpanzees.
>
> No but they are close relatives. I was driving at the idea that despite
> anatomical similarities with chimpanzees, orangutans etc, we are still
> classed as humans. However, it wasn't a very good example for two reasons:
> 1. humans descended from a common ancestor with apes and 2. the resolution
> was inappropriate: you'll simply point out that we're all still classed as
> primates.

It's not a single common ancestor, either -- we share a more recent
ancestor with the African apes (gorillas, chimpanzees, bonobos) than with
orangutans, and gibbons are outside the great apes + humans clade.

--Hominoidea
  |--Hylobates (gibbons)
  `--+--Pongo (orangutan)
     `--Hominidae
        |--Gorilla (gorillas -- obviously)
        |--Homo (us)
        `--Pan (chimpanzees & bonobos)

(Or is _Hominidae_ Clade(_Pongo_ + _Homo_)? I can never remember....)

> Ok, so we classify "birds" and "dinosaurs" within the "Dinosauria". Still, I
> think that modern group of mainly volant, feathered critters should be
> within a subgroup "birds" to separate them from another subgroup of mainly
> terrestrial, non-feathered critters called "dinosaurs". Hence birds can be
> called "dinosaurs" in the same way that humans can be called "primates", no?
> Forgive the simplistic thinking, but personally it helps me (if nothing
> else) to create a token division between two groups with quite different
> ecologies. [that reads like I'm being sarcastic, but I'm not really!]

Simplistic or not, that is absolutely correct! Phylogenetic
classifications regard _Aves_ as a clade within _Dinosauria_, just as
_Homo_ is a clade within _Primates_ (well, not everyone agrees that genera
should be converted to clades, but _Homo_ is within _Primates_
nonetheless). It's still a clade, but it isn't separated from its
ancestors. (And the modern clade, _Neornithes_, is within _Aves_ -- and
hence, by extension, within _Dinosauria_).

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