Re: The mystery of the furcula

["David Marjanovic" <david.marjanovic@gmx.at>]

> >>The furcula (fused clavicles) is found in some theropods and not others,
> and
> even _Longisquama_ has something that looks like a furcula.

This is an _interclavicle_.

> And if you're
> going to tell me that a furcula is an essential component of flight, then
> I'll point you in the direction of a few parrots that lack one.  They fly
> very well too.<<
>
> Good, but  I think the point is theropod researches use this, so I guess
> they are all wrong!

Pardon, I don't understand, what do they use?

> Ok, this brings up something I've been wanting to ask. IS there another
> group of animals that have such a wide diversity of teeth? I.e. spade like
> teeth to pencil like teeth.

Pterosauria? Pterodactyloidea? Proboscidea?

> I'm talking about a small group, possibly order
> and below.

Could you please explain what an order is? I mean, I know, Linnaean system,
between class and family, between super- and suborder, but what is an order?
How do we decide whether a clade is an order? What is a small group? Why is
Titanosauriformes* a small group? Is an order rather big or rather small
(just to multiply the ambiguities with one another)?

* Was this meant at the origin of this discussion? After all it includes
Brachiosauridae?