[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Sauropodz r kewl WAS: silly conversation on 2012 US presidential race

> Date: Wed, 18 Apr 2012 09:53:47 -0400
> From: schenck.rob@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Sauropodz r kewl WAS: silly conversation on 2012 US presidential 
> race
> On Wed, Apr 18, 2012 at 9:33 AM, Anthony Docimo <keenir@hotmail.com> wrote:
> >
> >
> > hoping the paragraph breaks don't vanish again.
> >
> I believe this is because you sent an email to the list as in a 'rich
> text', where it actually only accepts plain text. Rich text messages
> show up on the list as just a message saying 'this was rich text and
> can't be shown'. 


I get those from time to time, no argument; but lately, when I reply in plain 
text, sometimes the paragraph breaks vanish.



> >> They pretend to do that, too, but they don't. That's because "distinct"
> >> has never been quantified.
> snip
> >all the extant organisms as closely related to the tuatara as mice are 
> >related to muskrats
> In a way we can do that, we can build a phylogenetic tree with
> quantified branch lengths, calculate the length from mice to muskrats,
> get a number, and then find all taxa at the same difference from the
> tuatara. Now, given two researchers, they'll both produce trees with
> different branch lengths and thus get different answers. Hell given
> two researchers you'll probably get two different tree topologies too!
> > That doesn't sound like a good deal, does it? Because sometimes things 
> > *are* distinct and separate.
> I am sure D.M. will respond, but for my part, with living organisms,
> we have a species concept that allows us to quantify species; if they
> can't interbreed, they're distinct species. If they can fruitfully
> interbreed, they're just varieties of the same species.
> There is no way to quantify the difference, in a similar way, between
> genera or families.


 We've demolished groups such as Pachyderma, relocating its members (rhinos, 
elephants, etc) to their true relatives...and yet the tuatara, aardvark and 
pangolin are set aside in their own groups with no near extant relatives.


so, if there is no way to quantify it, why do we keep them separate?


(I don't know if there are any dinosaur equivilents of the aardvarks and 
pangolins, cladistically speaking)



> > I believe the technical response is "WTF?"
> I think there's some sense to this (even if we ultimately reject it).
> Consider the idea that most phyla appeared in the Cambrian. If a
> population of lizards separated into two species today, you'd have a
> hard time convincing anyone that one of them was a new phyla. So the
> differences that make up the phyla represent 'huge' differences that
> accumulated over a long period of time, and therefore the phyla
> originated in the pre-Cambrian. Orders in the Cretaceous, etc.
> Again, not advocating that, but I think that's the idea behind it.


 ah, okay; yeah, that makes sense for things further away in deep time.