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

Re: tiny-armed theropods

Jocelyn Falconnet:
"Branch length has nothing to do with relationships in cladistics -
but it would if you were a phenetician"
My understanding is that cladistics shows how organisms are related to
one another, whereas phenetics, the assumption was that it shows
relations, but in reality it was really just showing morphological
If you put me, my brother, my great grand children and my cousin into
a cladistic and phenetic analysis, the cladistic analysis would show
the correct relationship, while the phenetic analysis would possibly
only show how similar we all look.

On Sat, Oct 22, 2011 at 1:40 PM, Mike Keesey <keesey@gmail.com> wrote:
> Let's assume that Dinosauria originated in the MTr, say, 240 Mya.
> We'll assume the Megalosauroidea-Neotetanurae clade originated around
> the EJ/MJ boundary, say, 175 Mya. Times for the species are--Iguanodon
> bernissartenesis: ~125Mya, Megalosaurus bucklandii: ~165 Mya, Passer
> domesticus ~0ya.
> Total time divergence between I. bernissartensis and M. bucklandii:
> (240 - 125) + (240 - 165) = 190Ma.
> Total time divergence between P. domesticus and M. bucklandii: (175 -
> 0) + (175 - 165) = 185Ma.

This method seems quite sensible and contradicts my expectations. I
like it. I was thinking of M. and I. as close cousins and P. as a
great-great grandchild (for some arbitrarily large number of greats),
looks like my error is in how 'close' those cousins are.

Robert J. Schenck
Kingsborough Community College
Physical Sciences Department
S332 ph# 718-368-5792
Follow Me on Twitter: @Schenck
KCC Class Schedule on Google Calendar: http://tinyurl.com/mqwlcy