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

Re: Ancestors and descendants (story for Nick)

Hi guys,
Sorry I had a really busy day, so little time for e-mails, or thinking about how to respond to the various responses "the story to Nick" got.
I realize that am sort of in the "lion's den", at least my experience is that there are a greater percentage of stricter cladists among dinosaur researchers than probably any other group, while their numbers are relative low among other groups (e.g., botanists and malacologists and probably entomologists as well, at least in my experience).
The fact that higher vertebrates have relatively good fossil records, with a comparatively large number of characters upon which cladistic analysis can be done, I will admit that The Kinman System is not easily "sold" to such a group, but vertebrates are just a small segment of the diversity of life, and invertebrate zoologists, botanists, and microbiologists generally tend to be a little more receptive.
I'm sure someone older and more experienced, like Ernst Mayr, could answer you questions with ease, but I am still not very experienced at explaining my views to strict cladists, and I am playing catch-up when it comes to reptilian evolution. And in my 1994 book, I only had to decided between one formal order of dinosaurs or two (and choose the latter, although I did code them a sister groups, thus informally as a single dinosaur clade).
And I did put a marker for birds in the reptile classification, showing that the class of birds evolved from Order Saurischiformes. The book only went down to order level, but in a family level classification, I would put a similar marker showing which family of Saurischiformes the birds seem most closely related to (but I don't think anyone would attempt to narrow it down to generic level).
In this way, I can not only show proposed sister group relationships, but also reflect two very different views of birds: the more recent view of birds as just a subset of saurischians (which cladists prefer) and the traditional view (of eclecticists and most lay people) that birds have evolved into a group so different from reptiles that it not only merits special classificatory status, but that it has long been found a very useful distinction as well.
Some of your comments seem to indicate that you think I am ignoring the cladist point of view, because I am only reflecting it with markers for birds within the reptile classification. But this is the only way to fairly reflect both viewpoints, and to incorporate both cladistic information and divergence in a single classification (and Hull, in his 1979 Systematic Zoology paper reflected the sad fact that no such methods had been devised). In actuality the Kinman System had been developed during the previous two years, but Hull had no way of knowing that.
Anyway, I feel that it is a little unfair for cladists to criticize my system, just because it tries to reflect both sister group information and divergence at the same time. And until one reads the book, and sees how it works in a variety of groups of organisms, it is almost impossible to fairly judge it.
The Rhynchosaur question:
Getting late, but just wanted to quickly address the question on why rhynchosaurs don't get their own Class, but birds do, in my classification.
They are certainly distinctive, and I classified them as a separate Order Rhynchosauriformes in the book. But they are also very restricted in many ways, including number of species, the short time they existed compared to other groups, and although I am not expert in rhynchosaurs, I would guess that the morphological diversity could hardly compare to that of modern birds (ostrich, wren, penguin, owl, hummingbird, kiwi, crane). Rhynchosaur autapomorpies seemed distinctive enough to merit a separate Order in 1994, and I therefore make no apologies for that, even though it had only one family.
The fact that I am now proposing to put them and prolacertiforms into Thecodontiformes, that will be harder to defend. I will have to think on that a while when I am more rested, as there seems to be a lot of resistance to the recognition of such a "variegated" order. But the point I am making tonight is that rhynchosaurs meet few of the requirements that birds do for separate Class status (the story to Nick listed some well-known synapomorphies for modern birds, but one must also consider geological range, species diversity, morphological diversity, and various other things).
Getting late, Cheers, Ken Kinman
From: NJPharris@aol.com
To: dinosaur@usc.edu
CC: kinman@hotmail.com
Subject: Re: Ancestors and descendants (story for Nick)
Date: Fri, 23 Jun 2000 15:24:53 EDT

I must have missed one of Dr. Kinman's posts, but Jaime Headden supplied the
following quote:

> <With all these derived features, we can hardly call
>  this a dinosaur even if it does share some features
>  with them. This bird beastie has been doing some
>  serious evolving.>

It looks like we have some preconceived notions about what a dinosaur should
look like, don't we, Dr. Kinman?

Indeed, all those wonderful bird beasties have been doing lots of evolving.
In doing so they have hugely expanded the structural, behavioral, and
ecologial range of theropod dinosaurs, but *they have not left that range*:
birds are a subset of dinosaurian existence, and thus they should be part of
our concept of what it means to be a dinosaur.

Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com