[Taxacom] What taxon corresponds to "birds'?

Tue Nov 29 15:52:09 CST 2016

But is it a problem or just a choice? Closer to my experience is an older
division between 'microlepidoptera' (families of small to tiny moths) and
'macrolepidoptera' (medium to large moths) that is generally no longer used
to represent a phylogenetic arrangement since some tiny moths are more
closely related to some large moths or butterflies than other tiny or small
moths. However, there is nothing inherently wrong or problematic with
anyone using those groupings should they wish to for whatever purpose they
might have in mind.

John Grehan

On Tue, Nov 29, 2016 at 4:07 PM, Stephen Thorpe <stephen_thorpe at yahoo.co.nz>
wrote:

> If we consider extant taxa only, then there is a large morphological gap
> between birds and (other) reptiles. On the other hand, if we had full
> access to the complete fossil record, that gap could completely disappear
> into a continuum. As long as all extant birds are included in a named taxon
> (of whatever rank), where to draw the line in terms of fossils is going to
> be arbitrary and unimportant. The main issue is rank. Should Aves be
> subordinate to Reptilia, or can we tolerate paraphyly? Some say yes, some
> say no. That is the problem!
>
> Stephen
>
> --------------------------------------------
> On Wed, 30/11/16, John Grehan <calabar.john at gmail.com> wrote:
>
>  Subject: Re: [Taxacom] What taxon corresponds to "birds'?
>  To: "Kenneth Kinman" <kinman at hotmail.com>
>  Cc: "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu>
>  Received: Wednesday, 30 November, 2016, 9:31 AM
>
>  One could well sympathize
>  over the uncertainties of how inclusive to make a
>  particular taxonomic category, but it seems to
>  me to be disingenuous to
>  assert that there
>  is a problem of establishing a bird category because
>  "cladists
>  have so abused
>  that taxon name with very different definitions" since
>  the
>  inclusiveness of a taxonomic category
>  has nothing to do with cladistics.
>  It's
>  a basic principle of cladistics that relationships matter,
>  not the
>  inclusiveness of a category (other
>  than it being a monophyletic entity). It
>  matters not a cladistic hoot whether we decide
>  to group birds into a class
>  Paraves or an
>  expanded Aves, whether we include Archaeopteryx or not.
>  Such
>  choices are inherent problems for any
>  kind of taxonomy (as demonstrated by
>  Ken's own uncertainty as to what choice to
>  make) - or am I mistaken?
>
>  John Grehan
>
>  On
>  Mon, Nov 28, 2016 at 11:44 PM, Kenneth Kinman <kinman at hotmail.com>
>  wrote:
>
>  > Hi All,
>  >        For thousands of years (or
>  longer), there has long been a
>  >
>  classificatory distinction between reptiles and birds,
>  although
>  > Archaeopteryx eventually
>  showed that birds are clearly reptile
>  >
>  descendants.  This was reflected in both informal and
>  formal
>  > classifications as Classes
>  Reptilia and Aves.  But the more recent
>  > discovery of fossil intermediates has
>  blurred where to draw the line
>  > between
>  reptiles and birds.  And around the same time we had
>  adherents of
>  > phylogenetic
>  nomenclature  concluding that both paraphyly and ranked
>  > classifications are somehow
>  "unnatural".  And yet decades later the
>  > PhyloCode is still extremely controversial
>  and perhaps not likely to be
>  >
>  implemented anytime soon (if ever).
>  >
>        In the meantime, even among strict cladists, the
>  meaning or
>  > definition of Class Aves has
>  become increasingly muddled, between those who
>  > would make it a crown group (and thus a
>  synonym of Neornithes) or
>  > alternately
>  based on a group including Archaeopteryx, crown-group
>  birds,
>  > and all of their descendants.
>  >        Given this muddled situation, I
>  have long favored expanding that
>  > Class
>  (for birds) to include avian dinosaurs that seem to have
>  preceded the
>  > common ancestor of
>  Archaeopteryx and modern birds.  Given the importance of
>  > flight in the concept of
>  "birds", I have come to the conclusion that
>  > asymmetical flight feathers are a primary
>  evolutionary development in what
>  >
>  constitutes a "bird".
>  >
>    Therefore, given the muddled debate whether Aves is the
>  crown group
>  > or anchored instead on
>  Archaeopteryx, I would perhaps suggest that we
>  > recognize a Class Paraves for
>  "birds" rather than a Class Aves.  The
>  > discovery of Archaeopteryx long before all
>  the other intermediates between
>  >
>  reptiles and modern birds long made it a convenient anchor
>  for a very long
>  > time, but it no longer
>  seems to be so important given all the other forms
>  > since discovered (some older) with
>  adaptations for flight (the asymmetic
>  >
>  flight feather being a primary synamorphy, although even
>  though its gradual
>  > developmental can be
>  problematic given problems inherent in fossil
>  > specimens).
>  >
>    Therefore, should we start calling it Class Paraves, or
>  expand
>  > Class Aves to become a synonym
>  of Paraves.  I'm not sure which would be the
>  > best choice.  However, I am convinced
>  that we need to expand the concept of
>  >
>  "birds" as a Class separate from Class Reptilia.
>  Whether we call that
>  > Class Paraves or
>  an expanded Class Aves is the question.
>  >
>         ----------------------Ken
>  >
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