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Nesting birds (was RE: Marsupial forelimbs... or rather hindlimbs)

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of T. Michael Keesey
> On 11/26/07, Dann Pigdon <dannj@alphalink.com.au> wrote:
> >
> > Also; perhaps live young have an advantage over eggs in 
> some circumstances?
> > Most birds have specific requirements for nesting sites, whereas 
> > viviparous bats can breed just about anywhere there is a 
> surface for 
> > their young to cling to.
> Come to think of it, avians are basally ground nesters -- 
> when did tree-nesting begin? (And which clade is it limited to?)
Tinamous, ratites, galliforms (basally), and anseriforms (basally) seem to
all be ground nesters.

Of course, the relationships among Neoaves are rather... Um... Uncertain.

If we use Livezey & Zusi, the state at the base of Natatores is uncertain:
Pelecaniformes and their branch of Natatores have examples that nest low in
the trees, while Procellerariformes, penguins, (and I believe loons and
grebes) are ground nesters.

In Terrestrornithes: anyone know about the nesting habits of gruiforms,
turniciforms, ralliforms, and charadriforms? (These represent one of the two
clades within the land birds). The remaining clade of land birds are
unquestionably tree nesters basally.

So that state seems to polarize well up within terrestrornithine neoavian
neognath birds; it is not a basal avian condition at all.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
Fax: 301-405-0796

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA