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Mesozic birds were not sparrows



>
>6. T. H. says: "...there is no evidence that Mesozoic birds were
>tree nesters."
>
>But we would expect to it.

No, we wouldn't.

Among modern birds, tree nesting is restricted to only certain (albeit
speciose) clades of advanced birds. Ratites do not nest in trees. Phasanids do
not nest in trees.  Megapodes don't either.  Most of the sea birds do not,
either.

The primitive condition even among neornithine birds is GROUND NESTS!  The
expectation on phylogenetic grounds is that primitive birds, including most
(if not all) Mesozoic birds were ground nesters, not tree nesters.  Granted,
as some have pointed out on the net before, even relatively primitive birds
could have flown to offshore islands and the like to nest unmolested, but
those nests were almost certainly on the ground.

Using crows, sparrows, cuckoos, and the like as a model for nesting behavior
of Mesozoic birds is about the same as using canids, cetaceans, and
hominoids as models for the rearing behavior of Mesozoic placentals.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661

"There are some who call me...  Tim."