Timing of bird order origins

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>According to Charles Sibley in the presidential address from the XX
>Ornithological Congress, "There are few fossils of Mesozoic birds and most
>may not have left living descendants...The branches leading to the Ostrich,
>rheas, and the Emu-Cassowary-kiwi cluster occurred close together, probably
>in the late Cretaceous...the divergence [between waterfowl and gallinaceous
>birds] was probably in the late Cretaceous or early Tertiary...the divergence
>[between swifts and hummingbirds] was ancient, possibly in the late
>Cretaceous."

Although some of the molecular systemicists (including Sibley) used the
molecular clock to date the divergence of various bird clades (Ratites such
as Ostrich, Rhea, Emu, etc. vs others, etc.), there are not yet any fossils
to back up these claims.  However, it wouldn't be very supprising at all if
there were Cretaceous ratites, anseriformes, etc.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.