New Nature article - bird-like triassic footprints

[Dann Pigdon <dannj@alphalink.com.au>]

Bird-like fossil footprints from the Late Triassic
RICARDO N. MELCHOR, SILVINA DE VALAIS & JORGE F. GENISE
Nature 417:936-938

ABSTRACT (available free from the Nature site):

The study of fossilized footprints and tracks of dinosaurs and other
vertebrates has provided insight into the origin, evolution and
extinction of several major groups and their behaviour; it has also been
an important complement to their body fossil record. The known history
of birds starts in the Late Jurassic epoch (around 150 Myr ago) with the
record of Archaeopteryx, whereas the coelurosaurian ancestors of the
birds date back to the Early Jurassic. 

The hind limbs of Late Triassic epoch theropods lack osteological
evidence for an avian reversed hallux and also display other functional
differences from birds. Previous references to suggested Late Triassic
to Early Jurassic bird-like footprints have been reinterpreted as
produced by non-avian dinosaurs having a high angle between digits II
and IV and in all cases their avian affinities have been challenged.
Here we describe well-preserved and abundant footprints with clearly
avian characters from a Late Triassic redbed sequence of Argentina, at
least 55 Myr before the first known skeletal record of birds. These
footprints document the activities, in an environment interpreted as
small ponds associated with ephemeral rivers, of an unknown group of
Late Triassic theropods having some avian characters.

http://www.nature.com/nlink/v417/n6892/abs/nature00818_fs.html
(requires free registration to view the online abstract)


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Dann Pigdon                   Australian Dinosaurs:
GIS, Archaeologist          http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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