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>The discovery of Protoavis seems to indicate that Archaeopteryx is
>not the ancestor of all modern birds.
There are major doubts as to the identity of "Protoavis": many workers think
it may be a chimera of two or three different diapsid reptiles.
>Is Archaeopteryx on a separate line which has extincted?
Although many paleontologists (often on essentially orthogenetic grounds)
insist that Archaeopteryx existed too late to be ancestral to all other
birds, I have yet to see convincing evidence of more advanced birds of the
same time. Morphologically and temporally, Archaeopteryx is well suited to
being the ancestor of other birds. Granted, it is vanishingly unlikely that
we have sampled the actual ancestral POPULATION from which more advanced
>Is still possible that Dinosaurs are on the line which goes to
>Protoavis and then to the birds?
Given the lack of confidence in Protoavis, the question is irrelevant.
>Is there a relation between Archaeopteryx and the strange dino-birds
>Mononychus and Avimimus?
The phylogenetic position of either of these strange theropods is
uncertain. Either or both may be closer to birds than are other theropods,
within "birds" in a broad sense, or no more closely related to birds than
are some other groups of theropods (e.g., dromaeosaurids).
Thomas R. Holtz, Jr.
Dept. of Geology
University of Maryland
College Park, MD 20742