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Popular Support of the 2nd-Flight. Model
To the list, but to John Jackson in particular,
One cannot immediately say that 2nd-Flight. is a suppressed model
for birds and bird-like theropod evolution. It is, in fact, known to
at least one theropod worker outside of this list: Currie.
In a recent perusal of the _Encyclopedia of Dinosaurs_, I found a
few remarks on this very subject, though there was some disappointment.
Currie (1997) notes, without reference, that "Dromaeosaurids are
often considered to be the most bird-like of the small theropods. . .
. There are so many similarities between dromaeosaurids and birds that
some have even speculated that dromaeosaurids were birds that lost
their ability to fly. . . . All known dromaeosaurids are K in age,
although they no doubt originated sometime in the J, because other
maniraptoran taxa are known from the Late J." (p. 195)
Not to rehash Tom's words, but analysis of morphology (no
cladistics, here) seems to show a likelyhood of the Ornithomimosauria
and Troodontidae having as a common ancestor (assuming Bullatosauria
is not polyphyletic) somewhere in the Tithonian or even Kimmeridgian.
I'd say that the degree of similarity between the oviraptorosaurian
and bullatosaurian lines are so similar in their basal and _advanced_
forms that they would have originated only a little prior to that
former taxon. Then whence comes the tyrannosaurs, who might pop in
anywhere, but my short, quick calculations have not included them.
However, they would neccesarily come in as well at least Kimmeridgian.
All these lines, as early as the Bathonian, and that leaves plenty of
room for Archie and dromies to split.
It is further remarked by Padian and Chiappe (1997a) that there are
quite a few ghost taxa in the fossil record whose main components
cannot possibly be derived from anything other than a common ancestor
unique to their lineage, such as the Sauropodomorpha and the
Thyreophora, despite temporal and geological conflicts, and this has
little to do with cladistics.
The refs, if anyone's interested, are:
Currie, P.J. 1997. Dromaeosauridae, p. 194-195. (in Currie, P.J. and
Padian, K. (eds.) _Encyclopedia of Dinosaurs_ [Academic Press]).
Padian, K. and Chiappe, L.M. 1997a. Bird Origins, p. 71-79. (in
Currie, P.J. and Padian, K. (eds.) _Encyclopedia of Dinosaurs_
Calling for a minor armistice and general truce (at least until the
new material from Yuannan gets published),
Jaime A. Headden
Qilong, the website, at:
All comments and criticisms are welcome!
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