Re: The Two Principal Dinosaur Clades Defined

[Dinogeorge@aol.com]

In a message dated 96-01-21 04:19:33 EST, pharrinj@PLU.edu writes:

>I don't know.  BADD seems like a straw man to me that no one believes 
>literally.  Most authors I've read are pretty noncommittal about the 
>structure and habits of hypothetical stem groups.
>
>
>> >   If that is true, then BADD and BCF are not that far apart.  
>
>Well, BADD and BCF are pretty far apart, but BCF and what most scientists 
>actually believe aren't!


As an example of "what most scientists actually believe," allow me to insert
the following excerpt from page 33 of the forthcoming _Mesozoic Meanderings_
#2 third printing:

<<I have noticed an unfortunate evangelistic streak of arrogance and
dogmatism among cladists, as if cladistic methodology is the "best" or "only"
way to do taxonomy. Consider the following quotation from an article on
dinosaur cladistics from the June 1995 issue of Natural History (p. 35 cols.
1?2):

"Although [cladistics] is not a perfect method (all scientific probing is
subject to criticism and testing), cladistics is more reliable and objective
than using the age of fossils, or their occurrence in particular layers of
rock, to determine relationships. For example, cladistic analyses show that
birds evolved from a small, carnivorous dinosaur, probably very like
Deinonychus or Velociraptor. These dinosaurs, which belong to a group called
dromaeosaurs, lived in the Cretaceous, between 107 million and 72 million
years ago. Yet the oldest-known bird, Archaeopteryx, lived in the late
Jurassic, about 140 million years ago. If we relied on relative geological
age, we might conclude that the earliest birds gave rise to animals like
Deinonychus and Velociraptor, rather than the other way around. Cladistic
analysis indicates that the fossil record is probably not complete and that
an animal very similar to Deinonychus gave rise to both the birds and later
to the dromaeosaurs, including Deinonychus and Velociraptor. However, we have
yet to find fossils of this creature. By using characters in cladistic
analyses, we can test hypotheses about phylogenies, or family trees, but we
do not seek to specify ancestors and descendants. We only hypothesize which
animals are most closely related to each other. While using the geological
age of fossils does not result in the most reliable phylogenies, it does
provide an important context in which phylogenies can be placed. With
cladistics, we thus have a much more realistic and objective view of where
evolutionary lineages fit within geological time and where gaps exist in the
fossil record." [Gaffney, Dingus & Smith, 1995]

How many things can you find wrong in the above paragraph? (1) Nobody uses
"the age of fossils, or their occurrence in particular layers of rock, to
determine relationships." It is elementary paleontology to construct
phylogenies and taxonomies from the anatomical features of fossils, not their
position in the fossil record. And it misleads the reading public to give
cladistics this straw man to knock down. (2) It is misleading to state that
"cladistic analysis indicates that the fossil record is probably not
complete." This fact was known since the time the true nature of fossils
became understood, centuries before the rise of cladistics as a methodology.
 (3) It is false that "cladistic analyses show that birds evolved from a
small, carnivorous dinosaur, probably very like Deinonychus or Velociraptor."
No cladistic analysis is anywhere detailed enough to tell us anything more
than pure generalities about the physical appearance of the common ancestor
of birds and dromaeosaurs. Such analyses have presently described only a few
of the characters that might have been present in the ancestral species.
Indeed, in this work [Mesozioc Meanderings #2], I provide compelling reasons
to think that the common ancestor of birds, Deinonychus, and Velociraptor
resembled Archaeopteryx much more closely than it resembled those two
cursorial dromaeosaurs. (4) "If we relied on relative geological age, we
might conclude that the earliest birds gave rise to animals like Deinonychus
and Velociraptor, rather than the other way around." Indeed, considering the
quoted disparity in ages between the dromaeosaurs and Archaeopteryx, I often
wonder why the cladists haven't gone back to their drawing boards to give
their analyses some more thought. One of the features supporting BCF theory
is its full agreement with this aspect of the fossil record; the authors of
that paragraph really should read this book?with an open mind. Incidentally,
(5) the statement that dromaeosaurs "lived in the Cretaceous, between 107
million and 72 million years ago" is incorrect in both bounds. The genus
Palaeopteryx from Dry Mesa Quarry (Jensen, 1981; Jensen & Padian, 1989)
provides evidence of a dromaeosaur-like form (I consider it a potential
dino-bird) in the Late Jurassic Morrison Formation, while large dromaeosaur
teeth are found in western North America as late as the Lance Formation and
its equivalents, 65 million years ago (Derstler, 1994), and indeterminate
species of both Dromaeosaurus and Velociraptor are listed among Lance
dinosaurs by Breithaupt (1994b). Finally, (6) any statements about the
reliability and objectivity of cladistic analysis relative to other forms of
phyletic analysis must be considered groundless, because there is no way to
confirm that any phylogeny generated by any method whatsover is the True
Phylogeny. (This caveat applies to the BCF phylogeny as well.) At best, we
can only state that some of the cladistic phylogenies seem to converge toward
a phylogeny that, with some degree of confidence (calculated by certain
greatly suspicious statistical methods), may be the one True Phylogeny.
Whether such convergence is toward the one True Phylogeny or toward an
artifactual phylogeny resulting from hidden problems in the analytical method
is presently anyone's guess.>>

G. O.