[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
A number of people have sent notes to this board with favorable observations
on Alan Feduccia's views on nondinosaurian bird origins in his new THE ORIGIN
AND EVOLUTION OF BIRDS. Having read the chapters on the subject, I find them
full of basic errors and highly questionable assertions. Too many to detail
in full here. Here are a few.
AF asserts that the skull of Archaeopteryx is very avian, largely on
reconstructions done a decade ago. He ignores the work - some based on the
newest skull - by P Wellnghofer, A. Elzanowski L witmer and myself that shows
that the old restorations are in error, and that the skull was much more
theropodian than avian. Nor does he cite P. Currie's observation that the
occipital wing of the braincase of Archaeopteryx is very similar to that of
dromaeosaurs. AF even says (based on the impossibly blurry results of an old
CT scan) that Archaeopteryx had a double headed quadrate, after the new skull
has proven that this is absolutely false!
AF says theropod shoulder girdles are not bird-like. The fully articulated
skeleton of the new troodont Sinornithoides shows that the coracoids were
large, their outer surfaces faced forwards, were angled sharply on the
scapula blade, and articulated with long anterior grooves of a large sternal
plate (not ossified in this juvenile) just like birds (especially the
flightless sort). The shoulder girdles of dromaeosaurs and oviraptors were
constructed in the same manner. Also, many of these advanced theropods could
fold their arms in a near avian manner.
The similarity of the pubes of Archaeopteryx and theropods are dismissed. In
fact the pubic shafts of the former and dromaeosaurs share a plate-like,
slightly angled transverse cross-section not found in any other archosaurs.
AF states that the "thecodont" Postosuchus is close to the origin of
carnosaurs. This view is held by few if any today. All crurotarsal ankled
archosaurs such as Postosuchus belong to the group that includes
crocodilians, so Postosuchus is a near crocodilian, not a near dinosaur.
Little Triassic Megalancosaurus is proposed as an "avimorph" close to birds.
The only photograph included is the one of the front end that looks vaquely
avian. Not shown are photos of the rest of the skeleton, or a complete
skeletal restoration, which shows that this deeply bizarre diapsid reptile
mimics chameleons in design (without opposable toes and a prehensile tail!),
and is an extremely nonavimorph.
I happen to agree with AF that birds almost certainly evolved flight from
high places (and I will shoot the next person whom illustrates a running
Archaeopteryx chasing a dragonfly which are too fast and agile to be hunted
even by modern insect eating birds for heaven's sake!). Where we diverge is
in his unsubstantiated insistence that small theropods - despite many having
long clawed fingers and bird-like toes - were not good climbers.
I also agree with AF that although cladistics is very important, it is also
not phylogenetic nirvana. What AF does not know is how overwhelming is the
skull, skeletal, eggshell and nesting behaviour evidence that advanced
theropods are the ancestors of birds. Feduccia and other paleoornithologists
sometimes say that we dinoologists do not understand bird anatomy well
enough. Actually, we know birds quite well because they are the living
dinosaurs we look at all the time. The real problem is that some
paleoornithologists do not understand the anatomy of nonavian archosaurs well
Of course, I have been guilty of committing a "fantasy" by illustrating my
small theropods with feathers, for which "there is no evidence", and would
hinder the running of a biped by producing drag (is that why ostriches and
cheetahs are naked?). Guess I should start removing all those feathers from
my little dinosaur drawings.
AF concludes that body insulating feathers are not necessarily correlated
with endothermy despite the absence of a single living insulated endotherm in
the modern world. He says Stegosaurus had a "walnut" sized brain, and asserts
that there is correlation between brain size and metabolism even though
endothermic tuna have small simple brains while some ectothermic fish and
sharks have really big complex brains. This is typical of his section on
physiology, in which he embraces every arguement against dinosaur endothermy
and airily rejects all for.
This one in particular boggles my mind. Arguing that dinos were big because
they were ectotherms living on the warm Mesozoic, AF says that "One need only
to look at the highly active, large tropical reptiles, such as Nile
crocodiles and Amazonian anacondas, to see how ectotherms have surpassed
endotherms in the warm climates of the tropical zone" (its right there on p.
125). Surpassed? Surpassed elephants that reach 10 tonnes and nearly 14 ft
and giraffes that tower 18 ft in the Namib Desert? What about hippos and
In a recent interview AF accused those who support dinosaurian ancestory of
birds of being "arm wavers" without evidence to back up their new dogma. In
truth it is he who is committing unsupported arm waving, he cannot cite a
single character that is found in birds and nondinosaurian archosaurs that is
not also found in theropods. As for theropod-bird relationships being dogma,
it is no more or less so than is the theory of cynodont-mammal relationships,
the theory of evolution, or the theory of relativity.