Links | Books
On the Alleged Dinosaurian
Ancestry of Birds
© 1998-2000 Ashby
L. Camp. All Rights Reserved.
This article appeared in the April, 2000 issue of Origins, a journal of the British
he recent discoveries of Protarchaeopteryx robusta
and Caudipteryx zoui are being hailed as conclusive proof that birds
evolved from theropod dinosaurs. According to Kevin Padian, an expert in
the field and a long-time proponent of the dinosaur theory, these finds “should
lay to rest any remaining doubts that birds evolved from small coelurosaurian
dinosaurs.” This confidence has understandably taken root in the popular
press, where one writer described the dinosaur-bird link as “now pretty close
to rock solid.” The purpose of this article is to explain why the case for
dinosaurian ancestry of birds is far from closed.
The idea that birds descended from dinosaurs was first
suggested by Thomas Huxley in 1868 on the basis of skeletal similarities between
Archaeopteryx lithographica and Compsognathus longipes, a chicken-size
coelurosaur recovered from the same formation as Archaeopteryx.  Of
course, Compsognathus itself could not qualify as an ancestor for Archaeopteryx
because it was “too late in time (as a direct contemporary of Archaeopteryx)
and too specialized in the reduction of the manus to two digits.” Nevertheless,
Compsognathus was considered illustrative of the kind of creature from
which Archaeopteryx evolved. It was believed that the features shared
by the two species had been inherited from a common dinosaur ancestor that was
more like Compsognathus than Archaeopteryx.
A number of experts (e.g., Seely and Vogt) resisted Huxley’s
theory, arguing that the similarities between Compsognathus and Archaeopteryx
were probably the result of convergent evolution rather than common descent
from an earlier dinosaur. As a result, Huxley’s views never gained general
acceptance. In 1913 Robert Broom described Euparkeria, a small, 230-million-year
old thecodont, and argued that it was the common ancestor of both theropod dinosaurs
and birds. This made theropods an evolutionary side branch having nothing to
do with the origin of birds. Following the publication in 1926 of Gerhard Heilmann’s
classic, The Origin of Birds, the thecodont (as opposed to theropod)
ancestry of birds became a matter of textbook orthodoxy for the next fifty years.
The theropod theory of bird origins was revived in the
mid-1970s through a series of papers by John Ostrom. He detailed a number of
similarities between Archaeopteryx and theropods, focusing especially
on Deinonychus antirrhopus, a lightly built, 110-million-year old dromaeosaurid
that he discovered in 1964. Subsequent cladistic analysis supported and
refined Ostrom’s claim by identifying dromaeosaurids as the group that shared
the greatest number of derived characters with Archaeopteryx. 
By the mid-1990s, Ostrom’s theory had become “practically
dogma among vertebrate paleontologists.” Thus, even before the recent finds,
one was assured: “Birds are dinosaurs. And not all dinosaurs have gone extinct;
one group, the birds, survives. What did dinosaur meat taste like? A trip to
Kentucky Fried Dinosaur, or a mouthful of Dinosaur McNuggets can answer that
question!” With the report of Protarchaeopteryx and Caudipteryx,
the “theropodists” have openly declared victory.
Recent Finds (Round 1)
The discoveries of Protarchaeopteryx and Caudipteryx
were preceded by the discovery of Sinosauropteryx prima, a small theropod,
similar to Compsognathus, that had short, fibrous structures along its
spine and on other parts of its body. There were early rumors that the
structures were downy feathers, but that turned out not to be the case.
However, the belief that these filaments were holdover "protofeathers" is still
very much alive.
The holotype for Sinosauropteryx was found by farmer
Li Yin Fang in June 1996 in the Yixian Formation in Liaoning Province (a far
northeastern province of China). Mr. Li sold the fossil to a dealer who
sent it to Ji Qiang, the director of the National Geological Museum in Beijing.
The mirror-image counterslab found its way, presumably through the same dealer,
to Chen Pei-ji of the Nanjing Institute of Geology, as did another nearly complete
specimen of the same creature.
The following summer, farmers working for Ji Qiang in the
Yixian Formation found three turkey-size fossils that had well-preserved evidence
of true feathers. Ji Qiang and his colleague, Ji Shu-An, originally concluded
that the fossils represented a single species, which they thought bore a striking
resemblance to Archaeopteryx. They dubbed the creature Protarchaeopteryx
robusta and published a brief report describing it as a new genus of Archaeopterygidae.
It was not until they examined the specimens with Philip Currie in the fall
of 1997 that they concluded the fossils represented two quite different species
and that neither was as similar to Archaeopteryx as they had first thought.
They named the second species Caudipteryx zoui. 
The plumage on Protarchaeopteryx and Caudipteryx
is said to be identical to feathers on modern birds, but neither is believed
to have been capable of flight because they had relatively short forelimbs (wings)
and symmetrically-shaped feathers like those seen in flightless birds today. Proponents of the theropod theory consider them to be dinosaurs rather
than birds “because they lack a number of features seen in Archaeopteryx
and more advanced birds.”
The significance of these fossils depends largely on whether
they are feathered dinosaurs or flightless birds. To call them feathered dinosaurs
is to claim that they did not descend from birds. If that is correct, it means,
from an evolutionist perspective, either that they shared a feathered ancestor
with birds or that feathers evolved more than once. The latter option is considered
unlikely because feathers are such complex structures. So if these creatures
are feathered dinosaurs, the favored conclusion of evolutionists is that they
descended from the same feathered ancestor as birds, an ancestor that also would
be classified as a dinosaur.
If, on the other hand, Protarchaeopteryx and Caudipteryx
are flightless birds, they would provide little, if any, new ammunition for
the theropod theory. The fact they resemble coelurosaurs in a number of features
would be consistent with theropod ancestry, but they offer at best a marginal
advance of the similarity argument provided by Archaeopteryx, which argument
has failed to convince a minority of experts (who have attributed the similarities
to convergent evolution). As flightless birds, they would not have come by their
feathers independently of the avian lineage, and thus their existence would
not imply the existence of a feathered, pre-bird ancestor.
Dinosaurs or Birds?
Some extinct birds, such as Archaeopteryx, shared
quite a few features with some theropods. That raises the question of how one
can determine whether a creature is a bird that resembles a dinosaur or a dinosaur
that resembles a bird. Feathers had long been accepted as a distinctively avian
characteristic because they had never been found on any creature, living or
extinct, that was not a bird. The presence of feathers marked a creature
as a bird, but one is now told that this is an invalid criterion and that Protarchaeopteryx
and Caudipteryx were dinosaurs despite the fact they possessed feathers.
Before it can be concluded that feathers do not prove avian
rank, they must be found on a creature that clearly is not a bird. The evidence
for the creature’s non-avian status must be compelling enough to overcome the
presumption of avian status created by the presence of feathers. Only then can
one be confident that the diagnostic role assigned to feathers was erroneous.
If, for example, someone claimed to have found hair on a reptile, it would need
to be established that the creature was indeed a reptile, rather than a previously
unknown mammal, before hair was jettisoned as a uniquely mammalian trait.
The claim that Protarchaeopteryx and Caudipteryx
were dinosaurs rather than birds is made with a certainty far exceeding the
evidence. Larry Martin and Alan Feduccia, two experts on bird evolution, and
John Ruben, a zoophysiologist, are all convinced these creatures were flightless
descendants of earlier flying birds and were more "advanced" than Archaeopteryx.  The dating is certainly consistent with that view, as the new fossils are
believed to be some 25 million years younger than Archaeopteryx
(see note 16).
Ji et al. excluded Caudipteryx from Avialae
because it reportedly lacked the following features shared by members of that
clade (which features are defined as "derived" based on comparisons of Velociraptorinae,
Archaeopteryx, and some more modern birds): (1) quadratojugal joined
to the quadrate by a ligament, (2) quadratojugal-squamosal contact absent, and
(3) obturator process of the ischium reduced or absent. Yet, the interpretation
of each of these features is open to question.
One expert has stated that he was unable to find evidence
in Caudipteryx of suturing between the quadratojugal and quadrate (which
suggests they were joined by a ligament). The quadratojugal appeared to him
to be nearly identical to that of Archaeopteryx. He also believes that
Ji et al. probably had the ischium upside down and consequently misconstrued
the ischial process as a ventral rather than a dorsal structure. If that
is correct, the ischial process supports rather than opposes avian status.
Such disagreements among experts reveal that fossil interpretation
is more subjective than is commonly appreciated. As J. M. Clark noted in his
review of H.P. Schultze and L. Trueb, eds., Origins of the Higher Groups
of Tetrapods, (Ithaca, NY: Cornell University Press, 1991), “the book again
and again demonstrates that similarity lies in the eye of the beholder, and
that the particular hypothesis being advocated strongly colors perceptions of
morphological resemblance.” Given that a “feathered dinosaur” is the holy
grail of theropod advocates, there is certainly reason for caution regarding
the theropodists’ disputed interpretations of these fossils. After all, it was
zeal for the theropod hypothesis that prompted the premature characterization
of the fibrous structures on Sinosauropteryx as “downy feathers.”
As for the claim that the quadratojugal of Caudipteryx
contacted the squamosal, the squamosal was apparently not preserved. It is not
mentioned in the description of the skull and is not shown in the relevant diagram.
The fact Ji et al. state that “[t]he tall quadratojugal seems to have
contacted the squamosal” suggests strongly that this is a matter of inference
rather than observation (emphasis supplied).
Even if these features were correctly diagnosed by Ji et
al. that would not mean Caudipteryx was a dinosaur. Putting aside
the matter of feathers, Caudipteryx has a number of characters that point
to its avian status. Ji et al. include one such character in their phylogenetic
matrix, but other experts believe there are more. They cite such things
as the shortened tail with distal fusion, the reduced fibula, the ventral occiput,
the long premaxilla relative to the maxilla, the reduced and edentulous (toothless)
maxilla, the edentulous dentary, the small, moveable head of the quadrate, the
absence of a pubic foot, and the rounded, ball-like head of the femur.
When Caudipteryx was first reported, all theropods
were considered “irredeemable carnivores.” Caudipteryx,
on the other hand, was apparently an herbivore. Not only were its maxilla and
dentary edentulous, but both specimens of the creature included large masses
of gastroliths (“gizzard stones”), which are used for grinding plant matter. Because herbivory and gastroliths were both known in Avialae but neither
was known in any of the scores of theropod genera, their presence in Caudipteryx
seemed suggestive of avian status. Gastroliths have since been reported in an
ornithomimid species from the Upper Cretaceous, so this particular argument
for avian status is no longer available.
It is difficult to accept that the long hand-feathers of
Caudipteryx evolved within (nonavian) Maniraptora. The strong, grasping
hands of maniraptorans were an essential part of their weaponry, but the
well-formed feathers attached to Caudipteryx’s middle finger would prevent
the hand from being used as a grasping organ. What possible selective advantage
could be bestowed on a cursorial predator by the development of hand-feathers
that disable the function of one of its primary weapons?
The anticipated retort that the loss of use caused by
the development of hand-feathers coincided with and perhaps drove the shift
to herbivory does not address the real problem. One still must explain how the
survival advantage of developing hand-feathers on a maniraptoran would exceed
the survival disadvantage from the concurrent impairment of the grasping function.
A shift to an herbivorous diet may well reduce the degree of disadvantage resulting
from impairment of the hand, but unless the feathers provided a net advantage
to survival at each step in their development, they would never become established
in the population.
If, on the other hand, Caudipteryx was a secondarily
flightless bird, there is no need to conjure up an explanation of how long hand-feathers
on a maniraptoran could provide a net survival advantage. Those feathers would
be vestigial flight structures.
Ji et al. considered Protarchaeopteryx to
be more “primitive” than Caudipteryx because it reportedly lacked the
following “derived” features shared by Caudipteryx and Archaeopteryx:
(1) frontal process of premaxilla relatively long to very long, and (2) teeth
with unserrated crowns. But again, other experts were unable to confirm
these features in the fossils. Moreover, these experts found additional characters,
such as the absence of a pubic foot, which point to Protarchaeopteryx’s
Apart from the alleged serrations, the short, bulbous maxillary
and dentary teeth of Protarchaeopteryx look remarkably like those of
Archaeopteryx, complete with waisted crowns. Perhaps this is one
of the features that led Ji Qiang and Ji Shu-An to conclude originally that
Protarchaeopteryx bore a striking resemblance to Archaeopteryx.
Velociraptorine teeth, on the other hand, are laterally compressed so as to
be bladelike (as are the teeth of all dromaeosaurids).
Even if serrations are present, it is clear from the report
that they are quite unlike the serrations in dromaeosaurids. Ji et al.
state there were 35-50 serrations per 5 mm, but the number of serrations in
dromaeosaurids is only 16-18 per 5 mm. The serrations, therefore, do not
support the contention that these teeth were inherited from the ancestor of
dromaeosaurids. Protarchaeopteryx’s teeth look nothing like those of
Ji et al. acknowledged that in one feature Protarchaeopteryx
and Caudipteryx were more like modern birds than was Archaeopteryx
(see note 31). This means, according to the proposed phylogenetic positioning
of Protarchaeopteryx, that this feature was either (a) developed in Protarchaeopteryx
after it split from the lineage leading to dromaeosaurids or (b) was lost in
the dromaeosaurid lineage after Protarchaeopteryx split (since it is
not present in Dromaeosauridae). (The same holds for each of the derived avian
features suggested by other experts.)
If option (a) is correct, then Caudipteryx did not
inherit this feature from a common ancestor with Protarchaeopteryx. That
means the feature evolved independently in both Protarchaeopteryx and
Caudipteryx. It then evolved independently a third time within Avialae
at some point after Archaeopteryx (since it is a derived avian character
not present in Archaeopteryx). If the feature is so advantageous that
it evolved these three separate times, it seems most unlikely that it would
have been lost in the lineage leading to Archaeopteryx. If, however,
Protarchaeopteryx and Caudipteryx were secondarily flightless
birds, then the feature need have evolved only once after Archaeopteryx.
If option (b) is correct, then Caudipteryx could
have inherited this feature from a common ancestor with Protarchaeopteryx.
If so, then the feature evolved independently only one other time, within Avialae
at some point after Archaeopteryx. That scenario, however, raises the
question of why a feature so advantageous that it evolved on both sides of Archaeopteryx
would have been lost in both the dromaeosaurid lineage and in the lineage
leading to Archaeopteryx. Again, if Protarchaeopteryx and Caudipteryx
were secondarily flightless birds, this difficulty is removed.
The proposed positioning of Protarchaeopteryx and
Caudipteryx on the phylogenetic tree also implies that feathers were
a universal feature of dromaeosaurids. Yet, no dromaeosaurid has been found
with any evidence of feathers. The recently reported dromaeosaurid Sinornithosaurus
shows evidence of filaments, which some theropod advocates have hastily characterized
as “protofeathers” and “downy feathers,” but in the
words of Storrs L. Olson, Curator of Birds at the Smithsonian Institution, this
“is little more than wishful thinking that has been presented as fact.”
 Apparently the Sinosauropteryx affair has done little to instill
caution in the theropod faithful.
The absence of feathers on dromaeosaurids is admittedly
negative evidence, but one wonders if feathers are as difficult to preserve
as is often speculated. Feather impressions are visible on all seven of the
Archaeopteryx specimens, whereas an ossified sternum was preserved in
only one. Feathers were also found with Confuciusornis, Ambiortus,
Noguerornis, and numerous other fossil birds, not to mention the only
known specimens of Protarchaeopteryx and Caudipteryx.  If
dromaeosaurids did have feathers, it is most unfortunate for the theropod position
that no trace of them was preserved on any of the more than 20 individual creatures
that have been unearthed.
There are thus ample grounds for believing that Protarchaeopteryx
and Caudipteryx are extinct birds rather than dinosaurs. The rush to
a contrary judgment has more to do with a prior commitment to theropod ancestry
than with the weight of the evidence. These creatures have been pronounced dinosaurs
because that is what many people want them to be.
Recent Finds (Round 2)
Since the discovery of Protarchaeopteryx and Caudipteryx,
two filament-bearing dinosaurs from the Yixian Formation in China (middle Early
Cretaceous) have been reported in the formal scientific literature: a quite
fragmentary seven-foot-long therizinosaur dubbed Beipiaosaurus inexpectus  and an eagle-size dromaeosaurid (mentioned above) dubbed Sinornithosaurus
millenii.  Theropod advocates suggest that these filaments represent
an early stage in the development of feathers and thus link theropods to avian
ancestry, but this is pure speculation. As Dr. Olson put it in his recent open
letter, “[t]he statement [in Sloan 1999] that ‘hollow, hairlike structures
characterize protofeathers’ is nonsense considering that protofeathers exist
only as a theoretical construct, so that the internal structure of one is even
Moreover, if the filaments on the Yixian fossils existed
as external structures on the living animals, rather than being the result of
a peculiar (perhaps Yixian specific) breakdown of tissue in the course of fossilization,
then these filamentous structures either existed throughout Coelurosauria or
evolved more than once (since they are present in the compsognathid Sinosauropteryx).
If they existed throughout Coelurosauria, it is hard to imagine why they are
not present in such exquisitely preserved coelurosaurs as Compsognathus longipes
and Scipionyx samniticus. And if, contrary to the claim of Xing et
al. (1999a), therizinosaurs (such as Beipiaosaurus) are not nested
within Coelurosauria (see the discussion of therizinosaurs in subsection 2 below),
then the filamentous structures are even more widely distributed. This makes
it an even greater mystery why they have not shown up elsewhere. Of course,
one can wave the wand of “convergent evolution” and have filamentous
structures evolve independently as often as needed, but this rapidly begins
to look contrived.
The theropod faithful, undaunted by these issues, claim
(in the recent exhibit at National Geographic Society) “there is strong
evidence that a wide variety of carnivorous dinosaurs had feathers” and
depict Deinonychus and baby tyrannosaurs as having feathers. Dr. Olson
labels the claim “spurious” and says the depictions are “simply
imaginary and [have] no place outside of science fiction.”
An interesting aspect of Sinornithosaurus is that,
in numerous features, it is allegedly the most birdlike of all nonavian theropods.
Since it is the oldest known dromaeosaurid, predating Deinonychus by
some 14 million years, one is left to wonder why certain birdlike features are
absent in Deinonychus, only to be reappear in dromaeosaurids some 75
million years later (see note 73). It seems ad hoc to claim that avian features
first provided a selective advantage for dromaeosaurids (resulting in Sinornithosaurus),
then nonavian features provided a selective advantage (resulting in Deinonychus),
and then avian features once again provided a selective advantage (resulting
in the birdlike dromaeosaurids of the Late Cretaceous).
Another “feathered theropod,” dubbed Archaeoraptor
liaoningensis, has been reported in the popular press but has not yet
been published in a formal scientific journal. Though bold claims were made
for this fossil, Larry Martin says it “is one of the worst preserved specimens
in a long line of poorly preserved specimens.” It is what is facetiously
referred to as “paleontological road kill,” a specimen so compressed
that interpretation will be extremely difficult. To make matters worse, it now
appears that the fossil is a composite of two separate creatures. Someone added
to the specimen a tail from a dromaeosaurid![54A] As for the claim of feathers,
neither Martin, who has seen photographs of the specimen, nor a University of
Kansas colleague of his, who viewed the actual fossil, was able to identify
any feather impressions.
Some Issues Beyond the Recent Finds
1. Protoavis texensis. In 1983, Sankar Chatterjee,
a paleontologist at Texas Tech University, discovered some fossil bones in a
small mudstone block dating to 225 million years ago. In 1985, after six months
of carefully preparing the material, he realized he had discovered two individuals
of a previously unknown species. The larger specimen, the holotype, was about
the size of a pheasant, making it comparable to the largest Archaeopteryx
specimen. The smaller specimen, believed to be a juvenile, was about half that
size, making it comparable to the smallest Archaeopteryx specimen. Since
then, Chatterjee has collected 31 isolated postcranial elements, which have
been referred to this species. “Nearly every skeletal element is represented
among these specimens.”
The species, later dubbed Protoavis texensis, predates
Archaeopteryx by about 75 million years and, as described by Chatterjee,
is more like modern birds than is Archaeopteryx. It has a V-shaped furcula,
a keeled sternum, quill knobs in the hand for attachment of flight feathers,
birdlike cervical vertebrae, and a birdlike skull, pelvis and pectoral apparatus.
As Feduccia admits, “The features Chatterjee illustrates are without question
quite birdlike, and an early bird from the late Triassic is certainly possible.”
Regarding Protavis’s flight capability, Chatterjee
Protoavis shows many derived features associated
with flapping flight that are not encountered in Archaeopteryx. Of
particular importance are the keeled sternum, hypocleidium-bearing furcula,
strutlike coracoid, large flight muscles, and triosseal canal for the supracoracoideus
tendon (fig. 4.4). The glenoid cavity faces dorsolaterally, which permits
unrestricted movements of the humerus in all directions. The humerus is
an exceptionally strong bone and shows all the bumps and ridges for the
attachment of flight muscles. The specialized linkage system of elbow and
wrist joints would stiffen the entire extended wing into a plane to resist
twisting when exposed to air pressure during flight. The presence of feathers
is inferred indirectly from the development of quill knobs in the hand.
The furcula and keeled sternum must have accommodated large flight muscles.
The flexible furcula would act as a spring between the shoulder joints during
the flight strokes. The presence of a triosseal canal suggests that the
supracoracoideus muscle must have functioned effectively as a wing elevator
and that the animal could possibly take off from the ground. The enlargement
and partial fusion of pelvic bones, a relatively short horizontal femur
with antitrochanter articulation, and mesotarsal ankle joint all may indicate
that the hindlimb was modified as a landing gear.
Given that the prevailing view of bird origins (the theropod
theory) was developed with the assumption that Archaeopteryx was a very
early bird and that birds therefore arose in the Middle to early Late Jurassic,
the reaction to Protoavis texensis was predictable. The discovery
touched off what Feduccia describes as “a tremendously bitter and acrimonious
controversy ”that was laced “with sharp personal attacks.” Chatterjee’s
published descriptions of the material seem to have mollified his opponents,
but his interpretations continue to meet resistance. His find is slighted by
such remarks as: “The material has become a paleontological Rorschach test of
one’s training, theoretical bias, and predisposition.”
Another method used to dismiss Protoavis is to claim
that any conclusions about it are premature until “the paleontological community
has had adequate opportunity to evaluate the Protoavis material” so as
to “test the original observations and conclusions, and to draw their own.”
One is told that until then “all claims [about Protoavis] must be treated
tentatively, especially in view of the paradoxes it presents” (emphasis
supplied). This rule obviously has been suspended in the case of the so-called
“feathered theropods,” but in any event, one should not get the impression
that Chatterjee is alone in his assessment. As Lawrence Witmer recently pointed
out, “such esteemed paleornithologists as Evgeny Kurochkin and D. Stephen Peters
have regarded Protoavis as a bird in their published accounts of early
avian evolution.” Likewise, Chatterjee reports, “Many experts on fossil
birds came to our museum and confirmed my belief that the newly found material
exhibited a suite of distinct avian traits.”
It is noteworthy in this context that several researchers
have reported probable bird tracks from the Late Triassic to Early Jurassic.
In 1974 Ellenberger presented as avian a variety of Late Triassic-Early Jurassic
footprints from Africa, and in 1992 Lockley et al. reported on Early
Jurassic birdlike tracks from northern Africa and North America. In 1993
Weems and Kimmel described tracks from a Protoavis-like bird from the
Late Triassic of Virginia.
Advocates of theropod ancestry admit that “these footprints
deserve serious consideration,” but they are unwilling to consider them avian
in the absence of “reliable osteological evidence before the Late Jurassic”
(emphasis supplied). So rather than see these footprints as supporting
Chatterjee’s interpretation of the Protoavis material by showing the
presence of birds in the Late Triassic or Early Jurassic, skepticism about Chatterjee’s
interpretation, which is spawned in part by the implications of that interpretation,
is used to deny the significance of the footprints.
A Late Triassic bird that is more modern than Archaeopteryx
puts a fatal strain on the theropod theory. It pushes the origin of birds back
at least to the Middle Triassic, before the time of Eoraptor, the earliest
known dinosaur. Coelurosaurs and dromaeosaurids, those dinosaurs believed
to be anatomically similar to birds, first appear some 80 and 105 million years,
respectively, after the Middle Triassic (see note 73). To maintain the theropod
theory in the face of this, its proponents must claim not only that dinosaurs
existed in the Middle Triassic but that by that time they had also diversified
into the various theropod clades and had evolved into birds, all without leaving
a trace! As Witmer concedes, if that were so, “we should reasonably expect to
find Triassic representatives of the ornithomimid, tyrannosaurid, troodontid,
and dromaeosaurid clades, among others.”
Of course, if dinosaurs are eliminated as ancestral candidates,
something else will be put in their place. Evolution abhors ancestral vacuums.
It will, however, be a powerful demonstration of how deceiving cladistic analysis
can be. The fact two groups of creatures uniquely share similarities need not
mean that they inherited those similarities from a common ancestor. The similarities
may be due to convergent evolution, to creative design, or to some combination
of the two.
2. Too late. Accepting Archaeopteryx as the earliest
known bird by no means solves the timing problem posed by the theropod theory
of origins. Since Archaeopteryx dates to the Late Jurassic, some 150
million years ago, birds presumably originated quite a bit earlier. Even advocates
of theropod ancestry place the rise of birds in the Middle to early Late Jurassic. This means that the alleged dinosaur ancestor must have existed by at least
the Middle Jurassic. The problem is that no dinosaur with particularly
avian affinities is known before the Late Jurassic, and those with the most
birdlike characteristics do not appear until much later. This pattern has
led some experts to suggest the possibility that coelurosaurs were derived from
primitive birds (archaeopterygids)!
The recent claim that an Early Jurassic jaw fragment (with
two teeth) is that of a therizinosauroid (and thus that of a coelurosaur) does
not solve this problem. First, the specimen is too fragmentary to permit
a confident diagnosis. Convergence is believed to be “very common,” so
the most one can say is that this jaw fragment is consistent with that of a
Second, since this jaw fragment allegedly predates the
next oldest therizinosaur by some 94 million years, even if one assumes it belonged
to a creature in the therizinosaur lineage, it would be a leap to conclude that
such an ancient ancestor possessed the essential features of the later forms.
Nothing in evolutionary theory excludes the possibility that the jaw features
developed in the lineage before those features by which the group is included
within Coelurosauria. So until coelurosaurian features are documented in such
early members of the lineage, their presence remains an assumption.
Third, it is not at all clear that even the later therizinosaurs
should be included in Coelurosauria. Fastovsky and Weishampel report that segnosaurs
(see note 75) “have been likened to an offspring of a menage a trois
involving a theropod, a prosauropod, and an ornithischian.” It is therefore
no surprise that experts have variously allied them with prosauropods, ornithischians,
and sauropodomorphs. Though some have recently allied them with “the large,
strange, and poorly understood theropod Therizinosaurus,” thus placing
them within Theropoda, Fastovsky and Weishampel caution, “Only time and more
fossils will unravel the true affinities of these strange animals.”
Finally, even if therizinosaurs deserve to be included
within Coelurosauria, coelurosaurs below Maniraptora are not particularly strong
candidates for avian ancestors. This is evident from the fact that, though coelurosaurs
have long been known, the theropod theory of ancestry did not take hold until
the mid-1970s, after the discovery of the dromaeosaurid Deinonychus.
Only in Maniraptora did the number of avian features reach the “critical mass”
necessary to persuade a majority that they were not the result of convergence
(see note 6).
The Middle Jurassic teeth that have been tentatively
identified as dromaeosaurid fail to solve this timing problem for some of the
same reasons. Even if the teeth had clear dromaeosaurid morphology, it
would be impossible to know whether they actually belonged to a dromaeosaurid.
To draw that conclusion, one would have to assume that no other creature had
the same type teeth. And even if one assumes the teeth belonged to a creature
in the dromaeosaurid lineage, one could not know whether such an ancient representative
possessed the avian features present in those forms dated some 50 million years
Padian and Chiappe seem to think the issue of timing has
only to do with the late appearance of dromaeosaurids relative to birds, their
putative “sister group” (i.e., the group believed to be most closely related).
They frame the problem this way:
A difficulty regarded as insurmountable by opponents
of the theropod origin of birds (e.g., Feduccia, 1996) is the presumption
that the taxa identified as closest to Archaeopteryx among theropod—the dromaeosaurids—do not appear in the fossil record until Albian-Aptian
times (perhaps 110 million years ago: Deinonychus, Cloverly Formation,
Wyoming), whereas Archaeopteryx comes from Late Jurassic (Tithonian)
times (about 150 million years ago).
But this ignores the important point that the known dinosaurs
from the assumed ancestral time lack the characteristics that are used to unite
birds and dinosaurs. In other words, the problem is not simply that the
putative sister groups (dromaeosaurids and birds) appear with such a large stagger,
but also that no dinosaur old enough to qualify as an ancestor of birds has
the particularly birdlike traits on which the claim of dinosaurian ancestry
In the end, the response to this and all timing objections
is an appeal to the inadequacy of the fossil record. One must believe that,
in the case of birdlike dinosaurs, the vagaries of fossilization and discovery
have conspired to create a false picture. Yet, as Feduccia points out,
“we have a wonderfully preserved array of fossil reptiles from the Triassic,
Jurassic, and Cretaceous periods.” Benton lists from the Jurassic and Cretaceous
some 98 families of terrestrial reptiles, 49 families of terrestrial mammals,
and 29 families of birds. This translates into hundreds of genera and thousands
of species. One cannot, of course, disprove a negative, but the evidence seems
sufficient to create, within an evolutionist framework, a presumption that the
hypothesized ancestral theropods did not exist at the required time.
As for the late appearance of dromaeosaurids, Padian and
Chiappe admit it is “puzzling,” but they deny its significance on the basis
that the Mesozoic fossil record frequently contains large disjunctions in the
appearance of sister groups. They state:
For example, although stegosaurs and ankylosaurs are
regarded as sister taxa that must have diverged by the late Early Jurassic,
stegosaurs are not known before the Bathonian-Callovian (approximately 170
mya), whereas before the 1980s, ankylosaurs were not known before the Aptian-Albian
(approximately 110 mya; Weishampel, et al., 1990). The situation
is not unique to dinosaurs. No one doubts today that marsupials and placentals
are sister taxa within mammals, and monotremes are their sister taxon. Hence,
the split between therians (marsupials + placentals) and monotremes must
have taken place before the first recognizable marsupials and placentals
evolved. However, the first marsupials and placentals are known from Early
Cretaceous times (approximately 100 mya), whereas until recently, monotremes
were not known until the Oligocene (approximately 20 mya), a disjunction
of 80 million years—over twice that between Archaeopteryx and
Deinonychus (Carroll, 1988)!
Padian and Chiappe are saying to their evolutionist
opponents that since they accept other disjunctions in the appearance of sister
groups, it is inconsistent for them to complain about this one. This, of course,
has nothing to do with the merits of the complaint, with whether the disjunction
is relevant to the claim of ancestry. (Indeed, Padian and Chiappe acknowledge
its probative value when they say the absence of earlier dromaeosaurids is “puzzling,”
i.e., difficult to explain. Witmer describes the problem as “vexing.”)
It is, rather, an attempt to bar certain parties, in this case evolutionists,
from raising the issue. In law, this is known as an estoppel argument.
This argument loses its force when directed against those
who do not accept megaevolution. They cannot be charged with inconsistency in
raising the complaint. Such critics agree it is “puzzling” for sister taxa to
appear 40 million years apart and believe such stratigraphic disjunctions indicate
that the groups have been misconstrued as sister taxa.
Padian and Chiappe apparently recognize the weakness of
simply declaring the late appearance of dromaeosaurids to be irrelevant, so
they argue in the alternative that small maniraptorans are in fact known from
the Late Jurassic. But this is not helpful, since birds are classified
as maniraptorans and the bones in question (a distal radius and a femur) were
described as possibly belonging to a bird (see note 73). So Padian and Chiappe
are left to weakly claim: “These bones unfortunately could not be identified
to the generic level but nonetheless indicated that if they are not bones
of birds, then they are certainly those of their sister taxon, the dromaeosaurids”
(emphasis supplied). If the stratigraphic disjunction between birds and
dromaeosaurids is a genuine nonissue, one wonders why these experts are willing
to stretch so far to find a Jurassic dromaeosaurid.
3. Too specialized. In all the talk about shared anatomical
traits and “sister groups,” it is easy to lose sight of the fact that, even
if they were old enough, all known coelurosaurs are too specialized to have
been actual ancestors of birds. In other words, they have features believed
to have arisen in their lineage after it split from the lineage leading to birds,
which features disqualify them as actual ancestors. Thus, after explaining that
Compsognathus could not be ancestral to Archaeopteryx because
of its date and its specialization, Carroll says, “No other adequately known
theropod appears to be an appropriate ancestor.”
Even dromaeosaurids are not claimed to be suitable ancestors
of birds but merely the best approximation, based on speculation from cladistic
analysis, of what the hypothetical bird ancestor would look like. It is
admitted that “in some characters, such as the stiffened tail, dromaeosaurids
are too specialized to have been good ancestors for birds.” Indeed, the
smallest known dromaeosaurid (other than the eagle-size Sinornithosaurus,
for which no weight estimate is available) is estimated to have weighed 66 pounds,
compared to a mere one pound for the largest Archaeopteryx specimen (see
notes 4 and 9).
One can include among these characters the most conspicuous
feature of dromaeosaurids: the large, raptorial claw on the second toe of the
hind foot. This feature almost certainly was not present in the alleged common
ancestor of birds and dromaeosaurids, as it is not present in Archaeopteryx,
the basal bird, or in any of the other early birds (including Protarchaeopteryx
and Caudipteryx). It is a specialization that moves dromaeosaurids away
from the actual avian lineage.
It is thus difficult to understand how the presence of
such a claw in Rahonavis ostromi can be considered “a pretty clear link
to its dinosaur origins.” Given that birds are believed to be monophyletic
and that the raptorial claw is not present in the basal members of the group,
the appearance of the feature in more derived birds must, from an evolutionist
perspective, be due to convergent evolution (as is believed to have occurred
in troodontids). It thus does nothing to link birds to dinosaurs.
The alternative is to claim that the claw is the primitive
condition in Avialae. Without even considering Protoavis, that would
require one to hypothesize an undetected lineage of sickle-clawed birds extending
some 85 million years, from before Archaeopteryx to the time of Rahonavis.
Moreover, if sickle claws are a primitive avian feature, then their absence
in Protarchaeopteryx and Caudipteryx reinforces the conclusion
that these creatures are birds rather than dinosaurs. Theropod advocates will
not look favorably on that implication.
4. Similarities overstated. It is not widely known at the
popular level, but many of the key characters seen as uniting birds and theropods
are disputed. According to Feduccia, these include:
the nature of the pelvis (Martin 1991; Tarsitano 1991),
the homology of the digits (Hinchliffe and Hecht 1984; Hinchliffe 1985;
Martin 1991; Tarsitano 1991), the nature of the teeth (Martin, Stewart,
and Whetstone 1980); Martin 1991), the hallux (Tarsitano and Hecht, 1980;
Martin 1991; Feduccia 1993a), the ascending process of the astragalus (Martin,
Stewart, and Whetstone 1980; Martin 1991; also see McGowan 1984, 1985 and
reply by Martin and Stewart 1985), the pubis (Martin 1983a, 1983b, 1991;
Tarsitano 1991; also see Wellnhofer 1985), and even the supposed unique
semilunate carpal thought to be shared by Deinonychus and Archaeopteryx
(and modern birds) (Martin 1991; Tarsitano 1991).
Since the hypothesized relationship of theropods to birds
is based on the similarity of certain features, uncertainty about that similarity
casts doubt on the hypothesis. There is obviously more art in the interpretation
of these fossils than popular presentations would lead one to believe.
5. Lung questions. John Ruben, an expert in respiratory
physiology, concluded from an examination of Sinosauropteryx “that theropods
had the same kind of compartmentalization of lungs, liver, and intestines that
you would find in a crocodile”—and not a bird. The thoracic cavity and
the abdominal cavity of theropods appear to have been completely separated from
each other by the diaphragm, whereas birds have no such separation. In living
crocodilians, the function of this separation is to provide an airtight seal
between the cavities. Air is drawn into the bellows-type lungs by contraction
of the diaphragmatic muscles which creates negative pressure in the thoracic
One reason this is significant is that, as Ruben argues,
“a transition from a crocodilian to a bird lung would be impossible, because
the transitional animal would have a life-threatening hernia or hole in its
diaphragm.” According to Ruben, this means that if there is a relationship between
dinosaurs and birds, “it’s not the linear relationship you see in the museum
These results were confirmed by the subsequent work of
Ruben’s team on the maniraptoran Scipionyx samniticus.  This unique
specimen, which has the best preserved fossil organs of any dinosaur ever found,
revealed under ultraviolet light the arrangement of some of its internal organs.
As Ruben stated in an interview, “It seems clear that a bird’s radically
different system of breathing, in which air is continuously drawn through its
lungs, could not have evolved from the hepatic-piston system we see in this
Regarding the conclusions of Ruben’s team, Larry Martin
has stated, “There’s actually no way they could be wrong about this. The
Scipionyx specimen has the best preservation ever seen. It’s one of the
biggest discoveries of this decade. It tells us more about dinosaurs than any
other specimen. The positions of the dinosaur’s windpipe and colon serve as
independent checks that the animal did not have a bird’s breathing apparatus.”
In fact, it is impossible to imagine any animal whose lungs
could have given rise to those in birds. “No lung in any other vertebrate species
is known which in any way approaches the avian system.” Denton’s amazement
regarding the avian lung is apparent:
Just how such a different respiratory system could
have evolved gradually from the standard vertebrate design without some
sort of direction is, again, very difficult to envisage, especially bearing
in mind that the maintenance of respiratory function is absolutely vital
to the life of the organism. Moreover, the unique function and form of the
avian lung necessitates a number of additional unique adaptations during
avian development. As H. R. Dunker, one of the world’s authorities in this
field, explains, because first, the avian lung is fixed rigidly to the body
wall and cannot therefore expand in volume and, second, because the small
diameter of the lung capillaries and the resulting high surface tension
of any liquid within them, the avian lung cannot be inflated out of a collapsed
state as happens in all other vertebrates after birth. In birds, aeration
of the lung must occur gradually and starts three to four days before hatching
with a filling of the main bronchi, air sacs, and parabronchi with air.
Only after the main air ducts are already filled with air does the final
development of the lung, and particularly the growth of the air capillary
network, take place. The air capillaries are never collapsed as are the
alveoli of other vertebrate species; rather, as they grow into the lung
tissue, the parabronchi are from the beginning open tubes filled with either
air or fluid.
In Denton’s opinion, “The avian lung brings us very close
to answering Darwin’s challenge: ‘If it could be demonstrated that any complex
organ existed, which could not possibly have been formed by numerous, successive,
slight modifications, my theory would absolutely break down.’”
6. Flight question. A corollary of the theropod theory
of bird origins is that flight evolved from the ground up (cursorial theory)
rather than from the trees down (arboreal theory). There is, however, no plausible
explanation for how this could have occurred. The difficulty is so great that
Chatterjee, who supports theropod ancestry, suggested recently that some theropods
may have been tree climbers. If they were, they apparently left no evidence
of that ability. According to Fastovsky and Weishampel:
It has been argued that perhaps the earliest birds
scaled trees, and from that position learned to fly. There is, however,
no evidence for an arboreal proto-bird, no evidence for climbing adaptations,
and no evidence in the skeleton of any nonavian theropod for arboreal habits.
The cursorial theory of flight origin was first proposed
by Samuel Williston in 1879. He simply raised the idea that flight could have
evolved through a series of steps (running, leaping, jumping from heights, and
finally soaring) without addressing any of the details of how that might have
happened. The following year, O. C. Marsh proposed an arboreal theory of flight
origin, and this theory has since held sway with the majority of evolutionists.
The cursorial theory has, however, had several periods of revival.
In 1907 and 1923, Franz Baron Nopcsa elaborated on Williston’s
claim by suggesting that wings would develop to increase the speed of an animal
as it ran along the ground. “Nopsca’s ideas on the origin of flight were severely
criticized by other workers because the use of wings to increase running speed
has no living analogs and because outstretched wings would increase drag (Heilmann
1926; Ostrom 1974; Bock 1986).” Feduccia labels the theory an “aerodynamic
Roughly fifty years later, John Ostrom proposed a new version
of the cursorial theory. He suggested that wings developed from arms used to
catch insects. The “[f]eathers were first present as insulators and later became
elongated fly swatters.” This “insect net” theory was heavily criticized
on four major grounds, and in 1983 Ostrom rejected his own hypothesis.
The latest attempt to explain a cursorial origin of flight
is the “fluttering model” of Caple, Balda, and Willis published in 1983.
In this theory, the avian feathered wing and concomitant
flapping evolved in creatures with bipedal cursorial habit to control body
orientation during leaping and in landing. Feathered wings and flapping,
argue the authors, would increase the distance of the leap and therefore
the running creature’s ability to capture insect prey. . . . For them, the
most appropriate selection pressure for the enhancement of wings is stability
while running at high speed, perhaps to escape predation.
Like its predecessors, this theory has faced a barrage
of criticism. For example, Jeremy Rayner has calculated that the hypothesized
proavian would suffer a 30-40 percent drop in running speed as it leaped into
the air, which creates a serious problem in terms of attaining any type of flight.
The first “flights” of a fluttering proto-flapper would
have been at low speeds, where the energetic demands of flight are at their
most extreme (Clark, 1977), and the wingbeat cycle is at its most complex.
The fluttering model fails because it takes no account of the extreme morphological,
physiological and behavioural specializations required for flight.
Thus, Chatterjee is compelled to admit that “[t]he cursorial
theory, even in its modified form, is biomechanically untenable.” Fastovsky
and Weishampel, who also favor the theropod theory, likewise acknowledge:
Fundamentally, however, it has proven nearly insurmountable
to ‘design’ a cursorial theropod that developed flight by running along
the ground. Functional morphologists—that is, scientists who study the
function of particular anatomical structures—have been unable to satisfactorily
model the running-to-flight transition in early birds.
It is also significant, from an evolutionist perspective,
that there are no contemporary examples of cursorial bipeds that use forelimbs
for stability. As Walter Bock states:
I know of no small tetrapods about the size of Archaeopteryx
that are primarily terrestrial (e.g., not flying-running forms, or secondarily
flightless or degenerate flying forms) and use their forelimbs for balance
during fast running or during a leap. And I know of none using the forelimbs
as flapping structures to provide forward thrust to increase the length
of its leap.
In fact, kangaroos, which share several functional traits
with theropods (obligate bipedality, cursorial posture, short forelimbs, long
tail) and thus offer a modern analog for testing the theory, do not extend their
forelimbs during jumping. Rather, the limbs play a passive role. “To minimize
drag force, they are kept in a folded position in a strictly sagittal plane
during takeoff, midway through the leap, and during landing.” The use
of the forelimbs in these animals does not mimic a rudimentary flight stroke.
The idea that birds evolved from dinosaurs remains at best
a highly speculative hypothesis. One suspects its popularity has less to do
with the evidence for theropod ancestry than with the Darwinian aversion to
ancestral vacuums. When paleontologist Hans-Dieter Sues says, “Only dinosaurs
are anatomically suited to be the precursors of birds,” he is saying that,
when it comes to bird origins, it is dinosaurs or nothing. Since evolutionists
are convinced that every taxon arose from some other, “nothing” is not an option.
This philosophical predisposition induces them to read lineages into ambiguous
data. They compound that error by confusing these interpretive constructs with
One can state the matter no more forcefully than did Storrs
Olson in his November 1, 1999 letter to the most prominent scientist at the
National Geographic Society. He concluded with the following:
The idea of feathered dinosaurs and the theropod origin
of birds is being actively promulgated by a cadre of zealous scientists
in concert with certain editors at Nature and National Geographic
who themselves have become outspoken and highly biased proselytizers of
the faith. Truth and careful scientific weighing of evidence have been among
the first casualties of their program, which is now fast becoming one of
the grander scientific hoaxes of our age – the paleontological equivalent
of cold fusion. If Sloan’s article is not the crescendo of this fantasia,
it is difficult to imagine to what heights it can next be taken. But it
is certain that when the folly has run its course and has been fully exposed,
National Geographic will unfortunately play a prominent but unenviable role
in the book that summarizes the whole sorry episode.
 These finds are reported in Ji et al. (1998) and,
at a more popular level, in Ackerman (1998). “Theropod dinosaurs” refers to
a wide variety of bipedal, carnivorous dinosaurs. Many of the features that
distinguish them from other dinosaurs occur in the legs, feet, and hands. Fastovsky
and Weishampel (1996), 261, 271-272. In the Linnaean system of classification,
theropods are those creatures in the Class Reptilia, Subclass Diapsida, Infraclass
Archosauromorpha, Superorder Archosauria, Order Saurischia, Suborder Theropoda.
Carroll (1988), 615-621. In cladistic classification, “theropod dinosaurs” are
those creatures in the clades Reptilia, Diapsida, Archosauromorpha, Archosauria,
Ornithodira, Dinosauria, Saurischia, and Theropoda. Fastovsky and Weishampel
(1996), 86-89, 271-273. For a brief note on the classification differences,
see Glut (1997), 18. Conventional dating is assumed arguendo throughout
the paper. [RETURN TO TEXT]
 Padian (1998), 730. Coelurosauria is a subset of Theropoda.
In the Linnaean system of classification, theropods were traditionally divided
into the Infraorders Carnosauria and Coelurosauria. These taxa have been abandoned
in that system because the features once thought to distinguish the two groups
were found to be combined in a number of genera. Carroll (1988), 290, 621. Coelurosauria
as a clade designation includes compsognathids and the clade Maniraptora. Coelurosaurs
are distinguished from other theropods by their expanded circular orbit, semilunate
carpal in the wrist, short ischium, heightened ascending process of the astragalus,
and reduction of the transverse processes of the tail vertebrae. Fastovsky and
Weishampel (1996), 274-275; see also, Padian (1997), 550. [RETURN TO TEXT]
 Lemonick (1998), 83. [RETURN TO TEXT]
 Feduccia (1996), 28, 52. Compsognathus was considerably
larger than Archaeopteryx, its estimated weight being six to seven pounds
compared to about one pound for Archaeopteryx. Carroll (1988), 291; Carroll
(1997), 314. The estimated weight for the smallest Archaeopteryx specimen
is a mere 7-9 ounces. Swartz (1998), 356. “By comparison with the Solnhofen
Archaeopteryx, which is the largest example, the others in size, are
as follows: Solnhofen 100 percent, London 90 percent, Maxberg 87 percent, Berlin
77 percent, Archaeopteryx bavarica 66 percent, and Eichstatt 50 percent.”
Feduccia (1996), 35. The latest Archaeopteryx specimen was described
by Wellnhofer in 1993. He considered it sufficiently different from the others
in the relative length of its tibiae and hind legs to be named a new species,
Archaeopteryx bavarica. Feduccia (1996), 32. [RETURN TO TEXT]
 Carroll (1988), 340. Though Compsognathus is accepted
as a contemporary of Archaeopteryx, the precise location at which the
holotype was found is unknown. It was collected in the late 1850s, apparently
by physician and amateur fossil collector Dr. Oberndorfer. John Ostrom and Peter
Wellnhofer attempted to determine the precise source of the fossil “but were
only able to conclude that it came from lithographic facies of the Solnhofen
Limestone, probably from the Riedenburg-Kelheim area.” Glut (1997), 307. [RETURN TO TEXT]
 Feduccia (1996), 55, 67. Those convinced that the similarities
between dinosaurs and birds were the result of convergence include Mudge (1879),
Dollo (1882, 1883), Dames (1884), Parker (1887), Furbringer (1888), Osborn (1900),
Broom (1913), Heilmann (1926), Simpson (1946), de Beer (1954), and Romer (1966).
Feduccia (1996), 67. [RETURN TO TEXT]
 Padian and Chiappe (1997), 73. [RETURN TO TEXT]
 Feduccia (1996), 55. [RETURN TO TEXT]
 Padian and Chiappe (1997), 73; Feduccia (1996), 66. Dromaeosauridae
is a Family in the Suborder Theropoda. Carroll (1988), 621. Prior to the recent
discovery of Sinornithosaurus millenii, Dromaeosauridae was divided into
two Subfamilies: Velociraptorinae and Dromaeosaurinae. Velociraptorinae includes
the genera Deinonychus, Saurornitholestes, and Velociraptor.
Dromaeosaurus is the only “unquestionable” genus in Dromaeosaurinae,
but Adasaurus has been referred to it. Currie, (1997b), 194. Sinornithosaurus
millenii was placed within Dromaeosauridae but not within either of the
existing Subfamilies. Xing et al. (1999b). With the possible exception
of Sinornithosaurus millenii, the live weight of dromaeosaurids ranged
from 66 to 176 pounds, and most of them were six to ten feet in length. They
are distinctive in the possession of a highly mobile hand-wrist complex, unique
caudal vertebral adaptations, and a large, sickle-like claw on their feet. Ostrom
(1990), 269-271; Currie (1997b), 194-195. The holotype of Sinornithosaurus
millenii is eagle size (Sloan , 102), but one wonders whether that
specimen had reached full adulthood. [RETURN TO TEXT]
 The most influential of these analyses was Gauthier (1986).
See also, Holtz (1994). Cladistic analysis (also called phylogenetic systematics
and Hennigian systematics), which has gained prominence in the last twenty years,
is the classification of creatures into subsets on the basis of characters (recognizable
attributes) they uniquely share. Such characters are regarded as having been
inherited from a common ancestor who possessed them. It differs from the methodology
of “evolutionary systematics” in its exclusive focus on shared, derived characters.
Evolutionary systematics employs “an eclectic spectrum of evidence from all
lines of biological information to establish relations. Such lines of evidence
might derive from a blend of such disciplines as comparative anatomy and embryology,
functional anatomy and biomechanics, biochemistry, physiology, and behavior.”
Feduccia (1996), 56. [RETURN TO TEXT]
 Feduccia (1996), 66. [RETURN TO TEXT]
 Fastovsky & Weishampel (1996), 321. [RETURN TO TEXT]
 Chen et al. (1998), 150. [RETURN TO TEXT]
 In October 1996, Philip Currie said of the filaments,
“They look so much like the feather impressions seen in the bird fossils at
the same site that you can’t come to any conclusion other than the fact that
you’re dealing with feathers.” He then equivocated with, “Now, they may not
be feathers. They may be featherlike scales, they may be hair, they may be something
else. Until the detailed work is done on it, you can’t really tell. But the
bottom line is that, now, I don’t think there is any question that these dinosaurs
had insulation of some kind, and in all probability it was feathers.” Monastersky
(1996). See also, Gibbons (1996a) and Gibbons (1997a). It was reported in May
1997, however, that “[a]n international team of researchers that examined the
Chinese fossil now concludes that the fibrous structures are not feathers.”
Monastersky (1997). See also, Gibbons (1997c). [RETURN TO TEXT]
 In addition to Monastersky (1997) and Gibbons (1997c),
see, Chen et al. (1998), 152; Padian and Chiappe (1998a), 45; Ackerman
(1998), 78; Norell (1998), 33. [RETURN TO TEXT]
 The consensus is that these fossil beds are younger than
the Solnhofen Limestones in which Archaeopteryx was found, but there
has been disagreement over how much younger. An argon-argon analysis yielded
a date of about 121 mya, but radiometric dates of 137 - 142 mya have also been
reported. Gibbons (1996b), 1083; Anonymous (1997), 21. As of June 1998, ranges
of 135 - 120 mya and 145 - 125 mya were being quoted. E.g., Gibbons (1998),
2051; Monastersky (1998), 404. Norell used an estimated date of 135 - 122 mya.
Norell (1998), 33. Ackerman said the beds have “not yet [been] conclusively
dated but [are] probably more than 120 million years old—the Early Cretaceous
period.” Ackerman (1998), 86. Others were content to speak simply of an “Early
Cretaceous age.” E.g., Chen et al. (1998), 147. The most recent, and
purportedly definitive, dating effort yielded a middle Early Cretaceous date
of 124 mya. Swisher et al. (1999). [RETURN TO TEXT]
 Ackerman (1998), 76-77, 86; Monastersky (1996); Gibbons
(1996a), 720. [RETURN TO TEXT]
 The circumstances of the discoveries can be gleaned from
Gibbons (1998); Ackerman (1998), 86-89, 95; and Unwin (1998), 120. The original
article on these finds was Ji and Ji (1997). (This journal is in Chinese, but
the translation of the title is provided in Chen et al. , 152.) [RETURN TO TEXT]
 Mark Norell says of the feathers, “They are just like
feathers on modern birds.” Gibbons (1998). According to Philip Currie, "The
plumage on the new Chinese dinosaurs . . . is identical to bird feathers." Monastersky
(1998). Kevin Padian agrees that the feathers on Archaeopteryx “are not
much different qualitatively” than the feathers on these specimens. Padian (1998),
730. Regarding their presumed inability to fly, see, Monastersky (1998); Chen
et al. (1998), 151-152. One detects, however, some equivocation on the
flightlessness of Protarchaeopteryx. Thus, Ackerman reports that Protarchaeopteryx
“probably could not have achieved true powered flight” (emphasis supplied).
Ackerman (1998), 90. According to Feduccia, Protarchaeopteryx is within
the range of living volant birds (reliable source). [RETURN TO TEXT]
 Monastersky (1998) (reporting the comment of Mark Norell). [RETURN TO TEXT]
 After describing briefly the complexity of feathers, Fastovsky
and Weishampel state, “The importance of all this in an evolutionary sense is
that feathers evolved (or originated) only once. After all, what are
the chances of so complex a structure’s having evolved more than once? Using
parsimony, we must conclude that feathers evolved only one time.” Fastovsky
and Weishampel (1996), 294. Peter Wellnhofer agrees it is unlikely that a feature
as unusual as feathers evolved twice. Gibbons (1996a). [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 294, 304. [RETURN TO TEXT]
 Padian (1998), 729. [RETURN TO TEXT]
 Carroll states, “Hair is a uniquely mammalian tissue that
is not directly homologous with any derivative of the skin present in other
amniotes.” Carroll (1988), 411. [RETURN TO TEXT]
 Gibbons (1998); Monastersky (1998); Ruben’s opinion based
on a reliable source. All three have examined the fossils. [RETURN TO TEXT]
 Ji et al. (1998), 759 (and the supplementary information
made available on Nature’s web site <http://www.nature.com>). [RETURN TO TEXT]
 Personal communication. [RETURN TO TEXT]
 Clark (1992) (cited in Feduccia , 59). [RETURN TO TEXT]
 Theropod bias was also evident in Padian and Chiappe (1998a).
A subsequent letter by the original describers of Confuciusornis (Feduccia,
Martin, Zhou, and Hou) charged that the cover illustration of Confuciusornis
made it look more dinosaurian than it was. They wrote, “Although Confuciusornis
is a primitive, sauriurine bird, in life it would have appeared very much like
a normal perching bird, such as a small crow, not a feathered dinosaur. The
cover illustration has nothing to do with Confuciusornis.” Feduccia et
al. (1998). [RETURN TO TEXT]
 Ji et al. (1998), 754. [RETURN TO TEXT]
 According to the matrix provided as supplementary information
on Nature’s web site <http://www.nature.com.>, Protarchaeopteryx
and Caudipteryx shared the derived avian feature of a radial shaft to
ulnar shaft ratio that was smaller than 0.70 (character 49), whereas Archaeopteryx
did not. [RETURN TO TEXT]
 Personal communication. [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 261, 284-287. [RETURN TO TEXT]
 See, Ji et al. (1998), 759. Fastovsky and Weishampel
define a gastrolith as a “[s]moothly polished stone in the stomach, used for
grinding plant matter.” Fastovsky and Weishampel (1996), 435. Masses of gastroliths
similar to those in Caudipteryx have been found in moas, a group of extinct,
leaf-eating birds in New Zealand. Feduccia (1996), 5, 281-283. [RETURN TO TEXT]
 Gastroliths were known in some birds, crocodilians, sauropodomorphs,
and psittacosaurs. Fastovsky and Weishampel (1996), 125, 182 (n. 6), 254-255. [RETURN TO TEXT]
 Kobayashi et al. (1999). The authors reason from
phylogenetic analysis that herbivory evolved independently in the ornithomimid
species and in Caudipteryx. [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 282-283. [RETURN TO TEXT]
 Another possibility, open to creationists, is that (at
least some) land birds were descendants of an originally created kind whose
members were given feathers for some purpose(s) other than flight (perhaps for
one or more of the purposes theropodists use in arguing that feathers evolved,
e.g., insulation, camouflage, or display). [RETURN TO TEXT]
 Ji et al. (1998), 759 (and the supplementary information
made available on Nature’s web site <http://www.nature.com>). Ji
et al. do not claim that Protarchaeopteryx had an obturator process
or that its quadratojugal contacted the squamosal. These features admittedly
could not be determined. [RETURN TO TEXT]
 Personal communication. [RETURN TO TEXT]
 Ji et al. (1998), 753, 755; compare drawing at
Feduccia (1996), 80. [RETURN TO TEXT]
 Ostrom (1990), 270-271. [RETURN TO TEXT]
 Ji et al. (1998), 753; Feduccia (1996), 80. The
chart in Feduccia (from Chatterjee) lists Deinonychus and Dromaeosaurus.
Since Currie does not include the number of serrations among the dental distinctions
between velociraptorines and dromaeosaurines, they presumably do not vary significantly
in that regard. Currie (1997b), 195. [RETURN TO TEXT]
 Padian (1998), 729. [RETURN TO TEXT]
 Sloan (1999), 103, 105. [RETURN TO TEXT]
 Olson (1999). [RETURN TO TEXT]
 Feduccia (1996), 24-35. [RETURN TO TEXT]
 Regarding Confuciusornis, Ambiortus, and
Noguerornis, see, Feduccia (1996), 139-145. [RETURN TO TEXT]
 Ostrom (1990), 270. [RETURN TO TEXT]
 Xing et al. (1999a). [RETURN TO TEXT]
 Xing et al. (1999b). [RETURN TO TEXT]
 Olson (1999). [RETURN TO TEXT]
 Ibid. [RETURN TO TEXT]
 Sloan (1999). [RETURN TO TEXT]
[54A] Monastersky (2000); Kurtenbach (2000); Friend (2000). [RETURN TO TEXT]
 Monastersky (1999). [RETURN TO TEXT]
 Chatterjee (1997), 33-38. On the sizes of the Archaeopteryx
specimens, see also note 4. [RETURN TO TEXT]
 Chatterjee (1997), 38. [RETURN TO TEXT]
 Feduccia (1996), 38. For firsthand descriptions, see Chatterjee
(1991), (1995), (1997). [RETURN TO TEXT]
 Chatterjee (1997), 79-80. [RETURN TO TEXT]
 In a bit of an overstatement, Padian and Chiappe claim
“it has become nearly universally accepted that birds evolved from small carnivorous
dinosaurs most closely related to DROMAEOSAURIDS, probably sometime in the Middle
to early Late Jurassic.” Padian and Chiappe (1997), 71. Elsewhere they write,
“The reported find [of Protoavis], deep in the Late Triassic, was stratigraphically
unexpected given the consilience between the order of the bird-theropod cladogram
(e.g. Gauthier, 1986) and the sequence of appearance of these taxa, which suggested
that the origin of birds was in the Late (or perhaps Middle) Jurassic (Padian,
1985; Gauthier, 1986).” Padian and Chiappe (1998b), 12-13. [RETURN TO TEXT]
 Feduccia (1996), 38. [RETURN TO TEXT]
 Padian and Chiappe (1998b), 13. [RETURN TO TEXT]
 Ibid. [RETURN TO TEXT]
 Chatterjee (1997), x. [RETURN TO TEXT]
 Chatterjee (1997), 37. [RETURN TO TEXT]
 Chiappe (1995), 349. See, Ellenberger (1974) and Lockley
et al. (1992). [RETURN TO TEXT]
 Chatterjee (1997), 137. See, Weems and Kimmel (1993). [RETURN TO TEXT]
 Chiappe (1995), 349 (referring to Ellenberger  and
Lockley et al. ). [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 365. There is some question,
however, whether Eoraptor is a dinosaur. If not, then the earliest known
dinosaur is Herrerasaurus, also from the Late Triassic of Argentina.
Feduccia (1996), 90. The Middle Triassic date is calculated from the fact the
origin of birds is believed by theropod advocates to have preceded Archaeopteryx
by some 10-15 million years (see note 71). Since Protoavis is more derived,
it would require even more time to evolve. [RETURN TO TEXT]
 Chatterjee (1997), x. One can only marvel at Currie’s
faith in the theropod theory. He writes, “If birds were present during the Late
Triassic, then theropods are less likely to have been ancestral to birds”
(emphasis supplied). Currie (1997a), 231. [RETURN TO TEXT]
 Padian and Chiappe (1997), 71. Others (without regard
to Protoavis) claim that birds may have arisen as early as the Middle
Triassic. Feduccia (1996), 90. [RETURN TO TEXT]
 Ostrom states it this way: “The evidence strongly indicates
a close phyletic relationship between dromaeosaurids and primitive birds, and
one could argue that an (as yet unknown) Early or Mid-Jurassic dromaeosaurid
was ancestral to archaeopterygians and later birds.” Ostrom (1990), 276. [RETURN TO TEXT]
 The earliest known coelurosaurs, Compsognathus,
Coelurus, and Ornitholestes, are all from the Late Jurassic. The
earliest known dromaeosaurid, Sinornithosaurus, is from the middle Early
Cretaceous, some 25 million years later. Xing et al. (1999b). Deinonychus,
the next oldest dromaeosaurid, is from the late Early Cretaceous. With the exception
of Sinornithosaurus, the most birdlike dromaeosaurids are from the Late
Cretaceous, some 75 million years after Deinonychus. Feduccia (1996),
90; Padian and Chiappe (1997), 78; Hutchinson and Padian (1997), 132; Benton,
(1993), 699, 702. A distal radius and femur from the Late Jurassic were re-identified
by Jensen and Padian in 1989 as belonging to the clade Maniraptora, but no determination
was made whether they were from a dromaeosaurid or a bird. Jensen and Padian
(1989). Some teeth from Japan that have been attributed to Dromaeosauridae may
be older than Deinonychus, but the dating is disputed. Some “dromaeosaurid/troodontid-type”
teeth from the late Middle Jurassic of England have also been noted (see discussion
in text). Benton (1993), 702. [RETURN TO TEXT]
 Fallow (1997), 108-110; Feduccia (1996), 90. [RETURN TO TEXT]
 Zhao and Xu (1998). According to one recent classification,
Therizinosauroidea is a superfamily consisting of the families Alxasauridae
(consisting of the genus Alxasaurus) and Therizinosauridae (consisting
of the genera Enigmosaurus, Erlikosaurus, Nanshiungosaurus,
Segnosaurus, and Therizinosaurus). Glut (1997), 55-56. The genera
Alxasaurus, Enigmosaurus, Erlikosaurus, Nanshiungosaurus,
and Segnosaurus are also known as Segnosauria. Fastovsky and Weishampel
(1996), 226-227. [RETURN TO TEXT]
 “[B]iologists working with both modern and extinct groups
argue that convergence is very common.” Carroll (1988), 8. A classic example
is Thylacinus, a marsupial “wolf,” and the placental canids. Carroll
says, “The general body form [of Thylacinus] as well as details of
the dentition provide a strikingly close parallel with the placental
canids” (emphasis supplied). Carroll (1988), 435. [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 226. [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 228. See also, Glut (1997),
55. The recently discovered Beipiaosaurus inexpectus has been interpreted
as a primitive therizinosaur. Xing et al. (1999a); Sloan (1999), 103,
106. The authors believe it has features that show therizinosaurs to be coelurosaurian
theropods. [RETURN TO TEXT]
 Zhao and Xu state, “Isolated teeth tentatively
identified as dromaeosaurid have been found in Middle Jurassic deposits” (emphasis
supplied). Zhao and Xu (1998), 235. Benton refers to teeth from the late Middle
Jurassic as “dromaeosaurid/troodontid-type.” Benton (1993), 702. [RETURN TO TEXT]
 Padian and Chiappe (1998), 14. Padian and Chiappe would
now view Caudipteryx as the “sister group” of birds, but as previously
discussed, Caudipteryx is probably a flightless bird. [RETURN TO TEXT]
 Feduccia (1996), 90. He writes: “First, the timing is
off. Archaeopteryx occurs in the late Jurassic, some 150 million years
ago, and presumably birds originated much earlier, say, possibly medial to late
Triassic. However, the earliest dinosaurs, Eoraptor (if it is a dinosaur)
and Herrerasaurus [cites omitted], both from the late Triassic of Argentina,
lack the synapomorphies that are used to unite birds and dinosaurs” (emphasis
supplied). The same holds for Middle Jurassic dinosaurs. [RETURN TO TEXT]
 The desperation is palpable in the claim that the middle
Early Cretaceous Yixian Formation is a “refugium for relicts,” a pocket
of evolutionary holdovers, none of which left evidence of its existence during
the preceding ages. Zhexi (1999). Zhexi understates the difficulty of his position
by suggesting that the “ghost lineages” of the Yixian “relicts”
extend back to the Late Jurassic (some 25 million years). Without even considering
Protoavis, to qualify as ancestors of birds the “ghost lineages”
of the Yixian theropods would need to extend back at least to the Middle Jurassic,
another 25 million years (see notes 61 and 62). [RETURN TO TEXT]
 Feduccia (1996), 56. [RETURN TO TEXT]
 Benton (1993), 681-711, 717-734, 739-768. [RETURN TO TEXT]
 Padian and Chiappe (1997), 78. [RETURN TO TEXT]
 Chatterjee (1997), x. [RETURN TO TEXT]
 Of course, creationists have their own problems regarding
the fossil record, but explaining how evolutionary lineages could exist for
tens of millions of years without leaving a clear trace is not one of them. [RETURN TO TEXT]
 Padian and Chiappe (1997), 78. [RETURN TO TEXT]
 Ibid. [RETURN TO TEXT]
 Carroll (1988), 340. [RETURN TO TEXT]
 Chatterjee (1997), 7-8. He writes, “The common ancestor
of birds and dromaeosaurs has yet to be found in the fossil record. However,
we can speculate from cladistic analysis that this hypothetical bird ancestor
would be very similar to dromaeosaurs in general morphology.” He concludes,
“Dromaeosaurs are currently the best approximation of the hypothetical bird
ancestor and serve as a model when tracing avian ancestry.” [RETURN TO TEXT]
 Currie (1997b), 195. [RETURN TO TEXT]
 Zimmer (1998), 32 (quoting Catherine Forster). She told
the Associated Press, “This animal gives powerful new evidence to support the
theory that birds descended from dinosaurs,” and said it may be “the strongest
last nails in the coffin” for those who doubt that birds evolved from dinosaurs.
Anonymous (1998). Rahonavis dates from 65-75 million years ago. [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 278-279. [RETURN TO TEXT]
 Feduccia (1996), 68. The specifics are elaborated upon
at pp. 68-81. For a response from theropod advocates, see Padian and Chiappe
(1997), 73-78. Suffice to say that neither side is persuaded. The debate about
digital homology has received a fair amount of attention. Opponents of theropod
origins argue on the basis of embryological developmental patterns that the
three digits of the avian hand are II-III-IV, whereas it is agreed that the
digits of the theropod hand are I-II-III. If this is correct, the three digits
are not a shared feature inherited from a common ancestor and thus argue against
theropod ancestry. See, Burke and Feduccia (1997); Padian and Chiappe (1998b),
7-8. [RETURN TO TEXT]
 Gibbons (1997b), 1230. [RETURN TO TEXT]
 Ibid. [RETURN TO TEXT]
 Ruben et al. (1999). [RETURN TO TEXT]
 Browne (1999). [RETURN TO TEXT]
 Ibid. [RETURN TO TEXT]
 Denton (1998), 361. Padian and Chiappe state that bird
lungs “are extremely complex and are unlike the lungs of any living animal.”
Padian and Chiappe (1998a), 43. Pough et al. say, "The respiratory system
of birds is unique among living vertebrates." Pough et al. (1989), 621. [RETURN TO TEXT]
 Denton (1998), 361. [RETURN TO TEXT]
 Denton (1998), 361-362. [RETURN TO TEXT]
 Chatterjee (1997), 161-184. [RETURN TO TEXT]
 Fastovsky and Weishampel (1996), 313. [RETURN TO TEXT]
 Feduccia (1996), 97; Chatterjee (1997), 151. [RETURN TO TEXT]
 Chatterjee (1997), 151-152. Burgers and Chiappe have
recently argued that Archaeopteryx could have gained the velocity necessary
to take off from the ground by flapping its wings as it ran. Burgers and Chiappe
(1999). The validity of their analysis remains to be seen, but in any event,
it assumes the presence of Archaeopteryx-type wings to generate the hypothesized
forward thrust. It thus does not seem useful in explaining how such wings developed
in the first place. [RETURN TO TEXT]
 Feduccia (1996), 98. [RETURN TO TEXT]
 Chatterjee (1997), 153. See also Feduccia (1996), 98-101. [RETURN TO TEXT]
 Chatterjee (1997), 153; Feduccia (1996), 101. Though
Ostrom had abandoned the theory by 1983, he apparently did not formally publish
that opinion until 1986. [RETURN TO TEXT]
 Feduccia (1996), 102. Chatterjee describes the theory
According to these authors, the proavians might have
used their jaws to catch prey but employed their wings as bilateral stabilizers
during a jump into the air. Caple and colleagues maintained that the rudimentary
wings of proavians were effective for balance while running, jumping, and
turning, until they were able to take off at high speed. They speculated
that, when the proavians extended their forelimbs, minute increments of
lift made it easier to jump further and capture more prey. The motion of
the forelimbs for stabilization, according to them, would mimic the flight
stroke of a bird. Eventually, the proavians evolved larger airfoils that
enabled them to obtain even greater lift. Also, as lift increased it aided
in landings. Therefore, the proavians could slow down and direct their landings.
As a result, power flight evolved. Chatterjee (1997), 153-154.
This theory has recently been modified by assuming that
the hypothesized cursorial ancestors of birds specialized in pouncing on their
prey from elevated sites. Garner et al. (1999); Taylor (1999). So instead
of leaping on prey from trees, which they could not climb, they supposedly leaped
on prey from other structures that they could climb. Of course, one can only
speculate about the terrain in which these alleged avian ancestors hunted, but
even if there were a sufficient number of elevated sites that were frequented
by prey, the tail and sickle claws of dromaeosaurids seem ill suited for climbing
of any kind. It also seems unlikely that a predator apparently built for running
would catch its prey by waiting for it on a perch. And certainly an enhanced
pouncing ability cannot account for the presence of alleged “protofeathers”
(the filamentous structures) on the seven-foot-long Beipiaosaurus. In
addition, if one accepts Caudipteryx as a nonavian theropod, as do Garner
et al., the fact it was an herbivore rather than a leaping predator presents
an additional problem. Taylor’s attempt to counter this with the assertion that
Caudipteryx was an insectivore (Taylor , 32) is hindered by the
fact the only other theropod found with gastroliths was almost certainly an
herbivore. Kobayashi et al. (1999). [RETURN TO TEXT]
 Included in this list of critics are Jerison, Rayner,
Bock, Martin, Feduccia, Norberg, and Pennycuick. Chatterjee (1997), 155. [RETURN TO TEXT]
 Rayner (1988), 278. [RETURN TO TEXT]
 Chatterjee (1997), 155. [RETURN TO TEXT]
 Fastovsky and Weishampel, 313. [RETURN TO TEXT]
 Bock (1986), 68. [RETURN TO TEXT]
 Chatterjee (1997), 155. [RETURN TO TEXT]
 Ackerman (1998), 96. [RETURN TO TEXT]
Ackerman, Jennifer. 1998. Dinosaurs Take Wing. National
Geographic 194: 74-99.
Anonymous. 1997. Old Bird. Discover (March 21): 21.
Anonymous. 1998. Scientist: Fossil proves birds descended from
dinosaurs. Arizona Republic (March 19): A11.
Benton, M. J., ed. 1993. The Fossil Record 2. Chapman
& Hall. London.
Bock. W. J. 1986. The arboreal origin of avian flight. Memoires
of the California Academy of Sciences 8: 57-72.
Browne, Malcolm W. January 26, 1999. Turning Dinosaur Theory
on Its Paleobiological Tail. New York Times, Science Desk.
Burgers, Phillip and Luis M. Chiappe. 1999. The wing of Archaeopteryx
as a primary thrust generator. Nature 399: 60-62.
Burke, Ann C. and Alan Feduccia. 1997. Developmental Patterns
and the Identification of Homologies in the Avian Hand. Science 278:
Carroll, Robert L. 1988. Vertebrate Paleontology and Evolution.
W. H. Freeman. New York.
Carroll, Robert L. 1997. Patterns and Processes of Vertebrate
Evolution. University Press. Cambridge, England.
Chatterjee, Sankar. 1991. Cranial anatomy and relationships
of a new Triassic bird from Texas. Philosophical Transactions of the Royal
Society B 332: 277-346.
Chatterjee, Sankar. 1995. The Triassic Bird Protoavis.
Chatterjee, Sankar. 1997. The Rise of Birds. Johns Hopkins
University Press. Baltimore, MD.
Chen Pei-ji, Zhi-ming Dong and Shuo-nan Zhen. 1998. An exceptionally
well-preserved theropod dinosaur from the Yixian Formation of China. Nature
Chiappe, Luis M. 1995. The first 85 million years of avian
evolution. Nature 378: 349-355.
Clark, J. M. 1992. Review of Origins of the higher groups
of vertebrates: controversy and consensus. Journal of Vertebrate Paleontology
Currie, Phillip J. 1997. Theropods. In James O. Fallow and
M. K. Brett-Surman, eds., The Complete Dinosaur, 216-233. Indiana University
Press. Bloomington, IN.
Currie, Philip J. 1997. Dromaeosauridae. In Philip J. Currie
and Kevin Padian, eds., Encyclopedia of Dinosaurs, 194-195. Academic
Press. New York.
Denton, Michael J. 1998. Nature’s Destiny. Free Press.
Ellenberger, P. 1974. Paleovertebrata (Mem. Extraor.)
Fallow, James O. 1997. Dinosaurs and Geologic Time. In James
O. Fallow and M. K. Brett-Surman, eds., The Complete Dinosaur, 107-111.
Indiana University Press. Bloomington, IN.
Fastovsky, David E. and David B. Weishampel. 1996. The Evolution
and Extinction of the Dinosaurs. Cambridge University Press. Cambridge,
Feduccia, Alan. 1996. The Origin and Evolution of Birds.
Yale University Press. New Haven, CT.
Feduccia, Alan, Larry Martin, Zhonghe Zhou, and Lian-Hai Hou.
1998. Birds of a Feather. Scientific American (June): 8.
Friend, Tim. 2000. Dinosaur-bird link smashed in fossil flap.
USA Today (Jan. 25): web.
Garner, Joseph P., Graham K. Taylor, and Adrian L. R. Thomas.
1999. On the origins of birds: the sequence of character acquisition in the
evolution of avian flight. Proceedings of the Royal Society B 266: 1259-1266.
Gauthier, J. A. 1986. Saurischian monophyly and the origin
of birds. Memoires of the California Academy of Sciences 8: 1-55.
Gibbons, Ann. 1996. New Feathered Fossil Brings Dinosaur and
Birds Closer. Science 274: 720-721.
Gibbons, Ann. 1996. Early Birds Rise from China Fossil Beds.
Science 274: 1083.
Gibbons, Ann. 1997. Feathered Dino Wins a Few Friends. Science
Gibbons, Ann. 1997. Lung Fossils Suggest Dinos Breathed in
Cold Blood. Science 278: 1229-1230.
Gibbons, Ann. 1997. Plucking the Feathered Dinosaur. Science
Gibbons, Ann. 1998. Dinosaur Fossils, in Fine Feather, Show
Link to Birds. Science 280: 2051.
Glut, Donald F. 1997. Dinosaurs The Encyclopedia. McFarland
& Company. Jefferson, NC.
Holtz, T. R. 1994. The phylogenetic position of the Tyrannosauridae:
Implications for theropod systematic. Journal of Paleontology 68: 1100-1117.
Hutchinson, John R. and Kevin Padian. 1997. Coelurosauria.
In Philip J. Currie and Kevin Padian, eds., Encyclopedia of Dinosaurs,
129-133. Academic Press. New York.
Jensen, James A. and Kevin Padian. 1989. Small Pterosaurs and
Dinosaurs From the Uncompahgre Fauna (Brushy Basin Member, Morrison Formation:
?Tithonian), Late Jurassic, Western Colorado. Journal of Paleontology
Ji, Q. and S. A. Ji. 1997. Protarchaeopteryx, a new
genus of Archaeopterygidae in China. Chinese Geology 238: 38-41.
Ji, Qiang, Philip J. Currie, Mark A. Norell and Ji Shu-An.
1998. Two feathered dinosaurs from northeastern China. Nature 393: 753-761.
Kobayashi, Yoshitsugu, Lu Jun-Chang, Dong Zhi-Ming, Rinchen
Barsbold, Yoichi Azuma, and Yukimitsu Tomida. 1999. Herbivorous diet in an ornithomimid
dinosaur. Nature 402: 480-481.
Kurtenback, Elaine. 2000. Scientist Disputes China Fossil.
L.A. Times (Jan. 21): web.
Lemonick, Michael D. 1998. Dinosaurs of a Feather. Time
(July 6): 82-83.
Lockley, M. G., S. Y. Yang, M. Matsukawa, F. Fleming, and S.
K. Lim. 1992. Philosophical Transactions of the Royal Society B
Monastersky, R. 1996. Hints of a Downy Dinosaur in China. Science
News 150: 260.
Monastersky, R. 1997. Paleontologists deplume feathery dinosaur.
Science News 151: 271.
Monastersky, R. 1998. Feathered Dinosaurs Found in China. Science
News 153: 404.
Monastersky, R. 1999. Smuggled Chinese dinosaur to fly home.
Science News 156: 328.
Monastersky, R. 2000. All mixed up over birds and dinosaurs.
Science News 157: 38
Norell, Mark. 1998. First Came Feathers. Natural History
Olson, Storrs L. Open letter to Dr. Peter Raven at National
Geographic Society dated November 1, 1999 (available at http://www.trueorigin.org/birdevoletter.php).
Ostrom, John H. Ostrom, 1990. Dromaeosauridae. In David B.
Weishampel, Peter Dodson, Halszka Osmolska, eds., The Dinosauria, 269-279.
University of California Press. Berkeley, CA.
Padian, Kevin. 1997. Phylogeny of Dinosaurs. In Philip J. Currie
and Kevin Padian, eds., Encyclopedia of Dinosaurs, 546-551. Academic
Press. New York.
Padian, Kevin. 1998. When is a bird not a bird? Nature
Padian, Kevin and Luis M. Chiappe. 1997. Bird Origins. In Philip
J. Currie and Kevin Padian, eds., Encyclopedia of Dinosaurs, 71-79. Academic
Press. New York.
Padian, Kevin and Luis M. Chiappe. 1998. The Origin of Birds
and Their Flight. Scientific American (February): 38-47.
Padian, Kevin and Luis M. Chiappe. 1998. The origin and early
evolution of birds. Biological Review 73: 1-42.
Pough, F. Harvey, John B. Heiser, and William N. McFarland.
1989. Vertebrate Life 3rd ed. Macmillan. New York.
Rayner, J. M. V. 1988. The evolution of vertebrate flight.
Biological Journal of the Linnean Society 34: 269-287.
Ruben, John A., Cristiano Dal Sasso, Nicholas R. Geist, Willem
J. Hillenius, Terry D. Jones, and Marco Signore. 1999. Pulmonary Function and
Metabolic Physiology of Theropod Dinosaurs. Science 283: 514-516.
Sloan, Christopher P. 1999. Feathers for T. Rex? National
Geographic 196: 98-107.
Swartz, Sharon. 1998. Into Jurassic Air. Science 281:
Swisher, Carl C. III, Wang Yuan-qing, Wang Xiao-lin, Xu Xing,
and Wang Yuan. 1999. Cretaceous age for the feathered dinosaurs of Liaoning,
China. Nature 400: 58-61.
Taylor, Graham. 1999. Winging it. New Scientist (August
Unwin, D. M. 1998. Feathers, filaments and theropod dinosaurs.
Nature 391: 119-120.
Weems, R. E., and P. G. Kimmel. 1993. Upper Triassic reptile
footprints and coelacanth fish scales from the Culpepper Basin, Virginia. Proc.
Biol. Soc. Wash. 106: 390-401.
Xing, Xu, Tang Zhi-lu, and Wang Xiao-lin. 1999. A therizinosauroid
dinosaur with integumentary structures from China. Nature 399: 350-354.
Xing, Xu, Wang Xiao-Lin, and Wu Xiao-Chun. 1999. A dromaeosaurid
dinosaur with a filamentous integument from the Yixian Formation of China. Nature
Zhao, Xijin and Xu Xing. 1998. The oldest coelurosaurian. Nature
Zhexi, Luo. 1999. A refugium for relicts. Nature 400:
Zimmer, Carl. 1998. A Sickle in the Clouds. Discover
Home | Feedback | Links | Books | Donate
| Back to Top
© 2023 TrueOrigin Archive. All Rights Reserved.
powered by Webhandlung