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Time to do some actual peer review (#3 of 3)
>Do dino fossils support evolution?
DINOSAUR fossils. Dino was a character on The Flintstones.
>Last summer the dinosaurs returned! From June through early September, The
>Dinosaur World Tour: The Greatest Show Unearthed appeared at Vancouver's
>PNE Forum, and captivated tens of thousands of children and adults alike.
>The Tour is a sprawling $20 million multi-media show which includes 30
>complete dinosaur skeletons and 11 new never-before seen dinosaur species,
>including the amazing 20 ton, 30 metre long Mamenchisurus from China. The
>Tour has also received rave reviews in Edmonton, Toronto and Osaka where
>it was witnessed by over one million enthusiastic viewers. Combined with
>hands-on displays, multi-media technology, and digital dinosaur sounds, the
>exhibit is hailed as one of the top ten exhibits of the '90s.
>The 14,000 square feet Carnosaurs exhibit is currently on display at
>Edmonton's Provincial Museum, where close to 175,000 visitors are expected
>over its 6 1/2 month run. Carnosaurs features 13 life-size robotic
>dinosaurs in a Jurassic Park setting, and includes everything from CD-ROM
>technology to an eight-metre tall Tyrannosaurus Rex.
>Many Albertans will recall July's discovery in Dinosaur Provincial Park of
>Struthiomimus, a dinosaur skeleton from the family of ornithomimids ("bird
>mimics"). Philip Currie, head of dinosaur research at the Tyrrell Museum,
>told the Calgary Herald : "These guys look like ostriches without the
>feathers...they're built to move fast." (Calgary Herald, July 19, p. A1).
OK so far.
>It is interesting that dinosaurs that had long slim legs, small lightweight
>bodies, and in general appearance look somewhat like birds, such as ostrich
>mimic Struthiomimus, were "lizard-hipped". Conversely, dinosaurs that look
>more like low-slung tanks than graceful birds (eg. Ankylosaurus) were
>"bird-hipped". Therefore, one question that should be put to dinosaur
>experts is: If dinosaurs evolved into birds, wouldn't we expect to see
>"bird-hipped" dinosaurs looking more bird-like rather than the reverse?
Here's where the problems begin. This is a highly misleading paragraph
for two reasons.
1) Someone not familiar with the morphology of Dinosaurs could easily
conclude that all "lizard hipped" dinosaurs were like Struthiomimus, and all
"bird hipped" dinosaurs were like Ankylosaurus. This is nowhere near the case.
2) The rhetorical and, in my opinion, leading question asked in this
paragraph is never answered. As a result, someone not familiar with the
anatomy of birds and dinosaurs could conclude that the "bird hips" of
Ornithischians and the "bird hips" of Aves are identical. This, too, is not
the case. There is a similarity in the positioning of the bones, but in
terms of the actual morphological characteristics of the bones the "bird
hips" of Aves have more in common with the "lizard hips" of Saurischians
than with the "bird hips" of Ornithischians. These facts are not addressed
anywhere else in the article and, as a result, the readers are pointed in a
direction they should not be going. The unfortunate and misleading (and,
ultimately, incorrect) naming of the two main subgroups of Dinosaurs should
not be used to try to debunk evolution. It's a matter of early scientists
incorrectly reading and naming the anatomy, not true evolutionary progression.
>The notion that dinosaurs and birds are related dates back to the 1861
>discovery of a pigeon-size fossil named Archaeopteryx, which had a
>bird-like skull, perching feet, and was a powered flyer, with wings of the
>basic pattern and proportions of the modern avian wing. It also had
>feathers identical to modern flying birds. Evolutionary scientists believe
>Archaeopteryx was a transitional creature---related to dinosaurs but well
>along the evolutionary pathway to modern birds. Other scientists say that
>the fact it had claws on its wings does not necessarily indicate reptilian
>ancestry; they cite three birds living today---the South American hoatzin,
>African touraco, and ostrich---as each having claws on its wings and yet
>are true birds. Although Archaeopteryx had teeth, considered to be another
>reptilian feature, some fossil birds had teeth and some did not. That this
>should be true is not surprising, since this is true of all other classes
>of vertebrates---fish, amphibians, reptiles and mammals.
Another misleading paragraph, through error of omission. The reptilian
features of Archaeopteryx go far beyond the fact that Archaeopteryx's claws
had not yet fused like those of modern birds. Archaeopteryx had a reptilian
tail. The skull was constructed like that of a theropod dinosaur. The hip
is constructed like that of a theropod dinosaur, specifically the
Dromaeosaurids. The teeth of Archaeopteryx had a ridge of bone between each
tooth, a condition found only in the Dinosaur lineage. And there are more
similarities ... indeed, there are so many similarities that one and
possibly two Archaeopteryx skeletons were misidentified as Compsognathus for
You also leave out characteristics of modern birds that link them to a
reptilian ancestry, such as the fact that birds have scales.
>In 1993 some paleontologists hailed a small creature named Mononychus as "a
>new link between dinosaurs and birds" because it shares some features with
>modern birds, such as a keeled sternum and some fused wristbones. (On the
>April 26/93 Time cover, the creature is drawn having feathers instead of
>scales, which is entirely speculative.)
So what is Mononychus, dinosaur or bird? How does Mononychus help answer
the question "Do dinosaur fossils support evolution?"
>And according to Barbara Stahl, in
>Vertebrate History: Problems in Evolution, (pp. 349-350) "how [feathers]
>arose initially, presumably from reptiles scales, defies analysis...It
>seems, from the complex construction of feathers, that their evolution from
>reptilian scales would have required an immense period of time and involved
>a series of intermediate structures. So far, the fossil record does not
>bear out that supposition."
And it is unlikely to. Skin impressions only fossilize under certain
rare conditions. We have no idea whether the Dinosaurian lineages
considered to be closely related to birds had feathers or not. Indeed, to
my knowledge there are no skin impressions of such Mammals as the Sabre
Toothed Cat or Dire Wolf. Based solely on fossil and skeletal evidence, how
do we know those two animals didn't have feathers? Taking this analysis
further, there are no skin impressions from the majority of fossilized
birds. Based solely on fossil and skeletal evidence, how do we know they
had feathers? I don't much care for trying to use feathers as a method to
debunk evolution when we can't even tell that fossil birds had feathers and
fossil mammals had hair.
Indeed, this goes right back to the idea of the fossil record not showing
intermediate structures in the evolution of feathers. The fossil record
doesn't even show, in most cases, advanced feathers. Further, it appears
that the period of time some think necessary to derive feathers is being
used against the theory of feather evolution. Let's say, for the sake of
argument, that birds did indeed evolve from Dinosaurs. Let's also say, for
the sake of argument, that the lineage that would eventually evolve into
birds started down that road at the very dawn of Dinosaur evolution. The
first Dinosaur appears in the late Triassic, 235 million years ago. The
first bird shows up in the Mid Jurassic, 166 million years ago. That gives
feathers 70 million years to evolve. Whether this is sufficient time for
feathers to evolve in the hypothesis of Barbara Stahl, I do not know.
"Immense" could mean just about anything.
>Paleontologists say that in order for a complete dinosaur to fossilize, it
>had to be rapidly buried in large quantities of sediment. The contorted
>appearance of many skeletons suggest burial of dinosaurs which died in
>agony, or of freshly dead dinosaurs whose limbs were distorted by the
>sediment load and rapid water current which carried the load. [The Tyrrell
>paleontologists report that the ornithomimid was found in the "classic
>death pose" with neck and tail dramatically curved.]
I would prefer that the sentence "...suggest burial of dinosaurs which
died in agony" be removed or rewritten. The "contorted appearance" of many
fossilized skeletons does not "suggest" that they died in agony. Wording it
this way plants the idea in the reader's mind that they did, indeed, die
this way. Nobody with any credibility believes this idea any more, and it
should be sunk like the bad science that it is. An insurmountable body of
evidence, both from fossils and from modern observation and experimentation,
shows that dismemberment by scavengers and/or water flow, and the factors of
geology, are to blame for the appearance of many skeletons. Further, it
should be added that post-mortem drying of ligaments are also a source of
the contorted appearance, something that is also backed up by a huge body of
evidence and even occurs in humans if left out to dry.
>But could local slides and floods account for the formation of all dinosaur
>fossils, as well as billions of other fossil creatures found over the
>entire planet, from the highest mountains to the lowest canyons?
This question does not appear to say anything about whether dinosaurs
fossils prove evolution. Worse, the specific question ... do slides and
floods account for the formation of all dinosaur fossils ... is never answered.
>Gish, in his book Evolution: The Challenge of the Fossil Record asks: "If
>dinosaurs evolved from other reptiles over millions of years, why do we not
>find even one example of a transitional form in the fossil record?" Gish
>points out that paleontologists have never found, for example, any evidence
>that Stegosaurus evolved from an earlier form, showing the gradual
>development of tail spikes, plates, etc. He says this is true of every
>dinosaur ever found, whether Brachiosaurus, Tyrannosaurus, [Tyrannosaurus
>skeleton "Scotty" is currently being excavated near Eastend, Saskatchewan]
>or any other dinosaur; each type appears in the fossil record fully formed,
>right from the start.
Dr. Gish's book was published in 1985, meaning it was written more than
ten years ago. Fossil discoveries have come so thick and fast recently that
books written just 5 years ago are hopelessly out of date. These days, we
do have a fossil record showing progression in many of our favorite
Dinosaurs. I recently saw a picture of the fossil of an early Stegosaur
that not only had budding spikes and plates, it was a faculative biped, in
the process of evolving quadrupedality from the primitive dinosaurian
condition of obligate bipedality. This biped to quadruped progression is
shown in the fossil record of many of the other quadrupedal dinosaurs,
including the Sauropods.
>Added support for Gish's argument is the recent discovery in western
>Argentina of what may be the largest meat-eating dinosaur known, a
>12.5-metre-tall dinosaur christened Giganotosaurus carolinii (Nature, Sept.
>21). Despite the overall similarity in appearance to T. rex, according to
>Argentinian paleontologist Rodolfo Coria, Giganotosaurus was not related to
>it, and the two beasts "arose independently".
What does the mere existence of Giganotosaurus or its similarity to T.
rex have to do with the supposed lack of transitional fossils? This is a
poor argument to say the least ... a blanket statement without explanation.
The only thing I can figure is that you are trying to use Gish's argument to
say that different animals cannot evolve similar forms if they are
unrelated. As presented, Gish's argument says no such thing. Indeed, extant
animals, such as the Tasmanian Wolf and the North American Wolf, show that
it quite possible and indeed probable that unrelated animals in similar
environments will evolve similar form.
>To explain why transitional fossils are NOT found, Niles Eldredge and
>Stephen Jay Gould (1972) came up with the "punctuated equilibria" model of
>evolution, which is unique. It must be the only theory put forth in the
>history of science which claims to be scientific, but then explains why
>evidence for it cannot be found.
I don't pretend to know all the specifics of "punctuated equilibrium."
As I understand it, it states that animals remain in a static state until
environment pressure causes evolution. The more extreme the environmental
pressure, the more extreme and the quicker the changes.
Studies of extant animals show that this is indeed the case. One example
is the Galapogos Finches. In the early 70s there were two morphs of one
species of finch on one island: a large beaked morph and a small beaked
morph. A severe drought in the mid 70s brought about conditions that
favored the large beaked morph. Within a generation or two, nearly all the
finches were of the large beaked type and the small beaked were on their way
out. Then there was another drought, one that created conditions that
favored the small beaked morph. Within a generation or two nearly all the
finches were of the small beaked type and the large beaked were on their way
out. By the early 80s conditions had returned to normal, and now the
population of finches is shifting toward a hybrid morph, with a beak
intermediate between large and small. So within a DECADE you have two
shifts in the morphs of a single species of finch extant on the island, and
the appearance of a third.
Based on these changes, if the environment caused the right kind of
pressure, an entirely new species of finches might appear in a relatively
short period of time. Wallabies that were imported to Hawaii after the
settlement of Australia can no longer interbreed with Australian Wallabies.
North American fire ants can no longer interbreed with the populations of
fire ants in South American from which they came. Interbreeding is
fundamental to determining whether different populations of similar animals
are of the same species. We have two examples of extant animals, in the
course of a hundred years or so, evolving new species or sub-species.
These studies suggest that the early hypotheses that species change
slowly over millions of years were *wrong*. What these extant species show
is that there are little or no change in the species until environmental
pressure requires it, and then evolution happens QUICKLY. Genetic changes
can take as little as a century or two, and physical adaptation can take
place in the matter of a DECADE or two.
Would fossilization catch changes that happen in the course of several
hundred years? The geologic record has huge gaps in it measured in the
THOUSANDS of years. The fossil record is therefore going to have similar
gaps. With gaps thousands of years long in the fossil record and evolution
occurring over hundreds of years, it is not surprising at all that organisms
appear "fully formed" in the fossil record.
If evolution happens only during periods of extreme environmental stress,
one would expect to see these "fully formed" new species appearing in
sediments that showed vast environmental changes over the environment
preserved in the next older layer. Does the fossil record show this?
Indeed it does. For example, periods of large speciation occured at the
same time the Mesozoic inland sea of North America either grew or shrank.
Occurences of these types ... sea growth shrinking or obliterating habitats
and sea shrinkage opening vast new habitats ... cause extreme environmental
>The fossil record stands as a silent witness to the abrupt appearance of
>dinosaurs on the earth. If dinosaurs evolved from other reptiles and then
>evolved into birds (remember the ending of Jurassic Park?) there certainly
>isn't any evidence for it in the fossil record.
"isn't any evidence" translates into NO evidence, which is a 100% false
statement. Scientists do not just "make things up." There is a large body
of evidence, both from the fossil record and from studies of extant species,
that supports many competing theories of evolution.
Indeed, if one compares the first Dinosaurs of the mid-Triassic to those
at the end of the Cretaceous, one will find that the later dinosaurs are
much more advanced than the early ones. That's evolution, whether caused by
environmental pressure or the hand of god creating them.
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