PvM posted Entry 3049 on April 10, 2007 07:35 PM.
Trackback URL: http://www.pandasthumb.org/cgi-bin/mt/mt-tb.fcgi/3039

On UcD announces the Temple lectures by Marcus Ross speaking about the Cambrian explosion and Dr Peter Dodson who is speaking for evolution (I wonder for what or whom Ross was speaking?).

Paul Nelson wrote:

Also speaking (for evolution) will be dinosaur paleontologist Dr. Peter Dodson of the University of Pennsylvania. Dodson has been a skeptic of the dino-to-bird hypothesis, and has interacted with Ross at professional meetings. Their exchange today should be fascinating. The lectures begin at 6 and run to 8:30 PM. This event is free and open to the public.

While in early 2000 Peter Dodson may have been a skeptic of the dino to bird hypothesis, I have found two problems with Nelson’s claims, unless all he meant to say that Peter Dodson used to doubt the dino to bird hypothesis a decade or so ago but has changed his mind based on the evidence.

The paper to which Paul Nelson links, talks about Dodson’s objections to relying on cladistics only to reach the conclusion about the dino to bird link.

While skepticism is common in science, one should not conflate true scientific skepticism with ‘teach the controversy’ which is nothing more than a weakened down version of the ID thesis, since ID itself lacks scientific relevance. To correct for this minor problem, ID proponents have embarked on ‘teach the controversy’ which is little more than pointing out unsolved problems with evolutionary theory (in particular Darwinian theory).

Dodson is also one of the authors of “The Dinosauria” which was published in 2004.

The authors explain that

For example while in 1990 we merely paid lip service to the proposition that birds are dinosaurs, in this edition we embrace fully as a logical sequela of phylogenetic systematics that birds are part of therapoda.

Seems that these former ‘skeptics’ have been convinced by the collected evidence of the likelihood that birds are dinosaurs. Rather than arguing that such skepticism indicates the possibility of something, let’s call it for simplicity reasons ‘intelligent design’, these researchers have been convinced by the evidence in support of this thesis.
Not only will Intelligent Design never have the luxury to be scientifically involved in such hypotheses, but Intelligent Design has also shown itself to be utterly unable to accept (new) evidence which contradicts their philosophically and religiously motivated view points.

The result is that Science by skeptics leads to better science while science in the name of ‘teaching the controversy’ leaves gaps.

It seems that our friend Padian contributed the chapter Basal Avialae to this seminal work on dinosaurs.

Reviewers of Dinosaurus point out that

The most novel systematic chapters in this volume include the basal birds section, which succeeds at the difficult task of summarizing the exponential burst of new bird discoveries. Recall that little more than Archaeopteryx, a few enantiornithines, and Ornithurae were known at the last writing; now a six-page taxon list! The basal Saurischia chapter by Langer is an in depth analysis of various likely basal dinosaurs, most of which were very poorly known at the time of the last volume. The basal Tetanurae chapter by Holtz et al. is a comprehensive perspective that cleans up a lot of mess in this region of the theropod tree. The 75-page Sauropoda section is a huge leap forward from 14 years ago, thanks to a string of new discoveries around the world (and good phylogenetic analyses thereof; almost absent in the last edition) by the authors (Upchurch et al.) as well as Curry, Wilson, Sereno, and many others. Many of the Ornithischia chapters didn’t seem as novel to me. The Ankylosauria chapter (Vickaryous et al.) was more thorough (also the only section with computed tomography scan images). It is also clear that some needed stability of relationships within basal Iguanodontia (Norman) and Hadrosauridae (Horner et al.) has been attained.

In other words, it was ignorance which caused skepticism about phylogenetic relationships of birds and therapods, an issue which was resolved when more data were collected.
Which also shows how relying on research from even half a decade ago, can lead to unfortunate impressions. The same applies to the Cambrian explosion which was considered to be quite a problem for Darwinian theory by Valentine in the middle/late 90’s. However, based on the vast amounts of new data, the author has recently concluded that there are no problems for the Darwinian theory to explain the Cambrian explosion. Sadly enough ID proponents and other creationists are still quoting Valentine’s earlier observations while failing to provide a more updated version of his claims and arguments.

And finally, what is a YEC’er doing talking about the Cambrian explosion? After all, how can someone who has blindly accepted that the event took place 5000-10,000 years ago, evaluate the evidence about the Cambrian explosion? Of course Darwinian theory will fail when given such little time (dogs for instance share a common ancestor just 10,000 years ago).

Since Marcus Ross and Stephen Meyer are the authors of the Cambrian Explosion study kit, does this mean that Ross agrees with the following blurb?

The term Cambrian explosion describes the geologically sudden appearance of animals in the fossil record during the Cambrian period of geologic time. During this event, at least nineteen, and perhaps as many as thirty-five (of forty total) phyla made their first appearance on earth. Phyla constitute the highest biological categories in the animal kingdom, with each phylum exhibiting a unique architecture, blueprint, or structural body plan. The word explosion is used to communicate that fact that these life forms appear in an exceedingly narrow window of geologic time (no more than 5 million years). If the standard earth’s history is represented as a 100 yard football field, the Cambrian explosion would represent a four inch section of that field.

Or is the chicken language of ‘no more than 5 million years sufficient to include a much smaller period of time?

Or is it, as Krauze on TelicThoughts observes just a case of

Marcus Ross simply behaved like a good methodological naturalists, conducting his research as if the reptiles he studied were 65 million years old.

Wow

PS: Nelson and Ross still owe us a more in depth description of ontogenetic depth, which has missed its deadline by 3 years, which in most cases would be a record but for Paul Nelson it seems that it is just par for the course as his much touted thesis work is yet to be released.

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Comment #169143

Posted by djlactin on April 10, 2007 11:41 PM (e)

Can’t. Stop. Myself.

When explaining evolution and the fossil record, “We” must always be careful about our choice of words. Ill-considered phrases lead to confusion. Here’s one reason for the misconceptions held by creationist (and naive evolution-accepters):
During the Cambrian,

…perhaps as many as thirty-five (of forty total) phyla made their first appearance on earth.

(boldface added)

gaack! That line implies (a) instantaneous appearance and (perhaps) (b) that the phyla first appeared somewhere other than earth.

A much clearer and more accurate phrase is:

… perhaps as many as thirty-five (of forty total) phyla made their first appearance in the fossil record.

I know that most knowledgeable biologists would not be confused, but the quote-miners put on their helmets over things like this.

A little care saves a lot of grief.

Comment #169145

Posted by PvM on April 11, 2007 12:06 AM (e)

The blurb is by ID proponents in the ARN study kit for the Cambrian. Weasel words?

Comment #169195

Posted by wolfwalker on April 11, 2007 6:21 AM (e)

The paper to which Paul Nelson links, talks about Dodson’s objections to relying on cladistics only to reach the conclusion about the dino to bird link.

That’s putting it mildly. Gaaah. Even I, an amateur whose knowledge is now several years out of date, know enough about taxonomy to follow Dodson’s argument in the linked article. He absolutely and unequivocally accepts the dinosaur-to-bird theory of avian origins. He says so point-blank in the linked article:

Peter Dodson wrote:

It is probably fair to state that the bird-theropod link is as firmly established as any phylogenetic link could be (Padian and Chiappe, 1998a, bGo), and the position that was heretical for much of the 20th century undeniably has become the current orthodoxy. My own position is that there is every reason to believe that the ancestor of birds was a small coelurosaurian dinosaur.

Dodson’s objection to the dino-bird sequence as currently put forth is entirely a methodological one: he dislikes the cladists’ habit of developing the connection using fossils that are temporally dislocated from the actual sequence. As he says, the Liaoning fossils like Sinosauropteryx and Caudipteryx are all Early Cretaceous animals, while the actual evolutionary sequence that led to Archaeopteryx and later birds must have taken place in the Mid to Late Jurassic, several million years earlier than Liaoning. Which makes perfect sense to me: he wants to be sure, and the only way to be sure is to have a fossil sequence that’s correct in both morphology and chronology. If you have either one but not both, you could still be wrong. It isn’t likely, but it’s still possible.

The linked paper is only about Dodson’s objections to the picture of cladistics as final arbiter of phylogeny. He doesn’t doubt the underlying hypothesis – that is, the dinosaurian origin of Aves, often abbreviated as BADD, Birds Are Dinosaur Descendants – at all. Nelson is simply lying when he suggests that Dodson doubts BADD.

Comment #169204

Posted by TomS on April 11, 2007 7:34 AM (e)

I am somewhat puzzled by djactin’s remarks.

But perhaps still a better formulation would be something like this?

“… perhaps as many as thirty-five (of forty total) phyla have their time of divergence from other lineages.”

Many of the anti-evolutionists seem confused by the quite arbitrary title of “phylum”, and any talk which plays to that confusion - if someone is really worried about being quote mined - would be best avoided. An expression like “a phylum appeared” can be easily, IMHO, interpreted as saying that a phylum is an objective, concrete, entity - something that can “appear” - rather than being a term of convenience for classifiers. If someone were present at - let’s say, when the chordates “first appeared” - it would be a rather unremarkable event, just another speciation, which was only a “major event” because of the great variety of interesting descendants that that particular “first chordate species” would give rise to, and that species is designated as a “new phylum” only in view of what was to come.

(By the way, I speak as a non-scientist, so this is just an uninformed opinion.)

Comment #169213

Posted by Peter Henderson on April 11, 2007 8:31 AM (e)

And finally, what is a YEC’er doing talking about the Cambrian explosion? After all, how can someone who has blindly accepted that the event took place 5000-10,000 years ago, evaluate the evidence about the Cambrian explosion? Of course Darwinian theory will fail when given such little time (dogs for instance share a common ancestor just 10,000 years ago).

I really can’t resist posting this:

http://www.answersingenesis.org/radio/pdf/whatha…

and this:

http://www.answersingenesis.org/home/Area/Answer…

Comment #169219

Posted by Andrew on April 11, 2007 8:45 AM (e)

PvM wrote:

(but also quoting)
The Ankylosauria chapter (Vickaryous et al.) was more thorough (also the only section with computed tomography scan images).

So apparently good observers discover the evidence…

Sorry - In bit of a silly mood tonight

Comment #169233

Posted by Chuck C on April 11, 2007 9:34 AM (e)

The word explosion is used to communicate that fact that these life forms appear in an exceedingly narrow window of geologic time (no more than 5 million years).

Someone correct me if I’m wrong (I’m not a scientist of any stripe), but I thought that the Cambrian was something like 80-100 million years long, and that phyla appeared in a more or less dispersed pattern during some 50 million years within this time frame. Did the first fossil record of these phyla appear all at one point within the Cambrian?

Comment #169250

Posted by Pete Dunkelberg on April 11, 2007 10:50 AM (e)

For the number of phyla first known in the fossil recored from a period of about 10 million years within the early Cambrian, try ten.

More, you say? OK what are they and what is the specific time of each? For reference there’s a chart in Valentine’s book The Origins of Phyla.

Comment #169254

Posted by PvM on April 11, 2007 11:03 AM (e)

On the Origin of Phyla by Valentine is an excellent overview of this period. However it seems that ID proponents are more interested in Valentine’s position of the middle 90’s than his position based on the new data collected since then.

Comment #169382

Posted by Henry J on April 11, 2007 10:47 PM (e)

But perhaps still a better formulation would be something like this?

“… perhaps as many as thirty-five (of forty total) phyla have their time of divergence from other lineages.”

But, the fossil record only tells us roughly when a group got populous enough to start leaving behind fossils that would last until the present, not when that group first separated from other groups.

Henry