ARKANSAURUS FRIDAYI DISCUSSION PAGE II

This page is reserved for discussion, rebuttal and comment on my article concerning Arkansaurus fridayi, in which I raised doubts about the authenticity of the dinosaur cast exhibits which have been on display in various museums around the state for over 25 years. Check the first batch of feedback at this URL.

On 19 April 2003 I attended an undergraduate presentation on Arkansaurus fridayi given by ReBecca Hunt at Henderson State University in Arkadelphia. I spoke with her after her presentation and I got her permission to post some of her pictures (photographed by Greg Vogel) of the actual fossils.

Dinosaur Claw Fragments from Lockesburg
Arkansaurus photos on this page are by Greg Vogel and are used by permission from ReBecca Hunt. These three claw fragments were originally catalogued under a single number.

Here's something really important. These three specimens are plainly from three different claws, so we can see that they are three similar, general-purpose claws. Ms. Hunt described them to me as "walkin' around claws" similar in shape and function to the claws on a dog's foot. This is one more way that the Lockesburg find is unlike Ornithomimus, which has a swiss-army-foot with claws for every occasion.

Ms. Hunt answered my "missing bone" objection. She told me that the three claws were originally catalogued under a single number as if they were three fragments of one claw, which clearly they are not. So anybody comparing the transcript of Dr. Quinn's original presentation with the catalog would think a fossil or two had disappeared. So now that's cleared up.

(None of this would have come up if they had just shown me the fossils (or pictures) when I first came around.)

The center picture (used by permission from ReBecca Hunt) shows a new cast of Arkansaurus, articulated as in life, depicted in two colors of medium, plain as day showing what parts of the cast are from fossils and what parts are interpolated bones. I also saw photos of the original metatarsals in Ms. Hunt's presentation, and again plain as day, the metatarsals had not been arbitrarily extended, as I had suggested in the original article. So that's cleared up.

(None of this would have come up if they had just shown me the fossils (or pictures) when I first came around.)

So do I now believe it's fake? Not necessarily. So do I now believe it's genuine? Not necessarily. I don't have to believe or disbelieve. This isn't post time and nobody has to place any bets. There's nothing to gain by being right and nothing to lose by being wrong, and being right or wrong has nothing to do with how many people believe the way you do. Now, putting metaphysics aside, let's take another look at these here bones.

Above, the cast of A. fridayi is flanked by the two specimens which I found most closely resemble it. I base this resemblance on the parallel arrangement of the metatarsals and the three similar walkin' around dog claws. While A. fridayi (center) was found in New World cretaceous deposits. Elaphrosaurus (right) and Liliensternus (left) were both found in Old World jurassic deposits.

Ms. Hunt's presentation included comparative specimens as well. One of them was Elaphrosaurus, as above. The other two were Harpymimus and Nedcolbertisaurus. Here are Harpymimus (left), Arkansaurus (center) and Nedcolbertisaurus (right).

HarpymimusArkansaurusNedcolbertisaurus

So Ms. Hunt and I agree that Elaphrosaurus is good comparative material, but I have to object to her other two choices. Look at the claws on Harpymimus (This picture is from the Dinosauria, referenced in the original article). They're specialized. They've got flanges and cleats. The metatarsals look parallel viewed from this angle, but if viewed from the top, the proximal end is a little rotated. My objections to Nedcolbertisaurus come down to size and number of digits. Nedcolbertisaurus is the size of a chicken, while Arkansaurus is the size of a pony. Nedcolbertisaurus has four toes that we know of. Arkansaurus has three toes that we know of. Ms. Hunt insists that Arkansaurus might have had a fourth toe that was not found. I say the more imagination you have to use to compare two specimens, the weaker the comparison is. If you turn the lights down low enough, everything looks alike.

But by golly, that metatarsus in Nedcolbertisaurus has exactly the proportions of the metatarsus of Arkansaurus, doesn't it? Well, guess what! That's no accident. You can see in the right hand picture, the reconstruction on the left and the actual bones on the right. Typically, a paleontologist will use some imagination, some educated guessing and some comparative materials to fill in the blanks, and that's just what happened here. Dr. Kirkland used downscaled Arkansaurus bones to fill in the missing chunks of Nedcolbertisaurus. A picture of this Arkansaurus cast appears in his Nedcolbertisaurus publication listed in the footnotes. He even retained the Arkansaurus fractures in the Nedcolbertisaurus cast. He came to Little Rock to examine Arkansaurus back in 1990 or so while his Dinamation(tm) animated dino exhibit was in town. There was never any secret about him using Arkansaurus this way. So much has been borrowed that we have to be extra suspicious of similarities.

From a logic point of view that further weakens the comparison. While Nedcolbertisaurus has a similar metatarsal arrangement and similar claws and is from New World rocks, the size difference is huge AND it's got the wrong number of toes AND we have to consider whether it "looks like" Arkansaurus because parts of it were borrowed from Arkansaurus. Is this the best comparative material to be found in the Cretaceous New World? Harpymimus is from Mongolia. Elaphrosaurus and Liliensternus (obviously much closer matches that those other two) are both from Jurassic Africa.

Now if I found kangaroo bones in Arkansas, maybe that means there is a native population of kangaroos running around somewhere; but if we look at comparable animals that we know of, we see that bones like this are common in certain other parts of the world. Uncomfortable though it may be to contemplate, we have to consider the possibility that somehow those bones worked there way to here from there by some other means.

The fact remains that the two finds that most closely resemble Arkansaurus are both from Jurassic Africa. When you look at the New World Cretaceous, nothing is built like this any more. This design is out of place where it was found. Suppose you went down to the Toyota plant and saw a Model T Ford coming off the assembly line. You'd have to question it. It might turn out to be legit, but you'd have to question it.

If you have feedback on Arkansaurus, send email here.

RTJ--6/10/2003


Kirkland, Britt, Whittle, Madsen and Burge; A Small Coelurosaurian Theropod from the Yellow Cat Member of the Cedar Mountain Foormation (Lower Cretaceous, Barremian) of Eastern Utah; New Mexico Museum of Natural History and Science Bulletin #14, pages 239-248.


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