This is a picture of a cast of the bones of Arkansaurus fridayi, the only dinosaur bones ever found in Arkansas. They were taken from lower cretaceous deposits in a borrow pit excavated for the construction of a roadway in 1972 by J.B. Friday, who held onto them for a few months before somebody recognized them for what they were. Dr. Quinn of the Geology Department at the University of Arkansas examined the bones and declared them to be those of an Ornithomimus relative and the find was informally named to acknowledge the Lockesburg, Arkansas citizen on whose land the bones were found. Three casts were made. One went to the U. of A. at Fayetteville. One went to the Arkansas Geological Commission and one went to the Science and History Museum at MacArthur Park.
That's a summary of the official version which you can read at length on the Rockhounding Arkansas page.
Now I'm no Mike Wallace, and the stories I post here on the website aren't of any great importance; but I do go to some trouble to check the facts that I am presented before posting them for my internet pals to see. When I checked the facts on Arkansaurus, a lot of things didn't check out.
I went to the Arkansas Museum of Science and History at MacArthur Park to take a picture of the cast for this story and was told by the lady at the front desk that it was forbidden to take pictures in the museum. Fine. I wrote to the Museum Annex and requested information on the find. Lynn Cole, Curator of Life Science replied that Arkansaurus has never been officially described in the scientific literature and that the original fossils are at the University Museum in Fayetteville, Room 202. I got the same story from the Arkansas Geological Commission.
Also from Lynn Cole I got a photocopy of pages 276-277 of the 1973 abstracts from the South Central Section of the Geological Society of America in which the fossils were described by Dr. James Quinn. In that abstract, Quinn writes that the find was comprised of three metatarsals (those long bones), three phalanges and two claws. So six toe bones and one claw of the cast were extrapolated or copied or generalized from other fossils and hand-molded by Dr. Quinn to complete the foot. You can tell which bones were molded in the top picture, here repeated. The texture of the clay was such that it reacted differently to the paint or stain which was later applied. The molded joints are noticeably darker. Quinn's abstract also that mentions two vertebrae, one from the tail and one from the back, were also found.
I drove up to Fayetteville where I took a picture of their cast of the fossil and afterward I met with Mary Sutter, the curator of the University Museum. It turns out that Room 202 is a cloakroom/employee breakroom just off the museum lobby and is not used for storing exhibits. Mary told me that her museum does not have the fossils. She thinks they were bought by Texas Tech, "but don't hold me to that."
So I wrote Dr. Chatterjee, Curator of the Museum of Paleontology at Texas Tech. Dr. Chatterjee replied, "I have never heard of dinosaur fossils from Lockesburg, Arkansas. We have checked our record, but there is no entry from Arkansas. There may be some mistake somewhere."
In short, the bones are gone. The only dinosaur ever found here, misplaced. Our scientists and historians have just lost them. Fine. Let's take that at face value. Attribute it to the Jethro effect. Maybe the yankees are right. Maybe we are just that dummmmmb.
So lets take a good close look at the casts, since that's all we have.
To begin with, it's not really appropriate for the State University or the State Museum or the State Geological Commission to refer to this find by genus and species until it has been properly described in the scientific literature and we know that it isn't just another example of a previously described dinosaur. Whenever I consulted paleontologists from out of state and mentioned the word "Arkansaurus," I could practically hear their eyes rolling.
What else is wrong with this picture? Here have been found most of a foot and two vertebrae of a dinosaur. Lots of dinosaur species have been officially described based on thinner scraps. The entire population of known dinosaurs consists of just a few hundred officially described species. Somebody finds what amounts to a scientific reputation in a shoebox. Nothing remains but to write it up and send it in and you've got a big scoop of scientific legitimacy and a little slice of immortality. Yet nobody does it. Why?
I called J. B. Friday himself to ask if he knew the whereabouts of the bones. He said that he assumed the University had them and that he had made no effort to keep up with their disposition over the years. I spoke with Mrs. Friday and asked her whether the bones they turned over to Dr. Quinn were loose or whether they were imbedded in rock. She said they were loose.
So if the bones were loose, why are there chisel marks in the cast? These marks suggest that surrounding rock has been chipped away and the bones are arranged as they were found and are still partially imbedded in the matrix. The gouges are not original to the specimen. They were deliberately put into the cast. Whether they were intended as deception or decoration is up for grabs. I can imagine somebody unaccustomed to forming legitimate casts making a well-intentioned mistake. I can also imagine somebody phonying up a dinosaur fossil just to prove he can come up with a better monster than did his neighbors in Fouke the year before.
Yep, that's right. The Fouke Monster, the White River Monster and Arkansaurus all emerged in 1971-72. Probably just a coincidence.
As to the identification of the beast, I am not the first to suggest that this is likely not an Ornithomimus, yet Ornithomimus is what keeps getting printed. So lets trot out the evidence and put that notion to bed once and for all. At left is Struthiomimus velox, a typical Ornithomimid. Next to it is Arkansaurus. The scale in the S. velox picture is 5cm, so you can see that the S. velox specimen is similar in size to the Arkansaurus foot.
Note the metatarsals (the three long bones) in each specimen. In all Ornithomimids that middle metatarsal is tightly constricted at the top and is in back of the assembly at the heel. As you move down the bone, the middle metatarsal runs between the other two bones and emerges at the front by the time it reaches the toes. The metatarsals of Arkansaurus don't do that. The sides of the two outer metatarsals are flattened on the inside so that they will fit close to the middle metatarsal side-by-side down the length of the metatarsus. This, I understand is an arrangement typical of more primitive dinosaurs. In any case it doesn't have the metatarsal arrangement typical of Ornithomimids.
Also note the claws on S. velox. They have the typical burr found on all Ornithomimid examples. The bottom of the claw is flat or slightly cupped and there is a burr that flares out near the proximal end so that the bottom of the claw has an arrowhead or spade shape. Arkansaurus has no such ungual burr.
No ungual burr. The wrong metatarsal arrangement. Not an Ornithomimus.
So people have suggested that if this is not an Ornithomimus, it is likely to be among the Ornithopoda, many examples of which have been found nearby in Texas.
So here are a few examples of Ornithopoda taken from The Dinosauria (Weishampel et. al., University of California Press). From left to right they are Camptosaurus dispar (forelimb), Camptosaurus dispar (hindlimb), Ouranosaurus nigeriensis (forelimb) and Ouranosaurus nigeriensis (hindlimb). Iguanadon is the best known of this group, but sorry, I don't have any pictures of Iguanadon feet. All the Ornithopoda feet that I have seen examples of are stoutly engineered, very unlike Arkansaurus, and many have more than three functional toes.
This variance in the number of digits on the hindlimb probably accounts for the fact that hindlimbs are not usually used to identify Ornithopoda, so if Arkansaurus belongs in this group you're probably not going to prove it using this foot. It seems likely to me that people sometimes suggest that Arkansaurus is an Ornithopod only because Ornithopods have been found nearby in rocks of the same age as Mr. Friday's gravel pit and the word Ornithopoda is spelled enough like Ornithomimus so that we can pretend that the original identification wasn't all that far off.
Other experts (that is to say, experts like myself with no pertinent credentials) have suggested Oviraptor, Troodont, Elmisauridiae, Velociraptor, and the like. The answer is, "None of the above," and here's why: All of the dinosaurs mentioned above have claws that are curved and laterally compressed. The III and IV claws of Arkansaurus are either flat or slightly cupped on the bottom. Arkansaurus has claws shaped like little flatirons, not like sharpened sickles.
At right is a drawing of the foot of a typical oviraptor, Ingenia yanshini. I picked this example because it shows the claws in both top and side views. At left is a closeup of the claws of Arkansaurus. Very different claw shapes.
I went to visit with Dr. McFarland of the Arkansas Geological Commission and asked him some of these questions and photographed the Arkansaurus cast they have in a case in their lobby. Here is some of what he told me:
Yes, he said, he did indeed see the actual real shure-as-shootin' bones, not the cast, but the bones themselves, way back in 1973 when they came through the state offices. He looked to be about 50, so he must have been fresh out of grad school in '73.
He told me that Dr. Quinn had prepared the casts and gave the find its informal name. He also told me that Dr. Quinn had been a preparator at the Field Museum of Natural History in Chicago for some twenty years before he earned his degree in Geology and took his job with the geology department at the U. of A. So Dr. Quinn really knew his way around dinosaur bones and had oodles of experience preparing molds and casts.
Dr. McFarland further told me that there are only three official state-approved vertebrate paleontologists in Arkansas and that he was one of them. He added, though, that since Arkansas is not a big dinosaur state, his qualifications as a dinosaur expert are secondary to his qualifications as an invertebrate paleontologist. In short, any real, legitimate, dedicated dinosaur experts aren't going to find much work in their field in Arkansas, so three "dinosaur experts" with some marginal qualifications are simply designated by the state so that someone can be put in charge if a dinosaur fossil is discovered on public land.
He explained the chisel marks on the Museum of Discovery cast as window dressing--a matter of presentation. He also pointed out that there might be variances in the widths of some of the bones from cast to cast due to stretching of the mold, since the mold was not always supported in a sand pit while the casts were poured. He also cautioned that some of the details in the microstructure of the bone might be lost because chips and gouges and missing chunks were puttied over when the molds were prepared, and that would account for apparent differences in the three casts.
Repeating: Parts of the specimen were puttied over and missing parts filled in before the molds were made and the mold was not supported by sand when the casts were poured.
And Dr. Quinn was a preparator at the Field Museum in Chicago for twenty years.
New subject. If it isn't Ornithomimus, and it isn't any of all those other possibilities, what could it be? I've found a likely candidate, a ceratosaur named Liliensternus liliensterni (formerly known as Halticosaurus liliensternus). At right is a drawing of its footbones from The Dinosauria. At left are the two Arkansaurus casts you have already seen, repeated here for your convenience. While all the ceratosaurs had died off before the time of Arkansaurus, I have seen no other dinosaur foot that had such a prominent bump at the proximal end of the middle metatarsal--only on Arkansaurus and L. liliensterni. The claws are of the same type, slightly cupped and have no ungual burr. The metatarsals have the same side-by-side arrangement.
In addition to that, both #1 phalanges adjoining the II and III metatarsals of L. liliensterni are equal in length (8.3 cm along the axis) with a somewhat shorter #1 phalange on the IV metatarsal (4.7cm). The analogous phalanges in A. fridayi have similar proportions. It is not possible to measure exactly because the ends of some bones are concave and the cast obscures the sockets, but my measurements show that the three #1 phalanges of A. fridayi have very nearly, if not exactly the same measurements as the three #1 phalanges of L. liliensterni.
Once more, just to emphasize the coincidence: The three top knucklebones of Arkansaurus fridayi have the same measurements as the three top knucklebones of Liliensternus liliensterni.
I thought I was really onto something until I measured the metatarsals. They are as much as 14cm longer than the same metatarsals in Liliensternus. Then I remembered what Dr. McFarland at the Geological Commission showed me, that the hand-molded putty replacement parts in the U. of A. Museum cast were darker than the impressions of the actual fossilized material in the same cast. Look at that cast one more time and note the dark segments in the middle of all three metatarsals. Those bones might have been extended.
Fellers, I'm beginning to think Arkansaurus is a fake.
Is it possible that this cast is a rearrangement (turning a left foot into a right foot) of the fossil bones of Liliensternus, discovered in Germany and described by Friedrich von Huene of the University of Tubingen in 1934? I think it's possible.
There is an alternate explanation. A triassic dinosaur from Germany found its way into cretaceous rocks in Arkansas.
Reviewing the evidence: The three phalanges in the cast seem to match the three phalanges reported by Huene. The metatarsals of Arkansaurus, which are longer than the metatarsals of Liliensternus, show evidence of having been artificially extended.
This isn't absolute proof that Arkansaurus is a fake, but I think I have raised loads of doubt as to its authenticity. If the find proves to be genuine, nobody will be more pleased than I. If Arkansaurus is authentic it can be easily proven so by producing the original fossils and having them examined by a fancy-pants real-deal vertebrate paleontologist with real vertebrate paleontology credentials from a real accredited school and not by a petroleum geologist just standing in. It's going to have to be Bakker or Horner or one of those guys.
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Braden, Angela K., The Arkansas Dinosaur, "Arkansaurus fridayi." Arkansas Geological Commission, 1998.
Howard, Michael. Rockhounding Arkansas. http://www.rockhoundingar.com/dino.html
Huene, Friedrich von. Dezember 1934. Ein neuer Coelurosaurier in der thuringschen Trias. Paleontologische Zeitschrift, Band 16, Nr. 3/4.
Weishampel, David B., Peter Dodson and Halszka Osmolska. The Dinosauria. University of California Press, 1990.