Flat Tops Field Trip Specimens
10 - 11 August 2002
Western Interior Paleontological Society
by Jerry Suchan (gesuchan@earthlink.net)
Last Updated 28 January 2005
Here are some field fossil specimen photographs taken during the 10 - 11 August 2002 Western Interior Paleontological Society field trip to the Flat Tops area of central western Colorado. Since Kelly John Carney has posted some very nice pictures of the location at
http://www.kcarney.org/flattops/Flat_Tops.html
then I will use this opportunity to post only photographs of some of the specimens found
or observed during the trip. I say found or observed since some specimens were inappropriately
large for collecting but made fine photographs.
The abundant specimens are Upper Devonian in age and are from the Dyer member of the Chaffee Formation. They are around 350 MY old. The deposition is marine limestone, indicating a warm climate and clear tropical water. Other information indicates Colorado was near the equator about the time this formation was laid down. (Paleo information provided by trip leader Linda Soar.)
There are number of questions involving identification, collector and size associated with what I have to offer here. Unfortunately I failed to include a scale with some specimens when I photographed them. If you have any information such as suggested identification, name of the person who collected the specimen, or the actual size of the illustrated, please e-mail the information to me at geuschan@earthlink.net
Corals were common to this
location. This specimen, found in the quarry by John Rising was the largest by
far.
One of the most interesting fossils, found by Trick Runions, is a shark spine, probably Ctenacanthus.
I conferred with both WIPS members Linda K Soar and Wayne Itano about the identification of this specimen. Here is some of the information they provided.
*** Linda K Soar:
Bernie Spilka also found a spine in the Dyer several years ago at the Deep Lake locality, which he donated to the American Museum.
Bernie Spilka specimen
Bernie [wrote that] the identification of Ctenacanthus was
"probable", but not with certainty. There were certain features that were somewhat unique in the specimen, but I don't have any more details.
*** Wayne Itano:
The spine fragment is not easy to identify because it is only a fragment and because it shows no surface ornament. I am not sure if this is because it had no ornament or because the surface is worn. It may belong to the genus Ctenacanthus, which ranges from the upper Devonian to at least the lower Permian. Genus identification is uncertain at best. John Maisey wrote 3 long articles in the American Museum Novitates in the 1980s about Ctenacanthus, and these are the most complete references on the genus. You can also see my article in the Journal of Vertebrate Paleontology. (The following is linked to the abstract to this article, "CTENACANTHUS AND OTHER CHONDRICHTHYAN SPINES AND DENTICLES FROM THE MINTURN FORMATION (PENNSYLVANIAN) OF COLORADO", Journal of Paleontology: Vol. 77, No. 3, pp. 524–535.) See
http://www.oceansofkansas.com/ctenacanth.html
for a recent discovery of Permian Ctenacanthus in Kansas. Also see
http://www.devoniantimes.org/who/pages/ctenacanthus.html
for an upper Devonian specimen from Pennsylvania.
The CU Museum has 2 casts of Devonian Ctenacanthus spines from the Cleveland Shale of Ohio. These would be about the same age as the Dyer.
[The] photograph of a spine that Bernie Spilka found in the Dyer shows typical Ctenacanth ornament. It has been
donated to the American Museum in New York. Since it is embedded in
matrix, we can't see the cross section.
[There is also] a spine from the Dyer that is in the Denver Museum collections.
It is pretty smooth but might have originally had ornament like Bernie's specimen.
The Denver Museum has a nice Ctenacanthus spine with very well preserved ornament in the case under the big armored fish skull.
***
Wayne has been involved with shark spines for quite a while. The following is linked to his article, "Ctenacanthus sp.? from McCoy", from Trilobite Tales, Volume 9, Number 6, October 1992.
Yet another mystery fossil was found by Bill Bateman.
Plant or animal? Most striking is the texture. What could this possibly be a fossil of. Can anyone offer an argument to rule it out (or in ) as a fossil? This specimen is about six inch across.
Of a more mundane nature is this Crinoid hold fast found by ... ?
As all the crionoid fossils at this location were small and completely
disarticulated, this is an outstanding specimen. The specimen is maybe an inch
across.
This snail (gastropod) is preserved in cross section in one of the boulders in the area.
Many people found many snails at this location. Note this matrix contains several snails, including a small helical shaped one inside the largest snail. Since I reduced the resolution of this photograph you may have to look closely near the opening of the largest specimen to see the helical snail.
Brachiopods are the stepchildren of the location.
Not everyone cares for them, with a common attitude being "seen one seen em all". Actually they are very interesting fossils that came in many shapes and sizes. This one, like the snail above is preserved in cross section. Scale is about the same as the above photograph of the snail.
Sorry I posted this specimen in full resolution but it is such an interesting specimen that I couldn't help myself. It appears to be a brachiopod in cross section.
If so what is the double shells at the top of the specimen all about? Why is the specimen so asymmetric? Note the spines attached to the shell at both the right and the left. There were better specimens of brachiopods with spines found at this location, but this example is not bad. The interior of the specimen is filled with petrified mud (limestone) filled with other small fossils. Small crinoids sections are abundant (look close). The small shell near my finger appears to be a random fossil preserved in the petrified mud, but I have another specimen of a brachiopod in cross section with exactly the same shell preserved in it. Is it possibly some piece of anatomy that belongs to the brachiopod?
Really good nautaloid found by Terry Hiester, one of the field trip leaders.
This specimen is perhaps a little less than six inches long. Nautaloids were common at this location and several people found an example or two. A truly giant specimen was found by John Rising, and it is surely a different species than this one found by Terry. Unfortunately John's specimen was only a fragment, and even at that it is as large as a person's hand.
