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Hi All, Another chapter done on our study of the enigmatic Fort Apache Limestone! We found one orthocone, and juvenile coiled conchs in our search in 250 pounds of limestones. One larger specimen which we thought was a huge nautiloid turned out to be a big Straparollus gastropod when we finally made a clay cast of the mold in limestone. So without delay, here is this weeks write up! Lower Permian Nautiloids are found in both the Fort Apache Limestone, and overlying Kaibab formation. Far more commonly found in the Kaibab, they range in size from quarter sized to 12 inch monsters. But in the Fort Apache, we have found so far only two nautiloids in our years of searching. Fortunately, they are both different morphologically and offer an interesting cross section of cephalopod life in the Fort Apache Sea. It is notable that Winters, in his monumental GSA monograph memoir 89 found only the orthocone type and identified it tentatively as Psudorothoceras knoxense. Aperture comparison. The differences in similar mollusks can be ascertained by comparing the shapes of the openings. (Aperture) On the left, Bellerophon - a monoplacophoran has a decidedly triangular opening. Center are a gastropod called Knightites sp. which looks very much like a small Bellerophontid, but is a gastropod. And on the right, the cephalopods have a much larger and oval opening, such as the small pea sized specimen we found below. This little cutie was found mixed in with our first picks for gastropods out of the acid fines. This was the only one like this, and you can clearly see the septa evenly spaced along its periphery. The center is filled in with sediment thus appears as a mound here hiding the details of the inner whorls. View of the aperture, a bit crushed showing the inner whorls tucking into the opening oh-so-nautiloid style! Orthocone nautiloid section found at site 2 as well. This is an orthoceras type cf. Psudorothoceras knoxense. The septa can be seen inside the eroded openings in the outer conch. Fortunately, one end has a great view of one of the concave septa. This then would have been the side that the animal lived on in the conch. It is difficult to say how long the original conch was, perhaps 6 inches or so. We Well, thats it for this week. We were hoping for some really big nautiloids like we find in the overlying Kaibab formation - which is the same age. But no, that will have to wait till next year! Next weeks posting will be on the gorgeous Straparollus gastropods we found, ranging in size from pinhead to hefty 6 inchers.
Hi all, Im no paleo artist, but here is my one small step beyond stick figures drawing of what we got when we put together all the parts of the trilobite from the Fort Apache Limestone near Payson. We never found a whole one, but all the parts from molts were eventually revealed. While the major paper on the trilobites from 1960s listed the only trilobite found here was Anisopyge, we are not seeing this - I think it is Ditomopyge. All three pygidiums found do not match anisopyge! Anyway, here is my attempt at the recreation. Ok, you can start throwing tomatoes now. O
Hi all, As we go throgh hundreds of pounds of limestone for our current project, the acid bath fines are revealing some strange silicified remains. This one is an enigma for us! We have found half a dozen so far, and have no idea what they might be. However, we have some clues. First, there is no crinoid material from this deposit, so not likely a part of a calyx. Second, there is tons of urchin remains and so I suspect this might be a part of an urchin. Maybe a mount part? The pie wedge shaped pieces have straight sides and a perplexing hole in each one. All are very small, the mm scale is at the bottom. Anyone have some thoughts on what they may be?
Well preserved sponges are rare in Arizona except for Actinocoelia maeandrina in the Permian (Leonardian) age Kaibab Limestone. I found well preserved ramose sponges with hollow interiors about three miles south of the town of Forest Lakes in central Arizona. Using HCl acid, my silicified sponge was dissolved out of the Leonardian Fort Apache Member of the Schnebly (formerly Supai) Formation, which is mostly limestone in the area. The member contains a rich molluscan fauna dominated by pelecypods and gastropods. Echinoid pieces are common. Coral, bryozoan and nautiloids are rare; sponges are previously unreported. My sponge may be a new species or may be an extension of range of a known species. Collected in August 2013. For more information on the fossils of the Fort Apache Member see: Winters, S.S., 1963, Supai Formation (Permian) of eastern Arizona: Geological Society of America Memoir, 89, 99 p.