The Museum in Green River, Utah

 The Mancos Shale exhibit at the John Wesley Powell River History Museum in Green River Utah, is now open.  Along with a couple of dinosaurs and other murals, it is a very nice addition to the museum.  In the distance on the right you can see the ammonite I found and posted about back in this post, and after it was prepared in this post.

 

Here is a view of the specimen with the mural behind it.

  And the sign telling about the collection and preparation. 

And a few of the other ammonites I donated (the six on the left).  And more of the large mural behind it, unfortunately showing a wounded scaphite, or is that just the leftovers of a large marine reptile it just finished eating. ;)

For a cold, snowy, December day

San Rafael River cutting through the Swell

Just to remember those hot days of summer and early fall in the desert.  The Sinbad Formation of the Thaynes Group slopes down to river level on the left, bleached rocks of the Moenkopi Group up to the maroon Chinle Formation on the slopes of Assembly Hall Peak, with a cap of Wingate Sandstone, and Kayenta and Navajo above that on the cliffs beyond.  The leaves of the Fremont Cottonwoods just starting to foretell the cold and snow of today.

Of Cephalopods and Sponges

Early Ordovician orthoconic nautiloids in a sponge/algal deposit, back when life was just beginning to diversify.

 

Early Triassic ammonoids in a sponge/microbial deposit, back when life was beginning to re-diversify.  Just after the Permian-Triassic mass extinction.

Silica Replacement

An update for this old Calcite Replacement post.

 After finding another small ammonoid (above) in the same beds, and a discussion on TONMO, I've realized the pattern on the two fossils is that of "Beekite".  Not having a lot of experience with silicified cephalopod fossils around here, I got out the acid bottle, fizz on the matrix, no fizz on the fossil.  So instead of a Calcite replacement, they are replaced with Silica.  Beekite may be a mineral, but the word is more commonly used as a descriptive term for the concentric rings of the replacement material.  

The fossil from the first post showing the "Beekite Rings".

The First Utah Cephalopod Fossil

Title Page

Although fossil cephalopods had probably been collected by the Native Americans, fur trappers and early Immigrants for years, the 1859 Simpson Survey was one of the first scientific expeditions that collected fossils, and probably the first to collect cephalopods and have the results published.  Mr. Henry Englemann "the zealous geologist of the party", collected what is to my determination, the first fossil cephalopod to be mentioned in the scientific literature from what is now the State of Utah.   Englemanns's fossils were described and/or listed by F. B. Meek in: Appendix J., Report on the Palaeontological Collections of the Survey (p. 339-373 pls. I-V).

page 371

On page 371, in the list of Lower Carboniferous Forms, appears; Nautilus ____, undt. sp., No. 201.  It was not figured, only listed.  The given coordinates puts it just south of Fivemile Pass, a few miles west of Fairfield, a place I collected many brachiopods as a kid.  The Mississippian Manning Cyn. Shale and Great Blue Limestone both crop out in that area, so one of those formations is probably the provenance.

Though this report was completed before the Civil War, it was not printed by the government until 1876 because of it.

Unexpected ammonoid

Churkites cf. C. noblei

An internal mold of the body chamber, much like the first photo in THIS old post.  This fossil means some of the beds I was collecting in are older than I thought or this ammonoid ranged into younger rocks.  Only more collecting will determine how it fits in the column.

Payday for an Amateur Paleontologist

From the Merriam-Webster Dictionary "Amateur: one who engages in a pursuit, study, science, or sport as a pastime rather than as a profession".  It don't say anything about getting paid, just about having fun or making a job out of it.  I guess that one of the greatest means of compensation someone that does this for fun can receive, and retain an amateur standing, is to have a fossil named after them.  Well, I got paid.

 

 Kazakhoceras bylundi

It don't pay the mortgage or put food on the table, but that doesn't matter, that would be like getting paid to go to the amusement park.  Just the privilege of going out in the field with Dieter and Alan, spending a few days having fun, collecting and discussing the fossils, was compensation enough.

Thanks again Dieter and Alan!

KORN, D. & TITUS, A.L. 2011. Goniatites Zone (middle Mississippian) ammonoids of the Antler Foreland Basin (Nevada, Utah). Bulletin of Geosciences 86(1), 107–196 (60 figures, 37 tables, appendix). Czech Geological Survey, Prague.

Intraspecific variation in Forresteria

Forresteria alluaudi (Boule, Lemoine & Thevenin) 1907, from depressed, evolute, spinose to compressed, involute, almost smooth, a nice range of intraspecific variation. Is it any wonder why these, and some like these, were placed in 4 separate species in 3 separate subgenera (Reeside, 1932), Barroisiceras (Forresteria) forresteri, B. (F.) stantoni, B. (Alstadenites) sevierense, and B. (Harleites) castellense. Kennedy, Wright and Klinger (1983) put them all in synonymy with F. alluaudi.

Many ammonoids show intraspecific variation, including, for example, Placenticeras from the Cretaceous and, at least in my mind and experience, Anasibirites and Wasatchites from the Early Triassic. Found in the same bed or group of beds worldwide, to see one would tell you precisely what age the rock they were in is. Unlike the Triassic example, where there are differences in ornamentation and shape from one part of the world to another (maybe some kind of latitudinal or provincial thing), F. alluaudi is basically the same, that is different, wherever found.

Forresteria was named after the late Robert Forrester of Salt Lake City, Utah, who found the type material in southern Castle Valley, eastern Sevier County, Utah.

Scaphites hippocrepis and S. leei

Scaphites hippocrepis and S. leei, Early Campanian (Late Cretaceous) Scaphitids. A row of ventrolateral tubercles, an inner row of tubercles on the body chamber and a constricted collar at the aperture. Best seen on the micromorph of S. leei in #22 below, and on the macromorph in #27, are dorsal lappets.


Below is a drawing of the dimorphs of S. hippocrepis. The collar shows well but the dorsal lappet does not, at least not as well as on some of the other figures.

The lappets and their dorsal location on the aperture of the adult micromorph is the question at hand, just how much plasticity is there in the location of the lappets around the collar? Especially in their ancestors and descendants.

Figures from:

Cobban, W.A., 1969, The Late Cretaceous ammonites Scaphites leei Reeside and Scaphites hippocrepis (DeKay) in the western interior of the United States: U.S. Geological Survey Professional Paper 619, 29 p., 5 pls.