An external mold of the shell of Stroboceras
(Epistroboceras) texanum (Miller and Youngquist) 1948, from the
Manning Canyon Shale east of Provo.
The Mississippian Pennsylvanian Manning Canyon Shale occurs in north central Utah, it was deposited in the eastern part of the the Antler Foreland Basin. The shale is mined for brick clay at several locations in northern Utah County and southeastern Tooele County, mostly in the Pennsylvanian part of the formation. Fossil plants are very common in this part of the formation and are widely collected. The fossil plants are well documented from this part of the section. The lower, Mississippian, part of the formation, is a black shale, probably lower in clay content as it is not mined nearly as extensively as the upper part. Fossil Cephalopods occur only in the lower part of the Mississippian part of the section. They are mostly external molds of the phragmocone, with no original shell material left.
external mold of the shell of Eumorphoceras
girtyi Elias 1956
external mold of an unidentified orthoconic
nautiloid
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External mold
viewing suggestion:
the light is coming from the upper left, if you see it coming from the lower right the fossil looks like an internal mold squint or turn your head slightly and it may reverse |
I have made latex casts of some of the fossils I
found in
the Manning Canyon Shale east of Provo. They show external
features of the shell very well. They should appear normal unless
your eyes are
all fouled up from looking at the external molds above.
Latex cast of
Eumorphoceras girtyi Elias 1956
this specimen shows the growth lines very well and it appears that Eumorphoceras had lateral lappets,
at least in the pre-oxyconic stage
23mm dia.
Latex cast of
Eumorphoceras girtyi Elias 1956
with portion of a mold of the broken shell
notice the ammonitella in the center
24mm dia.
Latex cast of
Eumorphoceras girtyi Elias 1956
19mm dia.
Latex cast of a small crushed goniatite, possibly
Richardsonites?
18mm dia.
The mold and a cast of Eosyngastrioceras inexpectans Titus 2000
The following are coiled nautiloids, they both happen to have a perforate umbilicus so it is clear to see the difference in adolescent stages between the ammonoids above, with a small ammonitella (the small bulb shaped initial chamber) and the coiled nautiloids below, which seem to have started out with a rather large initial chamber.
Latex cast of
Stroboceras (Epistroboceras) texanum (Miller and Youngquist) 1948
31mm dia.
Latex cast (lateral view) of
Tylonautilus sp.
16mm dia.
Latex cast (ventral view) of
Tylonautilus sp.
For references you can go to the alphabetic list of Utah Fossil Cephalopods and then to the reference list