See our new paper here.
Monday, July 6, 2020
Some Prionitids Lumped
With a few very narrowly defined species, The Prionitidae is a family of very closely related ammonoids. However most collections, especially from the western US, always contained "Prionitid" or "Prionitid indet.", Prionitids with bullae or ribs, maybe nodes or tubercles, that just didn't fit with any of the other described genera or species. With new collections from the Smithian (Early Triassic) Sinbad Formation around the Utah/Arizona border, we were able to synonymize all these with ammonoids described in 1929 by Asa Mathews. By priority, Gurleyites smithi Mathews 1929 replaces Arctoprionites resseri (Mathews 1929). With a very wide range of intraspecific variation, the new taxon will fit just about anything that doesn't fit in one of the other defined taxa.
See our new paper here.
See our new paper here.
Tuesday, April 16, 2019
Sexual Dimorphism in Ammonites
Sexual dimorphism as represented by the ammonite Yezoites frontierense (Cobban 1952)
Previously referred to Scaphites frontierense, presumably, the female was much larger to carry eggs. Many extant cephalopods (the Blanket Octopus for example) show the same relative (?) dimorphism with the males much smaller than the females.
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Macroconch (female) 38mm on the left, microconch (male) 18mm on the right |
Thursday, March 28, 2019
Lower Ferron Sandstone and Juana Lopez Members of the Mancos Shale around the north side of the San Rafael Swell
In an attempt to show that the Juana Lopez Member of the Mancos Shale really does expose itself on the west side of the San Rafael Swell, I introduce some photos to help.
Lower Ferron east of Huntington, these beds contain Prionocyclus hyatti near Mounds. They also form a small cliff under the Ferron Sandstone south of here from Ferron south to Last Chance Creek.
Here on the east side are the same thin bedded siltstone beds, the same platy rubble, and the same concretion beds with the same fossils. The siltstone beds on the west side maybe get a bit thicker, up to 3 or 4 cm, even more reason not to refer them to the Blue Gate Shale.
References:
Dane, C. H., Cobban, W. A., and Kauffman, E. G., 1966, Stratigraphy and Regional Relationships of a Reference Section for the Juana Lopez Member, Mancos Shale, in the San Juan Basin, New Mexico, U.S.G.S. Bulletin 1224-H
Edwards, C., D. Hodgson, S. Flint, and J. Howell, 2005, Contrasting styles of shelf sediment transport and deposit in a ramp margin setting related to sea-level change and basin floor topography, Turonian (Cretaceous) Western Interior of central Utah, USA: Sedimentary Geology, v. 179
Molenaar, C. M., and Cobban, W. A., 1991, Middle Cretaceous Stratigraphy on the South and East Sides of the Uinta Basin, Northeastern Utah and Northwestern Colorado, U.S.G.S. Bulletin 1787-P
Lower Ferron east of Huntington (visible upper right). |
Juana Lopez Member east of Huntington (visible upper left) Prionocyclus macombi concretions in middle of cliff (right) and P. wyomingensis concretions at top of cuesta across wash. |
Juana Lopez Member east of Huntington. The same thin platy siltstone beds that appear on the east side of the swell appear here with the same platy rubble littering the slopes. The concretion beds are also the same.
Two beds of the Lower Ferron Sandstone with large round concretions just north of Mounds. Lower bed contains the ammonite Prionocyclus hyatti along with many other mollusks. |
Around the north side the Juana Lopez is still there above the Lower Ferron.
The same thin siltstone beds, the same platy rubble.
On the east side of the Swell, the beds above the Lower Ferron have been refered to the Juana Lopez. The only real difference I can see is a couple (2) of thin (2cm max) calcarenite beds. South and east of Green River the Juana Lopez has more and thicker calcarenite beds.
Juana Lopez Member just west of Grassy Siding, Mt. Elliot in right distance. Prionocyclus macombi concretions form edge of middle cuesta, P. wyomingensis concretions form orange lip of upper cuesta. |
Here on the east side are the same thin bedded siltstone beds, the same platy rubble, and the same concretion beds with the same fossils. The siltstone beds on the west side maybe get a bit thicker, up to 3 or 4 cm, even more reason not to refer them to the Blue Gate Shale.
References:
Dane, C. H., Cobban, W. A., and Kauffman, E. G., 1966, Stratigraphy and Regional Relationships of a Reference Section for the Juana Lopez Member, Mancos Shale, in the San Juan Basin, New Mexico, U.S.G.S. Bulletin 1224-H
Edwards, C., D. Hodgson, S. Flint, and J. Howell, 2005, Contrasting styles of shelf sediment transport and deposit in a ramp margin setting related to sea-level change and basin floor topography, Turonian (Cretaceous) Western Interior of central Utah, USA: Sedimentary Geology, v. 179
Molenaar, C. M., and Cobban, W. A., 1991, Middle Cretaceous Stratigraphy on the South and East Sides of the Uinta Basin, Northeastern Utah and Northwestern Colorado, U.S.G.S. Bulletin 1787-P
Wednesday, March 27, 2019
Another Payday
Wednesday, February 14, 2018
Giant Cephalopod Midden or Mosasaur Feces
Back in 2011, and again in 2013, Mark and Dianna McMenamin postulated a giant cephalopod created a midden with the bones of Icthyosaurs. The internet came alive with much fanfare, comments, news, etc. probably because of the size the cephalopod would have had to been to form such a midden.
Well, back in 1954 two well-known cephalopod paleontologists, John B. Reeside and William A. Cobban (one prominent then, and one then becoming prominent), postulated that concretions in the Mowry and Aspen Shales were possibly "fecal matter of some large carnivore--reptile, fish or cephalopod", and "The diet of the carnivore would have had to be almost entirely ammonites and fish, and the carnivore would perhaps, like the living octopus, have had to frequent a sort of lair, to which it repaired and in which the mucous-bound fecal matter could accumulate" (Reeside & Cobban 1954, 1960).
Some of these concretions were over 2 meters in diameter, so you have a mosasaur like that in the movie Jurassic World, a very large fish, or another Kraken. Though nowhere near the size of the Triassic Kraken.
I wonder, had there been the internet in 1954, would there have been the same or similar response?
The fossils were found in fossiliferous concretions containing thousands of ammonites, along with a few bivalves and bones of a few fish and a few pterodactyls in some. These fossiliferous concretions were rare among the many non-fossiliferous concretions. The authors reported that some concretions contained well over 4200 ammonites, from 10mm to 400mm in diameter, and these probably represented less than half the original content. Most fossils were preserved in 3D with most of the living chambers crushed or missing, and some had damage to the phragmocone.
It was these fossils that Reeside and Cobban used in their 1960 paper to show the advantages of a population approach in taxonomy to a strictly typological one, especially for ammonoids with a large amount of intraspecific variation. A significant moment for the lumpers of the world.
References:
McMemamin, M. A. S., and McMenamin, D. L. S., 2011. Triassic Kraken: The Berlin Icthyosaur Death Assemblage Interpreted as a Giant Cephalopod Midden: Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 310
McMemamin, M. A. S., and McMenamin, D. L. S., 2013. The Kraken's Back: New Evidence Regarding Possible Cephalopod Arrangement of Icthyosaur Skeletons: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 900
Reeside, J. B., Jr., and Cobban, W. A., 1954. Ammonite accumulations in the Cretaceous Mowry and Aspen shales: Science, v. 119, p. 255.
Reeside, J. B., Jr., and Cobban, W. A., 1960. Studies of the Mowry Shale (Cretaceous) and Contemporary formations in the United States and Canada: U.S. Geological Survey Professional Paper 355, 126 p.
Well, back in 1954 two well-known cephalopod paleontologists, John B. Reeside and William A. Cobban (one prominent then, and one then becoming prominent), postulated that concretions in the Mowry and Aspen Shales were possibly "fecal matter of some large carnivore--reptile, fish or cephalopod", and "The diet of the carnivore would have had to be almost entirely ammonites and fish, and the carnivore would perhaps, like the living octopus, have had to frequent a sort of lair, to which it repaired and in which the mucous-bound fecal matter could accumulate" (Reeside & Cobban 1954, 1960).
Some of these concretions were over 2 meters in diameter, so you have a mosasaur like that in the movie Jurassic World, a very large fish, or another Kraken. Though nowhere near the size of the Triassic Kraken.
I wonder, had there been the internet in 1954, would there have been the same or similar response?
Plate 28 from Reeside & Cobban 1960 |
It was these fossils that Reeside and Cobban used in their 1960 paper to show the advantages of a population approach in taxonomy to a strictly typological one, especially for ammonoids with a large amount of intraspecific variation. A significant moment for the lumpers of the world.
References:
McMemamin, M. A. S., and McMenamin, D. L. S., 2011. Triassic Kraken: The Berlin Icthyosaur Death Assemblage Interpreted as a Giant Cephalopod Midden: Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 310
McMemamin, M. A. S., and McMenamin, D. L. S., 2013. The Kraken's Back: New Evidence Regarding Possible Cephalopod Arrangement of Icthyosaur Skeletons: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 900
Reeside, J. B., Jr., and Cobban, W. A., 1954. Ammonite accumulations in the Cretaceous Mowry and Aspen shales: Science, v. 119, p. 255.
Reeside, J. B., Jr., and Cobban, W. A., 1960. Studies of the Mowry Shale (Cretaceous) and Contemporary formations in the United States and Canada: U.S. Geological Survey Professional Paper 355, 126 p.
Sunday, December 31, 2017
Adult size in Scaphites
Three adult specimens of Scaphites showing the size range. The two on the left are probably progenetic dwarfs of contemporary full size species. Pteroscaphites pisinnus (far left) from the Scaphites whifieldi Zone, undetermined example (center) from the Prionocyclus hyatti Zone, and Scaphites carlilensis (right) from the Prinocyclus macombi Zone. Only adults grow a hook for a body chamber. Sexual dimorphs have been reported for most Scaphites, with microconchs being about the same size as Macroconchs but a lot less inflated. The genus Yezoites may show dimorphic size differences comparable to that shown above, but that is for another post.
Monday, December 18, 2017
Ugly Map Colors
Too bad modern geology is taking a step backward with their geologic mapping colors. I have yet to see an official standard calling out the new colors. You used to get a choice at stratigraphy.org, but no more. Are they using a traditional system for the sake of tradition under the guise of priority. This is almost as bad as illustrating ammonoids upside down of their assumed life position (again, mainly tradition). It is like moving away from Metric Units back to Imperial feet and inches. Why random colors? The divisions are called Systems or in the case of rock units, Series. Why wouldn't the colors look better in order or series?
I tried to match the colors from the latest time scale from www.stratigraphy.org for the CGMW colors, and from the pdf linked below for the USGS colors
Hopefully no rocks on your map from the Cretaceous, Mississippian, or Cambrian come in contact with each other, they would be difficult to separate.
CGMW
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USGS
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Quarternary
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Neogene
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Paleogene
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Cretaceous
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Jurassic
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Triassic
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Permian
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Pennsylvanian
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Mississippian
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Devonian
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Silurian
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Ordovician
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Cambrian
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“preCambrian”
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Hopefully no rocks on your map from the Cretaceous, Mississippian, or Cambrian come in contact with each other, they would be difficult to separate.
CGMW
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USGS
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Cretaceous
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Mississippian
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Cambrian
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How about Jurassic, Pennsylvanian, and Silurian?
Why even use colors to distinguish different Formations or Series if they are so similar to others?
Are the old Standards to be changed?
The USGS published some suggestions back in 2005.
CGMW
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USGS
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Jurassic
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Pennsylvanian
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Silurian
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Why even use colors to distinguish different Formations or Series if they are so similar to others?
Are the old Standards to be changed?
The USGS published some suggestions back in 2005.
And the Geologic Data Subcommittee (GDS) of the Federal Geographic Data Committee (FGDC)
published standards for GIS in 2008.
Are these going to change? Will they use the random color system of the CGMW?
Some pages (just a few I've run across so far) already using the CGMW colors:
This map (from SVP) was modified from an existing map and strat column with the new colors.
Macrostrat using the new colors.
I think it is unfortunate that these new colors are being adopted, and it seems to me a step backwards.
Whine over :(
Are these going to change? Will they use the random color system of the CGMW?
Some pages (just a few I've run across so far) already using the CGMW colors:
This map (from SVP) was modified from an existing map and strat column with the new colors.
Macrostrat using the new colors.
I think it is unfortunate that these new colors are being adopted, and it seems to me a step backwards.
Whine over :(
Friday, November 10, 2017
Ammonoid Family Reunions (revised Feb. 11, 2021)
Two family reunions occurred in the distant past, the
Prionitids and the Cardioceratids, this is a short review of those events. The thing that draws attention to these two
reunions is that members of the two families gathered in abundance and almost to
the mutual exclusion of other families.
Both are recorded in rocks representing a relatively short time-span, a
single biozone, the smallest standard unit used in biostratigraphy, representing
a few hundred thousand years more or less.
Localities for the reunions in the western US are shown, but the events were probably global.
About 251mya the Family Prionitidae met in what is now the
western USA. This event took place all
over the world (? Tethys and northern Panthalassa), but for this report I will
stick to the event and those attending in the western US. This Family started with the Genus Meekoceras in the Early Smithian and
culminated with the family reunion in the Late Smithian with at least 6 species
in 4 genera with a few in open nomenclature.
·
Anasibirites
Mojsisovics, 1896 2 species
·
Hemiprionites
Spath, 1929 2 species
·
Wasatchites
Mathews, 1929 1 species
·
Gurleyites Mathews, 1929 1 species
With a few Xenoceltitids and Hedenstroemiids. (See Brayard et al. 2013, Jattiot et al. 2017,
Mathews 1929, Smith 1932, for composition of the fauna and Jattiot et al. 2015
for a revision of Anasibirites, Brayard et al. 2020 for a revision of Gurleyites) Recorded in the Thaynes Group, UAZ5 of Jattiot et al. 2017
Prionitid localities (from Brayard et al 2013) |
CARDIOCERATINAE Siemiradzki, 1891:
About 162mya the Subfamily Cardioceratinae gathered in the
Sundance Sea that covered much of Montana and Wyoming along with parts of Utah,
Colorado, Idaho, and South Dakota. This
reunion started with Quenstedtoceras
and Pavloviceras coming in from the
north in Montana, and closed with 18 species in 4 genera and 3 subgenera.
· Cardioceras
Neumayr & Uhlig, 1881
o
Scarburgiceras
Buckman, 1924 6 species
o
Cardioceras
Buckman, 1923 1 species
o
Goliathiceras
Buckman, 1919 2 species
· Scoticardioceras
Buckman, 1925 2 species
· Vertebriceras
Buckman, 1920 4
species
· Cawtoniceras
Buckman, 1923 3
species
With rare Perisphinctids.
(see Imlay 1982, and Reeside 1919 for composition of the fauna, and Howarth
2017 for a revision of the Stephanoceratoidea) This reunion is recorded in the cordatum Zone of the Swift Formation of Montana, the Sundance Formation of Wyoming, Montana, and South Dakota, and the Stump Formation of Utah, Idaho, and Colorado.
Cardioceratid localities (from Imlay 1982) |
Localities for the reunions in the western US are shown, but the events were probably global.
References:
Brayard, A., Bylund, K. G., Jenks, J., Stephen, D. A.,
Olivier, N., Escarguel, G., Fara, E. & Vennin, E., 2013, Smithian ammonoid
faunas from Utah: implications for Early Triassic biostratigraphy, correlations
and basinal paleogeography. Swiss Journal of Paleontology 132:141-219
Brayard, A., Olivier, N., Vennin, E., Jenks, J., Bylund, K., Stephen, D., McShinsky, D., Goudemand, N., Fara, E., Escarguel, G., 2020. New middle and late Smithian ammonoid faunas from the Utah/Arizona border: new evidence for calibrating Early Triassic transgressive-regressive trends and paleobiogeographical signals in the western USA basin. Global and Planetary Change 192
Howarth, Michael K., 2017, Part L, Revised, Volume 3B,
Chapter 6: Systematic descriptions of the Stephanoceratoidea and
Spiroceratoidea. Treatise Online 84:1–101, 66 fig.
Imlay, R. W., 1982, Jurassic (Oxfordian and Late Callovian)
Ammonites from the Western Interior Region of the United States, U.S.G.S.
Professional Paper 1232, 44 p., 26 pls.
Jattiot, R., Bucher, H., Brayard, A., Monnet, C., Jenks, J.
F. & Hautmann, M., 2015, Revision of the genus Anasibirites Mojsisovics
(Ammonoidea): an iconic and cosmopolitan taxon of the late Smithian (Early
Triassic) extinction. Papers in Palaeontology 2 (1):155 –188.
Jattiot, R., Bucher, H., Brayard, A., Brosse, M., Jenks,
J.F., Bylund, K.G., 2017, Smithian ammonoid faunas from northeastern Nevada:
implications for Early Triassic biostratigraphy and correlation within the
western USA basin. Palaeontographica A (Paleozoology, Stratigraphy), doi:
10.1127/pala/2017/0070.
Mathews, Asa A. L., 1929, The Lower Triassic Cephalopod
Fauna of the Fort Douglas Area, Utah, Walker Museum Memoirs Vol.1 No.1
University of Chicago Press, 46 p., 11 pls.
Reeside, J. B., Jr., 1919, Some American Jurassic Ammonites
of the Genera Quenstedticeras, Cardioceras and Amoeboceras, Family
Cardioceratidae, U.S.G.S. Professional Paper 118, 64 p., 24 pls.
Smith, J. P., 1932, Lower Triassic Ammonoids of North
America, U.S.G.S. Professional Paper 167,199 p., 81 pls.
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