Wednesday, October 10, 2007
Thursday, October 4, 2007
Saturday, September 22, 2007
Monday, July 30, 2007
Tuesday, June 12, 2007
Tuesday, June 5, 2007
Lucas, S. G., Goodspeed, T. H., and Estep, J. W., 2007, Ammonoid Biostratigraphy of the Lower Triassic Sinbad Formation,
Lucas, S. G., Krainer, K., and Milner, A. R. C., 2007, The Type Section and Age of the Timpoweap Member and Stratigraphic Nomenclature of the Triassic Moenkopi Group in Southwestern Utah, in, Lucas S. G. and Spielmann, J. A. eds. Triassic of the American West,
Thursday, May 31, 2007
Tuesday, May 8, 2007
Monday, April 9, 2007
Monday, March 26, 2007
Roger L. Batten and Wm. Lee Stokes, 1986, Early Triassic gastropods from the Sinbad member of the Moenkopi Formation,San Rafael Swell, Utah. American Museum Novitates no.2864, .33 p.Ron Blakeys web site.
Carr, T. R. and Paull, R. K., 1983, Early Triassic stratigraphy and paleogeography of the Cordilleran Miogeocline, in Reynolds and Dolly, eds., Mesozoic paleogeography of the west-central United States: Denver, Rocky Mountain Section of the Society of Economic Paleontologists and Mineralogists, Rocky Mountain Paleogeography Symposium 2, p. 39-55
Margaret L. Fraiser, Richard J. Twitchett, David J. Bottjer, 2005, aUnique microgastropod biofacies in the Early Triassic: Indicator of long-term biotic stress and the pattern of biotic
recovery after the end-Permian mass extinction, C. R. Palevol 4, 475–484
LUCAS, Spencer G., MILNER, Andrew R.C., and VICE, Garrett S., 2004, (abstract) EARLY TRIASSIC (SMITHIAN) PALEOGEOGRAPHY AND AMMONITES IN SOUTHWESTERN UTAH
Nützel, A. 2005. A new Early Triassic gastropod genus and the recovery of gastropods from the Permian/Triassic extinc−
tion. Acta Palaeontologica Polonica 50 (1): 19–24.
Woods A. D. and Bottjer, D. J., 2000, Distribution of Ammonoids in the Lower Triassic Union Wash Formation (Eastern California): Evidence for Paleoceanographic Conditions During Recovery from the End-Permian Mass Extinction: PALAIOS, V 15, p.535-545
With the amount of intermediate forms between Anasibirites kingianus (Waagen) 1895, and Wasatchites perrini Mathews 1929, is it reasonable to consider them as a dimorphic/polymorphic species?
From the website: "Because of the variable morphology in some populations all specimens are a seperate species, or all are one species with variable morphology. Mathews (1929) described (a) 32 species of Anasibirites, 5 species of Gurlyeites, 9 of Hemiprionites "Goniodiscus" and 1 of Kashmirites, and (b) 4 species of Wasatchites, 3 of Kashmirites and 1 of Keyserlingites, from Cephalopod Gulch near Salt Lake City, Utah. Later workers placed alot of them (a) in synonomy with Anasibirites kingianus (Waagen) and (b) in Wasatchites. In the Anasibirites Beds (about 300mm thick) of the Confusion Range of western Utah. there are representatives of all these genera, they grade from Hemiprionites to Anasibirites to Gurleyites to Wasatchites with intermediates between each."
Silberling (in Hose and Repenning, 1959) idententified these as Anasibirites kingianus and Wasatchites meeki without reference to any intermediate forms. See the two papers by E.T. Tozer (1971 and 1994) to see how he deals with these genera.
For reference, the Santonian (Late Cretaceous) ammonite Placenticeras syrtale is a polymorphic species which has been referred to many names of many ages (Kennedy and Cobban 1991, Kennedy Landman & Cobban 2001, Kennedy, Hancock, Cobban & Landman 2004, Wolleben 1967), to find one by itself you would be unable to place it in time or one of a number of subspecies described by Wolleben. There are 2 basic morphotypes of P. syrtale, a smooth shelled form (P. planum) and an ornamented form (P. syrtale, P. guadalupae, P. pseudocostatum, P. sancarlosensis etc.) much like the forms of Anasibirites and Wasatchites. The species or subspecies of P. syrtale exist in time for about 8 my with known ancestors and descendants and those of Anasibirites and Wasatchites for maybe 1 my, and I know of no ancestors or descendants.
Kennedy, Hancock, Cobban and Landman, 2004, A revision of the ammonite types described in F. ROEMER’S ‘Die Kreidebildungen von Texas und ihre organischen Einschlüsse’ (1852), Acta Geologica Polonica, No. 4, pp. 433-445
Kennedy, W. J., and W. A. Cobban, 1991. Upper Cretaceous (upper Santonian) Boehmoceras fauna from the Gulf Coast region of the United States. Geol. Mag. 128: 167–189.
Tuesday, March 20, 2007
Reference: Dagys, A., 1999, Evolution of the Family Sibiritidae and Detailed Biostratigraphy of the Siberian Upper Olenekian (Triassic), in Advancing Research on Living and Fossil Cephalopods, ed. F. Olóriz and F. Rodriguez-Tovar, 109-123. New York: Kluwer Academic/Plenum Press.
See Here for an update
Monday, March 19, 2007
Cooper, M. R., 1994, Towards a phylogenetic classification of the Cretaceous ammonites III, Scaphitaceae: Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 193 (2), 165-193.
referenced from Cobban, W.A., Walaszczyk, Ireneusz, Obradovich, J.D., and McKinney, K.C., 2006, A USGS zonal table for the Upper Cretaceous middle Cenomanian−Maastrichtian of the Western Interior of the United States based on ammonites, inoceramids, and radiometric ages: U.S. Geological Survey Open-File Report 2006-1250, 45 p.
I cant figure out why Cobban et. al. only noted the new genera Cooper proposed. It seems to me to note them is to accept them.
I think I will change them on the website when I get some time. The changes would be as follows:
The species carlislensis, warreni, ferronensis and whitfieldi will be referred to Coloradoscaphites.
The species preventricosus and impendicostatus will be referred to Anascaphites
The species depressus will be referred to Clioscaphites
The species vermiformis will be referred to Billcobbanoceras
The species uintensis, frontierensis and hippocrepis will stay in Scaphites
And the species praespiniger will stay in Trachyscaphites.