Talk:Morrison Formation

Corrected dating of the end of deposition of the Morrison Formation
If the Morrison Formation is dated from 155 Ma to 147 Ma then it must have ended at 147 Ma not 155 Ma. Also the NPS website (http://www.nps.gov/archive/dino/morrison.htm) for Dinosaur National Monument states that deposition ended 147 Ma. The NPS site also says that the unconformity lasted 15 Ma to 20 Ma not 30 Ma. Dr. Morbius 00:38, 27 May 2007 (UTC)

Oldest radiometric age: 156.3 + 2 Ma (TRUJILLO, K.C., K. R. CHAMBERLAIN, and A. STRICKLAND. 2006. Oxfordian U/Pb ages from SHRIMP analysis for the Upper Jurassic Morrison Formation of southeastern Wyoming with implications for biostratigraphic correlations. Geological Society of America Abstracts with Programs, 38(6): 7). Youngest age: 146.8+1 Ma (Bilbey, S.A. 1998. Cleveland-Lloyd Dinosaur Quarry - age, stratigraphy and depositional environments. Pp. 87-120, in The Morrison Formation: An Interdisciplinary Study (K. Carpenter, D. Chure, and J.I. Kirkland, eds.). Modern Geology, 22.)Anky-man 00:43, 22 October 2007 (UTC) —Preceding unsigned comment added by Anky-man (talk • contribs)
 * Now added - thank you! J. Spencer 04:47, 22 October 2007 (UTC)

Oldest date for the base of the Morrison Formation is based on two dates from the Tidwell Member, one at 156.77+/-0.55 Ma (Notom UT) and 156.84+/-0.59 Ma from Rainbow Park (Truillo and Kowallis, 2015 here: https://giw.utahgeology.org/giw/index.php/GIW/article/view/6/4 ). Currently 156.7 Ma is the date used. The previous youngest date of 146.8 has not been replicated and has been tossed out as possibly contaminated. The youngest current dates are several meters below the top of the Brushy Basin Member at 150.0+/-0.5 Ma at Little Cedar Mountain, UT (reference: Christiansen, E.H., Kowallis, B.J., Dorais, M.J., Hart, G.L., Mills, C.N., Pickard, M., and Parks, E., 2015, The record of volcanism in the Brushy Basin Member of the Morrison Formation: Implications for the Late Jurassic of western North America, in Anderson, T.H., Didenko, A.N., Johnson, C.L., Khanchuk, A.I., and MacDonald, J.H., Jr., eds., Late Jurassic Margin of Laurasia—A Record of Faulting Accommodating Plate Rotation: Geological Society of America Special Paper 513, p. 1–XXX, doi:10.1130/2015.2513(11). Carpenter, Kenneth (talk) 21:03, 30 November 2022 (UTC)

Update Table
I've noticed the table titled "Placeholders of the Placeholder Formation" remains unfilled and has been like that since July 19th. Is anyone going to edit it or can I go ahead and fill it in?Smokeybjb (talk) 01:06, 9 August 2008 (UTC)
 * If you want to, I'd say go ahead. J. Spencer (talk) 01:16, 9 August 2008 (UTC)
 * It either needs filling in or deletion, rather ugly and pointless as is. Vsmith (talk) 01:21, 9 August 2008 (UTC)

Thankyou. I'll start filling it in now. Smokeybjb (talk) 01:25, 9 August 2008 (UTC)

Reptiles of the Morrison Formation
Whatever happened to the table titled "Reptiles of the Morrison Formation"? Should it be readded, or should there be seperate tables for turtles, crocodilians, sphenodonts, e.t.c.? Smokeybjb (talk) 03:21, 11 August 2008 (UTC)
 * Paleobiota of the Morrison Formation Abyssal (talk) 14:50, 22 July 2010 (UTC)

Insects
I don't know that it is accurate to say "Insects were very similar to modern species, with termites building 30 m (100 ft.) tall nests". Termites, yes, OK, but could the the hymenoptera, diptera, beetles be described as very similar? Almost all the lepidoptera evolved in the Upper Cretaceous, parallel to flowering plants. And you don't really mean "species", or do you? I would have thought "order" or "family" was more like it. Just what were the insects found in the Morrison Formation? Macdonald-ross (talk) 10:59, 6 February 2013 (UTC)

External links modified (January 2018)
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