Re: [dinosaur] Dating of dinosaur age during history

Here is a look at some of the shifting boundaries over time:

https://urldefense.proofpoint.com/v2/url?u=https-3A__books.google.com_books-3Fid-3DteJYlWH9vg4C-26lpg-3DPA128-26ots-3DCw5pa2wTpH-26dq-3Dhistory-2520numerical-2520geologic-2520timescale-2520kelvin-2520holmes-26pg-3DPA128-23v-3Donepage-26q-3Dhistory-2520numerical-2520geologic-2520timescale-2520kelvin-2520holmes-26f-3Dfalse&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=o60kRii1wJH5js5aR6dvQC_pppuig6oPhvuZix3gcL0&s=rbQvbo9v78lbyWEWnXashNjJ8ZT0rW4ClQ6qJeA_KO4&e= 


On Sun, Nov 24, 2019 at 8:32 AM Thomas Richard Holtz <[email protected]> wrote:

> The 3 Ma date for the end of the Cretaceous was due to the influence of
> Lord Kelvin's time scale. He found that since there was no new way of
> energy warming the interior of the Earth it must be continuously cooling,
> and by his calculations it was something like 90 million years old at most.
> Subdividing this duration by the relative thickness of the different strata
> of the various time periods gave a duration of only about 3 million years
> for the Cenozoic.
>
> Famously the solution to both the missing internal heat for the Earth AND
> the method by which numerical ages of units could accurately be estimated
> was the same: natural radioactive decay.
>
> On Sun, Nov 24, 2019 at 2:37 AM Justin Tweet <[email protected]>
> wrote:
>
>> Norell et al. (1995) mentioned that in 1915 William Diller Matthew
>> produced a diagram that put the end of the Cretaceous at 3 million years
>> ago, with the whole Mesozoic lasting 9 million years. I've made perfunctory
>> searches occasionally but I've yet to find the diagram.-Justin
>>
>> Norell, M. A., E. S. Gaffney, and L. Dingus. 1995. Discovering dinosaurs
>> in the American Museum of Natural History. Alfred A. Knopf, Inc., New York,
>> New York.
>>
>> On Fri, Nov 22, 2019 at 12:55 PM [email protected] <[email protected]>
>> wrote:
>>
>>> It's more complicated than that. It is the level of 'golden spike' at
>>> Fortune Head that is assumed to be 541.0+-1.0 Ma. The boundary is defined
>>> by the first occurence of _Treptichnus pedum_, which is not an organism by
>>> itself, for one, and actually occurs in older levels at type section (
>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1017_S001675680100509X&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=o60kRii1wJH5js5aR6dvQC_pppuig6oPhvuZix3gcL0&s=jT_PrDaVLanujuHMEmJdVUiX0p224MSPeDQFR5FGO6w&e= 
>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1017_S001675680100509X&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=JjaSkxJpIYFPxbrFYwOkiR2V_WOCBtMGgfhCYjgujk8&s=JvzUvqvtGiYecSIn3OYJtsW_I1JPXYBolPLCE_ikCAc&e=> ).
>>> The first occurence of similar ichnofossils at ~538.5-539 Ma in the section
>>> discussed by Linnemann et al. is connected with change in lithology. I
>>> think it would be reasonable to assume that the first occurence of a
>>> certain behaviour at a specific site has more to do with regional onset of
>>> conditions favourable for the tracemakers than with the actual, global
>>> evolutionary origin of this specific behaviour. In other words, the
>>> Precambrian/Cambrian as defined by ichnofossils may be diachronous.
>>>
>>> Dnia 22 listopada 2019 16:54 David Marjanovic <[email protected]>
>>> napisał(a):
>>>
>>> At this opportunity I'll mention that even the 2019-5 version is already
>>> outdated in at least one respect: the beginning of the Cambrian is given
>>> there as 541.0 ± 1.0 Ma ago, but really happened later, between two
>>> volcanic-ash beds dated to 538.58 ± 0.19 and 538.99 ± 0.21 Ma ago.
>>>
>>> Linnemann, U., Ovtcharova, M., Schaltegger, U., Gärtner, A., Hautmann,
>>> M., Geyer, G., Vickers-Rich, P., Rich, T., Plessen, B., Hofmann, M.,
>>> Zieger, J., Krause, R., Kriesfeld, L. and Smith, J. (2018, printed 2019)
>>> New high‐resolution age data from the Ediacaran–Cambrian boundary
>>> indicate rapid, ecologically driven onset of the Cambrian explosion. *Terra
>>> Nova* 31, 49–58. doi: 10.1111/ter.12368
>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1111_ter.12368&d=DwMBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=GOz54pssGqhTNivBDHTkjZumNCitcgZmjLkI-t0JTXo&s=0dqpuYUYHxoLAjgcRInFAYOpJXfUKrRqe05O3xqTfFY&e=>
>>>
>>>
>>>
>>
>> --
>> Justin Tweet
>> Equatorial Minnesota
>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__equatorialminnesota.blogspot.com_&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=FjdGnDRT2LKfGH-Q9WvVLIz-e-P6BibT5DAeJu36pm8&s=wP8McmNtuCa2fE9m11vRD3MRjy44eSYsmrlFnvjowu4&e=>,
>> home of The Compact Thescelosaurus
>>
>
>
> --
>
> Thomas R. Holtz, Jr.
> Email: [email protected]         Phone: 301-405-4084
> Principal Lecturer, Vertebrate Paleontology
>
> Office: Geology 4106, 8000 Regents Dr., College Park MD 20742
>
> Dept. of Geology, University of Maryland
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.geol.umd.edu_-7Etholtz_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=o60kRii1wJH5js5aR6dvQC_pppuig6oPhvuZix3gcL0&s=urPKim2izvIdkN3eF51yazXFlUJ0jTf5lKLMC2jIs4M&e= 
>
> Phone: 301-405-6965
> Fax: 301-314-9661
>
> Faculty Director, Science & Global Change Program, College Park Scholars
>
> Office: Centreville 1216, 4243 Valley Dr., College Park MD 20742
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.geol.umd.edu_sgc&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=o60kRii1wJH5js5aR6dvQC_pppuig6oPhvuZix3gcL0&s=lK5bM2XhxRXt2u8MFwvcesiivF6z3fh40YH9CvZjZGc&e= 
> Fax: 301-314-9843
>
> Mailing Address:        Thomas R. Holtz, Jr.
>                         Department of Geology
>                         Building 237, Room 1117
>
>                         8000 Regents Drive
>                         University of Maryland
>                         College Park, MD 20742-4211 USA
>


-- 

Thomas R. Holtz, Jr.
Email: [email protected]         Phone: 301-405-4084
Principal Lecturer, Vertebrate Paleontology

Office: Geology 4106, 8000 Regents Dr., College Park MD 20742

Dept. of Geology, University of Maryland
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.geol.umd.edu_-7Etholtz_&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=o60kRii1wJH5js5aR6dvQC_pppuig6oPhvuZix3gcL0&s=urPKim2izvIdkN3eF51yazXFlUJ0jTf5lKLMC2jIs4M&e= 

Phone: 301-405-6965
Fax: 301-314-9661

Faculty Director, Science & Global Change Program, College Park Scholars

Office: Centreville 1216, 4243 Valley Dr., College Park MD 20742
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.geol.umd.edu_sgc&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=o60kRii1wJH5js5aR6dvQC_pppuig6oPhvuZix3gcL0&s=lK5bM2XhxRXt2u8MFwvcesiivF6z3fh40YH9CvZjZGc&e= 
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117

                        8000 Regents Drive
                        University of Maryland
                        College Park, MD 20742-4211 USA