Note, that a slow-down in speciation rates does not necessarily
imply a drop in total diversity. Those are different things.
Ben Creisler
A reminder that there are sites in New Mexico that have not yet been formally published that reportedly record the end of the dinosaurs into the early Paleocene, and don't show a drop-off in dinosaurs.Â
The death of dinosaurs and rise of mammals in the San Juan Basin of New Mexico, USA
by Stephen L. Brusatte, Thomas E. Williamson, Matthew T. Heizler, Daniel J. Peppe, Ross Secord, Adam Davis, C. Will Fenley, Andrew Flynn, Caitlin Leslie and Sarah L. Shelley
https://www.youtube.com/watch?v=lVBu3ff7FL4&feature=youtu.be&a
==
Also, I posted a video last week by one of the people involved in the (controversial) Tanis site research that shows undescribed pterosaur embryos, Triceratops skin, and dinosaur tracks, suggesting the ecosystem was still fine up to the impact, and evolution likely was not "stalled" for any particular reason.
The end of the dinosaurs with Jan Smit, Dutch professor of paleontology (video)
https://www.youtube.com/watch?v=DVoPwmwOMeg
On Wed, Dec 4, 2019 at 12:17 PM Thomas Richard Holtz <tholtz@umd.edu> wrote:
"There was a slow-down in speciation rates prior to the K-Pg, see:
Sakamoto, M.; Benton, M. J. & Venditti, C.
Dinosaurs in decline tens of millions of years before their final extinction
Proceedings of the National Academy of Sciences,Â2016, 113, 5036-5040
https://www.pnas.org/content/early/2016/04/13/1521478113.abstract"
Well, maybe. There are sampling issues that might be going on:Chiarenza, A.A., Mannion, P.D., Lunt, D.J.Âet al.ÂEcological niche modelling does not support climatically-driven dinosaur diversity decline before the Cretaceous/Paleogene mass extinction.ÂNat CommunÂ10,Â1091 (2019) doi:10.1038/s41467-019-08997-2
On Wed, Dec 4, 2019 at 2:59 PM Mailing <mailinglistinformation@gmail.com> wrote:
There was a slow-down in speciation rates prior to the K-Pg, see:
Sakamoto, M.; Benton, M. J. & Venditti, C.
Dinosaurs in decline tens of millions of years before their final extinction
Proceedings of the National Academy of Sciences, 2016, 113, 5036-5040
https://www.pnas.org/content/early/2016/04/13/1521478113.abstract
On 04/12/2019 19:16, David Marjanovic wrote:
Gesendet:ÂMittwoch, 04. Dezember 2019 um 16:51 Uhr Von:Â"Poekilopleuron" <dinosaurtom2015@seznam.cz>in his book "Dinosaurs Rediscovered", professor Mike Benton states that even if non-avian dinosaurs survived the K-Pg event, they would probably eventually perish some 50 or 40 million years ago (due to climatic changes and/or other perturbations). This is because of their limited ability to evolve new species in the last millions of years of the Cretaceous.There is no such thing as an inherent "ability to evolve new species" that doesn't depend on the environment, which changes. The idea that few new species _did_ evolve in the last few million years of the Cretaceous has long been abandoned: it was based simply on the fact that the Campanian record of North America is better than the Maastrichtian record of North America.
--
Thomas R. Holtz, Jr.
Email:Âtholtz@umd.eduÂÂÂÂÂÂÂÂ Phone: 301-405-4084
Principal Lecturer, Vertebrate PaleontologyOffice: Geology 4106, 8000 Regents Dr., College Park MD 20742
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/Phone: 301-405-6965
Fax: 301-314-9661ÂÂÂÂÂÂ ÂÂÂÂÂÂÂ
Faculty Director, Science & Global Change Program, College Park ScholarsOffice: Centreville 1216, 4243 Valley Dr., College Park MD 20742
http://www.geol.umd.edu/sgc
Fax: 301-314-9843
Mailing Address:ÂÂÂÂÂÂÂ Thomas R. Holtz, Jr.
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