[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: [dinosaur] The last known Tyrannosaurus individual



Please, never ever ever ever assume an average rate of sedimentation in a terrestrial depositional environment!! It is a flawed idea. Terrestrial sediments do not accumulate in a constant or regular fashion, as some lake deposits or marine deposits might. They happen in fits and starts, and indeed the very same channels which produce them erode the layers that were already there.

So in 3 meters of section of fluvial deposits, you might have 4 channels making up 90% of the thickness which each were deposited over ten years each, separated by floodplain deposits which were each deposited over the course of week each, but the age between the lowest sediment and the highest is 4000 years.

As to your particular question: the entire Hell Creek Project of Montana State University and now University of Washington happened more recently than the Braman reference. They haven't published their results, but some may well be closer to the boundary.

I hope this helps.

On Sat, Jan 20, 2018 at 7:30 AM, Poekilopleuron <dinosaurtom2015@seznam.cz> wrote:
Good day,

according to Braman et al. (1995) the last known individual of _T. rex_ (RTMP 81.12.1 - "Huxley Rex") was found exactly 10.5 metres (34.5 feet) below the K-Pg boundary in the Scollard Formation. I would like to ask, how much time does this gap represent? Was the sedimentation rate in the Scollard Fm. the same as in the Hell Creek Fm., where the rate is about 3 cm/1000 years (or 1 meter per ~30 000 years)? Does that mean this individual of _T. rex_ died some 300 000 years before the Chicxulub asteroid impact? Thank you in advance, Tom





--

Thomas R. Holtz, Jr.
Email:Âtholtz@umd.eduÂÂÂÂÂÂÂÂ Phone: 301-405-4084
Principal Lecturer, Vertebrate Paleontology

Office: 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 Scholars

Office: 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.
ÂÂÂÂÂÂÂ ÂÂÂÂÂÂÂ ÂÂÂÂÂÂÂ Department of Geology
ÂÂÂÂÂÂÂ ÂÂÂÂÂÂÂ ÂÂÂÂÂÂÂ Building 237, Room 1117

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