And now for something completely different...

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

...I will not talk about either commericialism and dinosaurs nor movies and
dinosaurs.  If you want to know my thoughts on the subject, check out the
dinosaur listserve archives.

Instead, I offer the following:

In some recent popular works I've been involved with, I've been using the
standard Harland et al. (1990) time scale for the Mesozoic.  I've recently
discovered (okay, I knew about it before, but finally bothered to copy...)
an updated, highly detailed reanalysis of the age dates for the stages of
the Mesozoic.  I thought I'd copy the basic information here so that folks
who want to update their webpages and so forth can do so.  If you are REALLY
interested in the details of the geochronology, the paper has the magnetic
timescale, the ammonite and nannofossil zones, and just about everything you
want.

Among other changes, the Maastricthian (latest Cretaceous) is shorter than
previously believed, the Campanian (Late Cretaceous) and Rhaetian (latest
Triassic) are longer, and in general the stage lengths turn out to be more
balanced than in Harland et al.

Oh, yes, and the Liaoning fossils of China are STILL Early Cretaceous by
Hou, Martin, and Feduccia's own absolute dates, and the Manicouagan impact
is still too old (at 214 +/- 1 Ma) to be the cause of the terminal Triassic
extinction event.

Source:

Gradstein, F.M., F.P. Agterberg, J.G. Ogg, J. Hardenbol, P. van Veen, J.
Thierry & Z. Huang.  1995.  A Triassic, Jurassic and Cretaceous time scale,
pp. 95-126.  IN W.A. Bergrgren, D.V. Kent, M.-P. Aubry & J. Hardenbol
(eds.), Geochronology, Time Scales, and Global Stratigraphic Correlation.
SEPM Special Publication No. 54.

Age estimates are Ma (million years ago) with uncertainty in my to 2
standard deviations.  Duration of the stage in my.
Unit                    Boundaries                      Duration
                        (For Stages, upper boundary)
Mesozoic Era            248.2 - 65.0 Ma                 183

Cretaceous Period       144.2 - 65.0 Ma                 79.2
Late Cretaceous Epoch   98.9 - 65.0 Ma                  33.9
Maastrichtian           65.0 +/- 0.1                    6.3
Campanian               71.3 +/- 0.5                    12.2
Santonian               83.5 +/- 0.5                    2.3
Coniancian              85.8 +/- 0.5                    3.2
Turonian                89.9 +/- 0.5                    4.5
Cenomanian              93.5 +/- 0.2                    5.4
Early Cretaceous Epoch  144.2 - 98.9 Ma                 45.3
Albian                  98.9 +/- 0.6                    13.3
Aptian                  112.2 +/- 1.1                   8.8
Barremian               121.0 +/- 1.4                   6.0
Hauterivian             127.0 +/- 1.6                   5.0
Valanginian             132.0 +/- 1.9                   5.0
Berriasian              137.0 +/- 2.2                   7.2

Jurassic Period         205.7 - 144.2 Ma                61.5
Late Jurassic Epoch     159.4 - 144.2 Ma                15.2
Tithonian               144.2 +/- 2.6                   6.5
Kimmerdigian            150.7 +/- 3.0                   3.4
Oxfordian               154.1 +/- 3.2                   5.3
Middle Jurassic Epoch   180.1 - 159.4 Ma                20.7
Callovian               159.4 +/- 3.6                   5.0
Bathonian               164.4 +/- 3.8                   4.8
Bajocian                169.2 +/- 4.0                   7.3
Aalenian                176.5 +/- 4.0                   3.6
Early Jurassic Epoch    205.7 - 180.1 Ma                25.6
Toarcian                180.1 +/- 4.0                   9.5
Pliensbachian           189.6 +/- 4.0                   5.7
Sinemurian              195.3 +/- 3.9                   6.6
Hettangian              201.9 +/- 3.9                   3.8

Triassic Period         248.2 - 205.7 Ma                42.5 
Late Triassic Epoch     227.4 - 205.7 Ma                21.7
Rhaetian                205.7 +/- 4.0                   3.9
Norian                  209.6 +/- 4.1                   11.1
Carnian                 220.7 +/- 4.4                   6.7
Middle Triassic Epoch   241.7 - 227.4 Ma                14.3
Ladinian                227.4 +/- 4.5                   6.9
Ansinian                234.3 +/- 4.6                   7.4
Lower Triassic Epoch    248.2 - 241.7 Ma                6.5
Olenekian               241.7 +/- 4.7                   3.1
Induan                  244.8 +/- 4.8                   3.4

And, for completeness sake, the Paleozoic-Mesozic (Tartarian - Induan)
boundary is:
248.2 +/- 4.8 Ma.

Do with this info what you will.                   

P.S.  Josh - you lousy, rotten, S.O.B... :-)  Congrats on getting to China.
Hope you took pictures...

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661