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

Re: MID-JURASSIC FORMATIONS IN CHINA



At 06:33 PM 4/2/97 -0500, you wrote:
>In preparing an article on Jurassic Chinese ornithopods, I have come across a
>few questions concerning some formations in the mid Jurassic of China.
>
>First, what is the most recently published age for the Shangshaximiao
>Formation?  I have conflicting dates of either Oxfordian or
>Bathonian-Callovian.  Which one is correct?

Good question!!  Although the Mamenchisaurus fauna (found in the
Shangshaximiao, the Keilozo, the Xiangtang, and Shishigou formations) have
typically been considered Late Jurassic (although never a precise date
within the epoch, so somewhere from Oxfordian to Tithonian), recent work on
the microfossils supports an older age.  Lucas (in a paper in the recent
Continental Jurassic volume) supports a Bathonian-Callovian age (late Middle
Jurassic) based on the conchostracan work of Chen et al.

>Secondly, is the Lower Shaximiao Formation the same as the Xiashaximiao?

Yes.

>I
>have not been able to find any reference to a Shaximiao Formation in "The
>Dinosauria," but there are two formations that have the suffex "-shaximiao"
>as part of their names - the Xiashaximiao and the Shangshaximiao - with the
>Xiashaximiao being the lower (older) one of the two.  Am I correct with my
>assumption that Xiashaximiao = Lower Shaximiao?

"Xia-" does mean "lower" in this context, so the Xiashaximiao is the Lower
Shaximiao Formation and the Shangshaximiao is the Upper Shaximiao Formation.

This is the Shunosaurus fauna, and seems to correlate with the Wucaiwan
Formation.

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