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Enormous Jurassic turtle bone bed from Xinjiang, China. (free pdf)

From: Ben Creisler

Non-dino but may be of interest. The pdf is free.

Oliver Wings, Márton Rabi, Jörg W. Schneider, Leonie Schwermann, Ge
Sun, Chang-Fu Zhou and Walter G. Joyce (2012)
An enormous Jurassic turtle bone bed from the Turpan Basin of Xinjiang, China.
Naturwissenschaften (advance online publication)
DOI: 10.1007/s00114-012-0974-5

A spectacular new terrestrial Konzentratlagerstätte is introduced from
the Turpan Basin of Xinjiang, China that probably belongs to the late
Middle Jurassic Qigu Formation. It contains a mass accumulation of
“xinjiangchelyid” turtles preliminarily identified as Annemys sp. In
the zone with the highest turtle concentration, complete and
articulated turtle skeletons are tightly packed at a density of up to
36 turtles per square meter. The fossiliferous layer is thickened here
and shows an erosional base. This high concentration zone outcrops
approximately 10 m in length and shows no decrease in turtle density
after exposing 2 m of the layer into the hillside. Adjacent is a more
expansive zone of at least 10 m by 30 m. In this region, the
fossiliferous layer is evenly thick, and approximately five, fully
disarticulated turtles are present per square meter. A conservatively
estimated 1,800 turtles may, therefore, have been deposited at this
site. It is likely that these aquatic turtles gathered in a retreating
water hole in a riverine environment during a drought, much as some
aquatic turtles will do today, but perished when the habitat dried up
completely. A following catastrophic rainfall event caused a debris
flow, possibly channelized in a dry river bed, which transported
complete turtles, disarticulated turtles, and mudstone clasts and
deposited them after a short distance. This taphonomic model is
consistent with previous environmental reconstructions of the Turpan
Basin during the late Middle Jurassic in predicting the episodic
breakdown of regional monsoonal circulation resulting in a seasonally
dry climate with severe episodic droughts.