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History, Sedimentology, and Taphonomy of Carnegie Quarry, Dinosaur National Monument, Utah
From: Ben Creisler
A new paper:
Kenneth Carpenter (2013)
History, Sedimentology, and Taphonomy of the Carnegie Quarry, Dinosaur
National Monument, Utah.
Annals of Carnegie Museum 81(3):153-232
The taphonomy of Dinosaur National Monument is presented based in part
on the extensive archival material of Earl Douglass. This material
includes unpublished manuscripts, diaries, notes, photographs, and
quarry maps, and is supplemented with the petrography of matrix still
encasing the original collections, as well as numerous site visits. A
new quarry map is presented based on the original Douglass map,
historical photographs, and a photo-mosaic of the current quarry face
made by the author.
Three-dimensionally preserved sand bars (>1.5 m tall), bone
distribution and orientation, and generally poorly sorted,
conglomeratic, multi-storied, trough-cross bedded sandstones indicate
repeated episodes (3–4) of flashy, rapid deposition in a Platte
River-like braided system (named the Quarry River) flowing
south-southeast. Modeling of the Quarry River using a one-dimensional
computer program (HEC-RAS 4.1.0) on a Platte River-like river under a
variety of flow conditions revealed possible flow velocities for the
Quarry River, as well as the effects on flow of bones on the riverbed.
These results are compared against the velocities required to move
bone based on various boulder transport equations developed for
paleofloods. The forces needed to move weighted casts of bone across a
subaqueous sand substrate were determined using a strain gauge. Casts
were also used to map turbulent flow around bones to better understand
sediment deposition leading to bone burial.
Several lines of evidence, including the varying degrees of skeletal
disarticulation, strongly suggest non-catastrophic mass mortality
during extreme droughts. Due to the lack of sweat glands, most
dinosaurs were probably water dependent, thus restricting distance
traveled for foraging. To avoid thermal stress, individuals sought
refuge in the river and death was primarily by malnutrition and
secondarily by disease. Opisthotonous induced by sickness in an
ostrich suggests a similar cause in some of the dinosaurs. Postmortem
damage to bone by insects is rare and is shown to be due to some
unknown osteophagic insect, but not dermestids.