The purpose of this report is to document
the occurrence of turtle tracks in the Judith River Formation of south-central Montana
in the Hidden Valley Quarry (Figure 1). In 1981, an avocational fossil
collector discovered dinosaur bones from what is now known as Careless Creek
Quarry (Fiorillo 1991), Wheatland County, Montana. This discovery led to a
series of excavations from 1984 to 1991, and again from 1994 to 1995,
throughout Wheatland and Golden Valley Counties (Figure 2).
These quarry excavations have
provided important paleontological insights into dinosaur phylogeny (Dodson 1986;
Dodson and Currie 1990), behavior, and taphonomy. For example, Careless Creek
Quarry produced an abundance of juvenile hadrosaurian dinosaurs that suggest
these dinosaurs nested in a coastal lowland environment (Fiorillo 1987a) in
contrast to previous hypotheses. With respect to taphonomic issues, nearly
one-third of the yield from Antelope Head Quarry contained bones with shallow,
subparallel sets of scratch marks on the bone surface, a feature attributable
to trampling activity (Fiorillo
1987b). Blob and Fiorillo (1996) illustrated the important role
that fossil size and shape can play in the composition of a microvertebrate
assemblage. In this contribution, trace fossils are used to infer the presence
and behavior of turtles. The tracks of modern tortoises were examined in order
to verify that the Judith River tracks were in fact made by turtles. This paper
reports the results of those observations and describes the tracksite as the
first record of turtle footprints in the Judith River Formation.
