Martin Lockley reports in Tracking Dinosaurs of
clams trampled by sauropods (see below). This
happened in the bed of a 150 million year old
lake in the Morrisson Formation of Colorado.
This find seems to me more informative regarding
the eco-system sauropods lived in. that's because
it's unlikely that the clams were later washed into
the sauropod tracks.
Take a look at a drawing of the tracks from
Tracking Dinosaurs at
Heinz Peter Bredow
Martin Lockley "Tracking Dinosaurs", 1991 page 145
Since dinosaurs had such a significant impact on the sub-
strates they trampled, we would expect them also to affect
plants and animals associated with these substrates. In 1862
it was reported that an Iguanodon had disturbed Cyrena clam
shells in the lower Cretaceous Wealden beds of England. An-
other example of clam carnage was reported from the Jurassic
Morrison Formation of Colorado. (4) In this instance a bronto-
saur had trampled and killed at least two dozen clams in the
space of a few strides (Fig. 11.3). Modern studies reveal that
livestock can trample and injure or kill freshwater clams.When
these poor creatures valiantly regenerate their broken shells,
they produce healed but mishappen forms that have been re-
ferred to as "molluscan monstrosities." (5)
(4) To date these are the only reports of dinosaurs
killing invertebrates. However, this type of
inadvertant dinosaur destruction must have
been quite common. Tylor. A. 1862. "On the
Footprints of an Iguartodon Lately Found at
Hastings." Quarterly Journal of the Geological
Society of London, v. 18, pp. 247-53. Lockley,
M. G., Houck, K., and Prince, N. K. 1986.
"North America's Largest Dinosaur Tracksite:
Implications for Morrison Formation Paleoe-
cology." Geological Society of American Bulletin,
v. 97, pp. 1163-76.
(5) Baker, F. C. 1901. "Some Interesting Mollus-
can Monstrosities." Transactions of the Academy
of Sciences, St. Louis, v. 11, pp. 143-6.