SOME INTERESTING TRACE FOSSILS

The following information and images concern some trace fossils (= tracks and trails left behind by the activities of various ancient animals) that my students and I found during the many decades that I taught my undergraduate and graduate paleontology classes, as well as  my field-mapping classes.

An unnamed feeding-trail? trace fossil in a slab of rock (10 inches length) consisting of metamorphosed muddy silstone. Early Cambrian age, Inyo Mountains, eastern California. 

Side view of Gyrolithes sp., a spiral trace fossil that reminds me of an "automobile spring" about 4.5 inches tall, in mudstone of the Eocene Cozy Dell Shale, Ventura County, Sespe Creek, southern California. Gyrolites burrows, like this one, are  probably the result of  activity of a decapod crustacean. This trace fossil is typically found in ocean waters largely unaffected by storms.

The next two views are of meniscate burrows from Miocene lacustrine-fluvial deposits in the Miocene non-marine Diligencia Formation, Orocopia Mountains, Riverside Coutny, southern California (see Squires and Advocate, 1984, for more information).

Side view of meniscate burrows. A U.S.A. quarter coin is used for scale.

Top view of another slab with meniscate burrows from the Miocene lacustrine-fluvial deposits in the Miocene non-marine Diligencia Formation, Orocopia Mountains, Riverside County, southern California. 

Top view of a large (about 10 inches diameter) circular-trace fossil in  fine-grained sandstone. Locally unknown. This specimen was displayed in my paleontology-classroom for decades (hopefully the specimen is still there). Many geologists have seen it, but, so far, no has been able to assign an ichnogenus name to it. 

Note: If you are interested in seeing some additional trace fossils that I have shown earlier, check out my blog post on Rusophycus, August 29, 2014. Especially interesting in that post are my images of a plaster cast of a Cambrian trilobite nestled inside of its resting/feeding? “burrow.”

Reference Cited:

Squires, R.L. & D.M. Advocate. 1984. Meniscate burrows from Miocene lacustrine-fluvial deposits, Diligencia Formation, Orocopia Mountains, southern California. Journal of Paleontology 58(2):593-597, figs. 1-2.