|The bluffs south of the Washington Avenue Bridge. Not recommended.|
One of the types of fossils Stauffer is associated with is scolecodonts, jaw elements of predatory polychaetes, aka bristle worms. Worms don't often leap to mind as great candidates for fossils, as opposed to, say, snails and clams, which have the enormous advantage of durable shells. Generally, this impression is quite correct; most worm-type creatures ("vermiform", if you're in the market for another vocabulary word) lack substantial hard parts and are limited to providing burrows and other trace fossils. Burrows are common fossils throughout the Paleozoic rocks of the Twin Cities, ranging from mm-scale to the diameter of a finger. Of course, not all of them are of a wormy persuasion, but for many soft-bodied invertebrates, they are all we will ever know of their existence. Dokken (1987) provides a good overview of Ordovician burrow types in Minnesota.
|A vertical burrow in the Platteville Formation in the vicinity of the Stone Arch Bridge, near the Steamplant.|
Stauffer (1933)'s scolecodonts came from several localities and formations in the Twin Cities, including the Washington Avenue Bridge bluffs (Glenwood Formation), the former Johnson Street Quarry (Platteville Formation), a well in St. Paul (Platteville), the Decorah Shale of the University of Minnesota campus, and the Ford Bridge bluffs (Decorah). He noted that the specimens were often water-worn and poorly preserved, and suggested that they had been exposed to erosion, with the original worms perhaps living in tidal flats or near the low water line, like some modern forms. Stauffer got a few dozen new species and genera out of his scolecodonts, probably too many, although parsing scolecodonts can be difficult (Eriksson 1999). More problematic is that Eriksson (1999) found that Stauffer's illustrations don't always correspond well to the actual fossils. As with so many other topics in paleontology, more research and more specimens would be welcome! More information (and images) concerning scolecodonts of a similar age can be found at Cincinnatian Fossils and Stratigraphy, Dry Dredgers, and Fossilid.info.
|Local scolecodonts from Stauffer (1933)|
...and obviously, I got stuck and wrote about worms.
Dokken, K. 1987. Trace fossils from Middle Ordovician Platteville Formation. Pages 191–196 in R. E. Sloan, editor. Middle and Late Ordovician lithostratigraphy and biostratigraphy of the Upper Mississippi Valley. Minnesota Geological Survey, St. Paul, MN. Report of Investigations 35.
Eriksson, M. 1999. Taxonomic discussion of the scolecodont genera Nereidavus Grinnell, 1877, and Protarabellites Stauffer, 1933 (Annelida, Polychaeta). Journal of Paleontology 73(3):403–406.
Stauffer, C. R. 1930. Conodonts from the Decorah Shale. Journal of Paleontology 4(2):121–128.
Stauffer, C. R. 1933. Middle Ordovician Polychaeta from Minnesota. Geological Society of America Bulletin 44(6):1173–1218.
Stauffer, C. R. 1935a. The conodont fauna of the Decorah Shale (Ordovician). Journal of Paleontology 9(7):596–620.
Stauffer, C. R. 1935b. Conodonts of the Glenwood beds. Geological Society of America Bulletin 46(1):125–168.
Stauffer, C. R. 1945. Some Pleistocene mammalian inhabitants of Minnesota. Minnesota Academy of Science Proceedings 13:20–43.
Stauffer, C. R., and G. A. Thiel. 1941. The Paleozoic and related rocks of southeastern Minnesota. Minnesota Geological Survey, St. Paul, MN. Bulletin 29.