Bienvenidos to my website. Here you will learn all about my 2004-2005 senior honors thesis project for the Geology Department of Amherst College in Amherst, Massachusetts.
This is me, digitally callibrating some unique Protichnites trackways in central Wisconsin.
The migration of animals from marine to terrestrial environments marks an important transition in the evolution of life on Earth. Trace fossils, or ichnofossils, of subaerial locomotion shed the most light on this subject because they are preserved in environments where body fossils are not. The earliest known specimens of this nature are arthropod trackways of the ichnogenus Protichnites from Upper Cambrian strata of Ontario. Continued examination of Cambrian strata for arthropod trackways in subaerial environments is thus important for furthering our understanding of the water to land transition.
Two Protichnites trackways from Wisconsin. The tracks are characterized by two rows of imprints, often arranged in V-shaped sets, and a medial impression, possibly due to a dragging tail.
In the summer of 2004, I worked with professor Whitey Hagadorn and a team of six other students in a multi-faceted field project in New York , Quebec, and Wisconsin . My part of the project focused on Protichnites trackways from Cambrian strata in these states. For reconnaissance and comparison purposes, I studied specimens in the field at Ausable Chasm, near Essex, New York, and quarries near Melocheville, Quebec, as well as museum specimens from the Redpath Museum of McGill University in Montreal, Quebec. These localities were known from documentations of Protichnites occurrences in the geologic literature. Most of the field work took place at the Krukowski Quarry near Mosinee, Wisconsin (see map to lower right), where 118 trackways were studied from loose slabs and in situ surfaces. The ichnofossils were described qualitatively and quantitatively, and I compiled a comprehensive data set that documented our work. A wide range of data points was retrieved for parameters such as width, but some consistencies were observed.
In Wisconsin, two surfaces were studied that exhibit arthropod trackways and indicators of subaerial exposure -fossilized raindrop impressions and wind-produced adhesion structures. These findings were especially important since the rock they are from is significantly older than the earliest known subaerial trackways. This research suggests that organisms could have been walking on land millions of years earlier than has been previously documented.
I complemented field work with a literature search of all reported occurrences of Protichnites, revealing 28 findings from every continent on the globe and spanning the rock record from the Cambrian to the Cenozoic. An analysis of their temporal, paleoenvironmental, and size distribution showed that ichnofossils that are named Protichnites change significantly through time, becoming smaller and coming from more terrestrial environments. I concluded that the term should be reserved for examples closely resembling the type specimens and similar specimens from the Late Cambrian of North America in order to avoid future confusion.
Additionally, an analysis of arthropods convergent in temporal, geographical, and morphological distribution with these Protichnites trackways suggests that they were made by either euthycarcinoids and/or aglaspids, and possibly other as of yet unknown creatures.
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