Mark Wilson March 9th, 2014
RICHMOND, INDIANA–Meet Coleman Fitch (’15) standing on the iconic outcrop of the Whitewater Formation (Upper Ordovician) on Route 27 about a mile south of Richmond (C/W-148; N 39.78722°, W 84.90166° — which has a nice Google Maps street view). This was his first day of fieldwork for his study of the complex relationship between borings and encrusters on brachiopods and mollusks. Note that Coleman has manfully taken off one glove for fossil collection. Despite the sun, we were freezing for science. Later in the day we collected from a warmer exposure of the Liberty Formation (Locality C/W-149) on IN-101 (N 39.48134°, W84.94843°).
Our collecting was very successful today. We found numerous examples of “half-borings” on trepostome bryozoan attachment surfaces, and many other curious fossils showing an interplay of early diagenesis (especially aragonite dissolution and calcite precipitation) and biotic processes.
Above is an example of the fun and complex fossils at the Whitewater locality. What processes do you think this specimen represents?
Tomorrow I meet William Harrison (’15) in northern Kentucky to search for bored bryozoans and bioclaustrations. It promises to be much warmer down there!
Mark Wilson March 9th, 2014
This is another fossil that has sat in a display case for decades in Scovel before I really examined it. Unlike last week’s specimen, though, it has no identifying label on its reverse. This is always a serious disappointment for science — no location! I show the fossil above with a front and back view (as much as there is a front or back). We are looking at an auditory bulla (part of the middle ear system) of an ancient whale. The most we can say is that this may be from a type of sperm whale that lived during the Neogene. Likely this specimen was collected on the east coast of the United States, maybe Maryland or Virginia.
Surprisingly, whale ear bones are rather common in the later fossil record. They seem to have been of denser bone than the rest of the whale skeleton, so they were better preserved. The auditory bulla is a bony cover for the delicate middle ear bones and tissues. In humans it is part of our temporal bone. Whales have several adaptations in their ears for hearing underwater. They have no external ear opening. They use instead the lower jawbone to transmit vibrations to the ear complex (something like what many snakes do). They have a pad of fat to enhance these vibrations for the tiny ear bones (tiny relative to the massive size of the whale). You can learn much more about fossil whale ear bones at this excellent blog post from the Virginia Museum of Natural History.
You are asking, though, fine enough, but how can I use a fossil whale ear bone? There’s a video to train you! These bones have “ancient, ancient memory” that is “preserved sonically”. Just be sure to hold it in your non-dominant hand and remember that “this is an art”. Do it correctly and you will have tapped into the wisdom of our ancient whale brothers and sisters. To think that every day I walked blithely by this portal to the Knowledge of the Ages.
Fraser, F.C. and Purves, P.E. 1960. Hearing in cetaceans: evolution of the accessory air sacs and the structure and function of the outer and middle ear in recent cetaceans. Bulletin of the British Museum (Natural History) 7: 1-140.
Ketten, D.R. 1997. Structure and function in whale ears. Bioacoustics 8: 103-135.