EES Distinguished Speaker Dr. Victoria McCoy Investigates "Exceptional Fossils"

  • Apr 6, 2019

Our Distinguished Speaker Series this week features Dr. Victoria McCoy.

"Exceptional fossils in carbonate concretions: three case studies"

Carbonate concretions are well-known for containing well-preserved soft tissue fossils. Concretionary fossilization is typically characterized by three features: exceptional preservation of labile soft tissue structures; biomolecules preservation; and three dimensional preservation. This combination of features makes fossils in carbonate concretions a valuable source of paleobiological information. Here I present three case studies investigating exceptional fossils inside carbonate concretions. (1) The Tully Monster is an enigmatic soft-bodied fossil organism known only from the siderite concretions of the Carboniferous Mazon Creek fossil site. Despite being studied for more than 50 years, there is still no consensus about which phylum the Tully Monster belongs to. Based on re-investigating the well-preserved soft tissue morphology and investigating for the first time the well-preserved biomolecules, I argue that the Tully Monster was most likely a chordate. (2) Eurypterids ('sea scorpions') are an extinct group of aquatic chelicerate arthropods, related to scorpions and horseshoe crabs. Here I present an investigation of a eurypterid preserved in a concretion showing exceptional, three-dimensional preservation of the soft tissue gill structures. The gill structure suggests that eurypterids are more closely related to arachnids than to horseshoe crabs, and also reveals a few interesting features of eurypterid respiration. (3) Horseshoe crabs, and related organisms, are known to fluoresce under UV light. This fluorescence is assumed to also occur in extinct horseshoe crabs, but has never previously been demonstrated. The Mazon Creek concretionary fossil site includes some exceptionally well-preserved specimens of the extinct horseshoe crab Euproops which still fluoresces, even after 300 million years of diagenesis. Chemical and histological investiagtions of these unique specimens -- which depend upon exceptional preservation of the labile exocuticle layer and the fluorescent biomolecules contained therein -- allow us to compare the ancient fluorescent to modern fluoresce, and may help us understand whether or not eurypterids fluoresced. 

Join us for this valuable source of paleobiological information on Friday, April 12, 2019 at 12:30 PM in Room 204, Natural Science Building on the East Lansing campus.