October 27, 2009 | David F. Coppedge

Trilobites Found in Fool’s Gold: What Does It Mean?

Trilobites are icons of the Cambrian and Ordovician periods.  When thousands are found in beds over a wide area encased in pyrite, with no sign of decay, what does it mean?  A team publishing their findings in Geology suggests it means rapid burial.1  Here’s the abstract from their paper:

Pyritization of soft tissues is extremely rare.  Pyritized fossils have been discovered at six new localities spanning 54 km of outcrop of the Ordovician Lorraine Group of New York State, suggesting that soft-tissue pyritization is widespread in the Taconic basin.  Notable new taxa with soft-tissue preservation include ostracods and other arthropods.  Such fossils are rare and occur within 4�9-cm-thick mudstones representing single rapid depositional events.  High ratios of reactive iron to total iron and high values of [delta]34S, together with a near-absence of disarticulated and fragmented skeletal material, suggest that organisms in these pyritic horizons were buried rapidly and underwent bacterial sulfate reduction in porewaters rich in highly reactive iron and low in organic carbon.  These conditions facilitated iron sulfide precipitation within and on decaying carcasses.  Such conditions occur repeatedly in some fine-grained distal turbiditic facies of the Taconic foreland basin.  Pyritized soft-bodied fossils await discovery elsewhere in the Lorraine Group.

The Taconic Basin covers a good deal of North America.  The soft-tissue preservation is exquisite; pictures in the publication look like golden ornaments.  They found partially and fully pyritized specimens with few molt indications, indicating that these animals were transported a short distance and buried quickly.  “The trilobites were deposited both dorsal-side up and ventral-side up and are not sorted by size, although there is some indication of current alignment,” they said.  The mudstones also encased brachiopods, cephalopods and a few bivalves.  The geologists speculated that repeated instances of rapid deposition occurred:

The discovery of new beds and localities with soft-tissue pyritization demonstrates that conditions required for exceptional preservation occurred repeatedly in the Taconic foreland basin.  Horizons with pyritized fossils may have escaped discovery due to the low abundance of fossils and their presence within beds rather than on bedding-plane surfaces.  Like the Burgess Shale, the Beecher’s-type taphonomic window is widespread.  Deposition of muddy turbidity currents in dysoxic bottom waters is common, and mudstone facies representing such conditions occur frequently in the Taconic basin, extending from Canada to the southern United States, and possibly elsewhere.

The rare conditions for pyritization of soft-tissues, however, should suggest that these unusual fossil horizons are temporally related. 

1.  Farrell, Martin, Hagadorn, Whiteley and Briggs, “Beyond Beecher’s Trilobite Bed: Widespread pyritization of soft tissues in the Late Ordovician Taconic foreland basin,” Geology, October 2009, v. 37, no. 10, pp. 907-910, doi: 10.1130/G30177A.1.

One must be cautious when reading the findings of uniformitarian geologists to separate the data from the interpretations.  They just said that these pyrite fossil beds, “like the Burgess Shale,” represent a widespread “taphonomic window” – i.e., a wide-area opportunity for fossilization (taphonomy).  But notice: they found very little evidence of decay; the fossils are mostly articulated (not separated into parts); they admit these had to be buried rapidly; they could be continental in extent.  Isn’t it instructive, too, that geologists have not been looking for such things; these “escaped discovery” till now, even though they could be found from Canada to Mexico.  Sounds like they must have been pursuing a fool’s goal.  Never in their wildest dreams would they consider that something global happened to bury these widespread fossils quickly in one event.  That’s because they are high on Charlie & Charlie* Brand Incense.  It slows down their mental metabolism and focuses their dreams on slow and gradual processeszzz operating over millionzzz and millionzzzzzz of yearzzzzzzzzzzzz.  The rest of us can be wide awake to see what these data are telling us.
*Lyell and Darwin

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Categories: Fossils, Marine Biology

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