Death Decay and Disarticulation Death

The taphonomic history of most organisms generally begins with their death, although in arthropods, including trilobites, molted exuviae also become a part of the preserved record. Death of organisms may involve gradual normal mortality. However, many of the spectacular Lagerstatten occurrences involve mass mortality of many individuals and species due to environmental crises (Brett and Seilacher 1991). These crises may include storm and seismic shock events, volcanic eruptions such as those at Pompeii, overturn of the water column, and anoxia. However, only the mortality events associated with episodes of burial will be recorded as such. Most bodies decay rapidly after death, with a resultant loss of soft parts.

Scavengers of all sorts are also part of the normal fauna, and a dead animal can be expected to become a food source for a wide variety of other animals, which in Paleozoic seas included other trilobites. The result of this is that a dead trilobite exposed on the seafloor can be expected to become disarticulated and the body parts scattered within a relatively short period of time. Consequently, very shortly after death the animal must be buried at least deeply enough to physically inhibit disarticulation. Lowered oxygen inhibits scavenging and also favors the preservation of intact skeletons.

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