Asaphiscus wheeleri Trilobite with Preserved Anomalocaris Bite

Asaphiscus wheeleri

Trilobite Order Ptychopariida, Family Asaphiscidae

Geological Time: Middle Cambrian

Size: 44 mm long

Fossil Site: Wheeler Shale Formation, Millard County, Utah

Anomalocaris BiteComing from the Cambrian Wheeler Formation deposits of Millard County Utah this is a detailed example of the trilobite Asaphiscus wheeleri. These trilobites are often found with disarticulated or missing free cheeks. This fine example is well-articulated, with a dark black exoskeleton which contrasts well with the grey shale matrix which derives its color from its high organic content. What makes this one of interest is the fact that a section of the pleural is missing, the result of the trilobite’s being bitten, presumably by an Anomalocaris. Since there is no evidence for growth at the edge, it was most likely the direct cause of death. Interestingly, these bites are typically found on the right side of the trilobite, indicating some preferred attack mode by the terror of the Cambrian. Evidently the predator here was directionally-challenged, coming in from the left of the hapless trilobite seen here.

Related: Cambrian Explosion Biota from Utah

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