Altiocculus Trilobite with Bite Mark

Altiocculus harrisi

Trilobites Order Ptychopariida, Family Alokistocaridae

Geological Time: Middle Cambrian

Size (25.4mm=1 inch): 14 mm long by 10 mm wide on a 50mm by 40 mm matrix

Location: Wheeler Formation, House Range, Millard County, Utah

Altiocculus harrissiDescription: Coming from the Cambrian Wheeler Formation deposits of Millard County Utah this is a detailed example of the trilobite Altiocculus harrisi. 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 gray shale matrix which derives its color from its high organic content. This is an uncommon trilobite, rarely seen in such a fine state. What makes this even more rare is the fact that a section of the right pleural lobe is missing, the result of the trilobite’s being bitten, presumably by an Anomalocaris. Interestingly, these bites are typically found on the right side of the trilobite, indicating some preferred attack mode by the Terror of the Cambrian. This is only the second example of this type of trilobite with a preserved bite mark I have come across, a rare occurrence on a decidedly-uncommon trilobite.

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