While it's virtually impossible to attribute these later wounds to any explicit attacker, in some earlier cases, especially during the Cambrian, those marks appear to be caused by specific predators such as the previously mentioned Anomalocaris - whose menacing appendages have been found in close association with trilobites everywhere from British Columbia to central Utah to southern China.Īs a side-note, since trilobites frequently shed their outer shell - much like many modern arthropods - the wounded exoskeleton of any surviving creature could not begin to heal until their subsequent molt occurred. On those blatantly bitten - or otherwise injured - shells, we can often see the appearance of asymmetric spines, indicators of previously healed injuries consistent with bite mark predation. Even in the Devonian and subsequent Carboniferous, a time when the entire trilobite line was in steep decline, the fossil record reveals evidence of their injuries, many of which the trilobite apparently survived. Still others apparently were able to generate increasingly thick calcite shells with each successive molt, providing these trilobites with a greatly enhanced ability to survive and pass along their genetic advantages.ĭespite their best efforts to protect themselves, however, the pathologic evidence indicates that trilobites were still often the subjects of predatory attack. Other trilobites had evolved to grow rows of menacing spines that covered their carapaces and afforded additional defense from predators. Current theory even speculates that some trilobites, such as the large Cambrian genus Olenoides (which often exceeded 12 cm in length), may have taken an occasional cannibalistic turn upon some of their smaller trilobite brethren. Fossilized trilobite carapaces sporting either healed or potentially fatal bite marks are pervasive in certain locales, such as the famed Middle Cambrian Elrathia kingi beds of Utah.īy the dawning of the Ordovician, 485 million years ago, a majority of trilobite species had developed the ability to enroll, which provided them with at least a degree of protection from the hostile world which surrounded them. Indeed, those ancient oceans were filled with an ever changing, and ever more dangerous array of predators, all seemingly intent on turning the local trilobite population into little more than an afternoon snack.įrom the moment they emerged on the world stage some 521 million years ago, trilobites were in constant peril from a lethal cast of predators, ranging from the legendary Cambrian-age Anomalocaris, to giant Silurian eurypterids, to armored Devonian fish. ![]() Such stark evidence offers emphatic proof that the primal seas in which these Paleozoic arthropods flourished for 270 million years rarely provided a hospitable environment. Judging by the variety of lethal-looking bite marks and healed injuries that frequently adorn their fossilized exoskeletons, it seems safe to say that life as a trilobite presented some daunting challenges.
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