アメリカ自然史博物館のインスタグラム(amnh) - 8月8日 22時49分

It’s time for Trilobite Tuesday! Exactly when trilobites started to generate defensive spines is a question still open to scientific speculation and debate. It appears that a few Lower Cambrian members of the Olenellid and Redlichid lines, such as Esmeraldina rowei, did possess a rudimentary form of this adaptation. But by the Middle Cambrian, such species as Kootenia randolphi (photo) and Olenoides superbus featured an imposing series of spines projecting along their axial lobe. A number of scientists believe that these initial spines may have been somewhat flexible, and perhaps were used by trilobites as swimming rudders as much as for protection. Some have speculated that spines may have served as nerve-filled sensory organs, increasing a trilobite’s ability to “feel” disturbances in the water around them. Others postulate, however, that these primitive projections represented nothing more than the start of an undersea “arms race” which saw creatures around the globe gearing up for daily battles for survival. #trilobitetuesday #trilobite #amnh #trilobitefossil

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