アメリカ自然史博物館のインスタグラム(amnh) - 7月26日 06時37分

It's time for Trilobite Tuesday! As superficially similar as some trilobites may appear to certain contemporary creatures--perhaps most notably, isopods and horseshoe crabs-- in all honesty, any and all such similarities are nothing more than shell deep. Indeed, appearances aside, the fact is that trilobites have no direct living relatives, and while they do share many of the key characteristics of the arthropod phylum with everything from brine shrimp to wood lice to lobsters, their primeval morphology marks their members as a totally unique line of the planet's family tree. So when you look at the fossilized remains of a trilobite, whether it is a one-inch long Cambrian Elrathia kingii, or a foot-long Ordovician Isotelus maximus (photo), please consider that lurking under those imposing calcite carapaces were creatures that represented one of our planet's first and most successful experiments with life. Quite simply, from their initial moments on the planet some 521 million year ago, few animals were ever as evolutionarily “perfect” in their morphological design as the amazing trilobite. #trilobite #trilobites #trilobitetuesday #trilobitetuesdays #fossils #fossil #extinct #extinction #naturalhistory #amnh

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