アメリカ自然史博物館のインスタグラム(amnh) - 8月23日 05時26分

It's time for Trilobite Tuesday!
Trilobites featured an almost dizzying array of sizes, shapes, spines and segments. Their body plans, while all following a fundamentally similar three-lobed pattern, presented an incredible diversity of design. Some trilobite species reached lengths in excess of two feet. Others never exceeded a fraction of an inch. Some had multi-faceted eyes sitting atop three-inch stalks… others had no eyes at all. During their 270 million year trek through evolutionary time, these amazing arthropods generated more than 25,000 scientifically recognized species. Such unimaginable longevity and multiplicity has continually presented paleontologists with a daunting yet elemental challenge; how to best categorize and distinguish one group of trilobites from another. Quite simply, the issue becomes one of finding the best manner in which to classify these primordial creatures so that we can gain at least a fundamental understanding of which family, genus and species produced a logical line of descendants. Once we begin to tackle this dilemma, we can then place the resulting trilobites, such as this Bathynotellus, into taxonomic orders that are manageable and to some degree practical. By doing so, scientists have tried to create some mentally digestible “order” out of relative chaos. #trilobite #trilobites #trilobitetuesday #amnh #fossil #fossils

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