Only very occasionally are the legs, antennae and digestive systems of trilobites preserved. This gallery shows some exceptional examples ranging in age from Early Cambrian to Early Devonian. The specimens come from China, Australia, Morocco, USA and Germany. Orders Redlichiida, Ptychopariida, Odontopleurida and Phacopida are represented. They provide extraordinary glimpses of what these extinct arthropods would have looked like in life and also rare views of the animals' internal anatomy. In addition to the photographs, X-radiographs and microCT scans are used here to illustrate limb morphology.

The finely preserved limbs and antennae shown here, even exhibiting minute claws and setal hairs, were recorded by early precipitation of pyrite. The pyrite has subsequently oxidized in the case of the Chinese and Moroccan fossils, leaving red and orange stains and external molds of tiny pyrite framboids. The mineralized alimentary canals and gastric caeca shown have recently been discussed by Robison & Babcock (2011), who suggested that phosphate precipitation in trilobite guts began within about a week of death. They inferred from the lack of sediment fill in the guts of Meniscopsia and Coosella that these animals were not sediment-deposit-feeders, but rather predaceous. Note that the Cedaria gut illustrated below is sediment-filled.

To complement all these images of beautifully preserved appendages, I've added a set of pictures to show what trilobites did with those limbs: walking, "galloping", burrowing and ploughing. Richard Fortey discussed the Omani occurrence I illustrate here in his book, "Trilobite!" He writes, "Sandstones and limestones formed low bluffs, so if you followed a single bedding plane you could crawl on your hands and knees over a Cambrian sea-floor which preserved every scratch and footprint." He concludes that, "Maybe we are getting as close to a particular moment of trilobite time as we ever should: one scrape of a limb, one flick of a hair."

I have also added some images from Raymond's 1920 work on the complete anatomy of trilobites, together with some notes on the history of discoveries ( http://lifeartearth.blogspot.com/2013/11/trilobite-limbs-antennae-and-guts.html ).

A new paper of relevance to the topic: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0184982