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The Verge Review of Animals: trilobites

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The Lego of the Ordovician seas

sulla55

This column is part of a series where Verge staffers post highly subjective reviews of animals. Up until now, we’ve written about animals without telling you whether they suck or rule. We are now rectifying this oversight.

When I was a teenager, I spent my summers up on North Hero, one of the Vermont islands in Lake Champlain. The island chain sits on top of the Trenton Group, a formation of rocks that date back to the Ordovician period. Find the right band of sedimentary rock, and you’ll likely find something peeking out at you when you start turning over pebbles: trilobites. I love finding these little treasures hidden amidst the crumbling outcrops here.

They were survivors, up until they went extinct

Trilobites have an epic history behind them, from the time they first appear in the fossil record 521 million years ago. They had a good run of the Earth for a while there, too: over 270 million years, which is longer than the time humans and dinosaurs have been around. Combined. They were survivors, up until they went extinct.

If you go to a museum or a rock shop, the trilobites will immediately grab your attention. There’s something perfect about them: their proportions, with an elegant cephalon, tapered lobes and tail are elegant in ways that lobsters or horseshoe crabs are not. That’s most interesting about their fossilized remains is their complexity and variety. Their heads are composed of fused plates, with faces which contained amazingly complicated eyes. Richard Fortey, author of Trilobite! Eyewitness to Evolution writes that "the eyes of trilobites are composed of elongate prisms of clear calcite," and that they were sophisticated in these early days of life. Their articulated, three-lobed body (from where they get their name), could contain anywhere from two to over a hundred segments, which protected the creature’s organs and legs.

Andrew Liptak

Paleontologists believe that the epic story of the trilobite began in what’s now Siberia, where they radiated out to take over the Cambrian seas. They exploded in diversity as they radiated across the world during the Cambrian and Ordovician eras. Their numbers began to decline throughout the Silurian, Devonian and Carboniferous periods, before completely petering out by the end of the Permian for reasons unknown. They’ve been absent from our oceans for hundreds of millions of years, although I hold out hope that some mad scientist will bring them back through genetic engineering.

The earliest trilobites that we know of are from an order called Redlichiida, which appeared midway through the Lower Cambrian and lasted until about the middle Cambrian. They were small, oval arthropods that had the distinctive three lobed exoskeleton and broad cephalon (headshield). They were followed by another order, which also appeared in the lower Cambrian, the Ptychopariida. You’ve probably seen these distinctive, button-sized trilobites at a gift shop or as a piece of jewelry. These little guys survived through the Ordovician era only to perish during the series of Ordovician–Silurian extinction events that wiped out nearly 85 percent of all marine species.

Some species sprouted spectacular spines

It was the Ordovician era that provided the best trilobites. The shores of Lake Champlain yield fragmented Triarthrus pieces, and the first trilobite that I ever bought was a crumbling Flexicalymene. Collecting trilobites was the perfect nerdy hobby for me when I was in high school: the sheer variety is pretty astonishing. Some species sprouted amazing spines from their backs, particularly later in the geologic timeline, which make for amazing conversational pieces for your home.

If threatened, they could curl up into a tight ball, using their outer exoskeleton and any available features to protect themselves. I’ve got a couple of those kicking around: tiny balls of black stone perfectly preserved for millions of years. If there's any upside to their extinction, it's in imagining what would happen if you stepped on one of these guys while enjoying a day at the beach.

Our fascination with trilobites goes back millennia with possible descriptions dating back to ancient times. Welsh naturalist Dr. Edward Lhwyd first formally described the fossils in 1679 in the Philosophical Transactions of the Royal Society in a letter titled "Concerning some regularly figured stones lately found, and observations of ancient languages." The regularly figured stones were Ogygiocarella debuchii, a species from the Ordovician rocks surrounding Dynevor Park in Wales. Just under a century later, trilobites were formally identified as a group of animals, with research conducted regularly throughout the decades to follow. We’ve been fascinated with them ever since, whether it’s coming across them in a store, or embedded in a stray piece of shale on a rocky beach in Vermont.

Trilobites

Verge Score: 9.4

9.4

Verge Score

Good Stuff

  • Awesome spines

  • Paleozoic roombas

  • Cuter than Horseshoe crabs

Bad Stuff

  • Completely and utterly extinct

  • Lego of the ocean floor

  • Closest living relatives are horseshoe crabs