Christmas decorations for the natural scientist

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This may end up being a feature of one article only, but I still wanted to write it. Every year I tweet about ‘the Christmas Eurypterid’ and just assume followers know what that means. Given my followers, that’s probably true. But just in case you don’t…So this is the Christmas Eurypterid, on my Christmas tree:

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It vaguely resembles a lobster without as many legs, without the same shaped tail, and with different eyes. I bought it from an American seller on Etsy several years ago (PaleoGirlCrafts – thanks to Laura Breen for finding that for me), but sadly they no longer seem to be active. Which at least makes it an endangered species!

As cute as it looks in craft form, eurypterids were actually top predators in the oceans when they were alive. For they have actually been extinct more than 200 million years. Yet in the seas from the Ordovician through to the Permian (that’s taking is back more than 450 million years) they would have been feared.

Eurypterid fossil, on display at North Carolina Museum of Natural Sciences By Ryan Somma, used under Creative Commons Attribution

Eurypterid fossil, on display at North Carolina Museum of Natural Sciences
By Ryan Somma, used under Creative Commons Attribution

While the toy is about 10 centimetres long, the real things got pretty big: well over 2 metres. Twenty times the one on my tree. Bigger than the tree itself.

They varied, many were more like my Christmas eurypterid, but the big ones were oceanic predators eating other invertebrates, small fish, and anything else that came past.

Reconstruction of a eurypterid Public Domain

Reconstruction of a eurypterid
Public Domain

Eurypterids were arthropods, the same group of invertebrate animals that includes spiders, insects, and crabs. Their closest living relative is the horseshoe crab. But no living arthropod gets close to the biggest eurypterid, in fact the largest eurypterid was probably the largest arthropod of all, if we are just thinking about the body. Some spider crabs may have a leg-span that gets them close to 4 metres across, though with a body of less than half a metre.

So there we have it. Cute on the Christmas tree, maybe less cute if you’d met one on a moonlit swim 390 million years ago!


There are other animals on my Christmas tree, so I may share others in future blog posts. But this is definitely the most interesting!

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This entry was posted in Evolution, Fossils, Geology, Invertebrates and tagged , , , , , , . Bookmark the permalink.

I welcome thoughts, comments and questions, so please feel free to share anything at all. Thanks, David

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