nature, she echoes
variation on a theme
of fractal design
changed over millennia
past fossils like growing leaves
Brachiopods (literally arm-foot) appeared at the beginning of the Cambrian and peaked during the Ordovician (490-445 mya).
What’s fascinating is that while most of them have gone extinct, some species of brachiopod are still around, so it’s a story of survival. Even though I’m working with fossils of creatures that died hundreds of millions of years ago, a number of their descendants and cousins are still on sea floors the world over. (Around 100 different genera still exist, over 5000 are known to have existed.)
Brachiopods are bottom feeding marine creatures with two shells. (You can see the lip of their joint nicely in the fossils I picked up.) They’re symmetrical when viewed from above, unlike bivalves.
Mine are members of the spiriferidia. I think they’re of the Mucrospirifer genus. Some of the rock hounds on deviantart are thinking along the same lines, but I don’t have a location of origin to narrow matters down.
The one I bought more recently was from southwest Ontario and identified as a Mucrospirifer thedfordensis from the mid Devonian. (That’s about 385 million years ago.) My previous stash were probably from the same general area. (I’ve been told New York State is another possible origin.) This genus reached its highest levels of number and diversity during this period, so it’s a probably a safe guess that all the ones I’ve worked with are all (loosely!) around the same age.
I’m not sure all of my original stash were of the same species to begin with; since some were chubbier like the thedfordensis and others were much slimmer, though they all share the same basic shape and nice curve. I don’t know how much variation existed between individuals of a species.
(I’m not very good at identifying fossils beyond the general. Anyone know of a good, *simple* guide for fossils? I like playing with ammonites too but can never divide them into species either.)
They would have lived in soft mud on the sea floor and attached to the bottom with a fleshy stalk. They were found all over the world. Brachiopods took a hit at the end of the Devonian period, but a diverse number survived into the next hundred million years. A lot of brachiopod species went extinct during the Permian Mass Extinction ( about 251 mya), along with a lot of the other ‘classic’ species we’re familiar with–like the trilobites. The corals of the era were so badly destroyed it took over 10 million years for them to recover, and 150 million for biodiversity to bounce back to pre-extinction levels. (Some of the Mucrospirifers survived the Permian Mass Extinction and held on into the Jurassic period.)
Walking past the brachiopods on a dealer’s table en masse they reminded me of fallen ginkgo leaves. I decided that I had to play with that resemblance by wrapping them with ‘stems.’ Now I want more to experiment with, and to learn how to properly identify the little suckers. I’d really like to take the term butterfly shells literally and do a butterfly shaped wrap somehow.
(Yes, I wrote a tanka over a fossil, I wrote a few about different types actually…)