Post by Joe Botting on Feb 12, 2011 5:22:47 GMT -5
Dear All,
Here’s a familiar scenario: someone shows me a weird circular thing made of radiating lines. I then get very excited, and explain it’s a choiid – a rare early sponge known mainly from the Burgess Shale-type faunas. The response? “Oh, so that’s what it is… I’ve be throwing these away for years!” It’s happened at least twice now, and the rate that they’re turning up, there are bound to be more. So, I thought I’d try it on you folks…
Has anyone seen one of these?
This is the simplest form, called Choiaella. Choia itself is more complicated, with long radiating spines as well. It’s been reconstructed for decades upside-down, and we know now that at least some species were on top of a tall stalk. Anyway, here’s an… imaginative… reconstruction from the Nanjing Palaeontology Museum. You can imagine what it would look like flattened in a mudstone.
Although known mostly from the Burgess Shale and equivalents, Choia is now known from the Ordovician of Morocco and the Silurian of Greenland and China (unconfirmed). Choiaella has turned up in the Ordovician and Silurian of southern Scotland, and now also the Ordovician of Wales (all these just happening to be the places we’re looking…). In other words, I’ve a hunch it’s everywhere. Can anyone confirm?
Here’s a familiar scenario: someone shows me a weird circular thing made of radiating lines. I then get very excited, and explain it’s a choiid – a rare early sponge known mainly from the Burgess Shale-type faunas. The response? “Oh, so that’s what it is… I’ve be throwing these away for years!” It’s happened at least twice now, and the rate that they’re turning up, there are bound to be more. So, I thought I’d try it on you folks…
Has anyone seen one of these?
This is the simplest form, called Choiaella. Choia itself is more complicated, with long radiating spines as well. It’s been reconstructed for decades upside-down, and we know now that at least some species were on top of a tall stalk. Anyway, here’s an… imaginative… reconstruction from the Nanjing Palaeontology Museum. You can imagine what it would look like flattened in a mudstone.
Although known mostly from the Burgess Shale and equivalents, Choia is now known from the Ordovician of Morocco and the Silurian of Greenland and China (unconfirmed). Choiaella has turned up in the Ordovician and Silurian of southern Scotland, and now also the Ordovician of Wales (all these just happening to be the places we’re looking…). In other words, I’ve a hunch it’s everywhere. Can anyone confirm?
