Today was an unexpected treat: my partner and I were wandering around the Darwin Centre at London’s Natural History Museum when we were invited to a live talk by one of the museum’s helpful staff.
I knew this would be fun and informative. I was not expecting it to be Mesozoic. The speaker was Tim Ewin, a leading expert on crinoids. He was telling us about some new finds he had made at the Tithonian/Kimmeridgian boundary of the Jurassic, in the Kimmeridge Bay region of England. His team had found one group of crinoids twice the size of others in the region. When he investigated the larger group, he discovered that the crinoids were living on top of a large Plesiosaur carcass. Today’s oceans benefit greatly from the death of a large vertebrate such as a whale. When it falls to the sea floor it can become home to thousands of scavengers from all walks of life. The eight metre long plesiosaur provided just such an ecosystem for a wide variety of scavenging fish, sharks, bryozoa, and the (5-pointed) stars of our talk: crinoids. Up ’til now, no crinoids were known to benefit from ‘whale drop’, so this find was a world first for our understanding of crinoid behaviour – as well as a source of two new species (increasing the total number of Kimmeridgian crinoid species by 10%.
What an excellent image this conjures up: a large marine reptile sinking to the bottom of the ocean floor, causing a build-up of organic sedimentation, allowing crinoids to rise above the level of hypoxia and flourish.
Pencil in hand, I’m determined to get this picture into the gallery. Too self-critical for my own good, me.