Mark Wilson November 14th, 2014
These fossils are a joy to present this week. Lizzie Reinthal (’14), Bill Ausich (Ohio State University) and I have a new paper out in the latest issue of the Journal of Paleontology. It is titled: “Parasitism of a new apiocrinitid crinoid species from the Middle Jurassic (Callovian) of southern Israel”. Allow me to introduce Apiocrinites feldmani, a new articulate crinoid species. In the image above we have fused columnals (the “buttons” that make up a crinoid stem) upwards through two radial plates (from the calyx) with two pits and associated swollen columnals (due to a nasty little parasite; see below). A gnarly beast it is, and that’s what makes this creature interesting. I posted another even more twisted specimen earlier.
This new species is named after my friend Howard Feldman of Touro College and the American Museum of Natural History in New York. He was a pathfinder with the Matmor Formation and its fossils in Hamakhtesh Hagadol, Negev, southern Israel.
Apiocrinites feldmani is a small crinoid that lived in a brachiopod-coral-sponge community with a larger cousin named Apiocrinites negevensis (named earlier by Bill Ausich and me). Above we see a pluricolumnal (range of articulated columnals) with the holdfast of another A. feldmani wrapped around them. (I’m also showing off my mad skills at extracting an image from its background.)
This pluricolumnal shows how bad the parasitic infection could get for many A. feldmani specimens. These gall-like growths are responses to some soft-bodied parasite that became embedded within the crinoid skeleton. The crinoid stems were deformed and likely lost considerable flexibility because of these parasites.
This is a cross-section through one of the pits in an A. feldmani stem. Note that the narrow end of the pit begins at the articulation between two columnals. The parasite apparently wedged into that space, forcing the crinoid to grow around it as it grew itself. The result was a conical pit with swollen columnals surrounding it.
Here we’re looking straight into one of the conical pits with a magnificent swelling around it. You can barely make out the articulation lines of the swollen columnals. Sometimes these cone-shaped pits were closed off by crinoid skeletal growth, presumably because the parasite inside died or otherwise left the premises. We don’t know the identity of this parasite, but we can surmise that it was a soft-bodied filter-feeder that probably gained an advantage from living high above the seafloor on these crinoid stems. Oddly, the larger A. negevensis crinoids in the same community did not have these parasites.
Living crinoids are afflicted by a variety of parasites. There are none today that have this sort of effect on the stems, but there are reports of fossil crinoids with similar pathologies all the way back to the Silurian (Brett, 1978).
Even after death these Jurassic crinoid stems provided homes for other organisms. Above is another cross-section through a stem of A. feldmani. “A” is one of the columnals, “B” is a section through an articulated bivalve filled with a relatively coarse sediment, and “C” is a fine sediment that filled in around the bivalve. The bivalve bored into the crinoid stem after death to make a crypt from which it could conduct its filter-feeding with some safety and seclusion.
Finally, here are the type specimens of Apiocrinites feldmani all packed up to be delivered to the Orton Geological Museum at Ohio State University. This museum has a large collection of echinoderms from around the world and so is an appropriate place for our treasures to reside awaiting further study.
This was a fun study that was part of Lizzie Reinthal’s 2013-2014 Independent Study project at Wooster. She concentrated on the taphonomy and sclerobiont successions as we both worked up the parasite and systematic story with our echinoderm expert friend Bill Ausich. There aren’t that many accounts of parasite-host relationships in the fossil record, so we’re proud to add one.
So many beautiful fossils in the Jurassic of southern Israel. More papers to come!
Ausich, W.I. and Wilson, M.A. 2012. New Tethyan Apiocrinitidae (Crinoidea, Articulata) from the Jurassic of Israel. Journal of Paleontology 86: 1051–1055.
Brett, C.E. 1978. Host-specific pit-forming epizoans on Silurian crinoids. Lethaia 11: 217–232.
Feldman, H.R. and Brett, C.E. 1998. Epi- and endobiontic organisms on Late Jurassic crinoid columns from the Negev Desert, Israel: Implications for co-evolution. Lethaia 31: 57–71.
Wilson, M.A., Feldman, H.R. and Krivicich, E.B. 2010. Bioerosion in an equatorial Middle Jurassic coral-sponge reef community (Callovian, Matmor Formation, southern Israel). Palaeogeography, Palaeoclimatology, Palaeoecology 289: 93–101.
Wilson, M.A., Reinthal, E.A. and Ausich, W.I. 2014. Parasitism of a new apiocrinitid crinoid species from the Middle Jurassic (Callovian) of southern Israel. Journal of Paleontology 88: 1212-1221.