Archive for July 15th, 2012

The coiled-and-ribbed fossil mystery deepens on Hiiumaa

July 15th, 2012

KÄINA, ESTONIA–It has been a rainy day on the Estonian island of Hiiumaa. The Wooster geologists stayed inside most of the day to work on their Geological Society of America abstracts. Bill Ausich and his Ohio State University team, though, returned to the Hilliste Quarry and continued to collect fossils. To our great surprise, they picked up two more specimens of that strange planispirally-coiled shell that Richa found on July 13. One is shown above, and the “venter” view is shown below. All specimens were found in a yellowish unit that matches the matrix in the fossils (although we’ll check in the lab to make certain). These new finds reduce the chances that the fossils are a product of “site contamination” in which a visitor discards specimens from a previous trip, often to make room for new ones. That is still a possibility, but an increasingly remote one.

So what are these? They look very much like Mesozoic ammonites, all the way down to deflections of ribs along the periphery as you might be able to see above. (Specimen photography in a hotel room has its challenges.) The earliest ammonoids, the larger group that contains ammonites, appear in the Devonian (the period after the Silurian), so it is unlikely we are looking at that group. They are certainly mollusks, though, so most likely gastropods (snails) or nautiloids. Coincidentally enough, Wooster alumnus James St. John has a webpage with a photograph of a coiled, ribbed nautiloid known as Graftonoceras, which you will note has many similarities with our mystery critter. The specimen he photographed is in the museum at, of all places, Ohio State!

Wooster’s Fossils of the Week: ribbed brachiopods (Middle Jurassic of Israel)

July 15th, 2012

These delightful brachiopods are from the Matmor Formation (Jurassic, Callovian) of the Negev in southern Israel. They are part of a long-term Wooster project describing and interpreting a diverse paleocommunity. The latest trip to study these fossils was this past March with Melissa Torma and our Israeli colleague Yoav Avni. The shells above are Burmirhynchia jirbaenesis Muir-Wood 1935. We identified them using the excellent work on Matmor brachiopods by Feldman et al. (2001).

The location in Makhtesh Gadol, Negev, Israel, where these specimens were collected.

Burmirhynchia jirbaensis was originally named from a collection of specimens found in the Biheh Limestone of the Jirba Range in British Somaliland (modern-day Somalia). This is a wonderful place for Jurassic paleontology, but not one I’m likely to visit soon!

Burmirhynchia is an important brachiopod in the Jurassic of the Tethyan Realm. It has been found throughout the Middle East, southern Europe, Africa and Australia. It has, apparently, been overly “split” into over 90 species, most of which are dubious at best (Shi and Grant, 1993). B. jirbaensis, though, is a legitimate species based on internal characteristics you can only see by sectioning or internal tomography (Feldman et al., 2001).

The genus Burmirhynchia was described in 1918 by an interesting character: Sydney Savory Buckman (1860-1929). Buckman is best known for his work on ammonites, but he was also a novelist, social reformer and (gasp) a fossil dealer (to support his geological work). He was born in Cirencester, England, but grew up in Dorset among some of the most spectacular Jurassic geology in the world. Buckman was briefly a farmer, but he most enjoyed amateur geology and working on collections in local museums. Ammonites were his passion — he worked on several large monographs describing hundreds of new species. (The complaints about his taxonomic splitting began then.) His most eccentric idea was that ammonites may have suffered from a kind of flatulence produced by “nervous apprehension of danger”, with the resulting gas increasing their buoyancy and helping them flee to safety. I don’t recall hearing that one in school!

Curiously enough, Sydney Savory Buckman made one progressive addition to the vocabulary of paleontology: in 1893 he invented the term “palaeo-biology” (Sepkoski, 2012).

References:

Buckman, S.S. 1918. The Brachiopoda of the Namyau Beds, Northern Shan States, Burma. Memoirs of the Geological Survey of India, Palaeontologia lndica, new series 3: 1-299.

Feldman, H.R., Owen, E.F. and Hirsch, F. 2001. Brachiopods from the Jurassic (Callovian) of Hamakhtesh Hagadol (Kurnub Anticline), southern Israel. Palaeontology 44: 637–658.

Sepkoski, D. 2012. Rereading the Fossil Record: The Growth of Paleobiology as an Evolutionary Discipline. University Of Chicago Press, Chicago, 440 pages.

Shi, X. and Grant, R.E. 1993. Jurassic rhynchonellids: internal structures and taxonomic revisions. Smithsonian Contributions to Paleobiology, Number 73, 190 pages.