Dear Paleolim Listserv, thank you to everyone who responded with
thoughts about my unknown “eyes”! I very much appreciate all your help.
In case others were curious as to what they were…. here is a synopsis
and some useful references.
_Unknown top middle of image on the left:_
The round, oval structures are resting stages (statoblasts) of bryozoans
("moss animals"). The ones in the photograph resemble those produced by
the genus Plumatella.
Bryozoan statoblasts/sessoblasts, most likely from the genus Plumatella.
/References/:
Bryozoan cysts. Cosmopolitan enough to ID to lower taxonomic levels
using Pennaks Freshwater Inverts of the US
Francis, D.R., 2001. Bryozoan Statoblasts. In: Tracking environmental
change using lake sediments. Vol. 4: Zoological indicators. Eds. Smol,
J.P., H.J.B. Birks and W.M. Last, Kluwer Academic Publishers, Dordrecht,
The Netherlands, p. 105-123.
Francis, D.R. 1997. Bryozoan statoblasts in recent sediments of Douglas
Lake, Michigan. ////J. Paleolimnology// 17:255-261.
Ricciardi, A. & H.M. Reiswig, 1994. Taxonomy, distribution, and ecology
of the freshwater bryozoans (Ectoprocta) of eastern Canada. Can. J.
Zool. 72: 339-359. LOTS OF PHOTOS
You can find descriptions and drawings of these structures in the
following publications:
Wood T.S. 1996. Plumatella nitens, a new species of freshwater bryozoan from North America (Ectoprocta: Phylactolaemata), previously misidentified.
Hydrobiologia 328: 147-153.
Wood T.S. & Okamura B. 2005. A key to the freshwater bryozoans of Europe and the British Isles with ecological notes. Freshwater Biological Association
Scientific Publication No. 63, Freshwater Biological Association, The Ferry House, Far Sawrey, Ambleside, Cumbria, UK.
/Web images:/
http://www.answers.com/topic/statoblasts
http://www.plingfactory.de/Science/GruKlaOeko/Teichleben/Andere/Bryozoa.html
http://www.bryozoans.nl/index_en.html
_The Other macrofossil top right (less consensus on this one but then
the image is not great!):_
Possibly ceriodaphnia ephippium
To the right looks like an ephippium of Moina (Cladocera).
The object to the right is the cladoceran, /Simocehalus/ sp.
ephippium of a daphnia (several genera possible)
The other structures (e.g. on the right side of the photograph) are
cladoceran ephippia. They resemble those produced, e.g., by the genus
Ceriodaphnia. You can find photographs of these ephippia in the following
paper:
Vandekerkhove J., Declerck S., Vanhove M., Brendronck L., Jeppesen E., Conde
Porcuna J.M. and De Meester L. 2004. Use of ephippial morphology to assess
richness of anomopods: potentials and pitfalls. J. Limnol. 63 (Suppl. 1):
75-84.
_Other hints in general for identifying similar macrofossils:_
Also, keep an eye out/check for Cladocera genus Simocephalus. The
ephippia are lighter in colouration and have single 'eyes/hump' compared
to Daphnia with 'double eyes/humps'. The ephippia are larger than
Plumatella statoblasts.
Thanks so much for everyone’s help. It is very much appreciated it.
Best
Michelle
--
Michelle Goman
Senior Research Associate
Cornell Quaternary Lab (CQUAL)
Dept. Earth and Atmospheric Sciences
Cornell University
phone: 607-255-4726
http://www.geo.cornell.edu/Research_Staff/goman/
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