Acritarchs

 


  1. Acritarch: Vandalosphaeridium walcottii, a spiny acritarch from a palynological preparation of carbonaceous mudstone of the Awatubi Member, Kwagunt Formation, Chuar Group of the Grand Canyon. Late Precambrian, 850 million years old. Photomicrograph by G. Vidal, Lund University. Copyright by and used with the permission of the Precambrian Paleobiology Research Group- Proterozoic (UCLA).

 

  1. Acritarch: Skiagia scottica, an Early Cambrian (560 million years old) spiny acritarch in a palynological preparation of black shale from the Buen Formation of northern Greenland. Courtesy of G. Vidal, Lund University. Copyright by and used with the permission of the Precambrian Paleobiology Research Group- Proterozoic (UCLA).

 

  1. Acritarch: Actipilion druggi from the Sylvan Shale, Oklahoma. Numerous thin-walled, filmy, transparent processes are visible in this light micrograph. Specimen is about 100 microns in diameter. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.

 

  1. Acritarch: Ballisphaeridium (?) sp. Light micrograph of a specimen showing subcircular outline of the vesicle, numerous short stiff processes, and a microgranulate vesicle surface. The processes are ornamented with scattered broad-based spinules. Specimen is about 75 microns in diameter. Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.

 

  1. Acritarch: Cymatiosphaera. Ordovician. SEM. Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.

 

  1. Acritarch: Multiplicisphaeridium. Ordovician. Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.

 

  1. Acritarchs showing vesicles and spines. Ordovician. SEM. Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.

 

  1. Acritarchs showing diversity of form. Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.

 

  1. Acritarch excystment along median split. Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.

 

  1. Acritarch (Peteinosphaeridium sp.) showing pylomes and opercula. Light micrographs. Fig. 1. Specimen showing subcircular to ovate outline of vesicle and prominent subcircular pylome plugged by laevigate operculum and surrounded by an elevated rim. Specimen is from the Sylvan Shale, Oklahoma. Upper Ordovician. Courtesy of Carl Mendelson, Beloit College. Fig. 2a. Specimen without operculum. Fig. 2b. Enlargement of pylome area in Fig. 2a, showing prominent thickened border. Specimen in Fig. 2a, b is from a roadcut along Highway 77 about 7.2 km south of Davis, Oklahoma. Ordovician. Collected by L. Eames and photographed by M. Miller, of Amoco Production Company, Tulsa Oklahoma. Copyright Cushman Foundation for Foraminiferal Research, Inc., 1987.