Wooster’s Fossil of the Week: fusulinids (Upper Carboniferous of Kansas)

They look like little footballs, at least the American variety of football. Fusulinids (the name indicating the fusiform shape) are about the size and shape of wheat grains. They were marine protists (single-celled eucaryotes) that lived from the late Early Carboniferous to the end of the Permian Period. Fusulinids are foraminiferans of the Superfamily Fusulinoidea named by Valerïan Ivanovich Möller (Imperial School of Mines, St. Petersburg) in 1878. They are critical index fossils for the Late Paleozoic, and I knew them intimately during my dissertation work in southern Nevada.

The shell of a fusulinid is very complex. It is made of a granular calcite wrapped along the axis of the football in a series of chambers with internal walls. Each coil wrapped completely over the earlier coils, making the shells involute. They are most commonly studied in section to reveal the internal complexity.
Cross-section of a fusulinid (Triticites) from the Permian of Iowa.

Fusulinid evolution was dramatic for a single-celled group. The earliest varieties were very small (one or two millimeters in length), and the later ones up to five centimenters long. Their internal features also increased in complexity, making each successive new species very easy to identify. This is why they are such good indications of geological time intervals. It is this biostratigraphic value that proved most useful to me as a young graduate student working in what seemed to me to be virtually featureless Carboniferous limestones.


Hageman, S.A., Kaesler, R.L. and Broadhead, T.W. 2004. Fusulinid taphonomy: encrustation, corrasion, compaction, and dissolution. Palaios 19: 610-617.

Möller, V.I., von. 1878. Die Spiral-gewundenen Foraminiferen des russischen Kohlenkalks. Mémoires de l’académie impériale des sciences de St-Pétersbourg, VII Série, Tome XXV, No. 9 et dernier.

Ross, C.A. 1967. Development of fusulinid (Foraminiferida) faunal realms. Journal of Paleontology 41: 1341-1354.

Stevens, C.H. and Stone, P. 2007. The Pennsylvanian–Early Permian Bird Spring carbonate shelf, southeastern California: Fusulinid biostratigraphy, paleogeographic evolution, and tectonic implications. Geological Society of America Special Paper 429, 82 p.

About Mark Wilson

Mark Wilson is a Professor of Geology at The College of Wooster. He specializes in invertebrate paleontology, carbonate sedimentology, and stratigraphy. He also is an expert on pseudoscience, especially creationism.
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5 Responses to Wooster’s Fossil of the Week: fusulinids (Upper Carboniferous of Kansas)

  1. Jerry B. Boysen says:

    The fusulinia I have does not look like the ones you have posted. What I have is solid on the inside and only 4 to8 grains from end to end and not porous looking like the ones you have. The grains on the outside of mine go end to end like yours but the inside is totally different. I have found some like yours, but, Cxxxx.com [Ed.: Link removed as it is commercial and has nothing to do with paleontology] says they are carnivore teeth and I am inclined to believe them as I have found them in Coral Reef along with Trilobites, Cystoids and Blastoids ( Cambrian to Silurian Periods) which would rule out Carboniferous if they were Fusulinia. I have found objects like yours in Cooper, Texas which is the Cretaceous Period. I have found vertebrae and bones ( as per Fossil Lake, Wyoming) along with the teeth from Cambrian to Cretaceous Periods. These little, almost micro Carnivores with the longest tail of any other Carnivore , might be aquatic.
    Please reply as to your thoughts on this.

  2. Mark Wilson says:

    Hi Jerry: Thanks for your comments. I can only assure you, though, that these really are fusulinids. This is what they look like, inside and out. For another source, check out this link: http://www.kgs.ku.edu/Extension/fossils/fusulinid.html
    Note that they are not solid on the inside. I suspect what you have are not fusulinids.

  3. Jerry Boysen says:

    Can I send you a picture of the fossil teeth from the website Cxxx.com. [Ed.: Website address again removed. It is for a nutritional supplement and has nothing to do with fossils.] Email me and I will send you pictures on my reply to you. I am not here to start an argument, but to obtain the truth of what it really is. I can also send pictures of the vertebrae and bones I have as well as pictures of the tree climbing carnivore from the book “The Lost World of Fossil Lake “ in Wyoming. The teeth look just like what some are calling Fusulinia (swirling chambers on the inside and not solid) and they cannot be as Fusulinia is only in Carboniferous and not Cretaceous or Ordovician. The Fusulinia I have are solid on the inside and not swirls. Please reply as I am interested in getting the right answers.

  4. Jerry Boysen says:

    The bottom picture of a 2 mm long Fusulinia, can you give me the website or book where you found it. I am really interested. It might help clarify my findings.

  5. Mark Wilson says:

    Hello Jerry: The website you listed (again) is for a questionable nutritional supplement and not about fossils in any way. The images I post in this blog are my own, unless I cite another source. The fusulinids pictured in this post come from our collections. I identified and photographed them. I assure you that they are fusulinids, and in my previous reply I gave you a webpage where you can read another account of this fossil group: http://www.kgs.ku.edu/Extension/fossils/fusulinid.html . I am happy to look at any images you have. You can email me at mwilson@wooster.com .

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