Phylum: Bryozoa
Class: Stenolaemata
Order: Fenestrida
Family: Fenestellidae
Genus: Fenestella Lonsdale, 1839

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Type Species: Fenestella antiqua (d’Orbigny, 1852)
History: (Nickles & Bassler, 1900)

  • 1839 Fenestella Lonsdale, Murchison’s Silurian System, p. 677.
  • 1841 Fenestella Phillips, Pal. Foss., p. 22.
  • 1844 Fenestella McCoy, Synopsis Carb. Foss. Ireland, p. 200.
  • 1845 Fenestella Lonsdale, Russia and the Ural Mountains, I, Appendix A, p. 629.
  • 1850 Fenestella King, Mon. Perm. Foss., p. 34.
  • 1854 Fenestella McCoy, British Pal. Foss., p. 49.
  • 1860 Fenestella Eichwald, Lethaea Rossica, I, p. 356.
  • 1874 Fenestella Nicholson, Pal. Province Ontario, p. 104.
  • 1881 Fenestella Shrubsole, Quar. Jour. Geol. Soc. London, XXXVII, p. 179.
  • 1882 Fenestella Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 150.
  • 1883 Fenestella Claypole, Quar. Jour. Geol. Soc. London, XXXIX, p. 31.
  • 1885 Fenestella Waagen and Pichl, Pal. Indica, ser. XIII, pp. 773, 776.
  • 1886 Fenestella Ulrich, Contr. American Pal., I, p.4.
  • 1887 Fenestella Foerste, Bull. Sci. Lab. Denison Univ., II, p. 83.
  • 1887 Fenestella Hall and Simpson, Pal. New York, VI, p. xxii.
  • 1889 Fenestella Miller, North American Geol. Pal., p. 302.
  • 1890 Fenestella Ulrich, Geol. Surv. Illinois, VIII, pp. 395,534.
  • 1894 Fenestella Počta, Syst. Sil. Bohême, VIII, t.1, p. 40.
  • 1895 Fenestella Whidborne, Devon. Fauna England, (Pal. Soc. Publi.), II, pt. 4, p. 165.
  • 1895 Fenestella Simpson, Thirteenth Ann. Rep. State Geologist New York for the year 1893, pp. 687, 724; Forty-seventh Ann. Rep. New York State Mus., pp. 881, 918.
  • 1896 Fenestella Ulrich, Zittel’s Textb. Pal. (Engl. ed.), p. 281.
  • 1897 Fenestella Simpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894, p. 500.
  • 1899 Fenestella Grabau, Bull. Buffalo Soc. Nat. Sci., VI, p. 159.
  • 1850 Fenestella (in error for Fenestella) D’Orbigny, Prodr. de Pal., I, p. 44.
  • 1874 Actinostoma Young and Young, Quar. Jour. Geol. Soc. London, XXX, p. 681.
  • 1885 Actinostoma Vine, Proc. Yorkshire Geol. Polyt. Soc., IX, p. 84.
  • 1895 Flabelliporina Simpson, Thirteenth Ann. Rep. State Geol. New York for the year 1893, pp. 703, 724; Forty-seventh Ann. Rep. New York State Mus., pp. 897, 918.
  • 1897 Flabelliporina Simpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894, p. 521.

Note (Bryozoa.net)

  • From 1935, the use of Fenestella was suspended because of the existence of a senior homonym as a genus name for a bivalve. For some years, species were referred to the genus Fenestrellina.
    In 1962 (Opinion 622 of the ICZN), Fenestella was validated for the bryozoan genus, and the name Fenestrella for a bryozoan was placed on the Official Index of rejected names.

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Stratigraphic Occurrences

Geologic Range
Ordovician – Permian

Geographic Occurrences

Map point data provided by iDigBio.
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Sequences (Formations)

  • C2 Sequence (Fairview)
  • C1 Sequence (Clays Ferry/Kope)

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Identification in Hand Sample:

  • Zoarium Morphology:
  • Zooecia: The branches contain two rows (seldom sporadically three) of adherent zooecia
  • Mesozooids:
  • Monticules:
  • Maculae:

Fenestella from the Lime Creek Formation of Rockwood, Iowa (CMC 32697)

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Gorjunova (2012)

  • Based on her analysis of phylogenetic lineages of fenestellid bryozoans, Schulga Nesterenko (1949, p. 313) already then believed that “within the genus Fenestella there are certainly several genera representing natural groups.” Her idea was developed by the French paleontologists Termier and Termier (1971). Based on their analysis of the species composition of the heterogeneous genus Fenestella, they were the first to propose the cross-sectional shape of autozooecia at their base as a basic criterion for classification of genera of fenestrate bryozoans.

Fossils of Ohio (1996):

  • Forms meshwork colonies of branches joined by cross-bars. There are two rows of zooids per branch

Elias & Condra (1957):

  • For a long time the genus Fenestella and its species have been recognized primarily or wholly on external features. The genus is customarily characterized by a netlike fenestrate expanse, which is made by regularly spaced, gradually spreading and occasionally bifurcating branches, interconnected by short and regularly spaced transverse links called dissepiments. The dissepiments in Fenestella and other Fenestellidae are “sterile,” that is containing no zooecia, while the branches contain two rows (seldom sporadically three) of adherent zooecia. Each zooecium has one opening called the aperture, and all apertures open on one side of the expanse, called the obverse, “celluliferous,” or front side. On this side there is usually a central longitudinal carina, which in most species is ornamented by nodes. The opposite side of the expanse is called the reverse or dorsal side and has no apertures. In most species the branches on the reverse bear longitudinal grooves or “striae” and may be adorned by nodes or spines.
  • The species of Fenestella customarily are recognized by measurements of spacing of the branches, apertures, and dissepiments, and by the size and ornamentation of these structures. The importance of the internal structure has been gradually recognized, however, especially by Russian paleontologists who pointed out the importance of the outline of the zooecial chamber as a specific character (Nekhoroshev, 1932, p. 35). The microstructure of the wall, including its encrusting tissue, also has been added to characteristics of species (particularly by Shulga-Nesterenko). The structure of the “zooecial cavity” in Fenestellidae, especially Fenestella, was elucidated by Ulrich (1890, p. 350-351), who also found in many species superior and inferior hemisepta located respectively on the roof and the floor of the zooecial cavity or chamber at or near the base and its vertical shaft or vestibulum. The rarely developed inferior hemiseptum has proved useful in the recognition of some species (Ulrich, 1890; Shulga-Nesterenko, 1941; Condra and Elias, 1944).
  • The detailed studies of the microstructure of the wall and of the encrusting tissue in Fenestella and related genera by Russian paleontologists and their attempts to use microscopic characters for recognition of genera and species from thin sections, commonly obtained by cutting cores from some deep bore-holes, added much to the knowledge of these Bryozoa and revived interest in their biology. Understanding of these and many other Paleozoic Bryozoa is still imperfect, however, and their relationship to the living and post-Paleozoic Bryozoa is an unsolved problem. The status of knowledge is illustrated by the following historical review of the more recent principal contributions to the morphology and anatomy of Fenestellidae and related families of Paleozoic Bryozoa and of the biological explanations suggested.

Treatise on Invertebrate Paleontology Part G (1953):

  • Zoarium funnel- or fan-shaped. Zooecia in 2 rows on each branch with 2 to 8 apertre in a single row adjoining one fenestrule. Front of branches with or without median keel and acanthopore spines present or absent.

Bassler (1911):

  • Zoarium flabellate or funnel shaped, celluliferous on the inner side; branches generally straight, sometimes flexuous, connected at regular intervals by dissepiments; apertures in two rows, separated by a plain or tuberculated median keel.

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