Mazon Monday #123: Annularia sphenophylloides #fossil #paleontology #MazonMonday #MazonCreek #fossils #carboniferous #pennsylvanian

This is Mazon Monday post #123.  What's your favorite Mazon Creek fossil?  Tell us at email:[email protected].

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Annularia is the extinct form genera given to the leaves of Calamites.  Annularia sphenophylloides is a smaller variety.  It was described in 1837 by August von Gutbier (1798-1866), a German paleontologist who described many Carboniferous plants from deposits in and around Germany.  His name is also associated with various Permian animals like Parasaurus geintzi, which is an extinct species of pareiasaur, a plant eating parareptile.   A. sphenophylloides was featured in Fossil Friday #119.

Annularia sphenophylloides appears on Page 63 of "A Comprehensive Guide to the Fossil Flora of Mazon Creek" by Jack Wittry.

1837. Annularia sphenophylloides Gutbier: p. 436
1879-80. Annularia sphenophylloides; Lesquereux: p. 48, pl. 2, figs. 8, 9
1899. Annularia sphenophylloides Gutbier; White: P. 163
1925. Annularia sphenophylloides Gutbier; Noé: pl. 5, figs. 2, 3
1958. Annularia sphenophylloides; Langford: p. 40, figs. 44, 45
1969. Annularia sphenophylloides Zenker; Crookall: p. 733, pl. 149, fig. 1
1969. Annularia sphenophylloides Gutbier; Darrah: p. 172, pl. 33, figs. 1, 2; pl. 43, fig. 7
1979. Annularia sphenophylloides; Janssen: p. 86, pl. 33, fig. 69

DESCRIPTION: The branches are thin and fork at right angles. The whorls are closely set and are nearly the same size on any one specimen. They consist of 12 to 20 leaves that are slightly elliptical, with the widest parts farthest from the stem. The leaves are 3 to 12 mm long, reflexed at the margins, confluent at their bases, and expand upward to their apices. Appearance of the leaf apex varies, from having a small cleft to those that are simply obtuse or obtuse with a small, short, sharp point. The venation consists of only a heavy midvein.

REMARKS: Annularia sphenophylloides is very common and the fourth most common species found in the Mazon Creek flora. Lesquereux said it best when he wrote this about the fossils in this taxon: "The plants present a very beautiful appearance, resembling small, open roses flattened upon the stone."

Specimens

Illinois State Museum, specimen 15510 in the Mazon Creek Collection

From "A Comprehensive Guide to the Fossil Flora of Mazon Creek"