This is Mazon Monday post #240. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Sphenopteris is a genus of seed ferns. Seed ferns, Pteridospermatphyta, as a group have a geologic range which spanned from the late Devonian to the late Cretaceous, although a few species seem to have survivied into the Eocene. Sphenopteris was a part of the forest understory.
Sphenopteris spinosa was described by Heinrich Göppert in 1841. Göppert (1800 - 1884) was a German botanist and paleontologist. He was a professor of botany and the curator of the botanical gardens in Breslau. In the 1840s, he demostrated the existence of plant cells in microscopic preparations of coal, which settled the long running debate as to the origin of coal. At that time, his private collection of specimens of fossil flora was considered the finest in the world.
George and Sydne Langford included Sphenopteris spinosa in their Christmas card of 1939. It's the fossil on the right. Langford classified S. spinosa as Diplothmema zobelli, which is included in his first book "The Wilmington coal flora from a Pennsylvanian deposit in Will County, Illinois", published in 1958.
Jack Wittry describes Sphenopteris spinosa on page 149 in "A Comprehesive Guide to the Fossil Flora of Mazon Creek".
Sphenopteris spinosa Göppert, 1841
1841. Sphenopteris spinosa Göppert: p. 70, pl. 12
1866. Hymenophyllites spinosus Göppert; Lesquereux: p. 436, pl. 34, fig. 3
1884. Sphenopteris solida Lesquereux: p. 769, pl. 101, fig. 3
1923. Sphenopteris spinosa Göppert; Kidston: p. 85, pl. 14, fig. 4
1925. Palmatopteris furcata (non Brongniart) Potonié; Noé: pl. 13, fig. 1 (re-figured here as Fig. 1)
1958. Sphenopteris spinaeformis (non Kidston); Langford: p. 275, fig. 501
1963. Diplothmema. Langford: p. 271, figs. 913-915
1969. Sphenopteris cf. spinaeformis (non Kidston); Darrah: p. 157, pl. 25, fig. 2
1979. Sphenopteris spinaeformis (non Kidston); Janssen: p. 111, fig. 92DESCRIPTION: The pinnae are alternate, touch each other, are broadly lanceolate, and gradually taper to a sharp, spine-like terminal point that is sometimes accompanied by a smaller lateral spine (see Fig. 2 inset), though these features are often buried in the matrix or missing. The rachis of the penultimate and ultimate pinnae are heavy and winged. The pinnules are highly variable along the rachis. Near the pinna base (see Fig. 3), they are nearly triangular, alternate, oblique, decurrent with a wide footstalk, and deeply divided. All pinnules are truncate or cuneate and expanded near the apex where they terminate in an assortment of rounded lobes. The upper pinnules (see Figs. 1, 2) become more narrowed with a wide, decurrent base and smaller, rounded lobes. The venation is distant and indistinct, consisting of a decurrent midvein that forks near the base and then divides again, producing a single vein for every lobe. These veins terminate at their apices. Fertile structures have not been described.
REMARKS: Sphenopteris spinosa is uncommon. The Mazon Creek examples of this taxon, like those in other localities, are often badly broken because of their delicate tissue. They often lack detail and are missing pinnules; those remaining are mostly broken or ragged.
Specimens
Field Museum PP 27660
Field Museum PP 58162
Field Museum PP 58178
