This is Mazon Monday post #249. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Pecopteris oreopteridia is a fern from the Carboniferous Period, which has been found in the Mazon Creek fossil deposits. It is fairly uncommon and resembles Crenulopteris acadica in appearance (see Mazon Monday #115). Besides the crenulated edge on mature Crenulopteris pinnules, often venation is the difference between specimens. Notice the single branch for the veins in P. oreopteridia, but multiple forks in the veins for C. acadica.
Venation of Pecopteris oreopteridia
Venation of Crenulopteris acadica
P. oreopteridia was originally named Filicites oreopteridis by Ernst Friedrich, Baron von Schotheim (1764 - 1832), who was a German paleontologist and politician. Hist most important work was "Die Petrefactenkunde" published in 1820. He followed that book with a folio atlas. Those books illustrated his collection of the plant and animal fossils animal of what he considered the "former world". His books were the first time where Linnaeus' binomial system was used in a German science publication.
Ernst Friedrich, Baron von Schlotheim.
It was later reclassified as Pecopteris oreopteridia by the French paleontologist Adolphe-Theodore Brongniart (1701-1876) in 1834, Brongniart is considered by many to be the father of paleobotany.
Photographic portrait of Adolphe-Théodore Brongniart (1801-1876), French paleobotanist, plant taxonomist and anatomist.
Jack Wittry discusses Pecopteris oreopteridia on page 122 of his "A Comprehensive Guide to the Fossil Flora of Mazon Creek".
Pecopteris oreopteridia Brongniart, 1834
1804. Filicites oreopteridis Schlotheim: p. 36, pl. 6, fig. 9
1834. Pecopteris oreopteridia Schlotheim; Brongniart: p. 317, pl. 104, fig. 2; pl. 105, figs. 1-3
1879-80. Pecopteris oreopteridis Schlotheim; Lesquereux: p. 238, pl. 41, fig. 8
1924. Asterotheca oreopteridia Schlotheim; Kidston: p. 495, pl. 118, figs. 1, 2; pl. 119, figs. 1-4
1958. Asterotheca abbreviata (non Brongniart); Langford: p. 161, fig. 273
1958. Asterotheca oreopteridia Schlotheim; Langford: p. 161, fig. 274
1969. Pecopteris oreopteridia Schlotheim; Darrah: p. 139-140DESCRIPTION: The penultimate rachis is smooth. The ultimate pinnae are alternate, flexuous, linear-lanceolate, with the pinnules becoming gradually more confluent toward the blunt, elongated terminal pinnule. The pinnules are oblong, often convex or raised above the matrix, and can be two or three times longer than they are wide. The pinnules are blunt, slightly oblique, and attached by their whole width to a smooth or weakly longitudinally striate rachis. The first pinnule on the lower or basiscopic side (see Fig. la circle) often appears enlarged. This is not a consistent feature which becomes much less apparent as all the pinnules become more oblong, eventually disappearing altogether (see Fig. 5). The venation consists of a heavy, straight midvein that is slightly decurrent at the base in smaller pinnules and extends to the tip, where it sometimes divides into two. The lateral veins are weak, somewhat distant, and rise at an angle of nearly 45°. The veins fork close to their base or slightly above and take on the shape of a tuning fork. They then meet the margin at a slightly oblique angle. The pinnules often appear to be covered by minute scales. The sori have an aster- othecoid appearance.
REMARKS: Pecopteris oreopteridia is uncommon. This taxon is closest in appearance to Crenulopteris acadica. The best way to distinguish between the two is by the venation-in C. acadica the veins fork twice.
Specimens
Field Museum FMNH PP 39992
Field Musem FMNH PP 28676
Field Museum FMNH PP 3271
From George's Basement as Asterotheca oreopteridia
