This is Mazon Monday post #39. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Macroneuropteris scheuchzeri is the subject of our Mazon Monday post this week. M. scheuchzeri is a seed fern (Pteridospermatophyta), which is a group of plants that went extinct during the late Cretaceous Period. They first show up in the fossil record during the late Devonian. Specimens are large and tongue shaped. They can have striking detail, including hair-like structures.... see the examples at the end.
The namesake for M. scheuchzeri is Johann Jakob Scheuchzer, a botanist in the 1700's. Wikipedia has a good account of its taxonomic history.
The most abundant species of this genus, Macroneuropteris scheuchzeri, has had a long taxonomic history since it was first recognized in fossils found near Oxford, England by Edward Lhuyd in 1669. He referred to these leaves as Phyllites mineralis. It is illustrated and noted in Lhuyd's Lythophylacii Britannici Ichnographia, an early manuscript on English fossils published in 1699 with the financial help of Isaac Newton.[1][2] The species was further described in the Herbarium Diluvianum written in 1723 by the botanist Johann Jakob Scheuchzer.[3] Nearly hundred years after Scheuchzer's death, the species was renamed Neuropteris scheuchzeri by professor Hoffmann in Christian Keferstein's 1826 atlas of German Geology, Deutschland, geognostisch-geologisch dargestellt.[4] In the 1800s, similar fossilized foliage was found in North America. The names Neuropteris cordata var. angustifolia, Neuropteris angustifolia, Neuropteris acutifolia, Neuropteris hirsuta, Neuropteris decipiens, and Odontopteris subcuneata were used for these but are now all considered to be forms of Macroneuropteris scheuchzeri. The genus was taxonomically refined in 1989 through epidermal research led by C. J. Cleal. Based on that work, the genus Neuropteris was divided into four genera, Neuropteris, Macroneuropteris, Neurocallipteris, and Laveineopteris.[5][6][7]
M. scheuchzeri is fairly common, but can be extremely common is some localities such as the Mazon River in Morris. In the book "The Keys To Identify Pennsylvanian Fossil Plants of the Mazon Creek Area", it was called Neuropteris scheuchzeri. That was changed in the 1977 due to the frond architecture and cuticle. It is correctly called Macroneuropteris in the "The Mazon Creek Fossil Flora".
The text below is from the "The Keys To Identify Pennsylvanian Fossil Plants of the Mazon Creek Area" with artwork by Don Auler.
The text from "The Mazon Creek Fossil Flora" by Jack Wittry gives a complete history of its name and useful information to help with identification.
Macroneuropteris scheuchzeri forma decipens Gastaldo, 1977
- 1866. Odontopteris uwortheni Lesquereux. p. 432, pl. 36, fig. 1
- 1879-80. Odontopteris subeuneata Lesquereux.p. 134, pl. 22, figs. 4, 5
- 1879-80. Odontopteris wortheni Lesquereux. p. 130, pl. 22, figs. 1, 2
- 1880. Neuropteris tecipens Lesquereux. p. 93
- 1884. Neuropteris decipens Lesquereux. p. 733, pl. 94, figs. 1, 2
- 1925. Neuropteris decpens Lesquereux. Noé, pl. 24, figs. 2-4; pl. 25; pl. 26; pl. 27, figs. 1, 2; pl. 28, figs. 2-5
- 1958. Neuropteris scheuchzeri Hoffman. Langford, p. 189, figs. 327-329
- 1958. Neuropteris inflata. Langford, (part text) p. 191, figs. 337, (?) 33s
- 1958. Odontopteris subcuneata Lesquereux. p. 238, figs. 426-431
- 1970. Neuropteris decipens Lesquereux. Darrah, p. 94, pl. 1, figs. 1-4; pl. 2, fig. 3; non pl. 3, fig. 2 = Odontopteris aequalis; pl. 5, figs. 1, 2; pl. 6, fig. 2; pl. 8, figs. 1-3; pl. 46, fig. 3; pl. 76, fig. 1
- 1977. Neuropteris scheuchzeri Hoffman. Gastaldo, p. 133-155, fig. 137
- 1979. Neuropteris scheuchzeri Hoffman. Janssen, p. 149, fig. 137
- 1979. Odontopteris subeuneata Lesquereux. Janssen, p. 161, fig. 155
- 1979. Odontopteris wortheni Lesquereux. Janssen, p. 161, fig. 154
DESCRIPTION: The ultimate pinnae are simple or trifoliate. The terminal pinnules are large, highly polymorphic, generally oblong, cordate at the base and slowly narrow to an obtuse apex. The lateral pinnules (see Fig. 4) are orbicular or ovate. When lower surface is preserved,stiff, widely spread hairs are seen (see Fig. 3 inset). The midvein is strong at the base and continues to near the apex. The lateral veins are arched, fine and distinct, forking four, rarely five times, with a vein count at the margin of 30 per centimeter.
REMARKS: Maeroneuropteris scheuchzeri forma decipens is very common, being the most abundant taxon found in the Mazon Creek flora. In the Mazon Creek area it appears to completely replace the typical form of N. scheuchzeri. The question of whether the Mazon Creek form named Neuropteris decipens by Lesquereux is a valid species or is a gigantic but otherwise typical Neuropteris scheuchzeri is difficult. The arguments for making it a junior synonym of N. scheuchzeri are that both are trifoliate, hairy, and large, with veins that arch and fork generally four times and a midvein that extends to the apex; and that they are found with many associated odontopterid forms. Darrah reported that the epidermal cells of N. decipens are very similar though larger, but they have a ratio greater than one would expect for the pinnule size difference. The arguments for retaining N. decipens as a separate species are its larger size, the fact that it is never acuminate at the apex (this is a character in the original figured type specimens of N. scheuchzeri), and that it has coarser venation (30 vs. 40 veins per centimeter at the margin) and more extreme and varied odontopterid forms in association. This last argument is based on Odontopteris aequalis as a growth form of N. decipens. This is not subscribed to here (see O. aequalis). What they both do instead, is produce an almost identical odontopterid form. One is called Odontopteris subcuneata, found in association with N. decipens, and the other is Odontopteris lindleyana, which is found with N. scheuchzeri.
The new genus name Macroneuropteris for scheuchzeri was described on cuticle and frond architecture studies of European examples of N. scheuchzeri. Also see Odontopteris wortheni and Odontopteris subcuneata.
M. scheuchzeri is frequently found with insect damage at the margins. The damaged areas are generally U-shaped and if it was made when the leaf was alive, a whitish line of scar tissue will grow along the injured veins. Insect damage may also be seen as as hole or the removal of just the epidermis layer of one side. When this type of damage happens, the fossil leaf has a fibrous appearance along a section of the margin. damage once thought to be caused by leaf miner insects, is no longer the case and is now believed that the damage occurred by some other means, most likely on the forest floor after the leaf had died.
