This is Mazon Monday post #100. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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This is the 100th Mazon Monday post! We hope you are enjoying these posts! If you have any suggestions or feedback, please send it along to email:[email protected].
Odontopteris subcuneata was a seed fern that belonged to the same group of plants called Medullosales. They slowly went extinct during the Cretaceous period. During the Carboniferous period they formed the forest understory. Plants like Alethopteris, Neuropteris, and Macroneuropteris were closely related and sometimes even a sub form. O. subcuneata has been found on the same plant with Macroneuropteris scheuchzerii and has been classified as a heteromorph (a derivation from the usual form) an placed info synonymy with M. scheuchzerii.
O. subcuneata was first described by Charles James Fox Bunbury in 1847. At that time, he was Britain's leading paleobotanist. He published a series of papers on the fossil floras of the Carboniferous, Jurassic, and Neogene. There is a book on Bunbury's life and contributions to paleobotany, which are significant.
During the 1850s, Charles James Fox Bunbury, 8th Baronet Bunbury, was Britain's leading paleobotanist, who published a series of papers on fossil floras of Carboniferous, Jurassic and Neogene age. He also planned a major synoptic review of paleobotany, to rival Brongniart's "Histoire de vegetaux fossiles". He was financially comfortably-off, and well-connected with the scientific community in the London of his day. However, he failed to fulfill his ambitions in this field due to a combination of a lack of experience, and that on the death of his father he had to take over the running of the family estate. Today he is mainly remembered as the author of a number of names of still widely used fossil-taxa. Nevertheless, he fulfilled an important role in maintaining paleobotanical interest in Britain during the middle part of the nineteenth century.
Odontopteris appears in the "ESCONI Keys to Mazon Creek Plants". Rounded pinnules are a dead giveaway for it, but it can get complicated with it's other forms.
ODONTOPTERIS
Odontopteris is a form-genus which is charac terized by a broad basal attachment with a se ries of veins entering the pinnules from the rachis. The midvein is absent or indistinct and does not continue to the apex. The veins do not form a network but fork once or twice. The pinnules are ovate, tongue shaped, or lincar. Most forms are associated with N. scheuchzeri but are actually immature pinnatifid forms.
Odontopteris subcuneata
O. subcuneata is a growth stage of N. scheuchzeri. The surface of the pinnule is smooth and the lower half of the base is drawn out into a half round auricle (see Figure 25 on page 13, Figure 96, and Figure 97). The veins enter the pinnule direct from the rachis. Occasionally there may be a faint indication of a midvein. Figure 96 illustrates some growth stages of Odontopteris.
There is a nice description of O. subcuneata by Jack Wittry in "A Comprehensive Guide to the Fossil Flora of Mazon Creek".
Odontopteris subcuneata Bunbury, 1847
1847. Odontopteris subcuneata Bunbury: p. 427, pl. 23, figs. la, b
1866. Odontopteris worthenii Lesquereux: p. 432, pl. 36, fig. 1
1866. Odontopteris heterophylla Lesquereux: p. 433, pl. 38, figs. 2-5
1870. Odontopteris subcuneata. Lesquereux: p. 390, pl. 8, fig. 10
1879-80. Odontopteris subcuneata. Lesquereux: p. 134, pl. 22, fig. 4
1879-80. Odontopteris worthenii Lesquereux: p. 130, pl. 22, fig. 1
1884. Odontopteris affinis Lesquereux: p. 742, pl. 97, fig. 4
1925. Odontopteris subcuneata Bunbury; Noé: p. 15, pl. 37, fig. 1, non fig. 2 = ?
1925. Odontopteris worthenii Lesquereux; Noé: p. 15, pl. 37, fig. 4, non fig. 3 = ?
1958. Odontopteris subcuneata Bunbury; Langford: p. 238, pl. 114, figs. 426-433
1979. Odontopteris subcuneata Lesquereux; Janssen: p. 161, fig. 155
1979. Odontopteris worthenii Lesquereux; Janssen: p. 161, fig. 154DESCRIPTION: The pinnae are linear-lanceolate and highly variable in their divisions. The rachis is thick and irregularly striate. The upper pinnae have distant pinnules at the top and are entire at their bases. Lower pinnae have only free and distant pinnules which are progressively smaller toward the pinna apex. The typical pinnule form is oblong, distant, oblique to the rachis, obtuse at the apex, and constricted and confluent at the base. The terminal pinnule is lanceolate and varies greatly in size with an obtuse apex. All veins are thin, close, and enter directly from the rachis, then divide and curve toward the margin at a density of 30 veins per centimeter.
REMARKS: Odontopteris subcuneata is uncommon. It was borne on the same plant that produced Macroneuropteris scheuchzerii. This can be seen in Fig. 1 where both forms are growing on the same pinna. The form O. subcuneata is now considered a heteromorph (a deviation from the usual form), and has been placed into synonymy with M. scheuchzerii by White (1899), Crookall (1959), and Laveine (1967). Like M. scheuchzerii, they may have "hairs" though this is a very rare occurrence in this species. Lesquereux described three species of Odontopteris from Mazon Creek as new: worthenii, heterophylla, and affinis. He also noted the presence of the previously erected taxon, O. subcuneata. All three of Lesquereux's species are now considered synonymies of O. subcuneata.
Specimens
