This is Mazon Monday post #202. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Lepidostrobus is a cone from lepidodendron tree. It was named in 1828 by Adolphe-Theodore Brongniart (1801 - 1876), who was a French paleontologist, considered by many to be the father of paleobotany. He also named Lepidostrobophyllum which are the individual cone bracts of which Lepidostrobus is the whole reproductive organ.
Photographic portrait of Adolphe-Théodore Brongniart (1801-1876), French paleobotanist, plant taxonomist and anatomist.
Principle parts of a lepidodendron tree from George's Basement.
Lepidostrobus represents a large diverse group of related cone species, including Lepidostrobus ornatus, Lepidostrobus hastatus, Lepidostrobus aldrichii, Lepidostrobus lancifolius, and Lepidostrobus foliaceus. Other related species with slightly different structure include Bothrodendrostrobus and Flemingites.
Lepidostrobus can be found on page 24 of Jack Wittry's "A Comprehensive Guide to the Fossil Fauna of Mazon Creek.
Lepidostrobus Brongniart, 1828
Lepidostrobus is the most commonly assigned generic name for the cones of arborescent lycophytes, and many cone species are erroneously included in this genus. Lepidostrobus includes a diverse group of cones. Some contain only a single type (monosporangiate) of microspore and are the true members of Lepidostrobus. Other cones produced two spore types (bisporangiate), which had both microspores and megaspores. The genus becomes Flemingites or possibly Bothrodendrostrobus in cones determined to be this type. This genus produced different spore types which were in separate sporangia on otherwise identical cone bracts (sporophylls). The taxonomic problems inherent in Lepidostrobus are daunting. There are two main general cone forms. One form is elongate with compact and slender sporophylls. Lepidostrobus ornatus is of this general form. This cone species is known to have examples reaching 50 cm long. All members of this group are monosporangiate and contain only microspores. The other type is like those figured below. They have an ovoid shape, are less compacted, and with fewer sporophylls. The sporophylls are broad and lanceolate or triangular. Complete examples of these types of cones are extremely rare. Most, if not all, members of this cone form were bisporangiate, but due to a lack of complete cones with spores available for study, they are retained in Lepidostrobus. Isolated bracts are common and assigned the generic name Lepidostrobophyllum. It is a common practice to call even a few attached bracts Lepidostrobus. The specific name of the cone is the same as the specific name of its isolated bracts, e.g., Lepidostrobophyllum hastatus are shed from Lepidostrobus hastatus. Also see Lepidocarpon and Achlamydocarpon.
Whole specimens of Lepidostrobus are extremely rare. As such, the 1912 Proceedings of the Iowa Academy of Science has a nice piece about the first reported "Petrified American Lepidostrobus". It was found near Indianola in 1904 by a Mr. Samuel Spear.
Abstract
One day in the summer of 1904 a broken Lepidostrobus petrified nicely by iron pyrites was sent to me by Mr. Samuel Spear, then residing four miles south of Indianola. Each year the specimen was exhibited to the class in Geology when Carboniferous plants were illustrated and the explanation given that it was a remarkably rare and choice specimen of a cone, the like of which I had never seen in any museum; but the real value of the specimen was not fully appreciated till I handed the specimen to Professor Stuart Weller at The University of Chicago in December, 1910. I had taken it with me that day, intending to carry it over to Professor Coulter for further information with reference to it. On seeing it, Professor Weller exclaimed that it was the very kind of a specimen that Professor Coulter had been seeking for years, no petrified Lepidostrobus having ever been reported in the United States. On Professor Coulter's request to section the specimen and describe it he was given full permission to do whatever was necessary to secure from it all the information possible. As the result of that work upon it we now have the splendid description and illustrations published by Professor Coulter and Dr. Land in the Botanical Gazette, Vol. 51, June, 1911.
Specimens
From the Illinois State Museum
Field Museum specimens from Wittry
