This is Mazon Monday post #255. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Over the years, the Field Museum published many pamphlets, leaflets, journals, bulletins, etc. There's a page on the museum website dedicated to sharing that wealth of knowledge. The popular/leaflet series was a series of booklets on popular topics for the general reader.
From the 1920's through the 1970's, The Field Museum's Division of Publications published four series of booklets on popular topics for the general reader. Written in non-technical language by Museum curators and associates, they were designed to give brief accounts of local flora & fauna, cultures & collections displayed in the Museum's exhibitions.
Below is a list of all of the titles published in the series, separated by their traditional subject divisions. Hyperlinked titles will take you to a page providing the full-text version on the Biodiversity Heritage Library. Titles that are not hyperlinked have not yet been digitized.
In 1933, leaflet 14 "A Fossil of the Coal Age" was published. It was written by Bror Eric Dahlgen (1877-1961), who was the acting curator of the Department of Botany. Dahlgren emigrated to the US from Sweden in the last 1800s. His professional career started in the field of dentistry. Later work on understanding the mammalian palate led to a position at the American Museum of Natural History. He wrote quite a few books during his career. These are also available as part of the Biodiversity Heritage Library. The following is a memorial published in the January 1962 edition of the Chicago Natural History Bulletin.
BROR ERIC DAHLGREN (1877-1961)
Dr. B. E. Dahlgren, Curator Emeritus of Botany, died of a heart attack at his home on December 16, 1961. This ended a varied career that began with emigration from his native Sweden to the United States when he was in his teens. After receiving his degree from the University of Minnesota, Dr. Dahlgren engaged in the practice of orthodontic dentistry in New York City at the turn of the century. His studies of the comparative anatomy of the mammalian palate led to use of the collections at the American Museum of Natural History, and subse-quently to an interest in problems of museum exhibition. Employing some of the materials and techniques of mechanical dentistry, Dahlgren constructed models of invertebrate animals, including insects, that were superior to any known at the time. Eventually he gave up the practice of dentistry and became a staff member at the American Museum.
In 1909, Dr. Charles W. Millspaugh, the Museum's first Curator of Botany, with the support of Mr. Stanley Field, President, induced Dahlgren to become head of the department's Division of Modeling. In 1935 Dr. Dahlgren be-came Curator of Botany, a title that was changed the following year to Chief Curator of Botany.
Under his direction a program of botanical exhibition was begun that resulted in the famed Stanley Field Collection of Plant Models and botanical exhibits considered to be the finest anywhere. Among the most spectacular of these is the restoration of a Carboniferous forest on display in Hall 38 of the Museum. Illustrations of this restoration have appeared in most textbooks of geology published since the completion of the exhibit.
Dr. Dahlgren was an authority on wax palms and conducted a number of botanical collecting expeditions to Jamaica, British Guiana, Brazil, and Cuba.
"A Fossil of the Coal Age" describes what was known about Carboniferous coal forests at the time. The Pennsylvanian Period was thought to be 250 million years ago. There's a photo of the Field Museum's diorama of a coal forest from the 1930's. It looks pretty familiar to the current model. Check out the amphibian!
DETAIL OF THE CARBONIFEROUS FOREST RESTORATION IN FIELD MUSEUM
The large tree in the center background is a tree-like clubmoss, Sigillaria, partly hidden by the trunks of a Lepidophloios and a tree-fern with large leafscars on the stem and concealed above by fronds of this fern (Psaronius) and foliage of Lepidodendron. Ascending the Lepidophloios trunk is a seed-fern (Lyginopteris) with delicate forking fronds, one of which is shown bearing seed (Lagenostoma). The strap-shaped foliage in the upper left corner is that of the gymnosperm Cordaites and below on the left are two seed-ferns {Neuropteris decipiens above, N. heterophylla below) each presenting a seed-bearing frond. The small plant at the bottom center and right is Sphenophyllum. The large fallen trunk is a Sigillaria with a small herbaceous clubmoss, Selaginellites, spreading over its surface. The slender log on the ground is a Lepidodendron with rhombic leaf cushions. On this trunk is seen one of the large roaches of the period and beyond is one of the four-legged inhabitants of the swamp forests, a Carboniferous amphibian.
There are maps that show the distribution of Carboniferous fossils. Interestingly, plate tectonics was unknown at the time, but the super continent of Pangaea had been theorized.
FIG. 23. Distribution of the Carboniferous flora in the northern hemisphere and of the closely related Permian Gondwana or Glossopteris flora in the southern, indicated on a map of the continents in their present position. From Zimmermann.
FIG. 24. Map of the world in Carboniferous time, the continents forming a single large mass. The positions of the poles are indicated by the dotted circles and the direction of their movements by arrows. K Carboniferous deposits, Etraces of glaciation, S-sand, desert, G-gypsum deposit. After Kö Köppen-Wegener, from Zimmermann.
The book has some very nice photos and drawings.
FIG. 8. A fragment of a branch of a calamite in a Carboniferous sandstone nodule, showing the type of calamite foliage (Annularia radiata) most common at Mazon Creek, Illinois, and represented in the group. Note: this is now knowm as Annularia inflata.
Fig. 7. A split sandstone nodule from Mazon Creek, Illinois, with an included fossil leaf. (Neuropteris decipiens), a fragment of a frond of the large seed-fern shown in the group. Note: not sandstone (!), but iron carbonate, FeCO3. This now known as Macroneuropteris scheuchzeri
Fig. 11.A slab of Carboniferous limestone from Mazon Creek, Illinois, showing fragments and a large fossil clubmoss cone (Lepidostrobus ovatifoliua)
Fig. 10. An impression in sandstone of the Pennsylvanian period of the surface pattern on the trunk of an ancient clubmoss {Lepidodendron obovatum Sternberg). Mazon Creek, Illinois.
Fig. 20. Primitive winged insect of the Carboniferous age {Stenodictya lobata Brongniart) from Handlirsch (order Palaeodictyoptera).
