This is Mazon Monday post #178. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Fabiany Herrera, Assistant Curator of Paleobotany at the Field Museum of Natural History, was the lead author of a new paper about Mazon Creek plant research. The paper is entitled "Investigating Mazon Creek fossil plants using computed tomography and microphotography" and was recently published in the journal Frontiers in Earth Science. The research utilized high tech imaging methods to reveal previously unseen detail in Mazon Creek Tetraphyllostrobus and Crossotheca fossil specimens. The paper is Open Access and can be read and downloaded from the Frontiers website.
Dr. Fabiany Herrera will be speaking at ESCONI's September 2023 General Meeting on September 8th, 2023. Here is his bio from the Field Museum website.
Fabiany Herrera grew up in Colombia, surrounded by the Andes and its many types of forests; from montane to rainforests. He first became interested in rocks and mountains during his high school years and quickly fell in love with fossil and living plants later as an undergraduate student. Some of Fabiany's work includes the earliest evidence of Neotropical rainforests in South America (~60 million years old), enigmatic plants from Mongolia and China (~125 million years old), and fossil floras from Central America (~35-20 million years old).
Here is the paper's abstract.
Abstract
More than 20,000 siderite concretions from the Mazon Creek area of northern Illinois, United States are housed in the paleobotanical collections of the Field Museum. A large proportion contain fossil plants of Middle Pennsylvanian age that often have excellent three-dimensional morphology and sometimes anatomical detail. Approximately eighty plant taxa have been recognized from the Mazon Creek Lagerstätte, but few have been studied in detail, and in some cases the systematic affinities of these fossils need reevaluation. The three-dimensional (3D) preservation of Mazon Creek fossil plants makes them ideal candidates for study using x-ray micro-computed tomography (μCT), and here we apply these techniques to more accurately reconstruct the morphology of specimens of Tetraphyllostrobus Gao et Zodrow and Crossotheca Zeiller. The mineralogical composition of the fossil plant preservation was studied using elemental maps and Raman spectroscopy. In-situ spores were studied with differential interference contrast, Airyscan confocal super-resolution microscopy, and scanning electron microscopy, which reveal different features of the spores with different degrees of clarity. Our analyses show that μCT can provide excellent detail on the three-dimensional structure of Mazon Creek plant fossils, with the nature of associated mineralization sometimes enhancing and sometimes obscuring critical information. Results provide guidance for selecting and prioritizing fossil plant specimens preserved in siderite concretions for future research.
FIGURE 1. Strobilus of cf. Tetraphyllostrobus broganensis (PP54628). (A) Light photographs of part and counterpart of strobilus in a sideritic concretion. (B) Detail of top and middle portion of strobilus in A (left) showing two orthostichies that suggest a decussate arrangement of the sporophylls. Note the white patches of aluminosilicates on the surface of the strobilus. (C) Computed tomography images showing longitudinal (left and top right) and transverse (bottom right) sections. Note the V-shaped sporophylls in lateral view that are directed downwards proximally and upwards distally, and the curved sporophyll outlines in transverse section. (D) Reflective isosurface renderings showing buried surface of the strobilus in A (left) and a lateral view of that portion of the strobilus embedded in the matrix. Note four of six sporophylls in each apparent whorl which complement the pair of sporophylls visible on the surface in A (left). (E) Surface rendering from A (left) processed with MeshLab (shader: slicingplane) and highlighting the ribbed external surface of sporophylls. (F) Surface rendering from D (left) processed with MeshLab (shader: depthmap) showing the four buried sporophylls at each whorl. Scale bars: 10 mm.
FIGURE 4. Branching axis cf. Crossotheca trisecta (PP58059). (A) Light photographs of part and counterpart in a sideritic concretion. Note the stout central axis (arrow) and white patches of aluminosilicates on surface of the fossil. (B) Computed tomography image showing the stout axis and two secondary axes with attached synangia. (C) Isolated virtual rendering showing the 3D architecture of the branching axis. (D) Detail from C (arrow) showing a synangia in lateral view attached to a simple lamina (upper arrow) and view from below showing the arrangement of the sporangia in two rows (lower arrow). (E) Virtual surface rendering from C processed with MeshLab (shader: radiancescaling, lit sphere effect). (F) Mirror image of virtual cast surface rendering from C processed with MeshLab (shader: x-ray). Scale bars: 10 mm (A, B, C, E and F); 5 mm (D).
