WANG, XIN* and DAVID DILCHER. Florida Museum of Natural History, University of Florida, Gainesville, FL 32611-7800. - Mesofossils from Mid-Cretaceous Sediments in Kansas.
Study of mesofossils charcoalified during fire events have triggered
an explosion of knowledge about the existence of gymnosperms and
angiosperms during the Cretaceous. We collected sediments rich in
charcoalified materials from the Dakota Formation near Black Wolf,
Kansas. Sieving these samples yielded a variety of mesofossils,
including different parts of ferns, gymnosperms and angiosperms. Up to
now, we have identified about 50 types (127 pieces) of seeds, 1 type
(33 pieces) of fruit, 12 types (22 pieces) of seed/flower parts, 6
types (87 pieces) of cone scales, 3 types (9 pieces) of fern shoots, 8
types (17 pieces) of gymnosperm and/or angiosperm shoots, 4 types (11
pieces) of gymnosperm leaves, 7 types (40 pieces) of gymnosperm cones,
2 types (3 pieces) of angiosperm inflorescences. These fossils form
unique assemblages from each sedimentary bed sampled at Black Wolf.
Preserved with these charcoalified mesofossils are also aquatic fern
megaspores which were not charcoalified, this fact implies that some
plant fragments derived from an aquatic environment were also
incorporated into these sediments. The presence, domination and
preservation of different taxa in the assemblages suggest that these
plants survived repeated fire events. The anatomical study of
mesofossils provides us more a detailed picture of ancient vegetation
and more hints for the systematics of plants, data about mesofossils
bridges the gap between studies of megafossils and palynology, and
gives us a new perspective on the Dakota flora and its ecology.
Key words: Angiosperm, Charcoal, Cretaceous, Dakota Formation, Fire event, Mesofossil