Herendeen, Patrick , Crane, Peter , Takahashi, Masamichi , Leslie, Andrew , Glasspool, Ian , Ichinnorov, Niiden , Gombosuren, Tsolmon , Nyamsambuu, Odgerel .
Exceptionally well-preserved Early Cretaceous seed plants from Mongolia and their evolutionary significance.
Fieldwork in east-central Mongolia has yielded new, abundant, diverse, and exceptionally well-preserved Early Cretaceous (Aptian-Albian) seed plants from two localities (Tevshiin-Govi, Khuren Dukh). In this paper we present preliminary results on the Tevshiin-Govi locality, which is a small opencast lignite mine, southwest of Ulaanbaatar. At several levels in the mine, mummified fossil plants occur matted together in compressed, lignitic, but otherwise very little altered deposits that are dominated by linear leaves of several different kinds. Cuticular details are well-preserved and reproductive structures are diverse, informative and common. Preliminary study indicates the presence of at least a dozen fossil seed plants represented by a large number of dispersed plant organs. The co-occurrence of well-preserved mesofossils with mummified larger plant parts, such as leaves and shoots, provides a rare opportunity to reconstruct several of these seed plants from multiple organs. Well-preserved reproductive structures from Tevshiin-Govi include several different kinds of seeds, as well as a variety of ovulate cones and cone scales, some of which are clearly coniferous but others are of less certain relationship. There are at least two types of cones that are referable to the Pinaceae. Cones and dispersed cone scales of the extinct genus Schizolepis are abundant in some samples. Also abundant in some samples are Swedenborgia-like cone scales. There are several cupules bearing seeds that appear to be similar to those of corystosperms. We have documented several types of dispersed seeds in the assemblage, including one with a long micropyle similar to seeds of Bennettitales-Erdtmanithecales-Gnetales (BEG) group from the Early Cretaceous of eastern North America and Europe. Of particular interest is a possible link between a distinctive and enigmatic, woody, ovoid reproductive structure, represented by hundreds of specimens in certain samples, and leaves previously assigned to Podozamites. The reproductive structures are 10-12 mm long, ovoid and are borne singly at the apex of a slender axis or stalk. They dehisce into four lobes from the base. The structures are pointed at the apex with no obvious opening or stigmatic surface. Internally they have a slender central column that seems to bear seeds. Ongoing research is focused on securing the additional structural details needed to understand the systematic placement of the great variety of interesting and enigmatic reproductive structures from the two localities.
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1 - Chicago Botanic Garden, Senior Scientist, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
2 - Yale University
3 - NIIGATA UNIVERSITY, DEPT OF ENVIRON FACULTY SCIENCE, 8050 2-NO-CHO IKARASHI NISHI-KU, NIIGATA, N/A, 950-2181, Japan
4 - Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
5 - Field Museum of Natural History
6 - Mongolian Academy of Science
7 - National University of Mongolia
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Tuesday, July 10th, 2012
Time: 4:00 PM