Abstract Detail

Paleobotanical Section

Na, Yuling [1], Manchester, Steven  [2], Sun, Chunlin [1].

Middle Jurassic palynology of the Daohugou area, Inner Mongolia, China, with palaeogeographical, paleoecological and paleoclimatic implications.

Since the discovery of the salamander Jeholotriton in 2000, the Daohugou area (in Chifeng City, Inner Mongolia, China) has drawn increasing attention from paleontologists. Although abundant paleontological findings, including tadpole, dinosaur, pterosaur, salamander, mammals, bivalves, crustaceans, insects and plants, have been documented recently, no record of palynoflora has been reported previously. We collected palynological samples from this locality, and conducted a detailed taxonomic analysis in order to augment the megafossil plants, extend documentation of the Middle Jurassic palynoflora and examine implications for palaeogeography, paleoecology and paleoclimate in north China during the Jurassic. Forty-eight genera and 83 species of palynomorphs were identified. Pollen of gymnosperms dominates numerically, followed by spores of pteridophytes. Most taxa, including bisaccate pollen of conifers, monosulcate pollen of Cycadales, Bennettitales or Ginkgoales, along with Cyathidites, Deltoidospora, Granulatisporites, Osmundacidites and Classopollis, are common elements during the Jurassic. Based on comparisons with similar palyno-assemblages in the Jurassic of China, the age of Daohugou locality should be late Middle Jurassic. This is in consistent with the stratigraphic position and the previously obtained radiometric dates on overlying volcanic rock. Palynomorphs in Daohugou mainly include reprsentatives of bryophytes, lycophytes, ferns, pteridosperms, Ginkgoales, Cycadales, Bennettitales, Ephedrales and some conifers. Based on our collection and preliminary research on megafossils from the same locality, during the Middle Jurassic, this area was rich in bryophytes, horsetails, ferns, ginkgoaleans, czekanowskialeans, conifers, and some taxa of cycads. Among them, Ginkgoales, Czekanowskiales and conifers mainly indicate the climate of warm-temperate to temperate regions with seasonal variations. Bryophytes, horsetails, ferns and cycads can also be found in warm areas. Therefore, palaeogeographically, the Middle Jurassic Daohugou flora is attributed to the warm-temperate to medium temperate zone with seasonal change. By studying the ecological and climatic preferences of the main plant groups, five types of palaeoenvironment in Jurassic Daohugou are proposed: 1) mesic upland (Pinaceae, Podocarpaceae, Czekanowskiales and Bennettitales), 2) mesic lowland (Pinaceae, Podocarpaceae, Ginkgoales, Czekanowskiales and Cycadales, together with some hygrophilous bryophytes, lycophytes and ferns), 3) dry upland (Czekanowskiales), 4) dry lowland (Czekanowskiales, Cheirolepidiaceae and Ephedrales) and 5) waterside (plants growing along streams or near lakes, including bryophytes, lycophytes, ferns and probably some pteridosperms). According to the plant assemblage, Daohugou flora corresponds to that of the Middle Jurassic Northern Floristic Province of China, which experienced a transition from humid, warm climate to hotter climate with seasonal drought.

1 - Jilin University, Research Center of Palaeontology and Stratigraphy, 938 Ximinzhu Street, Changchun, Jilin, 130026, China
2 - University of Florida, Florida Museum of Natural History, PO Box 117800, Gainesville, FL, 32611, USA

Keywords:
Palynology
Middle Jurassic
Daohugou, Inner Mongolia, China
palaeogeography
Paleoecology
Paleoclimate.

Presentation Type: Oral Paper:Papers for Sections
Session: 8
Location: Whitewater/Grove
Date: Monday, July 28th, 2014
Time: 9:30 AM
Number: 8005
Abstract ID:392
Candidate for Awards:Isabel Cookson Award