Search

Premise: The Aptian–Albian (121.4–100.5 Ma) was a greenhouse period with global temperatures estimated as 10–15°C warmer than pre‐industrial conditions, so it is surprising that the most reliable CO2 estimates from this time are <1400 ppm. This low CO2 during a warm period implies a very high Earth‐system sensitivity in the range of 6 to 9°C per CO2 doubling between the Aptian‐Albian and today. Methods: We applied a well‐vetted paleo‐CO2 proxy based on leaf gas‐exchange principles (Franks model) to two Pseudotorellia species from three stratigraphically similar samples at the Tevshiin Govi lignite mine in central Mongolia (~119.7–100.5 Ma). Results: Our median estimated CO2 concentration from the three respective samples was 2132, 2405, and 2770 ppm. The primary reason for the high estimated CO2 but with relatively large uncertainties is the very low stomatal density in both species, where small variations propagate to large changes in estimated CO2. Indeed, we found that at least 15 leaves are required before the aggregate estimated CO2 approaches that of the full data set. Conclusions: Our three CO2 estimates all exceeded 2000 ppm, translating to an Earth‐system sensitivity (~3–5°C/CO2 doubling) that is more in keeping with the current understanding of the long‐term climate system. Because of our large sample size, the directly measured inputs did not contribute much to the overall uncertainty in estimated CO2; instead, the inferred inputs were responsible for most of the overall uncertainty and thus should be scrutinized for their value choices. [ABSTRACT FROM AUTHOR]

The second integument of the angiosperm ovule is unique among seed plants, with developmental genetics that are distinct from those of the inner integument.sup.1. Understanding how the second integument should be compared to structures in other seed plants is therefore crucial to resolving the long-standing question of the origin of angiosperms.sup.2-6. Attention has focused on several extinct plants with recurved cupules that are reminiscent of the anatropous organization of the basic bitegmic ovules of angiosperms.sup.1-6, but interpretations have been hampered by inadequate information on the relevant fossils. Here we describe abundant exceptionally well-preserved recurved cupules from a newly discovered silicified peat dating to the Early Cretaceous epoch (around 125.6 million years ago) in Inner Mongolia, China. The new material, combined with re-examination of potentially related fossils, indicates that the recurved cupules of several groups of Mesozoic plants are all fundamentally comparable, and that their structure is consistent with the recurved form and development of the second integument in the bitegmic anatropous ovules of angiosperms. Recognition of these angiosperm relatives (angiophytes) provides a partial answer to the question of angiosperm origins, will help to focus future work on seed plant phylogenetics and has important implications for ideas on the origin of the angiosperm carpel. Analysis of recurved cupules from a newly discovered Early Cretaceous silicified peat in Inner Mongolia, China and comparison with other potentially related Mesozoic plant fossils provides insight into the origins of angiosperms., Author(s): Gongle Shi [sup.1] , Fabiany Herrera [sup.2] , Patrick S. Herendeen [sup.2] , Elizabeth G. Clark [sup.3] , Peter R. Crane [sup.4] [sup.5] Author Affiliations: (1) State Key Laboratory [...]

Neogene plant fossils from low latitudes of China are critical for understanding the history of plant diversity and paleoenvironment in that region. Here we describe well-preserved Cercis fruit fossils from the Fotan Group (~14.7 Ma) in Fujian, southeastern China. Based on detailed morphological and anatomical comparisons with extant and fossil species, we refer to these fossils as Cercis zhangpuensis sp. nov. Cercis zhangpuensis, most similar to C. chinensis A.V. Bunge among extant species of the genus. The currently described species is the southmost fossil record of the genus in Asia. In addition, we have studied cuticle structures of Cercis pod fossils for the first time. The occurrence of Cercis fossils indicates that the genus existed in Fujian, China since the middle Miocene. Available fossil records indicate that Cercis firstly appeared in North America during the Eocene, then spread in Europe and Asia since the Oligocene, with its distribution attaining the peak in the Miocene. We conclude that East Asia may represent one of the major centres of diversification of Cercis in the Miocene. [ABSTRACT FROM AUTHOR]