The so-called Triassic-Jurassic Extinction(~202millionyearsago) killed off the big reptiles that up until then had ruled the planet, thus clearing the way for dinosaurs to take over. But why did dinosaurs thrive when other creatures died? The so-called Triassic-Jurassic Extinction(~202millionyearsago) killed off the big reptiles that up until then had ruled the planet, thus clearing the way for dinosaurs to take over. But why did dinosaurs thrive when other creatures died? Now a new study led by researchers from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) and Columbia University answers this question. It reveals that Triassic dinosaur species—then a minor group largely relegated to the higher latitudes—regularly endured freezing conditions, suggesting they were well-adapted to the cold in a way that non dinosaurian species were not. Thus, when the Central Atlantic Magmatic Province (CAMP) caused years to decades of global volcanic winter at the end of the Triassic, dinosaurs were able to survive while then-dominant reptiles could not. The study was published in Science Advances on July 2. The researchers’ conclusion relied on two key findings: First, the researchers found physical evidence of dinosaur footprints from the Junggar Basin in Xinjiang Uygur Autonomous Region of northwestern China. During the Late Triassic to Early Jurassic, this region was located at about 71 degrees north, well above the Arctic Circle. The footprints showed that dinosaurs were present along shorelines. Second, when the researchers analyzed deep lake deposits, they found abundant pebbles up to about 1.5 centimeters in diameter within normally fine sediments. Far from any apparent shoreline, the pebbles had no business being there. That left only one plausible explanation: They were ice-rafted debris (IRD). Finding evidence of IRD was crucial to the study because it provided important climate clues. IRD is created when ice abuts a coastal landmass and incorporates bits of underlying rock as it freezes. At some point the ice becomes unmoored and drifts into the adjoining water body. When it melts, the rocks drop to the bottom, mixing with normally fine sediments. Geologists have extensively studied ancient IRD in the oceans, where it is deposited by glacial icebergs, but rarely in lake beds; the Junggar Basin discovery adds to the scant record. The researchers said the pebbles were likely picked up during winter, when lake waters froze along pebbly shorelines. When warm weather returned, chunks of ice floated away with pebbles in tow and later dropped them. “This shows that these areas froze regularly and the dinosaurs did just fine,” said study co-author Dennis Kent, a geologist at Columbia University’s Lamont-Doherty Earth Observatory. The researchers then used phylogenetic bracket analysis to conclude that the dinosaurs were primitively insulated with feathers. This insulation allowed them to adapt to intense volcanic winters and cold polar conditions so they could take advantage of the Arctic’s deciduous and evergreen vegetation. “The key to their eventual dominance was very simple. They were fundamentally cold-adapted animals. When it got cold everywhere, they were ready, and other animals weren't,” said Paul Olsen from Columbia University. While the end of the Triassic is often associated with deadly temperature spikes due to high carbon dioxide concentrations from volcanic eruptions, those same eruptions also deflected a great deal of sunlight, leading to volcanic winters. “Severe wintery episodes during volcanic eruptions may have brought freezing temperatures to the tropics, which is where many of the extinctions of big, naked, unfeathered vertebrates seem to have occurred,” said SHA Jingeng from NIGPAS. “Where as our fine feathered friends acclimated to colder temperatures in higher latitudes did okay.” After the biological extinction event at the end of the Triassic, dinosaurs rapidly increased in size and expanded their geographic range, with the total number of dinosaurs nearly doubling. From then on dinosaurs started their135-million-year-long terrestrial domination of Earth. Fig. 1 The supercontinent of Pangaea 202 million years ago, shortly before the Triassic-Jurassic Extinction. (Image by Olsen et al.)
Fig. 2 A shale cliff in the Junggar Basin in northwestern China, where scientists found ice-rafted pebbles amid otherwise fine-grained sediments. (Image by Paul Olsen)
Story Source: Materials provided by Columbia Climate School. Original written by Kevin Krajick. Note: Content may be edited for style and length. Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
What would happen in the near future with continued global warming? What environmental conditions would the life on Earth most likely confront? The episodes of climate changes in the Earth’s deep past, similar to the current global warming, may provide valuable clues to these questions. What would happen in the near future with continued global warming? What environmental conditions would the life on Earth most likely confront? The episodes of climate changes in the Earth’s deep past, similar to the current global warming, may provide valuable clues to these questions. A recent study led by scientists from China, U.S., and New Zealand reveals that an abrupt warming linked to massive carbon emission during an icehouse climate state caused approximately 20% of anoxic areal extent of the seafloor, and significant biodiversity drop. The finding was published by the Proceedings of the National Academy of Sciences of the United States of America on May 2, 2022. As is known, we are currently living under the Cenozoic icehouse climate that has started since 34 Myr ago. However, global temperature rises rapidly under this icehouse over a couple of centuries, in tandem with accelerated ablation of polar glaciers, rising sea-level, and aggravating marine de-oxygenation, and undoubtedly leading to a significant drop in biodiversity. Where would the global warming lead us to in the future? There are substantial uncertainties regarding the modeling results based on current observations, which drive the current focus on understanding past episodes of carbon emission and ocean deoxygenation, particularly under an icehouse climate state. The Late Paleozoic Ice Age (LPIA, between 360 and 280 million years ago) is the longest-lived and the only icehouse that recorded the transition from icehouse to greenhouse climate states since the occurrence of advanced plants and terrestrial ecosystem. The LPIA is also the only geological period that is featured by low atmospheric CO2 and high O2 concentrations, highly comparable to those of the modern day. It is, therefore, critical to study carbon emissions and their consequences during the LPIA for better understanding the processes and feedbacks of the icehouse Earth system, and thus for more precisely predicting the future environmental and biodiversity changes. A international research team led by Dr. CHEN Jitao from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), Dr. WANG Xiangdong from the Nanjing University, and Dr. Isabel P. Montanez from the University of California, Davis studied the Carboniferous strata from the southern China for over 10 years, with respect to sedimentology, stratigraphy, paleontology, and geochemistry. The Naqing and Narao sections from the Luodian region, Guizhou Province crop out continuous Carboniferous carbonate successions that register geochemical signal of sea water. Scientists collected samples by every 20 cm for over 40-m-thick strata from the two sections and carried out carbon and uranium isotopes to explore the global carbon cycling and marine anoxia. "We utilized global carbon cycle model (LOSCAR) and paleo carbon dioxide concentrations to simulate a total amount of 9,000 Gt C emitted over 300 kyr, causing an increase in sea-surface temperature by ~4℃", CHEN says. "We also modelled an increase in areal extent of the anoxic seafloor from 4% to 22%, causing a dramatic decrease in biodiversity" CHEN Added, "and finally, we performed climate model simulations using the fully coupled Community Earth System model (CESM) to explore the potential mechanisms for the marine anoxia, which are linked to enhanced thermocline stratification and increased nutrient fluxes during the warming." The study further finds that warming-induced marine anoxia may be more pronounced in a glaciated than in an unglaciated period. Reference: Chen, J.T., Montanez, I.P., Zhang, S., Isson, T.T., Macarewich, S.I., Planavsky, N.J., Zhang, F., Rauzi, S., Daviau, K., Yao, L., Qi, Y.P., Wang, Y., Fan, J.X., Poulsen, C.J. Anbar, A.D., Shen, S.Z., Wang, X.D., 2022. Marine anoxia linked to abrupt global warming during Earth’s penultimate icehouse, PNAS, https://doi.org/10.1073/pnas.2115231119. Fig. 1. An abrupt global warming occurred at ~304 Ma under the Carboniferous icehouse climate state, consistent with doubling of atmospheric carbon dioxide, significant negative excursion in carbon isotopes, sea-surface temperature increase, and drop in biodiversity. Fig. 2. Carbon and uranium isotopes recorded in the Naqing section, Guizhou Province, southern China, showing remarkable negative excursions across the Kasimovian-Gzhelian boundary. Modeling results suggest a distinct perturbation in global carbon cycle and an increase in marine anoxia. Fig. 3. Comparison between the KGB warming event during the late Carboniferous icehouse and greenhouse C-perturbation events over the last 300 Myr, indicating that the KGB warming had a more extreme impact on the marine redox landscape relative to its rate of C injection and SST increase than the other events. Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
Assembly of Gondwana commenced in the Neoproterozoic with final disassembly of the supercontinent completed by the Cretaceous. The configuration of major continental blocks (e.g., India, Australia, East Antarctica, and Africa) of Gondwana has been well reconstructed. However, paleopositions of some small continental fragments along the periphery of Gondwana are still in controversy. Assembly of Gondwana commenced in the Neoproterozoic with final disassembly of the supercontinent completed by the Cretaceous. The configuration of major continental blocks (e.g., India, Australia, East Antarctica, and Africa) of Gondwana has been well reconstructed. However, paleopositions of some small continental fragments along the periphery of Gondwana are still in controversy. The Baoshan, Tengchong, Lhasa, South Qiangtang, and Sibumasu terranes were located along the northern margin of Gondwana before late Early Permian rifting. A substantial amount of work has been carried out, aiming at reconstructing the paleopositions of these terranes from various disciplines such as sedimentary provenance, paleomagnetism, and paleobiogeography. These studies led to various paleogeographic models of northeastern Gondwana. Recently, a paleogeographic study based on detrital zircon U-Pb ages and Hf isotopic values from Paleozoic strata of northeastern Gondwana, which is conducted by GAO Biao, his advisor Prof. CHEN Jitao, and Prof. QIE Wenkun from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), in collaboration with the scientist Prof. WANG Xiangdong from Nanjing University. Primary component analysis (PCA) was used to visualize the relative relationship between these terranes and East Gondwana, in addition with the glacier distribution pattern on northeastern Gondwana in the late Paleozoic. The research achievements were published in the international journal Sedimentary Geology. Based on a total of 8209 detrital zircon U-Pb ages and 1606 zircon Hf isotopic values from Paleozoic strata of northeastern Gondwana, a new paleogeographic model has been reconstructed. It indicates that the South Qiangtang, Baoshan, and part of Sibumasu were outboard of the northern margin of Indian Gondwana during the Paleozoic, whereas the Lhasa and Sumatra terranes were located along the northern margin of Australia. Based on provenance shifts of late Paleozoic glaciogenic sedimentary rocks in northeastern Gondwana, two main ice sheets are hypothesized to have developed during the late Paleozoic. This study further confirms the model of a multicenter glacier distribution pattern on Gondwana during the late Paleozoic ice age from a perspective of provenance. The research is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the Second Tibetan Plateau Scientific Expedition and Researh Program. This is a contribution to IGCP 700 and DDE (Deep-time Digital Earth) projects. Reference: Gao, B.*, Chen, J.T.*, Qie, W.K., Wang, X.D., 2022. Revisiting the paleogeographic framework of northeastern Gondwana in the late Paleozoic: implications from detrital zircon analysis. Sedimentary Geology. Available online 11 April 2022. https://doi.org/10.1016/j.sedgeo.2022.106144. Schematic geological map of Southeast Asia and detrital zircon samples locations Primary component analysis (PCA) of detrital zircon characteristic age population
Reconstruction of northeastern Gondwana with regional ice centers during the late Paleozoic ice age Contact: LIU Yun, Propagandist Email: yunliu@nigpas.ac.cn Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences Nanjing, Jiangsu 210008, China
