Animals originated and evolved during a unique time in Earth history-the Neoproterozoic Era. This paper aims to discuss (1) when landmark events in early animal evolution occurred, and (2) the environmental context of these evolutionary milestones, and how such factors may have affected ecosystems and body plans. With respect to timing, molecular clock studies-utilizing a diversity of methodologies-agree that animal multicellularity had arisen by ∼800 million years ago (Ma) (Tonian period), the bilaterian body plan by ∼650 Ma (Cryogenian), and divergences between sister phyla occurred ∼560-540 Ma (late Ediacaran). Most purported Tonian and Cryogenian animal body fossils are unlikely to be correctly identified, but independent support for the presence of pre-Ediacaran animals is recorded by organic geochemical biomarkers produced by demosponges. This view of animal origins contrasts with data from the fossil record, and the taphonomic question of why animals were not preserved (if present) remains unresolved. Neoproterozoic environments demanding small, thin, body plans, and lower abundance/rarity in populations may have played a role. Considering environmental conditions, geochemical data suggest that animals evolved in a relatively low-oxygen ocean. Here, we present new analyses of sedimentary total organic carbon contents in shales suggesting that the Neoproterozoic ocean may also have had lower primary productivity-or at least lower quantities of organic carbon reaching the seafloor-compared with the Phanerozoic. Indeed, recent modeling efforts suggest that low primary productivity is an expected corollary of a low-O2 world. Combined with an inability to inhabit productive regions in a low-O2 ocean, earliest animal communities would likely have been more food limited than generally appreciated, impacting both ecosystem structure and organismal behavior. In light of this, we propose the "fire triangle" metaphor for environmental influences on early animal evolution. Moving toward consideration of all environmental aspects of the Cambrian radiation (fuel, heat, and oxidant) will ultimately lead to a more holistic view of the event.

The temporal and environmental context of early animal evolution: considering all the ingredients of an ‘explosion’

Chemical weathering characteristics of Late Cretaceous Nenjiang Formation from the Songliao Basin (Northeastern China) reveals prominent variation at Milankovitch band and their paleoclimatic implications

Metamorphism and geochronology of garnet mica schists from the Kuluketage area: Implications for reconstructions of the Tarim Craton in supercontinent Columbia

Sea level rise caused by global warming is one of the biggest challenges facing humankind. Deepening the understanding of the mechanism of global sea level change during the greenhouse period is the key to meeting this challenge. Large-scale, rapid sea-level changes frequently occurred during the greenhouse period lacking ice sheets. However, conventional sea level change models cannot explain this phenomenon, exposing their shortcomings. Estimation of global pore space in sediments and big data studies have indicated that global sea level changes may also be related to climate-related continental groundwater volume changes. We review the mechanism of sea level change caused by astronomically driven continental groundwater activities and propose a new Sponge Continent hypothesis: astronomical forcing drives climate change, causing filling and discharge of continental aquifers (by analogy, a sponge), which may in turn impact large-scale changes in global sea levels and inland lake level during the greenhouse period. We summarize recent technological breakthroughs related to the reconstruction of deep time sea- and lake-level changes. First, lake level change has been proposed as an indicator for the fluctuation of continental groundwater volume. Second, the sedimentary noise model and SediRate-Fischer method were proposed for the reconstruction of sea- and lake-level changes from sedimentary successions. Among these, the sedimentary noise model is developed based on the principle of the Milankovitch theory of climate change and time series analysis techniques. The noise model contains two complementary methods: dynamic noise after orbital tuning (DYNOT) and lag-1 autocorrelation coefficient (<italic>ρ</italic>1). The DYNOT method measures the noise intensity in paleoclimate time series, i.e., the ratio of non-Milankovitch variation to total variation. By calculating the lag-1 autocorrelation coefficient of the target paleoclimate time series, the <italic>ρ</italic>1 model can independently test the noise changes related to sea level variations. The <italic>ρ</italic>1 value decreases with the increase of noise intensity, and vice versa. The relative intensity of the sedimentary noise is anti-phased with the sea level change. When the sea level increases, the sedimentary noise decreases, and vice versa. This model can also be applied to the studies of lake level changes. Third, cyclo-magnetostratigraphy can provide a global synchronous stratigraphic correlation framework, which is vital for the evaluation of the aquifer eustasy and Sponge Continent hypothesis. The hypothesis of aquifer eustasy and Sponge Continent can be supported by geological evidence from the greenhouse period. This paper reviews recent progress related to astronomically forced sea level changes and/or lake level changes in chronological order. Some of them support the predicted antiphase relationship between the sea level curve and the contemptuous lake level curve as predicted by the Sponge Continent hypothesis. However, many unsolved issues about the nature and mechanisms of sea level change are to be explored. First, estimates of groundwater volume remain in dispute. Second, there is a lack of quantitative indicators for deep time groundwater variations. Third, the timing and mechanism of groundwater changes in continental aquifers are still unconstrained. Potential research directions are also discussed, including groundwater storage estimate, research methods, storage-drainage mechanism of groundwater reservoirs, etc.

天文驱动的温室时期地下水储库与海平面变化

Sea level rise caused by global warming is one of the biggest challenges facing humankind. Deepening the understanding of the mechanism of global sea level change during the greenhouse period is the key to meeting this challenge. Large-scale, rapid sea-level changes frequently occurred during the greenhouse period lacking ice sheets. However, conventional sea level change models cannot explain this phenomenon, exposing their shortcomings. Estimation of global pore space in sediments and big data studies have indicated that global sea level changes may also be related to climate-related continental groundwater volume changes. We review the mechanism of sea level change caused by astronomically driven continental groundwater activities and propose a new Sponge Continent hypothesis: astronomical forcing drives climate change, causing filling and discharge of continental aquifers (by analogy, a sponge), which may in turn impact large-scale changes in global sea levels and inland lake level during the greenhouse period. We summarize recent technological breakthroughs related to the reconstruction of deep time sea-and lake-level changes. First, lake level change has been proposed as an indicator for the fluctuation of continental groundwater volume. Second, the sedimentary noise model and SediRate-Fischer method were proposed for the reconstruction of sea- and lake-level changes from sedimentary successions. Among these, the sedimentary noise model is developed based on the principle of the Milankovitch theory of climate change and time series analysis techniques. The noise model contains two complementary methods: dynamic noise after orbital tuning

Astronomically forced changes in groundwater reservoirs and sea level during the greenhouse world

Obliquity-forced aquifer-eustasy during the Late Cretaceous greenhouse world

Late Paleoproterozoic orogenic evolution of the northern Tarim Craton, NW China: Insights from phase equilibrium modeling and zircon U-Pb geochronology of metapelitic granulite in the Kuluketage area

Possible response of N2O emission to marine redox fluctuation during the Ediacaran-Cambrian transition in Nanhua Basin, South China

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Pengcheng Ju

Papers

Obliquity-forced aquifer-eustasy during the Late Cretaceous greenhouse world

Late Paleoproterozoic orogenic evolution of the northern Tarim Craton, NW China: Insights from phase equilibrium modeling and zircon U-Pb geochronology of metapelitic granulite in the Kuluketage area

Metamorphism and geochronology of garnet mica schists from the Kuluketage area: Implications for reconstructions of the Tarim Craton in supercontinent Columbia

Possible response of N2O emission to marine redox fluctuation during the Ediacaran-Cambrian transition in Nanhua Basin, South China

Publisher Correction: Phosphorus availability on the early Earth and the impacts of life