Internal waves arise by perturbations that disturb the hydrostatic equilibrium between gravity and buoyancy at the pycnocline. In comparison to tempestites and turbidites, internal waves produce episodic high-turbulence events and remobilize the sediment at the depth where the pycnocline intersects the sea floor. Internal waves, internal tides and their associated currents have long been observed and measured on modern shelves and continental slopes, yet very little is known from the rock record for a long time. Over the past decade, more and more authors noticed the influence of internal waves on the development of heterotroph metazoan reefs through the Phanerozoic. Recently, Dr. LI Qijian from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences conducted a research on the bryozoan reefs in the lower Hanchiatien Formation, which crop out in the lower part of this formation at the southern tip of Chongqing, Southwest China. These reefs occur as massive argillaceous limestones, varying in size from 1.6 to 2.8 m in thickness and 6 to 16 m in diameter. The reefs are surrounded by gray-green shales and silty shales (Fig. 1). Distinct vertical ecozonation is present, and four growth stages have been recognized, represented by four facies types from bottom to top: (1) auloporid coral-echinoderm-bryozoan packstone/floatstone, (2) fenestrate bryozoan-echinoderm bafflestone, (3) Fistulipora-Asperopora framestone, and (4) Fistulipora framestone (Fig. 2). Of note, no traces of algae or cyanobacteria (not even thin microbial crusts) have been observed in the Hanchiatien reefs, arguing that the bryozoan reefs developed below the photic zone but in nutrient-rich, agitated water. Such conditions are commonly observed in areas where a pycnocline arrives at a shelf, slope, or ramp. In the studied section, internal waves, probably initiated by tides, propagate landward, shoal, and eventually break at a depth where the pycnocline intersects the seafloor. In tropical mid- to outer-ramp settings, these bryozoan reefs showcase an unusual reef community in heterozoan carbonates, which were probably influenced by internal waves. This study was financially supported by the National Natural Science Foundation of China, and the Chinese Academy of Science. This study is a contribution to the IGCP-653‘The onset of the Great Ordovician Biodiversity Event’. Reference: Qijian Li, Andrej Ernst, Axel Munnecke, Shenyang Yu, Yue Li, Early Silurian (Telychian) bryozoan reefs in the epeiric sea of South China: Are heterotrophic metazoan buildups promoted by internal waves?. Sedimentary Geology (2018), doi:10.1016/j.sedgeo.2018.07.008 Photomicrographs of reef limestones of the lower reef horizon. (A) Fistulipora framestone. (B) Close-up of the box in A showing fistuliporid bryozoans. (C) Fistulipora-Asperopora framestone. (D–E) Close-ups of the boxes marked in D showing different bryozoans. Note that some Asperopora colonies developed on the top of fenestellid bryozoans (red arrows). A = Asperopora, F = Fistulipora.
Tiaomaphyton fui gen. et sp. nov. Xu, Fu et Wang from the Middle Devonian Tiaomachian Formation, Hunan, South China The Middle Devonian flora of South China constitutes a key component of Palaeozoic floras and is characterised as being dominant of endemic plants. However, the study of the Middle Devonian flora was mainly based on materials from the upper Yangtze region, such as the Xichong Flora from Yunnan Province, southwestern China (Yangtze Block). Central Hunan, especially the palaeogeographic Cathaysia Block, though develops non-marine Middle Devonian deposits, well-described plant fossils that can be compared with those from other coeval floras were rare. It is significant for understanding plants evolution, comparing floras and palaeogeography to study Middle Devonian flora from Hunan Province. Recently, a new protolepidodendrid lycopsid is described from the Middle Devonian Tiaomachian Formation of Changsha, Hunan, by the workgroup of prof. XU Honghe, Associate Prof. FU Qiang and graduate student WANG Yao from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences. The plant has slender stem and oval leaf base. Its leaf trifurcates into a lamina with three segments in one plane curving adaxially and a heel of small tip downwardly. The central segment is the longest, whilst all three segments are close and paralleling arranged. The sporangium attached adaxially to the sporophyll by a pad is ellipsoidal and oval in shape and with longitudinal dehiscence. The plant Tiaomaphyton fui was named after its locality Tiaomajian Town. The present plant Tiaomaphyton fui from the Middle Devonian of central Hunan, which palaeogeographically belongs to the Cathaysia Block, one of the two sub-regions of the whole South China Plate. The study gives a better understanding of the Middle Devonian flora of the Cathaysia Block and has palaeogeographic implications to the South China Plate. A floristic distinction between the Cathaysia and Yangtze blocks is suggested and it is probably caused by the special palaeogeographic pattern of the South China Plate. This paper will be published recently in the Journal “Review of Palaeobotany and Palynology”. Paper information: Xu H-H, Fu Q, Wang Y. 2018. A new protolepidodendrid lycopsid from the Middle Devonian of Hunan, South China and its palaeogeographic implications. Review of Palaeobotany and Palynology. 256, 63-69. https://doi.org/10.1016/j.revpalbo.2018.06.003
Zosterophyllum sinense (Zosterophyllopsida) from the Lower Devonian Cangwu Formation of Guangxi, South China: the type specimen (PB6477, left) and the reconstruction (right) The zosterophyllopsid, an important group of the early land vascular plants, was widespread on a number of palaeocontinents of the Early Devonian and acts as a dominant plant member of the South China Early Devonian flora. Most previous studies were based on specimens from Yunnan, whilst few studies were given to Lower Devonian plants from Guangxi. Though, Zosterophyllum sinense was reported by Li and Cai in 1970s, more detailed information was obscure. It is significant for understanding plants evolution, comparing floars and palaeogeography to study zosterophyllosids from Guangxi Province. Recently, Professor XU Honghe and WANG Yi, Associate Professor FU Qiang and graduate student WANG Yao from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Scienses have re-observed the type specimens of Zosterophyllum sinense from Lower Devonian of Guangxi and collected new specimens from the same locality. This research carries a further study on the rooting system, terminal spikes and sporangial dehisce characteristics of Z. sinense, revises it diagnosis and reconstructs this plant. The plant with tufted habit consists of the below-ground part (rhizome area) and the above-ground part (axes and terminal spikes). The rhizome area is formed by dense masses of axes extending towards several directions and the axes above-ground are smooth and often branching K-shaped or anisotomous near-ground. Spike comprises the central fertile axis and loosely and helically arranged sporangia. The sporangium is pear-shaped or fan-shaped in face view and fusiform to oval in lateral view. The sporangium dehisces into two unequal sporangial valves and the abaxial valve is larger than the adaxial one. Palaeogeographically, Guangxi belonged to the Cathaysia Block, a sub-region of the South China Block, while previous Lower Devonian floristic records were mainly from Yunnan, which belonged to the Yangtze sub-region of the whole South China Block. Though, the Cathaysia and Yangtze blocks belonged to a continental terrane, there was an epicontinental sea between the two blocks during the Palaeozoic. Plant fossils in this study suggest a floristic distinction between the two blocks. This paper will be published recently in the Journal “Review of Palaeobotany and Palynology”, as below: Reference: Wang Y., Xu H-H, Wang Y, Fu Q, 2018. A further study of Zosterophyllum sinense Li and Cai (Zosterophyllopsida) based on the type and the new specimens from the Lower Devonian of Guangxi, southwestern China. Review of Palaeobotany and Palynology. 258, 112–122.
patial and temporal distribution of the Yichang Uplift Stratigraphic hiatuses of variable time intervals within the Rhuddanian to early Aeronian (Llandovery, Silurian) are identified in the area bordering East Chongqing, West Hubei and Northwest Hunan in central China. Their distribution suggested the existence of a local uplift, traditionally named the Yichang Uplift. The diachronous nature of the basal black shale of the Lungmachi Formation crossing different belts of this Uplift signifies the various developing stages during the uplifting process. The present paper by Prof. CHEN Xu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and collegues define the temporal and spatial distribution pattern of the Yichang Uplift, which might be one of the important controlling factors for the preservation and distribution of the shale gas in this region. The present work is a sister study to the published paper, “Stage-progressive distribution pattern of the Lungmachian black graplolitic shales from Guizhou to Chongqing, Central China”. These two studies provide a complete Ordovician-Silurian black shale distribution pattern in the Middle and Upper Yangtze, a region with the major shale gas fields in China. This research was published in Science China Earth Sciences as a cover story, and it was supported by Strategic Priority Research Program of Chinese Academy of Sciences, the National Natural Science Foundation of China and the National Science and Technology Major Project of China. Reference: Chen X, Chen Q, Zhen Y, Wang H, Zhang L, Zhang J, Wang W, Xiao Z. 2018. Circumjacent distribution pattern of the Lungmachian graptolitic black shale (early Silurian) on the Yichang Uplift and its peripheral region. Science China Earth Sciences, 61: 1195–1203.
Canada has an extensive record of Triassic marine sediments documenting abundant ammonoid faunas of mid and high palaeolatitudes, ranging from Griesbachian to late Rhaetian. Along with the material from Nevada (low palaeolatitude), British Columbia provides an excellent example for discussions on ammonoid palaeogeography and latitudinal gradient of taxonomic richness. Some Anisian ammonoids reported from British Columbia for the first time Recently, Dr. JI Cheng from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and colleague from Switzerland reported new material of Anisian (Middle Triassic) ammonoids from British Columbia based on populatioanl approach and recognized six species which were only found in Nevada before. The occurrence of low-palaeolatitude restricted species in BC indicates that exchanges between low- and mid-palaeolatitude regions were actually more significant than previously documented. Moderate levels of exchange existed not only during middle Anisian but also during the late Anisian. The new material largely improved the correlation of ammonoid unitary association zones between the two regions. These revised biochronological correlations indicate that BC biochronozones were not necessarily of larger duration than those from Nevada. Along with increasing sampling efforts, BC biochronozones tend either to be exact correlative of Nevada zones, or to intercalate between them. Therefore, the common view that geographically differentiated evolutionary rates originates from the latitudinal gradient of taxonomic richness does not hold for Anisian ammonoid faunas along the Palaeopacific margin of North America. The relative lower diversity of ammonoid in higher latitude is most likely due to the low carbonate content, instead of different origination and extinction rates. Middle and upper Anisian revised ammonoid zonation of north-eastern British Columbia This research has recently been online published in Papers in Palaeontology. Paper information: Cheng Ji and Hugo Bucher. 2018. Anisian (Middle Triassic) ammonoids from British Columbia (Canada): biochronological and palaeobiogeographical implications. Papers in Palaeontology.
Pedunculotheca diania Sun, Zhao et Zhu gen. et sp. nov. from the Chengjiang Biota, Yunnan Province, China Hyoliths are a taxonomically problematic group of Palaeozoic lophotrochozoans that are among the first shelly fossils to appear in the Cambrian period. On the basis of their distinctive exoskeleton, hyoliths have historically been classified as a separate phylum with possible affinities to the molluscs, sipunculans or lophophorates – but their precise phylogenetic position remains uncertain. Recently, Dr. SUN Haijing, Prof. ZHAO Fangchen and colleagues from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences with Dr. Martin Smith from the Durham University, describe a new orthothecide hyolith from the Chengjiang Lagerstatte (Cambrian Series 2 Stage 3), Pedunculotheca diania, published in Proceedings of the Royal Society B: Biological Sciences. Reconstruction of adult Pedunculotheca diania in feeding position The new taxon exhibits a non-mineralized attachment structure that strikingly resembles the brachiopod pedicle – the first report of a peduncular organ in hyoliths. This organ establishes a sessile, suspension feeding ecology for these orthothecides, and – together with other characteristics (e.g., bilaterally symmetrical bivalve shell enclosing a filtration chamber and the differentiation of cardinal areas) – identifies hyoliths as stem-group brachiopods. The phylogenetic analysis indicates that both hyoliths and crown brachiopods derived from a tommotiid grade, and that the pedicle has a single origin within the brachiopod total group. Shell microstructures, in particular, the ‘canaliculate’ microstructure and ‘punctae’, those have been afforded great importance– turn out to have multiple origins across the brachiozoans. Identifying hyoliths as stem-group brachiopods not only resolves character polarity within the group itself, that Pedunculotheca is more primitive than hyolithides and other orthothecides which are united by the secondary loss of a pedicle and the morphology of their metamorphic shell; but also indicates a profound adaptive strategy change at the end of the Cambrian, that the dramatic decline of stem brachiopods and linguliforms with a high metabolic overhead were supplanted by the radiation of lineages expert in economic living. Reference: Sun H, Smith MR*, Zeng H, Zhao F*, Li G, Zhu M. 2018 Hyoliths with pedicles illuminate the origin of the brachiopod body plan. Proc. R. Soc. B 20181780. DOI:10.1098/rspb.2018.1780
Some fossil specimens of Austrohamia acanthobractea from the Daohugou biota The Cupressaceae is the only conifer family that distribute in all continents except for Antarctica, and it is especially remarkable for the diversity of morphology, species, and habitat preference exhibited by its members. The fossil record suggests that the ancestral groups of Cupressaceae originated during the Triassic. During the middle-late Mesozoic, the diversity and geographical distribution of Cupressaceae are crucial and the ancestors of all subfamilies appeared and differentiated. However, detailed investigations on morphology and anatomical characteristics of the Mesozoic Cupressaceae taxa are still very limited compared with their rich fossil record, which impede the understanding of the early morphological diversity and evolution of the middle-late Mesozoic Cupressaceae plants. Recently, a research team of the Mesozoic plants represented by Dr. DONG Chong, Prof. WANG Yongdong and Prof. YANG Xiaoju from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) provide new insight into the whole-plant reconstruction and phylogeny on Austrohamia acanthobractea —a Cupressaceae taxon from the Middle Jurassic Daohugou biota in northeastern China. The study revealed the exquisite details of the vegetative shoots and leaf cuticles, ovulate cones and in situ ovules, pollen cones and in situ pollen grains, providing a complete supplementary depiction on the morphological and anatomical information of this Jurassic cypress plant. The update result was recently published in “International Journal of Plant Science”, a well-known scientific journal published in University Press of Chicago in USA. Whole-plant reconstruction of Austrohamia acanthobractea. Austrohamia, the oldest macrofossil record of Cupressaceae was originally reported from the Early Jurassic in the Argentina of the southern Hemisphere. In addition to the type species, Austrohamia acanthobractea is the second fossil record of the genus. The co-occurrence of Austrohamia in the Jurassic of both the Southern and Northern Hemispheres appears to suggest an intercontinental disjunction between Gondwana and Laurasia. A. acanthobractea is the most common species among the plant fossils from the Daohugou biota. These rich and well-preserved fossil materials with many details makes it to be one of the most completely studied Jurassic Cupressaceae species. In addition, by using the morphological cladistic analysis, the researchers show that the two species of Austrohamia form a polytomy with the expanded Cunninghamioideae clade This supports the original interpretation that the genus is closely related to Cunninghamia and Cunninghamia-like fossils. This study is of great significance for a comprehensive understanding of ancestor groups and diversity of early Cupressaceae. Reconstructed phylogeny for Cupressaceae (left) and figures of bract-scale complexes (right). The Daohugou Lagerstatte is well known for its rich and well-preserved fossil invertebrates, vertebrates and plants, and represents a deposit with some terrestrial elements. In contrast, detailed studies on systematics and diversity in some key plant fossil taxa of this biota is very poorly documented, thus needs more and urgent comprehensively study. This new result by DONG et al. will thus promote and deepen the investigation of key plant fossils in the Daohugou biota. This study was supported by the Strategic Priority Research Program (B) of CAS and the National Natural Science Foundation of China. Reference: Dong, C., Wang, Y. D., Yang, X. J., Sun, B. N., 2018. Whole-Plant Reconstruction and Updated Phylogeny of Austrohamia acanthobractea (Cupressaceae) from the Middle Jurassic of Northeast China. International Journal of Plant Science, 179 (8), 640-662. Doi: 10.1086/699665.
It took less than 30,000 years, and maybe only thousands, to kill more than 90% of sea creatures and most land species, according to the most precise study ever published about the mass extinction marking the end of the Permian Period. A recent study published in the Geological Society of America Bulletin on September 19 suggests an answer.
Outcrop photos of the Permian-Triassic boundary interval at Penglaitan (image by NIGPAS) It took less than 30,000 years, and maybe only thousands, to kill more than 90% of sea creatures and most land species, according to the most precise study ever published about the mass extinction marking the end of the Permian Period. Earth’s greatest mass extinction, also known as the “Great Dying,” occurred about 252 million years ago. By some estimates, over 90% of sea creatures and most land-dwelling reptiles disappeared. Even usually resilient plants and insects suffered near annihilation. But how long did it take to wipe out the vast majority of life on Earth? What could have caused such a massive die-off? A recent study published in the Geological Society of America Bulletin on September 19 suggests an answer. Scientists from China, the USA and Canada combined new high-resolution radiometric dating of seven closely spaced layers of volcanic material from South China’s Penglaitan section with detailed biostratigraphy and geochemical analyses. Results show the duration of the end-Permian mass extinction to be about 31 thousand years, essentially instantaneous by geological standards. “The mass extinction may have occurred in only thousands of years, but the analytical uncertainty of current CA-ID-TIMS dating technique prevents us from getting a more meaningful constraint for less than 30,000 years,” said Prof. SHEN Shuzhong from the Nanjing Institute of Geology and Palaeontology (NIGPAS) of the Chinese Academy of Sciences, the lead author of this paper. Fieldtrip investigation on the Penglaitan section (image by NIGPAS) The study also suggests that the sudden extinction may have been caused by Siberian flood-basalt eruptions, along with local intensive explosive volcanism that may have started some 420 thousand years before the mass extinction. These events may have significantly reduced the stability of Late Permian ecosystems to the point where a single extreme incident finally resulted in a sudden ecosystem collapse. For decades, scientists have studied the Permian-Triassic boundary at Meishan in Zhejiang Province, South China, which serves as the international reference for the boundary. But this “condensed section” – a lot of time represented by a small thickness of sediments – makes it difficult to discern if the extinctions were abrupt or gradual. To deal with this problem, SHEN and colleagues from CAS, MIT, the National Museum of Natural History (Washington, D.C.) and the University of Calgary focused their attention on the Penglaitan section in South China‘s Guangxi Autonomous Region. The Penglaitan sediments were deposited in shallow, tropical waters where sediments accumulated more than 100 times faster than in the Meishan beds, making the Penglaitan sediment much thicker than Meishan for a comparable period of time. In other words, only a few centimeters of rock at Meishan are equivalent to meters of sediment in Penglaitan. The expanded section at Penglaitan allowed the scientists to study the events at the Permian-Triassic boundary at a much higher temporal resolution. In addition to the higher sedimentation rates, the Penglaitan section has better geochronologic and stratigraphic controls, and rich palaeontological data, enabling examination of the fine structure of the extinction and coeval environmental perturbations. SHEN and his colleagues documented a rich Late Permian biota at Penglaitan, with at least 10 major marine fossil groups, including brachiopods, ammonoids, sponges, corals, conodonts, foraminifera, bryozoans, bivalves, and trilobites. Twenty-nine of the 66 Permian species identified in the section disappeared within or at the top of a single bed of volcanic ash-rich sandstone (Bed 141). Moreover, there is no “survival interval” of Permian taxa extending into the Early Triassic. This highly diverse marine ecosystem suddenly disappeared during the time of deposition of Bed 141. The radiometric ages of the Siberian Traps volcanism match the radiometric dates recovered from the volcanic ash beds preserved at Penglaitan and Meishan. The overlap in dates suggests that the environmental effects of volcanic gases like carbon dioxide, methane and sulfur dioxide could have been deadly. A lethal greenhouse warming, oceans depleted of dissolved oxygen, acid rain, and atmospheric pollution by heavy metals would have made life difficult. Detailed fossil ranges and conodont zones in the uppermost Changhsingian and lowermost Triassic of the Penglaitan section and their correlation with the extinction and survival interval of the Meishan section (image by NIGPAS) Previously, scientists working on the problem were not even sure whether there was one pulse or two pulses of extinction at the Permian-Triassic boundary, or whether some Permian species actually survived into the earliest Triassic beds. These problems could not be resolved in condensed sections like Meishan. In contrast, the Permian deposits at Penglaitan contain more than 50 volcanic ash layers and volcanic ash-rich sandstone beds, possibly produced by pyroclastic flows from the nearby volcanic arc eruption centers in South China, thus presenting a clearer picture of the extinction period. The abrupt change in deposition from the uppermost Permian limestones and ash-rich sandstones to black shale with centimeter-scale limestone interbeds in the lowermost Triassic clearly represents a major shift in the oceanic environment. The Permian extinction has in the past been linked to a time of rapid climate warming, potentially produced by carbon dioxide and methane emissions from the massive Siberian flood basalt eruptions. High-resolution paleotemperature measurements across the mass extinction interval suggest a substantial warming of up to 10 degrees Celsius immediately after the mass extinction event. “This might explain the shift in sediment type from limestones in the Permian to early Triassic black shales, indicating ocean anoxia,” said SHEN. A warming climate may cause ocean currents to become sluggish while at the same time bringing increased nutrients into the sea from increased weathering and river runoff. The reduction in mixing of oxygen-rich waters from the ocean surface with deeper waters, and the increase in ocean productivity triggered by the increased nutrient supply, could have led to increased organic carbon deposition and resulting ocean anoxia. Related article: SHEN, S.-Z., Ramezani, J., Chen, J., Cao, C.-Q., Erwin, D.H., Zhang, H., Xiang, L., Schoepfer, S.D., Henderson, C.M., Zheng, Q.-F., Bowring, S.A., Wang, Y., Li, X.-H., Wang, X.-D., Yuan, D.-X., Zhang, Y.-C., Mu, L., Wang, J., and Wu, Y.-S., 2018, A sudden end-Permian mass extinction in South China: GSA Bulletin, https://doi.org/10.1130/B31909.1.
Insect pollination played an important role in the evolution of angiosperms. Recently, a research group provide new insight into the niche diversity, chemical communication, and defence mechanisms of Mesozoic pollinating insects. This research was recently published in Nature Communications on September 17th, 2018. Ecological restoration of kalligrammatids. a, Jurassic kalligrammatids in the Daohugou forest. b, Cretaceous kalligrammatids in the Burmese amber forest (image by YANG Dinghua) Romeo and Juliet, a romantic but sentimental love story happened in Italy. Now there is a more ancient version, which happened between gymnosperm and pollinating lacewings described as “butterflies of the Jurassic”. Insect pollination played an important role in the evolution of angiosperms. Little is known, however, about ancient pollination insects and their niche diversity during the pre-angiosperm period due to the rarity of fossil evidence of plant–pollinator interactions. Recently, a research group led by Prof. WANG Bo from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) provide new insight into the niche diversity, chemical communication, and defence mechanisms of Mesozoic pollinating insects. This research was recently published in Nature Communications on September 17th, 2018. One of the most intensely investigated examples of pollination niches is the morphological match between the insect proboscis and floral tube length originated from Darwin’s publication in 1877. Kalligrammatid lacewings are among the largest and most conspicuous Mesozoic insects with siphoning mouthparts. The researchers from NIGPAS reported 27 well-preserved kalligrammatids from late Cretaceous Burmese amber (99 million years ago) and Chinese Early Cretaceous (125 million years ago) and Middle Jurassic (165 million years ago) compression rocks. Jurassic and Cretaceous kalligrammatids from China. The lengths of kalligrammatid proboscides vary greatly, from 0.6 to 3.2 mm in amber inclusions and from approximately 5 to 18 mm in compression fossils. The high diversity of kalligrammatids and large variation in their proboscis lengths strongly suggest diverse plant hosts with different floral tube lengths and pollination niche partitioning may have been present among some Mesozoic insects. If pollination niches were partitioned, as in extant ecosystems, this likely increased pollination effectiveness and reduced costs in pollination mutualisms, thus contributing to the high diversity of pollinating insects and the success of pollinator-dependent plants during the Cretaceous period. Kalligrammatid species diversification was potentially promoted by coevolution between pollinating kalligrammatids and their host plants under highly partitioned pollination niches. Traits such as wing eyespots, which likely functioned as a defence in large-sized species, and sexually dimorphic antennae, which were likely used for pre-mating chemical communication, elucidate how kalligrammatids survived in the Mesozoic terrestrial ecosystem under intense competition. However, such elaborate associations between kalligrammatids and their host plants (mostly confined to gymnosperms) could have been a main factor contributing to the extinction of kalligrammatids, which likely occurred during the late Cretaceous with the decline in gymnosperm diversity. Reference: Liu Qing, Lu Xiumei, Zhang Qingqing, Chen Jun, Zheng Xiaoting, Zhang Weiwei, Liu Xingyue*, Wang Bo* (2018) High niche diversity in Mesozoic pollinating lacewings. Nature Communications, 9: 3793. DOI:10.1038/s41467-018-06120-5
Scientists from China and the UK reported two Middle-Late Triassic entomofaunas, providing not only the earliest records of several modern insect elements, but also new insights into the early evolution of freshwater ecosystems.This study confirms that holometabolous and aquatic insects experienced extraordinary diversification about 237 million years ago. The research was published in Science Advances on September 5, 2018. Photographs of typical insect fossils from Tongchuan and Karamay entomofaunas (Image by NIGPAS) Recently, scientists from China and the UK reported two Middle-Late Triassic entomofaunas, providing not only the earliest records of several modern insect elements, but also new insights into the early evolution of freshwater ecosystems. This study confirms that holometabolous and aquatic insects experienced extraordinary diversification about 237 million years ago. The research was published in Science Advances on September 5, 2018. Dr. ZHENG Daran and Prof. WANG Bo, researchers at the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences, discovered a late Ladinian Tongchuan entomofauna and a Carnian Karamay entomofauna in northwestern China. These entomofaunas provide new evidence for understanding the process of insect diversification. The Tongchuan entomofauna contains at least 28 insect families in 11 orders, making it among the most diverse Triassic entomofaunas. The Karamay entomofauna comprises 10 insect families in six orders, including caddisfly cases and the earliest known water boatmen. The Tongchuan entomofauna includes are diverse fossil beetles with bodies, making them potential key calibration points for the molecular phylogenetic analysis of beetle phylogeny. Another interesting discovery is the earliest caddisfly cases (Trichoptera) in both entomofaunas. The true Trichoptera was thought to have diverged from Amphiesmenoptera in the earliest Jurassic. The Holometabola are the most diverse insects in the Tongchuan and Karamay entomofaunas and are represented by diverse beetles and scorpionflies. Holometabola were thought to have become dominant in the global entomofauna starting in the mid-Mesozoic. Thus, its high diversity and abundance in Tongchuan and Karamay are relatively unexpected, revealing a radiation of Holometabola during the Middle Triassic. In addition, water boatmen are abundant in the Karamay entomofauna, making them the earliest record of aquatic bugs. These aquatic insects developed new herbivore and carnivore guilds that persist to the present. The diversification of aquatic insects was thought to be part of the “Mesozoic Lacustrine Revolution,” which dates to the Middle Mesozoic. The current study suggests, however, that this diversification had already begun by the Middle Triassic, thus providing new insights into the early evolution of freshwater ecosystems. Compared to other insects, Holometabola were probably more resilient to Early Triassic environmental disturbances, since their development would have allowed greater buffering from environmental variability. After the Early Triassic, various plants started to appear during the Middle Triassic and spread later, probably further contributing to the radiation of holometabolous and aquatic insects. Reference: Zheng Daran, Chang Su-Chin*, Wang He, Wang Jun, Feng Chongqing, Xie Guwei, Fang Yan, Zhang Haichun, Wang Bo* (2018) Middle-Late Triassic insect radiation revealed by diverse fossils and isotopic ages from China. Science Advances, 4: eaat1380. doi:10.1126/sciadv.aat1380.
