Research Progress---- Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences

Giant sperm and reproductive organs in 100-million-year-old ostracods

The vast majority of fossil soft parts are extremely rare but provide invaluable information of ancient autoecology such as reproductive behavior. Recently, an international research group from China, Germany, and the United Kingdom used X-ray micro-computed tomography to analyze an ostracod assemblage which is composed of 39 individuals in one amber piece from Cretaceous Burmese, reveal that the reproduction behavioural repertoire has remained unchanged over at least 100 million years. These results also double the age of the oldest unequivocal fossil animal sperm. The study was published in Proceedings of the Royal Society B on 2020.
　　The small bivalved crustacean ostracods are the most abundant fossil arthropods since the Ordovician and play an important role in paleoenvironmental reconstruction and evolutionary biology. Ostracods are also a good biostratigraphic indicator, which are very important in the oil-gas exploration. The vast majority of fossil ostracods are represented by calcified shells, and their soft parts are extremely rare but provide invaluable information of ancient ostracod autoecology.
　　Recently, Dr. WANG He and Prof. WANG Bo from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), and other researchers from Ludwig-Maximilians-Universitat München and Queen Mary University of London, presented exceptionally-preserved ostracods with soft parts (appendages and reproductive organs) from mid-Cretaceous Myanmar amber (approximately 100 million years old).
　　The ostracod assemblage is composed of 39 individuals in one amber piece and includes males, females and juveniles. X-ray micro-computed tomography was used to obtain high-resolution three-dimensional images of their soft parts. The micro-CT reconstruction provides direct evidence of the male clasper, sperm pumps (Zenker organs), hemipenes, eggs and female seminal receptacles with giant sperm.
　　For copulation, cypridoidean males use their sexually dimorphic fifth limbs, which have hook-like endopods, to grasp a female while introducing their hemipenes into the female’s paired vaginas. The male’s pair of Zenker organs then transfers the exceptionally long but immotile sperm via the male hemipenes into the female. The Zenker organ is readily identified in extant cypridoidean ostracods as a large, spiny, sclerotized part of the deferent sperm duct. Muscle fibers alongside the organ connect the numerous spines, which are often arranged in a number of whorls that are taxonomically characteristic at family level. Once in the female, the sperm are pushed up the two long sperm canals, each ending in a sac-like seminal receptacle for sperm storage; here, they finally become motile, arrange themselves into a more organized assemblage and fertilize eggs during the process of oviposition.
　　Research results reveal that the reproduction behavioral repertoire, which is associated with considerable morphological adaptations, has remained unchanged over at least 100 million years—a paramount example of evolutionary stasis. These results also double the age of the oldest unequivocal fossil animal sperm. The appearance of complex reproductive mechanism involving giant sperm improves mating success and may have been an important contributor to the late Mesozoic explosive radiation of the superfamily Cypridoidea, which today includes the vast majority of nonmarine ostracod species.
　　We are grateful to Vladimir Blagoderov, Ryszard Szadziewski, and Kornelia Skibińska for helpful discussions, WU Suping for helping with the micro-computed tomography reconstruction and YANG Dinghua for the artist’s reconstruction of the ostracods in life.
　　This research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the Second Tibetan Plateau Scientific Expedition and Research, and the National Natural Science Foundation of China.
　　Reference：Wang H, Matzke-Karasz R, Horne DJ, Zhao X, Cao M, Zhang H, Wang B. 2020 Exceptional preservation of reproductive organs and giant sperm in Cretaceous ostracods. Proceedings of the Royal Society B 20201661. http://dx.doi.org/10.1098/rspb.2020.1661.
　　The studied ostracods from Myanmar amber
　　Preserved body parts in fossils in comparison with modern analogues. (a) Right 5th limb of male with clasping organ (top). (b) Eucypris virens: right 5th limb of male with clasping organ (top). (c) Two eggs in female partly cut open. (d) E. virens: empty egg shell. (e) Zenker organ. (f) Cyclocypris ovum: Zenker organ. (g) Mass of sperms in location of seminal receptacle in female. (h) Mytilocypris mytiloides: densely packed sperm filling of a seminal receptacle. (i) Paired hemipenes. (j) Fabaeformiscandona subacuta: paired hemipenes. (k) Sperms in female. (l) Pseudocandona marchica: sperms in female
　　Artist’s reconstruction of ostracods in life (a mating pair) by YANG Dinghua

2020-09-16

Exceptionally preserved specimens reveal the reproductive strategies and biological affinity of extinct chitinozoans

Chitinozoans are extinct microfossils widely recorded in the Ordovician to Devonian strata (ca. 480~359 Ma) and playing important roles in biostratigraphy. However, their biological affinity is still debated since the first description in 1931.
　　Chitinozoans are extinct microfossils widely recorded in the Ordovician to Devonian strata (ca. 480~359 Ma) and playing important roles in biostratigraphy. However, their biological affinity is still debated since the first description in 1931.
　　Generally, previous hypotheses about their biological affinity fall into two main camps since 1930s: first of all, relationship with various groups of protists, which mostly consist of ideas based on the vesicle morphology during the 1930s to 1980s. However, none of these hypotheses are totally convincing because of the hermetically sealed vesicle, which seems to disable any communication between the inner chamber of chitinozoans and the environment, and thus precludes the possibility of obtaining food. Secondly, eggs of unknown metazoans, a hypothesis generated by the discovery of the cocoon-like preservation during the 1960s to 1980s. The "egg hypothesis" was subsequently reinforced by the perception that there was no fossil record of immature individuals or evidence of any reproductive process in chitinozoan assemblages. A recent study has, however, questioned the prevailing "egg hypothesis" by documenting a large morphological variation in chitinozoan populations that is inconsistent with the variation found in modern and fossil eggs of aquatic invertebrates, and thus suggested that chitinozoans were independent microorganisms (Liang et al., 2019).
　　Recently, 20 exceptionally preserved specimens were discovered or re-examined among hundreds of thousands of specimens processed from the Middle and Late Ordovician (ca. 467~445 m.y. old) limestones of Laurentia and Baltica. Associate researcher LIANG Yan from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), and other paleontologists from Estonia, the United States, the United Kingdom and Central South University, have carried out new research on the biological properties of chitinozoans and gained new understanding. This study has been published online of Geology.
　　The inner structures of these unusual specimens were analysed by a novel combination of imaging techniques, including the near-infrared microscopy (NIR), the focused ion beam scanning electron microscopy (FIB-SEM) and X-ray micro-computed tomography (micro-CT). These unusual specimens (Figs. 1, 2) are turned out to precisely record successive reproductive moments—the missing reproduction stages in the life history of chitinozoans.
　　Studies of the inner ultrastructure (Figs. 3, 4) are carried out and spongy materials have been detected for the first time. Together with the test wall, those spongy materials are turned out to be made of clustered rounded spherical particles with a diameter around several tens to over one hundred nanometers, which are the basic material building the organic test of chitinozoans.
　　The reproductive strategies—hitherto undescribed, which produce either one or several offspring at a time, have been discussed and reconstructed (Fig. 5). The reproduction resembles budding and strobilation, representatively, but with significant differences.
　　The morphology, geometric shapes, significant within-population variation, widespread distribution in disparate paleoenvironments, and the new evidence for two modes of asexual reproduction make it plausible to link chitinozoans, at least the taxa presented in this study, with protists.
　　Financial support was provided by the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, the Estonian Research Council, and the State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology.
　　Reference:
　　Liang, Y.*, Hints, O., Tang, P., Cai, C.Y., Goldman, D., Nolvak, J., Tihelka, E., Pang, K., Bernardo, J., Wang, W.H.*, 2020. Fossilized reproductive modes reveal a protistan affinity of Chitinozoa. Geology, v. 48. https://doi.org/10.1130/G47865.1.
　　Liang, Y.*, Bernardo, J., Goldman, D., Nolvak, J., Tang, P., Wang, W., Hints, O.*, 2019. Morphological variation suggests that chitinozoans may be fossils of individual microorganisms rather than metazoan eggs. Proceedings of the Royal Society B 286, http://dx.doi.org/10.1098/rspb.2019.1270.
　　Fig. 1 Reproductive specimens under Micro-CT. The offspring test can be obviously observed in the chamber of the parental specimen
　　Fig. 2 NIR (A, L) and FIB-SEM analyses of the reproducing chitinozoans
　　Fig. 3 Morphological ultrastructure of reproductive specimens
　　Fig. 4 Ultrastructure of the sponge structure (left) and the test wall (right)
　　Fig. 5 Hypothetical 3D perspective drawing of the reproductive cycle of Cyathochitina campanulaeformis (Fig. 2L)

2020-09-14

Dinganthus sheds new light on the evolution of flowers

Although the Darwinism has deeply rooted in the mind of public, how the flowers evolved has been a puzzle for evolutionary biologists over centuries. Science listed the evolution of flowers a one of the 125 worldwide scientific questions.
　　Although the Darwinism has deeply rooted in the mind of public, how the flowers evolved has been a puzzle for evolutionary biologists over centuries. Science listed the evolution of flowers a one of the 125 worldwide scientific questions.
　　There is a long-held hypothesis in botany that a flower is a telescoped shoot. This idea has been cherished by many botanists and supported by various studies of living flowers, but there is no related fossil evidence proving or rejecting this hypothesis. Ignorance of the history of flowers makes people more or less hesitant whenever talking about this hypothesis.
　　Recently, a paper titled as "A unique flower in Miocene amber sheds new light on the evolution of flowers" was published in a scholarly journal Palaeoentomology. This paper was authored by LIU Xuedie and LIU Zhongjian from the Fujian Agriculture and Forestry University, Diez José Bienvenido from University of Vigo, FAN Yong from Fushun Amber Institute, and WANG Xin from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS). A flower Dinganthus pentamera embedded in a 15-20 million year-old Dominican amber was documented. Dinganthus was dedicated to the former president of Peking University and leading mathematician, Dr. DING Shisun (1927-2019). The specimen is deposited in the Fushun Amber Institute.
　　Dinganthus is small, only 3-4 millimeters in dimensions. It is three dimensionally preserved in a piece of amber uncovered from the Miocene stratum. The good preservation and modern observation technology (Micro-CT) allow the key features of the flower to be clearly demonstrated. The flower includes bracts, tepals, stamens, and gynoecium. And this flower has five tepals with recurved fringes and ten curving stamens surrounding gynoecium with a curved style in the center. Each stamen is filamentous, with a tetrasporangiate anther on the top. This flower belongs to the largest group in angiosperms, Eudicots.
　　Although the history of Eudicots has been pushed back to the mid-Cretaceous (about 100 million years ago) by another flower in amber Lijinganthus, there is no meaningful fossil evidence suggesting how the flowers evolved.
　　Different from the typical eudicot flowers, which usually have their calyx, corolla, stamens and gynoecium crowded onto the same point of flower axis (receptacle), Dinganthus have these organs spatially distanced along the flower axis, as if these parts were arranged along an axis. Despite its young age, the unique morphology of Dinganthus, using fossil evidence for the first time, tells botanists: a flower could be a condensed shoot, a long-held idea in the past centuries.
　　This new evidence and its insight will help botanists to decipher the essence of flowers, and also helps palaeobotanists to understand the bizarre-appearing flowers such as Archaefructus and Yuhania.
　　This research is supported by the Strategic Priority Research Program (B) of Chinese Academy of Sciences and the National Natural Science Foundation of China.
　　 Reference: Xue-Die Liu, José Bienvenido Diez, Yong Fan, Zhong-Jian Liu，Xin Wang, 2020，A unique flower in Miocene amber sheds new light on the evolution of flowers, Palaeoentomology, 3:423-432. https://doi.org/10.11646/palaeoentomology.3.4.15.
　　Dinganthus and Dr. Shiun Ding (1927-2019). Left, Dinganthus in a MicroCT rendering. Right, the former president of Peking University and leading mathematician, Dr. Shisun Ding.
　　The three dimensional reconstruction of Dinganthus.

2020-09-14

Fluid inclusions in halite reveal signs of tertiary transgression in eastern China

From Late Cretaceous to early Tertiary in eastern China, a large number of inland saline oil and gas basins developed, such as Shengli Oilfield, Zhongyuan Oilfield, Jiangsu Oilfield and Jianghan Oilfield. Since the discovery of marine calcium algae and ostracod fossils in Shengli Oilfield in 1979, whether marine transgression has occurred in eastern China has become the focus of petroleum academic debate. The horizon where transgression occurs often enriches evaporite and main source rock. Therefore, this problem has caused academic debate for more than 40 years.
　　From Late Cretaceous to early Tertiary in eastern China, a large number of inland saline oil and gas basins developed, such as Shengli Oilfield, Zhongyuan Oilfield, Jiangsu Oilfield and Jianghan Oilfield. Since the discovery of marine calcium algae and ostracod fossils in Shengli Oilfield in 1979, whether marine transgression has occurred in eastern China has become the focus of petroleum academic debate. The horizon where transgression occurs often enriches evaporite and main source rock. Therefore, this problem has caused academic debate for more than 40 years.
　　Among them, Professor HE Chengquan from Nanjing Institute of Geology and paleontology, Chinese Academy of Sciences (NIGPAS), thinks that some dinoflagellate fossils from Shengli oil field in Bohai Bay Basin are marine origin, and they appear in the transgressive sediments in western Xinjiang at the same time. While according to the geochemical analysis of marine geologists from TongJi University, the strontium isotopic compositions of calcareous nannofossil shells are obviously higher than that of the same period of seawater, indicating that these organisms lived in inland salt lake environment which is obviously different from that of seawater.
　　Seawater intrusion can occur in a short period of time, which is difficult to preserve in geological records. Salt deposits can record very short-term geological events in geological history. In order to solve this puzzle, Associate Professor MENG Fanwei, of Nanjing Institute of Geology and paleontology, Chinese Academy of Sciences (NIGPAS), cooperated with Professor NI Pei of Nanjing University and Dr. Galamay of Ukrainian Academy of Sciences to conduct a preliminary study on the drilling of Jintan Salt Mine in Jiangsu Province, China. In the lower part of salt deposit in the Jintan basin, the brine composition in the fluid inclusion is similar to the seawater in the same period, while the brine component in the upper part of the salt deposit is gradually transformed into the inland salt lake component. The research results have been published in Marine and Petroleum Geology online, a well-known international academic journal in the field of petroleum geology.
　　This discovery strongly supports the view that transgression exists in eastern China. However, due to the influence of inland environment after seawater intrusion, the sedimentary environment of "marine source continental facies" has been formed, and the composition of brine has changed greatly.
　　This discovery not only solves the long-standing controversy in the petroleum field of China, but also provides a theoretical basis for the correct evaluation of source rocks from Late Cretaceous to early Tertiary in oil and gas fields in eastern China.
　　The research was supported by the China Israel cooperation project of NSFC and the original innovation project "from 0 to 1".
　　Reference: Fan-wei Meng, Anatoliy R. Galamay, Pei Ni, Naveed Ahsan, Saif Ur Rehman, Composition of middle-late Eocene salt lakes in the Jintan Basin of eastern China: Evidence of marine transgressions, Marine and Petroleum Geology, Volume 122, 2020, 104644, https://www.sciencedirect.com/science/article/pii/S026481722030427X
　　Photomicrographs showing primary fluid inclusion banding in hopper halite from the Jintan Basin
　　Results and comparative analysis of fluid inclusions in the Eocene non-marine halite (our data) with modern seawater (McCaffrey et al., 1987), marine Eocene halite (after Ayora et al., 1994) on a Janecke diagram (after Valyashko, 1962)

2020-09-04

New Ediacaran fronds from the Yangtze Gorges area

Ediacara-type organisms are an assemblage of macroscopic, soft-bodied eukaryotes that are prosperous in the late Ediacaran (~571–539 Ma). They constitute a unique macroscopic fossil biota prior to the Cambrian explosion—the Ediacara biota, representing a landmark in the evolution of early macroscopic organisms.
　　Ediacara-type organisms are an assemblage of macroscopic, soft-bodied eukaryotes that are prosperous in the late Ediacaran (~571–539 Ma). They constitute a unique macroscopic fossil biota prior to the Cambrian explosion—the Ediacara biota, representing a landmark in the evolution of early macroscopic organisms.
　　Probably there is nothing as enigmatic as the iconic frondose fossils in the Ediacara biota. A typical frondose fossil consists of an upright leaf-like body (petalodium), a connecting stem, and a basal attachment disc. Frondose fossils are widespread and abundant in the Ediacara biota. However, due to their simple external morphology and preservation without internal anatomical information, such information about their phylogenetic affinities still limited. Early researchers interpreted them as early pennatula phosphorea according to the similarity of their overall morphology, but ontogenetic and phylogenetic evidence has rejected this hypothesis. Recent studies suggest that these frondose fossils might represent crown- or total-groups of the Metazoa.
　　In 2014, a type of frondose fossil—Charniodiscus was reported from the Shibantan biota (i.e., the Shibantan assemblage of the Ediacara biota) in the Ediacaran Dengying Formation, Yangtze Gorges area, Hubei, China. However, recent studies have revealed that the type species of Charniodiscus is a frondose fossil with fractal branching and multiple petalodia. Hence, it is questionable to place the frondose fossils from the Yangtze Gorges area in Charniodiscus.
　　Lately, PhD candidate WANG Xiaopeng, Assoc. Prof. PANG Ke, and Prof. CHEN Zhe et al. from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) and Prof. XIAO Shuhai from Virginia Tech scrutinized and revised a major group of frondose fossils from the Shibantan biota. Related results have been published online in Journal of Paleontology recently (free open access).
　　The study shows that the morphological of the frondose fossils from the Yangtze Gorges area are more similar to Arborea which is a bi-petaloid frondose fossil without fractal branching pattern, rather than the type species of Charniodiscus. As a result, the researchers placed these fronds into Arborea. They identified four species of Arborea from the Shibantan biota, including the type species Arborea arborea, Arborea denticulata new species, and two unnamed species, Arborea sp. A and Arborea sp. B. Biometric and principle component analysis were also conducted, and these results showed that Charniodiscus sp. from the Bonavista Peninsula, Newfoundland, Canada is indistinguishable from Arborea arborea. Therefore, they are synonymized. This research also shows that frondose fossils still have a high diversity even in the latest Ediacaran, providing important evidence for understanding the evolution during the transition between the Ediacaran and Cambrian.
　　The Shibantan Member in South China and the Khatyspyt Formation in Arctic Siberia represent the only two carbonate successions that are known to host morphologically complex, soft-bodied Ediacara-type macrofossils. This study also includes taphonomic analysis and a model to explain the preservation mechanism of Arborea. authigenic calcite might have played an important taphonomic role in the preservation of Arborea from the Shibantan biota.
　　This research was supported by the Chinese Academy of Sciences, the National Natural Science Foundation of China, the Chinese Ministry of Science and Technology, the Science Foundation of Jiangsu Province of China, and the State Key Laboratory of Palaeobiology and Stratigraphy.
　　Reference: Wang, X., Pang, K.*, Chen, Z.*, Wan, B., Xiao, S., Zhou, C., Yuan, X., 2020. The Ediacaran frondose fossil Arborea from the Shibantan limestone of South China. Journal of Paleontology, in press. DOI: 10.1017/jpa.2020.1043.
　　Arborea deticulata n. sp. from the Shibantan biota
　　Arborea arborea from the Shibantan biota
　　Arborea sp. A (1-4) and Arborea sp. B (5-6) from the Shibantan biota
　　Petrographic observations and proposed preservation mechanism of Arborea

2020-08-25

Discoveries of middle Cambrian hurdiid radiodonts from North China

As enigmatic stem-group euarthropods and some of the earliest apex predators, the radiodonts are iconic animals of the Cambrian Explosion. Distinctive features of this group include a head with a pair of frontal appendages and a radial oral cone, and a trunk with swimming flaps and setal structures. As one of the two main lineages of radiodonts, the hurdiids are characterized by a tripartite cephalic carapace composed of a dorsal central element and paired lateral elements, a pair of frontal appendages bearing elongate blade-shaped endites and a tetraradial oral cone.
　　As enigmatic stem-group euarthropods and some of the earliest apex predators, the radiodonts are iconic animals of the Cambrian Explosion. Distinctive features of this group include a head with a pair of frontal appendages and a radial oral cone, and a trunk with swimming flaps and setal structures. As one of the two main lineages of radiodonts, the hurdiids are characterized by a tripartite cephalic carapace composed of a dorsal central element and paired lateral elements, a pair of frontal appendages bearing elongate blade-shaped endites and a tetraradial oral cone.
　　Our understanding of the morphological and ecological diversity of hurdiids has greatly improved in recent years, which has revealed the important roles of hurdiids in the complex Cambrian ecosystems. Although the Hurdiidae has a cosmopolitan distribution in the Cambrian, their Miaolingian occurrences are restricted to Laurentia and the knowledge of their diversity during this time has potentially been biased and incomplete.
　　Recently, leading by Prof. ZHAO Fangchen, postgraduate SUN Zhixin and Dr. ZENG Han from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) described two hurdiid genera from the middle Cambrian at Shandong province, which represent the first discoveries of hurdiid radiodonts in North China. Relevant results have been published in the journals Palaeogeography, Palaeoclimatology, Palaeoecology and Journal of Paleontology.
　　Cordaticaris striatus gen. et sp. nov. was collected from the middle Cambrian (Miaolingian, Drumian) Zhangxia Formation in Linyi City, Shandong Province. This new taxon is characterized by a heart-shaped central element with linear ornament, frontal appendages equipped with nine blade-like endites including seven subequal elongate endites, a node-bearing ‘peytoia’-type oral cone, and a trunk covered with rows of setal structures. Cordaticaris not only enriches the taxonomic diversity of Hurdiidae, but also further exhibits the great morphological disparity of hurdiids. The discovery of soft-bodied fossils in the Zhangxia Formation also stresses the great potential of the Miaolingian strata of North China for the preservation of non-biomineralized organisms.
　　Cambroraster, first discovered from the Burgess Shale in 2019, is readily distinguishable from other hurdiid taxa by its central head sclerite with deep posterior notches, a rounded anterior margin, and posterolateral processes bearing multiple spines. New specimens of Cambroraster were collected from the Upper Shale Member of the Mantou Formation (uppermost Wuliuan) in Weifang City, Shandong Province. This discovery suggests that Cambroraster had dispersed over a wide biogeographic range, and indicates that the Upper Shale Member of the Mantou Formation is a promising Burgess Shale-type Lagerstatte.
　　This work is financially supported by the Strategic Priority Research Program (B) of Chinese Academy of Sciences, National Natural Science Foundation of China, Jiangsu Basic Research Project, and the State Key Laboratory of Palaeobiology and Stratigraphy.
　　Reference: Sun, Z.X., Zeng, H., Zhao, F.C.*, 2020. A new middle Cambrian radiodont from North China: implications for morphological disparity and spatial distribution of hurdiids. Palaeogeography. Palaeoclimatology, Palaeoecology 558:109947. https://doi.org/10.1016/j.palaeo.2020.109947.
　　Sun, Z.X., Zeng, H., Zhao, F.C.*, 2020. Occurrence of the hurdiid radiodont Cambroraster in the middle Cambrian (Wuliuan) Mantou Formation of North China. Journal of Paleontology, https://doi.org/10.1017/jpa.2020.21.
　　The central element and oral cone of Cordaticaris striatus, and stratigraphic and paleogeographic distribution of hurdiid radiodonts
　　Artistic reconstruction of Cordaticaris striatus on the Cambrian sea（Image Credit: Joschua Knüppe）
　　Cambroraster cf. falcatus from the Cambrian (Miaolingian, Wuliuan) Upper Shale Member, Mantou Formation in Weifang City, Shandong Province, North China, and the dorsal (left) view and ventral (right) view of a Cambroraster model

2020-08-21

New progress on the Silurian conodonts from Baoshan, Yunnan, SW China

The Baoshan region (Sibumasu Terrane) of Yunnan Province, SW China, is one of the best locations to study the Wenlock to Pridoli conodonts in China. Conodont fauna of the “Lichaiba” and Niushiping formations were preliminarily reported during the IGCP 591 Field Meeting in 2014.
　　The Baoshan region (Sibumasu Terrane) of Yunnan Province, SW China, is one of the best locations to study the Wenlock to Pridoli conodonts in China. Conodont fauna of the "Lichaiba" and Niushiping formations were preliminarily reported during the IGCP 591 Field Meeting in 2014.
　　Recently, a more detailed analysis of conodont collections from the Silurian strata of the Laojianshan section in the Baoshan region was carried out by Dr. CHEN Zhongyang, Prof. WANG Chengyuan and their colleagues from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), together with Dr. Peep Mannik from Tallinn University of Technology. A revised dating of the section is provided based on the conodont biostratigraphy. The results have been published online in Geological Journal.
　　In stratigraphically ascending order, the Pterospathodus amorphognathoides amorphognathoides Zonal Group, the Pterospathodus pennatus procerus Superbiozone, the Ozarkodina sagitta sagitta Biozone, the Kockelella ortus absidata Biozone, the Kockelella crassa Biozone, the Polygnathoides siluricus Biozone and the "Ozarkodina" eosteinhornensis s.l. Interval Biozone were recognized. Several landslides were also recognized, especially two major landslides which cover the base of the "Lichaiba" and Niushiping formations respectively.
　　The conodont faunas recovered indicate that the "Lichaiba Formation" corresponds to the upper Telychian–upper Wenlock, and the Niushiping Formation to the Ludlow–Pridoli. Part of the Ireviken Event, that is, from Datum 3 to Datum 4 can be recognized from the studied section. The late Telychian conodont fauna from the Laojianshan section is characteristic of distal, open-shelf depositional environments.
　　This research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Science and Technology Major Project of China, the State Key Laboratory of Palaeobiology and the Eesti Teadusagentuur. This is also a contribution to the IGCP Project 652 'Reading geologic time in Paleozoic sedimentary rocks'.
　　Reference: Chen, Z.Y., Mannik, P., Wang, C.Y.*, Fang, X., Chen, T.E., Ma, X., Zhang, Y.D., Silurian conodont biostratigraphy of the Laojianshan section, Baoshan, Yunnan Province, SW China. Geological Journal. https://doi.org/10.1002/gj.3813
　　Range chart of conodont species from the Laojianshan section
　　Conodonts from the "Lichaiba" Formation

2020-08-21

New Study Sheds Light on Evolution of Hell Ants from 100 Million Years Ago

Among the earliest fossil ants known, haidomyrmecine ‘hell ants’ from Cretaceous amber reveal an ancient and dramatic early burst radiation of adaptive forms. These eusocial Cretaceous taxa diverged from extant lineages prior to the most recent common ancestor of all living ants and possessed bizarre scythe-like mouthparts along with a striking array of horn-like cephalic projections. Despite the morphological breadth of the fifteen thousand known extant ant species, phenotypic syndromes found in the Cretaceous are without parallel and the evolutionary drivers of extinct diversity are unknown.
　　Among the earliest fossil ants known, haidomyrmecine ‘hell ants’ from Cretaceous amber reveal an ancient and dramatic early burst radiation of adaptive forms. These eusocial Cretaceous taxa diverged from extant lineages prior to the most recent common ancestor of all living ants and possessed bizarre scythe-like mouthparts along with a striking array of horn-like cephalic projections. Despite the morphological breadth of the fifteen thousand known extant ant species, phenotypic syndromes found in the Cretaceous are without parallel and the evolutionary drivers of extinct diversity are unknown.
　　Now, an international research group from U.S., France, and China has proposed a mechanistic explanation for aberrant hell ant morphology, and thus providing new insight into the evolution of hell ants. The research was co-led by Prof. WANG Bo from the Nanjing Institute of Geology and Palaeontology (NIGPAS) of the Chinese Academy of Sciences. Results were published in Current Biology on August 6.
　　The researchers have provided a mechanistic explanation for aberrant hell ant morphology through phylogenetic reconstruction and comparative methods, as well as a newly reported specimen. They reported a remarkable instance of fossilized predation that provides direct evidence for the function of dorsoventrally-expanded mandibles and elaborate horns.
　　These findings confirmed the hypothesis that hell ants captured other arthropods between mandible and horn in a manner that could only be achieved by articulating their mouthparts in an axial plane perpendicular to that of modern ants. The head capsule and mandibles of haidomyrmecines are uniquely integrated as a consequence of this predatory mode and covary across species while finding no evidence of such modular integration in extant ant groups.
　　The results of this study suggest an extinct early burst adaptive radiation into morphospace that is unoccupied by any living taxon, triggered by an innovation in mouthpart movement and subsequent modular covariation between mandible and horn. The new results also suggest that hell ant cephalic integration – analogous to the vertebrate skull – triggered a pathway for an ancient adaptive radiation and expansion into morphospace unoccupied by any living taxon.
　　Reference: Barden P.*, Perrichot V.*, Wang Bo* (2020) Specialized predation drives aberrant morphological integration and diversity in the earliest ants. Current Biology. https://doi.org/10.1016/j.cub.2020.06.106.
　　Reconstructions of haidomyrmecine hell ants
　　Phylogeny and cephalic homology of hell ants and modern lineages
　　Morphospace and evolutionary integration of living and Cretaceous ants

2020-08-18

New biostratigraphic framework for the Triassic-Paleogene in Qinghai-Xizang plateau

Known as the third pole of the earth, the magnificent Qinghai-Xizang plateau used to be a vast ocean millions of years ago and its vicissitudes have become one of the hotspots of the geological research. Stratigraphy is the basis for diachronic reconstruction of this process, with biostratigraphy the most fundamental method and fossils often the most reliable evidence for the age of strata. However, due to extreme natural conditions and intense tectonic deformation and metamorphism, fossil collection and biostratigraphic research in the Qinghai-Xizang plateau are very difficult and the progress has been very slow. The Neo-Tethys realm in southern Xizang, as represented by the Yarlung Zangbo Suture Zone, is such a prominent sample where the Mesozoic and Cenozoic strata bear many problems and arguments, which has already become a restrict to other researches.
　　Known as the third pole of the earth, the magnificent Qinghai-Xizang plateau used to be a vast ocean millions of years ago and its vicissitudes have become one of the hotspots of the geological research. Stratigraphy is the basis for diachronic reconstruction of this process, with biostratigraphy the most fundamental method and fossils often the most reliable evidence for the age of strata. However, due to extreme natural conditions and intense tectonic deformation and metamorphism, fossil collection and biostratigraphic research in the Qinghai-Xizang plateau are very difficult and the progress has been very slow. The Neo-Tethys realm in southern Xizang, as represented by the Yarlung Zangbo Suture Zone, is such a prominent sample where the Mesozoic and Cenozoic strata bear many problems and arguments, which has already become a restrict to other researches.
　　Recently, Professor LI Jianguo and his colleagues from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) established a new integrated biostratigraphic framework for the Triassic–Paleogene strata in Neo-Tethyan realm in southern Xizang based on a combination of their own material and progress and other previous researches. The results have been published online in the Journal of Asian Earth Sciences, an international comprehensive journal of geology.
　　Many blanks in biostratigraphy got filled in this framework and much progress has been made for fossils that were never or weakly studied in the past, particularly microfossils such as conodonts, radiolarians, and miospores. For those well-studied fossils, essential supplement or improvement has been made. The new framework is improved by a series of new biostratigraphic zones, many of which are well correlated with the international standard, such as those of Lower Triassic conodonts and ammonites, uppermost Triassic–Lower Jurassic ammonites, and Upper Cretaceous planktonic foraminifers and calcareous nanofossils. A total of four integrated biostratigraphic charts are compiled in units of period, all consisting of key fossils for stratigraphic division and correlation of that period, such as ammonites, conodonts, bivalves, radiolarians, foraminifers and calcareous nanofossils. Based on these biostratigraphic advances, the authors also discussed and clarified some questions or arguments on the definition, division, correlation and age of some Triassic to Paleogene strata in southern Xizang.
　　The duration of the new integrated biostratigraphic framework is roughly the time that the Neo-Tethys Ocean evolved from its opening by the rifting of Lhasa-Gondese block from the northern margin of Gondwana to its closure as a consequence of the Indian–Eurasian collision. In this respect, this research will provide as an important stratigraphic reference for the study of the evolution of Neo-Tethys and other geological researches on the Qinghai-Xizang Plateau.
　　The relevant research was supported by the Second Tibetan Plateau Scientific Expedition and Research, the Strategic Priority Research Program (B) of the Chinese Academy of Sciences and the National Natural Science Foundation of China.
　　Reference: Jianguo Li*, Miaoqin Lin, Yixiao Wu, Hui Luo, Jungang Peng, Lin Mu, Bo Xu, Chao Zhang, 2020. New biostratigraphic framework for the Triassic–Paleogene in the Neo-Tethys realm of southern Xizang (Tibet), China. Journal of Asian Earth Sciences, https://doi.org/10.1016/j.jseaes.2020.104369.
　　The new integrated biostratigraphic charts of the Triassic-Paleogene strata in the studied area

2020-08-17

The Middle Devonian Jiwozhai patch reef in Dushan of South China: A palaeobiodiversity hotspot in deep time

Reefs are the most complicated and diverse ecosystems in the ocean, with highest levels of species diversity, habitat diversity, community structure and functional diversity. Therefore, they represent one of the most significant genetic treasures in the evolution of Earth life. Metazoan reef ecosystem reached its Phanerozoic acme in Givetian (Middle Devonian), however, detailed studies on the reef biodiversity, ecological interactions and community composition of Givetian reefs are still lacking, limiting our further understanding of the palaeobiodiversity change pattern and evolutionary model of reef ecosystem in critical geological time intervals.
　　Reefs are the most complicated and diverse ecosystems in the ocean, with highest levels of species diversity, habitat diversity, community structure and functional diversity. Therefore, they represent one of the most significant genetic treasures in the evolution of Earth life. Metazoan reef ecosystem reached its Phanerozoic acme in Givetian (Middle Devonian), however, detailed studies on the reef biodiversity, ecological interactions and community composition of Givetian reefs are still lacking, limiting our further understanding of the palaeobiodiversity change pattern and evolutionary model of reef ecosystem in critical geological time intervals.
　　Recently, a systematic study of the Givetian reef biodiversity was carried out by an international research group led by Assoc. Profs. QIE Wenkun and LIANG Kun, Mater HUANG Jiayuan from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), and collaborators from Brunel University, Guizhou University and Wuhan Center of Geological Survey, China Geological Survey. Related paper has been published online in Palaeogeography, Palaeoclimatology, Palaeoecology.
　　The team focuses on the detailed palaeontological and palaeoecological analysis of a Givetian reef located in Dushan Formation, Dahekou section, Guizhou Province, South China. In this study, 665 samples were collected in-situ in 7 m2 by 28 quadrats (50í50 cm) of the vertical reef outcrop, with 2804 thin sections being made and 10823 fossils being described. Detailed statistics of biodiversity and community paleoecology were carried out based on these large amounts of systematic data.
　　As so far, a total of 83 species belonging to 44 genera of 8 phyla were identified within 7 m2 of the Jiwozhai patch reef, including rugose corals (29 species, 9 genera), stromatoporoids (16 species, 10 genera), tabulate corals (13 species, 9 genera), brachiopods (16 species, 8 genera), Bryozoans (4 species, 4 genera), calcified cyanobacteria (3 species, 3 genera), chaetetids (1 species, 1 genera) and tubeworms (1 species, 1 genera). Among them, stromatoporoids (N=755), tabulate corals (N=630), rugose corals (N=198) and chaetetids (N=144) are the most common organisms. Consistent with the densely distributed species at Jiwozhai, complex ecological relationships, including extensive encrustations (N=716), spatial competition (N=35) and symbiosis (N=58) have also been found among different organisms. The in-situ collection of fossils and the sketch of the reef outcrop with high density clarify the spatial distribution characteristics of the reef organisms in Middle Devonian, which shows the stability of the spatial distribution of the main reef-building organisms while the discrepancy between the secondary reef-building organisms and the reef-dwelling organisms.
　　This study would provide important reference for the further correlation of global paleogeography and interpretation of the evolution and distribution patterns of the reef diversity during geological time.
　　This work is financially supported by the Strategic Priority Research Program (B) of Chinese Academy of Sciences, National Natural Science Foundation of China and Geological Survey Projects of China Geological Survey.
　　Reference: Huang, J., Liang, K.*, Wang, Y., Liao, W., Guo, W., Kershaw, S., Jeon, J., Qiao, L., Song, J., Ma, J., Li, Y., Tu, B., Tian, Y., Wang, Y., Wang, Y., Ma, J., Luo, M., Qie, W.*, 2020. The Jiwozhai patch reef: A palaeobiodiversity hotspot in middle Givetian (Devonian) of South China. Palaeogeography, Palaeoclimatology, Palaeoecology, https://doi.org/10.1016/j.palaeo.2020.109895
　　The Givetian Jiwozhai patch reef of Middle Devonian in Dushan, Guizhou
　　Stromatoporoids and chaetetids in the Jiwozhai patch reef
　　Biotic interactions among the reef organisms in the Jiwozhai patch reef
　　Statistics of biodiversity and abundance (Frequency) of Jiwozhai reef

2020-08-11