Fossil wood is among the significant proxies for terrestrial paleoclimate and paleogeographical reconstruction in Earth history. Abundant and diversified Mesozoic fossil woods are well recorded in China; however, Triassic fossil wood is rare. A Sino-French research team leading by Prof. WANG Yongdong from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences(NIGPAS) have found a new fossil wood from the Late Triassic Xujiahe Formation (Norian to Rhaetian) in Guangyuan of northern Sichuan Basin, southwestern China (dated to ca. 200 Ma). The fossil wood material consists of two well-preserved specimens yielding secondary xylem with distinct growth rings. Bordered pits on the radial tracheid walls are mostly contiguous, biseriate alternate, locally uniseriate and strongly flattened. Cross-fields show a large window-like pore. This anatomy is typical for an important fossil wood morphogenus Xenoxylon Gothan. Based on a novel combination of radial and cross-field pitting type and ray height, a new species, Xenoxylon guangyuanense sp. nov. is recognized. The finding of this new fossil wood taxon contributes to a better understanding of the yet poorly documented Xenoxylon early radiation during the Late Triassic. This study was conducted by Dr.TIAN Ning (Shenyang Normal University), Prof. WANG Yongdong and Dr. LI Liqin from NIGPAS, Dr. Marc Philippe from University of Lyon 1, France, as well as other experts from Qufu Normal University and Chinese Academy of Geological Sciences, Beijing. Xenoxylon is a paleobiogeographically significant conifer genus, which is considered to be an index for the cooler and/or wetter climates of Northern Hemisphere throughout theLate Triassic–Late Cretaceous range. The occurrence of Xenoxylon in the Sichuan Basin of southern China may indicate a short-term cooling event episode, sandwiched within a period during which warm and wet climate conditions largely prevailed over lower latitude regions of the Northern Hemisphere. Such a cooling event in the Sichuan Basin which was located at a low paleolatitude on the eastern rim of Tethys may be in accordance in time with the temperature decline event in Norian–Rhaetian boundary uncovered by oxygen isotope (δ18O) record in Italy of the western rim of Tethys. This study is jointly supported by the State Key Programme of Basic Research of Ministry of Science and Technology, China, National Natural Sciences Foundation of China, Innovation Project of CAS and the funding from State Key Laboratory of Palaeobiology and Stratigraphy (NIGPAS). Related information: Tian N, Wang Y D*, Philippe M, Li LQ, Xie XP , Jiang ZK , 2016. New record of fossil wood Xenoxylon from the Late Triassic in the Sichuan Basin, southern China and its palaeoclimatic implications. Palaeogeography, Palaeoclimatology, Palaeoecology, 464: 65-75(*corresponding author).
Anatomical structures of Xenoxylon guangyuanense sp. nov. from the Upper Triassic of the Sichuan Basin, showing growth rings, trachrids and cross-field pitting
A joint team of researchers from China and Britain has revealed a new fossil fauna, the Anji Biota, which document post-extinction sponge-dominated communities from uppermost Ordovician rocks of South China. More than 75 sponge species represent multiple lineages that survived the Late Ordovician mass extinction. Sponges also flourished after other mass extinctions and may have facilitated ecosystem recovery by stabilizing sediment.
Diverse 444 million-year-old sponges from the Anji Biota of China, thriving as everything around them died (by Botting, J. P.) New deposits with exceptionally well-preserved fossil communities are always exciting, but some are more interesting than others. Windows into particularly important times or environments can tell palaeontologists much more than narrow views into a time that is already well known. A window into the aftermath of the second-biggest mass extinction since the rise of animals is therefore very interesting indeed. The end-Ordovician crisis, 445 million years ago, resulted in 85% of species dying out. It was the result of a sudden, intense ice age, followed by an equally rapid warming, and corresponding changes in ocean chemistry and circulation. The plankton started to recover quite quickly, but until now we have known little about life on the deeper parts of the sea floor. The only exceptional fossil deposit known from this interval before now is the peculiar glacial lagoon environment of South Africa's Soom Shale. A joint team of researchers from China (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, et al.) and Britain (National Museum Wales) has revealed a new fossil fauna preserving delicate skeletons and soft tissues, from the immediate aftermath of the Ordovician mass extinction. The Anji Biota was discovered in the bamboo forests of Zhejiang Province, China, in a narrow band of mudstone exposed at several sites up to 10 km apart. The fauna is extraordinarily diverse, with nearly 100 species found in the first phase of collecting. The surprise, though, is that this diversity is almost entirely composed of sponges. The Anji Biota records an astonishing range of different sponge species, in many different major groups, with a total diversity exceeding that of equivalent modern faunas. Most post-extinction survivor ecosystems are made up of small, stunted species that managed to thrive and are found everywhere. In the Anji sponge fauna, the sponges are large and complex, and although some species formed forests on the sea floor, many others were very scarce or extremely localised. It doesn't look like a survival fauna at all; these simple animals were flourishing. Sponges were not quite the only animals on the sea floor, however. Together with thousands of sponges, a few conical-shalled nautiloids were also recovered, and a single fossil sea scorpion complete with legs. The sea scorpions were a very rare group in the Ordovician, and well-preserved specimens are almost entirely limited to these sites of exceptional preservation. Why was this post-extinction world so completely dominated by sponges? As lead author Joe Botting explains, “We think the sponges thrived because they can tolerate changes in temperature and low oxygen levels, while their food source (organic particles in the water) would have been increased enormously by the death and destruction all around them.” Sponges are known today as ecosystem engineers, encouraging biodiversity by stabilising sediment and providing habitats. In the case of the end-Ordovician crisis, such an abundance of sponges over wide areas might well have helped the ecosystem to recover. The team also notes that mass sponge remains have been recorded after other mass extinction events, suggesting that this is a common pattern after ecological collapse. There are lessons for the present, as well. If the past is anything to go by, then as marine ecosystems begin to collapse due to human activities, we should expect to see sponges rule the seas once again. Reference: Botting, J. P., Muir, L. A., Zhang Y-D.*, Ma, X., Ma, J-Y., Wang, L-W., Zhang, J-F., Song, Y-Y., Fan, X., 2017. Flourishing sponge-based ecosystems after the End-Ordovician mass extinction. Current Biology. http://dx.doi.org/10. 1016/j.cub.2016.12.061.
Radiodontans - Giant predators in Paleozoic seas Recorded in exceptionally preserved Lagerst？tten, the radiodontans (including anomalocaridids) are cosmopolitan, soft-bodied, stem-group arthropods that inhabited Paleozoic seas. They are notable for their unique morphology, peculiar ecology and basal position in arthropod evolution. The early Cambrian Chengjiang Lagerst？tte has yielded some of the oldest radiodontans, including three unquestionable taxa – Anomalocaris saron, Amplectobelua symbrachiata and Lyrarapax unguispinus. However, recent discoveries of the Burgess Shale Hurdia Walcott, 1912 and the Fezouata Aegirocassis benmoulae Van Roy et al., 2015 highlight the presence of another radiodontan group (Hurdiidae) characterized by a tripartite head sclerite complex consisting of one central element and a pair of lateral elements. Recently, Dr. ZHAO Fangchen and PhD. candidate ZENG Han from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and their colleagues reported six morphotypes of possible hurdiid head sclerite elements from the Chengjiang Lagerst？tte, some of which are closely associated with other typical radiodontan body parts. These sclerite elements provide detailed anatomy, such as mammillary tubercles and soft tissue reticulate structure, to help understand the morphology and biology of all hurdiid head sclerites. A common single dorsal plate in Anomalocaris saron and Amplectobelua symbrachiata is confirmed. Although the morphologically diverse central and lateral elements of the Hurdiidae and the conserved dorsal plate of the Anomalocarididae and Amplectobeluidae reflect a major distinction in radiodontan body plans, they share a fundamental structure of double layers of cuticle. The Chengjiang specimens not only clarify the morphology and biology of the radiodontan head sclerites in general, but also illuminate the diversity and disparity of radiodontans in their early evolutionary history. This research was funded by the National Natural Science Foundation of China, the Ministry of Science and Technology of China, and the Chinese Academy of Sciences. Article information: Han Zeng, Fangchen Zhao*, Zongjun Yin, Maoyan Zhu. 2017. Morphology of diverse radiodontan head sclerites from the early Cambrian Chengjiang Lagerst？tte, south-west China. Journal of Systematic Palaeontology, doi: 10.1080/14772019.2016.1263685
Stratigraphic column and the sample depth in the Kuhfeng Formation at the Pingdingshan East Section in Chaohu City, Anhui Province. The Guadalupian Epoch represents one of the most critical intervals during the Earth history which is characterized by a series of global geological and biological events. Establishing the Guadalupian geological timescale is essential for evaluating the tempo of global geological events occurred in the Guadalupian. However, the Guadalupian is poorly constrained by radioisotopic dates in comparison with the high-precision dates from the Lopingian and lowest Triassic in South China and the Cisuralian in southern Urals, Russia. Recently, Dr. ZHANG Hua from Nanjing Insititute of Geology and Palaeontolgy, Chinese Academy of Sciences and his colleagues reported combined CA-ID-TIMS and SIMS U-Pb zircon geochronology for three ash beds from the base and lower part of the Kuhfeng Formation in the Chaohu area, southeastern China. The basal Kuhfeng Formation volcanic ash yields a CA-ID-TIMS weighted mean 206Pb/238U date of 272.95 ± 0.11 Ma (MSWD = 1.9, n = 7). That serves as the best estimate for the age of CGB in South China for the first time. This new date is 0.65 ± 0.51 myr older than the interpolated Cisuralian-Guadalupian boundary age from 2016 International Chronostratigraphic Chart (ICC) or the 2012 Geologic Time Scale, and is an improvement to the previous stage boundary calibrations. The new geochronology increases the duration of the Guadalupian Epoch to 13.85 ± 0.51 myr, 1.35 ± 0.57 myr longer than that of the ICC 2016. This work is supported by NSFC (41420104003, 41290260 and 41273081) and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB18030400). Wu, Q., Ramezani, J., Zhang, H.* (Corresponding author), Wang, T.T., Yuan, D.X., Mu, L., Zhang, Y.C., Li, X.H., Shen, S.Z., Calibrating the Guadalupian Series (Middle Permian) of South China, Palaeogeography, Palaeoclimatology, Palaeoecology. http://dx.doi.org/10.1016/j.palaeo.2016.11.011.
Field photographs (a, b and c) and polished slab (d) of three different taphonomic types in Gigantoproductus shell beds Storm beds or tempestites are distinct facies criteria, which are generated by storm winds, such as cyclones and hurricanes in tropical latitudes and blizzards in middle and high latitudes. Storm shell beds, which are one common type of tempestites, were commonly formed in the tropical belt resulting from hurricane formation. According to the study on the relationships between taphonomy of shell beds and their palaeogeographical locations in the late Ordovician and its comparison with the modern hurricane distribution, it was found that non-amalgamated shell beds were located in hurricane-free zone within 10° of the palaeoequator, whereas, amalgamated shell beds occurred in hurricane zone between latitude 10° and 30°. The development of hurricanes is probably caused by the temperature difference between the high and low latitudes, induced by the occurrence of glacial deposits on the polar areas. At present, the South China Block is commonly believed to be located near the palaeoequator during the Mississippian, but its precise location is still unclear. In addition, the age of the glacial development on the Gondwana is also debated during this time. To better understand the palaeo-latitude location of the South China Block and the age of the Gondwana glaciation during the Mississippian, the brachiopod (Gigantoproductus) storm shell beds were detailly documented from the Yashui, Duanshan and Gandongzi sections in South China by Dr. YAO Le from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and Prof. ARETZ Markus from the University of Toulouse Ⅲ. The shell beds are characterized by sharp and erosional base, internal accumulations of amalgamated shells with erosional structure, and parallel lamination and ripple bedding structures in the uppermost part, indicating obvious characteristics of tempestites. In the shell beds, three taphonomic and sedimentologic types have been distinguished, which are: (1) mostly articulated and convex-down shells in wackestone and packstone, which are developed in distal tempestites with weak water energy around the storm wave-base; (2) dominated disarticulated and convex-up shells in packstone that occur between distal and proximal tempestites in medium hydrodynamic force between the storm wave-base and fair-weather wave-base; and (3) highly fragmented shells in grainstone formed in proximal tempestites under strong hydrodynamic energy above the fair-weather wave-base. The occurrences of proximal and distal tempestites suggest that they were formed by winnowing and transporting under storm surges. During the late Viséan to Serpukhovian, the widely distributed storm shell beds in South China reflect that the South China Block was located in hurricane zone between latitude 10° and 30° during this time interval, when ice caps formed on the Gondwana continent. This paper was published in Geologica Belgica and financially supported by the National Natural Science Foundation of China, the Strategic Priority Research Program (B) of the Chinese Academy of Sciences and the Ministry of Science and Technology Foundation Project. Reference: Gigantoproductid brachiopod storm shell beds in the Mississippian of South China: implications for their palaeoenvironmental and palaeogeographical significances. Geologica Belgica, 19/1-2: 57-67.
(a) Modern frequency and intensity map of hurricane tracks; (b) Locations of amalgamated shell beds and non-amalgamated shell beds in South China and northern England respectively, hurricane and hurricanefree zones and palaeo-latitudes during the late Viséan to Serpukhovian
Rice is one of the most important crops used to feed our global population. In China, rice has a long history of cultivation. According to archaeobotanical studies in the last decade, the Middle and Lower Yangtze River regions have been proved as the areas where rice was domesticated first. However, the prehistory of the domestication of rice in the tropical areas of South China is yet poorly understood. Recently Dr. MAO Limi from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences together with the colleagues from Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, reported phytolith evidence recovered from a sediment core in the central-east coast of Hainan Island, China, which indicates that domesticated rice might grow on the Hainan Island in 5600 cal a BP. The early timing of rice domestication on Hainan Island supports the hypothesis of the spread of rice agriculture from its origins in the Middle and Lower Yangtze River and its tributaries. The new findings of phytolith evidence also highlights the practice of growing rice since 2000 years ago in the Lingnan region of the Nanyue Kingdom. The discovery of microfossil evidence such as phytoliths, starch and pollen grains should inspire more archaeological research focused on the origins and consequences of the spread of domestic rice agriculture to Hainan Island. This work was part of the Strategic Priority Research Program lead by Chinese Academy of Sciences (CAS), and was jointly conducted by Institute of Vertebrate Paleontology and Paleoanthropology, Nanjing Institute of Geology and Palaeontology, Institute of Geology and Geophysics, Institute of Archaeology, and partially supported by LPS. Reference: Yan Wu*, Limi Mao*, Can Wang, Jianping Zhang, Zhijun Zhao (2016) Phytolith evidence suggests early domesticated rice since 5600 cal a BP on Hainan Island of South China. Quaternary International 426：120–125 （* Corresponding author）
Calathium-microbial framestone (left: Thin section photomicrographs of the Calathium-microbial framestone; right: Reconstruction of the framestone) As an obconical macrofossil with porous double-wall, Calathium was commonly present in reefs of Early to early Middle Ordovician age. The Calathium-bearing reefs thrived globally during the Early Ordovician, but this ecosystem collapsed in Middle Ordovician. A rare case of Calathium-microbial reefs was found from the middle part of the Yijianfang Formation (Darriwilian, late Middle Ordovician) of the Bachu area, located in the northwestern margin of the Tarim Basin, northwestern China. Previous investigations mainly focused on the description of the principal reef builders and facies differentiation. The framework structures of these reefs have not been investigated in detail. Recently, Dr. LI Qijian from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences has provided the first description of the frameworks in typical Middle Ordovician Calathium-microbial reefs from the Tarim Basin. Three facies types are distinguished within the reef limestones: (1) Calathium-microbial framestone, (2) echinoderm-Calathium bafflestone, and (3) bryozoan-microbial bindstone. As a dominant type, the Calathium-microbial framestone shows a three-dimensional skeletal framework that is mainly constructed by Calathium and stabilized by microbialites. Although most specimens are toppled, Calathium displays well-developed lateral outgrowths, which connected individuals of the same species. Morphological characters of Calathium in thin sections show that calathids are hypercalcified sponges rather than receptaculitid algae. Unlike the Early Ordovician lithistid sponge-Calathium reefs, the Tarim reefs studied contain very few lithistid sponges. Instead, bryozoans are fairly common and act as the most important non-microbial encrusters, attaching to the walls of Calathium. The Tarim Calathium-microbial reefs exhibit a striking similarity to the Calathium-echinoderms communities in the Late Ordovician reefs from Tennessee, which provides valuable insights into the evolution of Calathium-bearing reefs and into the nature of the reef ecosystems at this Early Paleozoic turning period, i.e. before the most dramatic change of biotic composition in the late Darriwilian. This study was financially supported by the National Natural Science Foundation of China (41521061, 41290260, 41072002, and XDB10010503). The study entitled “Dissecting Calathium-microbial frameworks: The significance of calathids for the Middle Ordovician reefs in the Tarim Basin, northwestern China” has been published online in Palaeogeography, Palaeoclimatology, Palaeoecology, doi: http://dx.doi.org/10.1016/j.palaeo.2016.08.005.
New specimen of Eoconfuciusornis collected from the Early Cretaceous lake deposits in Hebei, northern China. Image by Wang Xiaoli. A team of international scientists led by researchers from the Chinese Academy of Sciences reported recently the oldest fossil evidence of beta-keratin from feathers of a 130 million-year-old basal bird from the famous Early Cretaceous Jehol Biota. Feathers and feather-like epidermal structures are well documented in several groups of non-avian dinosaurs and basal birds. Round-to-elongated microbodies associated with these feathers and feather-like structures were first interpreted as microbes. But more recently, these bodies were reinterpreted as remnant melanosomes and, subsequently, hypotheses of dinosaurian color, behavior, habitat, and physiology were proposed based upon this reinterpretation. However, melanosomes and microbes overlap completely in size and shape, and thus these hypotheses are equally plausible. Palaeontologists from the Nanjing Institute of Geology and Palaeontology (NIGPAS), the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Linyi University and North Carolina State University, adopted multiple molecular and chemical methods in paleontological study to seek and determine the existence of melanosomes in bird feather fossils. Scientists applied immunogold to identify protein epitopes at high resolution, by localizing antibody-antigen complexes to specific fossil ultrastructures. Their study reported fossil evidence of feather structural protein (betakeratin). "Multiple independent analyses of both microbodies and associated matrix recovered from the fossil feathers confirm that these microbodies are indeed melanosomes," said Dr. PAN Yanhong from NIGPAS and corresponding author of the research paper. Their study showed that these bodies are found deep into a dense cortex in parts where it is preserved, consistent with modern feathers. Scientists also presented the first in-situ high resolution chemical evidence to distinguish melanosomes from bacteria in fossil feathers and show that the matrix in which they are embedded is keratinous. "This study represents a breakthrough in the study of ultrastructures of fossil feathers and has provided the methods to apply to the controversial issue of whether the microbodies in many feathered dinosaurs and early birds are really melanosomes, and sheds new light on molecular preservation within normally labile tissues preserved in ancient fossils," said Prof. ZHOU Zhonghe from IVPP, a co-author of the paper. The study was supported by the Chinese Academy of Sciences, National Natural Science Foundation and the Ministry of Science and Technology of China. Yanhong Pan, Wenxia Zheng, Alison E. Moyer, Jingmai K. O'Connor, Min Wang, Xiaoting Zheng, Xiaoli Wang, Elena R. Schroeter, Zhonghe Zhou, and Mary H. Schweitzer, 2016, Molecular evidence of keratin and melanosomes in feathers of the Early Cretaceous birdEoconfuciusornis, http://www.pnas.org/cgi/doi/10.1073/pnas.1617168113.
PAN Yanhong Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences E-mail: yhpan@nigpas.ac.cn Related News:https://www.eurekalert.org/pub_releases/2016-11/caos-bdi111816.php https://www.eurekalert.org/pub_releases/2016-11/ncsu-kam111816.php http://www.dailymail.co.uk/sciencetech/article-3957800/Dinosaurs-finally-true-colours-Oldest-red-pigment-130-million-year-old-feather.html http://phys.org/news/2016-11-keratin-melanosomes-million-year-old-bird-fossil.html https://www.sciencedaily.com/releases/2016/11/161121174452.htm https://www.sciencenews.org/article/cretaceous-bird-find-holds-new-color-clue http://scienmag.com/beta-keratin-discovery-in-bird-feather-fossil-may-help-identify-paleo-color/ http://www.upi.com/Science_News/2016/11/21/130-million-year-old-bird-fossil-yields-keratin-melanosomes/3341479762174/ http://www.scmp.com/news/china/policies-politics/article/2047947/chinese-feather-fossil-suggests-answer-130-million-year
U-Pb concordia diagrams, cathodoluminescent (CL) images of zircons and frequency histograms of detrital age populations from samples. Major advances in land plant evolution and diversification occurred in the Middle to Late Devonian. The fossil records contain tree-sized plants that comprised early forests of the Middle-Late Devonian at different continents. The appearance and the development of forest ecosystem imparted dramatic changes on the Earth system and furthermore caused a rapid decline of atmospheric carbon dioxide during the Devonian. However, isotopic dating for the Middle to Late Devonian floras was never carried out. Recently, Prof. XU Honghe from Nanjing Institute of Geology and Palaeontoloty, Chinese Academy of Sciences cooperates with the University of Hong Kong, having made a geochronological research for Middle Devonian Hujiersite Flora. The flora is preserved in the Hujiersite Formation, which is best represented at the 251 Hill section, which is composed of a normal fault, containing abundant mega-plant fossils and spores. In this study, the geological background of the 251 Hill section is investigated and two tuffaceous sandstone samples were collected from the normal fault near the plant fossil bearing beds. U-Pb ICP-MS analysis of detrital zircons from these samples gave a maximum depositional age of 385 Ma (late Givetian stage) for the hanging wall and 380 Ma (early Frasnian stage) for the footwall of the section. This study thus reports a novel Givetian–early Frasnian age constraint for Hujiersite Flora. Based on conchostrachans and plant fossils, previous studies suggested a late Middle Devonian age for the Hujierste Formation. However, some disagreements exist and radio-isotopic age determination for this fossil-bearing section is absent. The Hujiersite flora resembles the Givetian to Frasnian Campo Chico Flora of Venezuela. The geochronologic constraint is consistent with previous age interpretations from biostratigraphic correlations. Reference: Zheng, D.R., Xu, H.H., Wang, J., Feng, C.Q., Zhang H.C., Chang, S.C. 2016. Geochronologic age constraints on the Middle Devonian Hujiersite flora of Xinjiang, NW China. Palaeogeography, Palaeoclimatology, Palaeoecology, 463: 230–237.
Cupules of Umkomasia mongolica of different size (probably aborted at different stages of development) The so-called “Mesozoic seed ferns”, a loose assemblage of extinct gymnosperms, are generally taken to comprise Caytonia, corystosperms and peltasperms. These three groups, together with the Permian glossopterids, have been considered of crucial importance for understanding the phylogeny of seed plants and the evolution of their key structural features, including especially the carpel and ovule of angiosperms. However, phylogenetic relationships among these groups, and their relationships to other lineages of living and fossil seed plants, remain uncertain, in large part because of incomplete knowledge and uncertain homologies among their reproductive organs. In a recent study, Dr. SHI Gongle from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and colleagues from the US, Mongolia, Japan and Germany described a new species of corystosperm seed-bearing organ, Umkomasia mongolica, based on abundant, three-dimensional lignified mesofossils from the Early Cretaceous of Mongolia. Individual seed-bearing units of U. mongolica consist of a bract subtending an axis that bifurcates, with each fork (cupule stalk) bearing a cupule near the tip. Each cupule is formed by the strongly reflexed cupule stalk and two lateral flaps that partially enclose an erect seed. The seed is borne at, or close to, the tip of the reflexed cupule stalk, with the micropyle oriented toward the stalk base.
Seed-bearing unit of Umkomasia mongolica from ventral and dorsal surfaces, showing the subtending bract (dark green), bifurcating axis (blue) and lateral flaps of cupules (light green) The corystosperm cupule is generally interpreted as a modified leaf that bears a seed on its abaxial surface. However, U. mongolica suggests that an earlier interpretation, in which the seed is borne directly on an axis (shoot), is equally likely. Current hypotheses of seed plant relationships place great weight on whether the seeds in different groups are borne “terminally on a shoot”, or adaxially or abaxially on modified leaves. For corystosperms, the axial interpretation suggested by U. mongolica, points to a possible relationship to Ginkgo, while the reflexed cupule may suggest a relationship to angiosperms. These two ideas may not be incompatible. If the fundamental phylogenetic division between angiosperms and all extant gymnosperms is correct, as suggested by analyses of molecular data, then corystosperms, Caytonia and perhaps other extinct groups, may be close to the point at which the two extant clades diverged. Reference: Shi G., Leslie A.B., Herendeen P.S., Herrera F., Ichinnorov N., Takahashi M., Knopf P., Crane P.R., 2016. Early Cretaceous Umkomasia from Mongolia: Implication for homology of corystosperm cupules. New Phytologist 210: 1418-1429.
