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The global diversity of Proterozoic eukaryote fossils is poorly quantified despite its fundamental importance to the understanding of macroevolutionary patterns and dynamics on the early Earth. Here we report a new construction of fossil eukaryote diversity from the Paleoproterozoic to early Cambrian based on a comprehensive data compilation and quantitative analyses. The resulting taxonomic richness curve verifies Cryogenian glaciations as a major divide that separates the “Boring Billion” and Ediacaran periods, with the former characterized by a prolonged stasis, and the latter by greater diversity, more-rapid turnover, and multiple radiations and extinctions. These contrasting evolutionary patterns and dynamics provide a framework to test competing hypotheses on biosphere and geosphere coevolution in the Proterozoic Eon. 

Abstract Macrofossils with unambiguous biogenic origin and predating the one-billion-year-old multicellular fossilsBangiomorphaandProterocladusinterpreted as crown-group eukaryotes are quite rare.Horodyskiais one of these few macrofossils, and it extends from the early Mesoproterozoic Era to the terminal Ediacaran Period. The biological interpretation of this enigmatic fossil, however, has been a matter of controversy since its discovery in 1982, largely because there was no evidence for the preservation of organic walls. Here we report new carbonaceous compressions ofHorodyskiafrom the Tonian successions (~950–720 Ma) in North China. The macrofossils herein with bona fide organic walls reinforce the biogenicity ofHorodyskia. Aided by the new material, we reconstructHorodyskiaas a colonial organism composed of a chain of organic-walled vesicles that likely represent multinucleated (coenocytic) cells of early eukaryotes. Two species ofHorodyskiaare differentiated on the basis of vesicle sizes, and their co-existence in the Tonian assemblage provides a link between the Mesoproterozoic (H.moniliformis) and the Ediacaran (H.minor) species. Our study thus provides evidence that eukaryotes have acquired macroscopic size through the combination of coenocytism and colonial multicellularity at least ~1.48 Ga, and highlights an exceptionally long range and morphological stasis of this Proterozoic macrofossils. 

Abstract The terminal Ediacaran Shibantan biota (~550–543 Ma) from the Dengying Formation in the Yangtze Gorges area of South China represents one of the rare examples of carbonate-hosted Ediacara-type macrofossil assemblages. In addition to the numerically dominant taxa—the non-biomineralizing tubular fossilWutubusand discoidal fossilsAspidellaandHiemalora, the Shibantan biota also bears a moderate diversity of frondose fossils, includingPteridinium,Rangea,Arborea, andCharnia. In this paper, we report two species of the rangeomorph genusCharnia, including the type speciesCharnia masoniFord, 1958 emend. andCharnia gracilisnew species, from the Shibantan biota. Most of the ShibantanCharniaspecimens preserve only the petalodium, with a few bearing the holdfast and stem. Despite overall architectural similarities to otherCharniaspecies, the Shibantan specimens ofCharnia gracilisn. sp. are distinct in their relatively straight, slender, and more acutely angled first-order branches. They also show evidence that may support a two-stage growth model and a epibenthic sessile lifestyle.Charniafossils described herein represent one of the youngest occurrences of this genus and extend its paleogeographic and stratigraphic distributions. Our discovery also highlights the notable diversity of the Shibantan biota, which contains examples of a wide range of Ediacaran morphogroups. UUID:http://zoobank.org/837216cd-4a4a-4e13-89e2-ee354ba48a4c 

Abstract The colonization of land by fungi had a significant impact on the terrestrial ecosystem and biogeochemical cycles on Earth surface systems. Although fungi may have diverged ~1500–900 million years ago (Ma) or even as early as 2400 Ma, it is uncertain when fungi first colonized the land. Here we report pyritized fungus-like microfossils preserved in the basal Ediacaran Doushantuo Formation (~635 Ma) in South China. These micro-organisms colonized and were preserved in cryptic karstic cavities formed via meteoric water dissolution related to deglacial isostatic rebound after the terminal Cryogenian snowball Earth event. They are interpreted as eukaryotes and probable fungi, thus providing direct fossil evidence for the colonization of land by fungi and offering a key constraint on fungal terrestrialization. 

The Shibantan Lagerstätte (551–543 Ma) in the Yangtse Gorges area in South China is one of the best-known examples of terminal Ediacaran fossil assemblages preserved in marine carbonate rocks. Taxonomically dominated by benthic organisms, the Shibantan Lagerstätte preserves various photoautotrophs, biomineralizing tubular fossils, Ediacara-type macrofossils (including rangeomorphs, arboreomorphs, erniettomorphs, palaeopascichnids, a possible dickinsoniomorph, the mobile bilaterian Yilingia and soft-bodied tubular fossils), abundant ichnofossils and a number of problematic and dubious fossils. Shibantan fossils provide intriguing insights into ecological interactions among mobile bilaterians, sessile benthic Ediacara-type organisms and microbial mats, thus offering important data to test various hypotheses accounting for the decline of the Ediacara biota and the concurrent expansion of bilaterian bioturbation and mobility across the Proterozoic–Phanerozoic transition. 

Abstract Bituminous limestone of the Ediacaran Shibantan Member of the Dengying Formation (551–539 Ma) in the Yangtze Gorges area contains a rare carbonate-hosted Ediacara-type macrofossil assemblage. This assemblage is dominated by the tubular fossil Wutubus Chen et al., 2014 and discoidal fossils, e.g., Hiemalora Fedonkin, 1982 and Aspidella Billings, 1872, but frondose organisms such as Charnia Ford, 1958, Rangea Gürich, 1929, and Arborea Glaessner and Wade, 1966 are also present. Herein, we report four species of Arborea from the Shibantan assemblage, including the type species Arborea arborea (Glaessner in Glaessner and Daily, 1959) Glaessner and Wade, 1966, Arborea denticulata new species, and two unnamed species, Arborea sp. A and Arborea sp. B. Arborea arborea is the most abundant frond in the Shibantan assemblage. Arborea denticulata n. sp. resembles Arborea arborea in general morphology but differs in its fewer primary branches and lower length/width ratio of primary branches. Arborea sp. A and Arborea sp. B are fronds with a Hiemalora -type basal attachment. Sealing by microbial mats and authigenic cementation may have played an important role in the preservation of Arborea in the Shibantan assemblage. The Shibantan material of Arborea extends the stratigraphic, ecological, and taphonomic ranges of this genus. UUID: http://zoobank.org/554f21da-5f09-4891-9deb-cbc00c41e5f1