Taungurungia gen. nov., from the Lower Devonian of Yea, central Victoria, Australia

This paper records a new genus Taungurungia, which is the first new taxon with emergences to be described from the Lower Devonian of Victoria. The fossil is preserved primarily as a compression and impression, and lacks internal anatomy. The fossil extends our knowledge of known variations within early land plants, with most characteristics, such as emergences and H- or K-branching, redolent of affinities with the zosterophylls. However, having a large ovate terminal sporangium, the fossil adds to taxa that in some cases have been provisonally allied to the zosterophylls with elongate sporangia; this further demonstrates the need for reassessment of the Zosterophyllopsida.

Terrestrial-type nitrogen-fixing symbiosis between seagrass and a marine bacterium

Symbiotic N2-fixing microorganisms have a crucial role in the assimilation of nitrogen by eukaryotes in nitrogen-limited environments1–3. Particularly among land plants, N2-fixing symbionts occur in a variety of distantly related plant lineages and often involve an intimate association between host and symbiont2,4. Descriptions of such intimate symbioses are lacking for seagrasses, which evolved around 100 million years ago from terrestrial flowering plants that migrated back to the sea5. Here we describe an N2-fixing symbiont, ‘Candidatus Celerinatantimonas neptuna’, that lives inside seagrass root tissue, where it provides ammonia and amino acids to its host in exchange for sugars. As such, this symbiosis is reminiscent of terrestrial N2-fixing plant symbioses. The symbiosis between Ca. C. neptuna and its host Posidonia oceanica enables highly productive seagrass meadows to thrive in the nitrogen-limited Mediterranean Sea. Relatives of Ca. C. neptuna occur worldwide in coastal ecosystems, in which they may form similar symbioses with other seagrasses and saltmarsh plants. Just like N2-fixing microorganisms might have aided the colonization of nitrogen-poor soils by early land plants6, the ancestors of Ca. C. neptuna and its relatives probably enabled flowering plants to invade nitrogen-poor marine habitats, where they formed extremely efficient blue carbon ecosystems7.

Early land plants from the Lower Devonian of central Victoria, Australia, including a new species of Salopella

Early land plants with elongate sporangia held in the palaeobotanical archives of Museums Victoria were examined. The fossil plants are from Yea (?upper Silurian) and near Matlock (Lower Devonian) in central Victoria, and are of interest because they contribute to our understanding of the evolution of early land plants in a region in which research has been limited. Both Salopella australis and Salopella caespitosa were originally described over 30 years ago and this reinvestigation has resulted in the emending of the diagnosis of Salopella australis and the erection of a new morphotaxon Salopella laidae sp. nov. based primarily on differing branching architecture and sporangial morphology. Salopella laidae comes from Yea Formation and possesses regular isotomous branching over at least two orders of branching, terminating in elongate sporangia that are wider than their subtending axes, differing from S. australis, which possesses only one dichotomy emanating from at least two erect parallel parent axes with sporangia that are the same width as their subtending axes. A recently collected specimen of Salopella caespitosa was also examined and adds to our understanding of this taxon, which was previously only known from one specimen. Consideration is given to the possible sources of these early land plants based on other early land plants with a similar grade of organisation.

MUDDYING THE WATERS: MODELING THE EFFECTS OF EARLY LAND PLANTS IN PALEOZOIC ESTUARIES

ABSTRACT The Paleozoic evolution of vegetation transformed terrestrial landscapes, facilitating novel sedimentary processes and creating new habitats. This transformation left a permanent mark on the sedimentary record, perhaps most strikingly via an upsurge in preserved terrestrial mudrock. Whereas feedbacks between evolving vegetation and river structure have been widely studied, Paleozoic estuaries have so far received scant attention. Located at the interface between the land and sea, the co-adjustment of estuarine morphology and plant traits are fundamentally tied to a varied range of geochemical cycles, and determine how global silicate weathering patterns may have varied over time. Here we employ an eco-morphodynamic model with an in-built vegetation code to simulate estuarine morphology through five key stages in plant evolution. An abiotic model (early Precambrian?) saw mud deposition restricted to fortuitous instances of limited erosion along bar-flanks. Estuaries colonized by microbial mats (Precambrian onwards) facilitated mud accretion that sufficiently stabilized bar surfaces to promote extensive mudflat development. Small-stature, rootless vegetation (Silurian–Early Devonian) introduced novel above-ground baffling effects which led to notable mud accumulation in lower-energy environments. The incorporation of roots (Early Devonian) strengthened these trends, with root structures decreasing the mortality of the occupying plants. Once the full complement of modern vascular plant architectures had evolved (Middle Devonian), dense colonization promoted the formation of in-channel islands accompanied with system-wide mud accumulation. These simulations suggest estuaries underwent profound change during the Paleozoic, with the greening of the continents triggering processes and feedbacks which render all previous source-to-sink sediment pathways non-uniformitarian.

Russian development and toponymy of the Pelym region according to written and field sources of the 18th–21st centuries

The paper is aimed at the study of the under-investigated Russian toponymy of the north of the Sverdlovsk Region, specifically, of the oikonyms — the names of villages — along the lower reaches of the Pelym River. The basin of the Pelym River, a tributary of the Tavda River, is of interest as the Mansi native territory. It is also an area of the early land development by the Russians beyond the Urals, which began at the end of the 16th century. The objective of this study is to establish the origins of the earliest layer of names of the Russian villages along the Pelym River and to trace the history of their functioning from the 18th century to the present day. The work is based on the material of historical documents (customs books of the town of Pelym of the second half of the 17th century), information from written, statistical, and cartographic sources (travel materials of academician G.F. Müller of 1742, expeditions of B. Munkácsi in 1888–1889, lists of the settlements of the Ural and Sverdlovsk regions, and modern maps of the region), as well as field materials of the 1960s collected by the Ural University Toponymic Expedition. Research methods include descriptive, etymological, comparative, reconstruction, and statistical analysis of linguistic material. It has been ascertained that almost all considered oikonyms have anthroponomical origins and are derived from the surnames of first settlers. They reflect the history of the deve-lopment of the Pelym region, including its active settlement by the Russian riflemen Streltsy (villages Krivonogova, Khudyakova, Kuznetsova, Tolmacheva etc.). The names of the Russian villages which were founded in the Mansi native territory were subjected to adaptation in the Mansi language, or the Mansi were gi-ving them their own names, which is clearly shown by the materials of B. Munkácsi of the late 19th century (Po-nomareva village → Panamarovskaya in Russian and Varaulėχ-pɵwėl in Mansi, Kadaulova (Kaidaulova) village → Khɵitėl-p. in Mansi etc.). Of the 17 Russian oikonyms of the lower Pelym known in the 18th century and recorded by G.F. Müller in the description of his travel in 1742, only one has survived to this day — the name of the village of Vekshina, which is still extant. The memory of the disappeared Pelym villages and their names are preserved by the local microtoponyms present on the modern maps, as well as by the surnames of the descendants of the inhabitants of these villages.