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1. DWELLING IN THE DEAD ZONE—VERTEBRATE BURROWS IMMEDIATELY SUCCEEDING THE END-PERMIAN EXTINCTION EVENT IN AUSTRALIA

   https://doi.org/10.2110/palo.2020.007  

   McLoughlin, Stephen; Mays, Chris; Vajda, Vivi; Bocking, Malcolm; Frank, Tracy D.; Fielding, Christopher R. (August 2020, PALAIOS)

   null (Ed.)

   ABSTRACT A distinctive burrow form, Reniformichnus australis n. isp., is described from strata immediately overlying and transecting the end-Permian extinction (EPE) horizon in the Sydney Basin, eastern Australia. Although a unique excavator cannot be identified, these burrows were probably produced by small cynodonts based on comparisons with burrows elsewhere that contain body fossils of the tracemakers. The primary host strata are devoid of plant remains apart from wood and charcoal fragments, sparse fungal spores, and rare invertebrate traces indicative of a very simplified terrestrial ecosystem characterizing a ‘dead zone' in the aftermath of the EPE. The high-paleolatitude (∼ 65–75°S) setting of the Sydney Basin, together with its higher paleoprecipitation levels and less favorable preservational potential, is reflected by a lower diversity of vertebrate fossil burrows and body fossils compared with coeval continental interior deposits of the mid-paleolatitude Karoo Basin, South Africa. Nevertheless, these burrows reveal the survivorship of small tetrapods in considerable numbers in the Sydney Basin immediately following the EPE. A fossorial lifestyle appears to have provided a selective advantage for tetrapods enduring the harsh environmental conditions that arose during the EPE. Moreover, high-paleolatitude and maritime settings may have provided important refugia for terrestrial vertebrates at a time of lethal temperatures at low-latitudes and aridification of continental interiors. 

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2. Draft genome sequence of the glasshouse-potato aphid Aulacorthum solani

   https://doi.org/10.1093/g3journal/jkaf013  

   Torres, Joseph; Rozo-Lopez, Paula; Brewer, William; Saleh_Ziabari, Omid; Parker, Benjamin_J; Bergstralh, ed., D. (January 2025, G3: Genes, Genomes, Genetics)

   Abstract Aulacorthum solani is a worldwide agricultural pest aphid capable of feeding on a wide range of host plants. This insect is a vector of plant viruses and causes injury to crops including stunted growth from the loss of phloem. We found that the publicly available genome for A. solani is contaminated with another aphid species, and we produced a new genome using a barcoded isogenic laboratory line. We generated Oxford Nanopore and Illumina reads to assemble a draft genome, and we sequenced RNA to aid in the annotation of our assembly. Our A. solani genome is 671 Mb containing 7,020 contigs with an N50 length of 196 kb with a BUSCO completeness of 98.6%. Out of the 24,981 genes predicted by EGAPx, 22,804 were annotated with putative functions based on homology to other aphid species. This genome will provide a useful resource for the community of researchers studying aphids from agricultural and genomic perspectives. 

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3. Himatiichnus mangano igen. et isp. nov., a scalidophoran trace fossil from the late Ediacaran of Namibia

   https://doi.org/10.1098/rsos.240452  

   Turk, Katherine A; Pulsipher, Mikaela A; Mocke, Helke; Laflamme, Marc; Darroch, Simon_A F (October 2024, Royal Society Open Science)

   Himatiichnus manganoigen. et isp. nov., a new trace fossil from the late Ediacaran Huns Member of the Urusis Formation, southern Namibia, comprises intertwining tubes exhibiting dual lineation patterns and reminiscent of both modern and early Cambrian examples of priapulid worm burrows. These similarities support the interpretation of a total-group scalidophoran tracemaker forH. mangano, thus providing direct evidence for the first appearance date of Scalidophora in the late Ediacaranca539 Ma. This new material is thus indicative of the presence of total-group scalidophorans below the Cambrian boundary and supports inference of a lengthy Precambrian fuse for the Cambrian explosion. 

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4. Differential impact of two major polychaete guilds on microbial communities in marine sediments: a microcosm study

   https://doi.org/10.3389/fmars.2023.1119331  

   Deng, Longhui; Fiskal, Annika; Bölsterli, Damian; Meier, Dimitri; Meile, Christof; Lever, Mark Alexander (June 2023, Frontiers in Marine Science)

   Even though sediment macrofauna are widespread in the global seafloor, the influence of these fauna on microbial communities that drive sediment biogeochemical cycles remains poorly understood. According to recent field investigations, macrofaunal activities control bacterial and archaeal community structure in surface sediments, but the inferred mechanisms have not been experimentally verified. Here we use laboratory microcosms to investigate how activities of two major polychaete guilds, the lugworms, represented byAbarenicola pacifica, and the clamworms, represented byNereis vexillosa, influence microbial communities in coastal sediments.A. pacificatreatments show >tenfold increases in microbial cell-specific consumption rates of oxygen and nitrate, largely due to the strong ventilation activity ofA. pacifica. While ventilation resulted in clearly elevated percentages of nitrifying archaea (Nitrosopumilusspp.) in surface sediments, it only minorly affected bacterial community composition. By comparison, reworking – mainly by deposit-feeding ofA. pacifica– had a more pronounced impact on microorganismal communities, significantly driving down abundances of Bacteria and Archaea. Within the Bacteria, lineages that have been linked to the degradation of microalgal biomass (e.g., Flavobacteriaceae and Rhodobacteraceae), were especially affected, consistent with the previously reported selective feeding ofA. pacificaon microalgal detritus. In contrast,N. vexillosa, which is not a deposit feeder, did not significantly influence microbial abundances or microbial community structure. This species also only had a relatively minor impact on rates of oxygen and nitrogen cycling, presumably because porewater exchanges during burrow ventilation by this species were mainly restricted to sediments immediately surrounding the burrows. Collectively our analyses demonstrate that macrofauna with distinct bioturbation modes differ greatly in their impacts on microbial community structure and microbial metabolism in marine sediments. 

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5. Tectono‐sedimentary history of the upper Cedar Mountain Formation, Central Utah, USA

   https://doi.org/10.1111/sed.13211  

   Tucker, Ryan T; King, M Ryan; Mohr, Michael T; Renaut, Ray K; Crowley, James L; Fekete, Jack W; Makovicky, Peter J; Zanno, Lindsay E (July 2024, Sedimentology)

   ABSTRACT Current investigations into the Albian–Cenomanian sedimentary record within the Western Interior have identified multiple complex tectono‐sedimentary process–response systems during the ongoing evolution of North America. One key sedimentary succession, the upper Cedar Mountain Formation (Short Canyon Member and Mussentuchit Member), has historically been linked to various regionally and continentally significant tectonic events, including Sevier fold‐and‐thrust deformation. However, the linkage between the Short Canyon Member and active Sevier tectonism has been unclear due to a lack of high‐precision age constraints. To establish temporal context, this study compares maximum depositional ages from detrital zircons recovered from the Short Canyon Member with that of a modified Bayesian age stratigraphic model (top‐down) to infer that the Short Canyon Member was deposited atca100 Ma, penecontemporaneous with rejuvenated thrusting across Utah [Pavant (Pahvant), Iron Springs and Nebo thrusts]. These also indicate a short depositional hiatus with the lowermost portion of the overlying Mussentuchit Member. The Short Canyon Member and Mussentuchit Member preserve markedly different sedimentary successions, with the Short Canyon Member interpreted to be composed of para‐autochthonous orogen–transverse (across the Sevier highlands) clastics deposited within a series of stacked distributive fluvial fans. Meanwhile, the muddy paralic Mussentuchit Member was a mix of orogen–transverse (Sevier highlands and Cordilleran Arc) and orogen–parallel basinal sediments and suspension settling fines within the developing collisional foredeep. However, the informally named last chance sandstone (middle sandstone of the Mussentuchit Member) is identified as an orogen–transverse sandy debris flow originating from the Sevier highlands, similar to the underlying Short Canyon Member. During this phase of landscape evolution, the Short Canyon Member – Mussentuchit Member depocentre was a sedimentary conduit system that would fertilize the Western Interior Seaway with ash‐rich sediments. These volcaniclastic contributions, along with penecontemporaneous deposits across the western coastal margin of the Western Interior Seaway, eventually would have lowered oxygen content and resulted in a contributing antecedent trigger for the Cenomanian–Turonian transition Oceanic Anoxic Event 2. 

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