Vol 53, No 7 (2019)

The Ediacara fauna is traditionally regarded as the first complex, diverse and widespread macroscopic life. The uncertainty of systematic position of its members has led to very different views on the early evolution of metazoans. In part, this may be due to a lack of data on sclerotization: a hard skeleton is a part of the archetype of the most taxa known from the fossil record, whereas the Ediacara fauna as a whole is most often considered soft-bodied, which complicates comparison. Here we report the Late Precambrian frond-like fossils (Petalonamae) from the Vendian assemblage of the Southeastern White Sea area (∼555.3 Ma), which show evidence of elaborate skeleton composed of a regular meshwork reinforced by dense longitudinal and circular bands. Judging from the nature of preservation and the dynamics of the environment Ediacaran fronds secreted a relatively rigid but flexible skeleton. The fact that frond-like Petalonamae had a supporting structure similar to that of sponges and cnidarians seems to be a powerful argument in favor of their metazoan affinity. The new observations indicated also that the widespread skeletonization had occurred long before the “Cambrian skeletal revolution”.

This paper continues our revision of Yu.L. Pelman’s collection of the linguliformean brachiopods and of our own material from the Early–Middle Cambrian of the Siberian Platform (for previous papers see (Ushatinskaya and Korovnikov, 2014, 2016). The present paper focuses on the order Acrotretida. Linnarssonia, Homotreta, Prototreta, Opistotreta, and Kostjubella (family Acrotretidae) were restudied using the scanning electron microscope. Kostjubella (family Acrotretidae) and Erbotreta (family Ceratretidae) are described for the first time from the Siberian Platform. Some species described by Pelman are placed into synonymy. Two new species, Linnarssonia ulakhani and Erbotreta elankii, are established.

Several new tribes, genera and species of Curculionoidea are described from the earlymost Eocene Oise amber (France), viz., the new tribes Oiserhinini trib. nov. (type genus: Oiserhinus gen. nov.) (in Anthribidae: Anthribinae), Palaeotanaini trib. nov. (type genus: Palaeotanaos Kirejtshuk, Legalov et Nel, 2015) (in Brentidae: Apioninae), Sciabregmini trib. nov. (type genus: Sciabregma Scudder 1893) (in Curculionidae: Molytinae); the new genera Oiserhinus gen. nov. (type species: Oiserhinusinsolitus sp. nov.), Oisecalles gen. nov. (type species: Oisecalles latosquamosus sp. nov.) in Cryptorhynchini: Cryptorhynchina), Rhinoporkus gen. nov. (type species: Rhinoporkus gratiosus sp. nov.) (in Dryophthorinae: Dryophthorini), Jantarhinus gen. nov. (type species: Jantarhinus compressus sp. nov.) (in Conoderinae: Conoderini), Jantaronosik gen. nov. (type species: Jantaronosik nebulosus sp. nov.) (in Curculioninae: Acalyptini), Tolstonosik gen. nov. (type species: Tolstonosikoisensis sp. nov.) (in Entiminae: Eudiagogini); and the new species Oiserhinusinsolitus sp. nov., Sciabregmasquamosa sp. nov., Oisecalles latosquamosus sp. nov., Rhinoporkus gratiosus sp. nov., Jantarhinus compressus sp. nov., Jantaronosik nebulosus sp. nov., and Tolstonosikoisensis sp. nov. The generic name Protoceletes Rheinheimer, 2007, syn. nov. is synonymized under Electrotribus Hustache, 1942. New combination of name (Electrotribuswolfschwenningerae (Rheinheimer, 2007), comb. nov. is established. Synopsis of the weevil findings from described groups are presented.

The Fe/Co ratio (ppm) in the kerogen from different-aged clastic sediments (Early Proterozoic–Mesozoic) varies from 17 to 4100, and δ¹³C value varies from –14.8 to –32.6‰. The relationship between Fe/Co and δ¹³C is determined by the composition of microbial biota in paleobasins and superimposed metamorphic processes. The kerogen from the Vendian deposits of the East European Platform, containing a large amount of saprophytes and actinomycetes is characterized by the maximum Co concentration. The kerogen from deposits metamorphosed under amphibolite-facies conditions are characterized by the minimal δ¹³C and the maximum Fe/Co ratio values.