On the way from Asia to America: eutriconodontan mammals from the Early Cretaceous of Yakutia, Russia.

Eutriconodonta are an important group of early crown mammals with a wide distribution in the Jurassic-Cretaceous of the Northern Hemisphere and few occurrences in the Southern Hemisphere. Three taxa of eutriconodontans are known from the Early Cretaceous high-latitude Teete vertebrate assemblage in Yakutia, Russia: Sangarotherium aquilonium (Eutriconodonta incertae sedis), Gobiconodon sp. A (large), and Gobiconodon sp. B (small) (Gobiconodontidae). These three taxa are based on four specimens and indicate a remarkable taxonomic diversity of eutriconodontans at this locality. The coexistence of two Gobiconodon species, large and small, is characteristic for several Early Cretaceous vertebrate assemblages in Asia. Gobiconodon sp. A from the Teete locality is the largest species of this genus known from Asia, but is smaller than the North American G. ostromi. The spreading of Gobiconodon from Asia to North America likely occurred during the Aptian-Albian faunal dispersal event. The discovery of Gobiconodon in the Teete locality is further evidence for a dispersal route via Beringia from Asia to North America which previously has been postulated based on the occurrence of Asian dinosaur taxa in western North America at this time. The questionable record of Gobiconodon from Europe and its lack from eastern North America make a dispersal from Asia to North America via Europe less probable.

Wear patterns and dental functioning in an Early Cretaceous stegosaur from Yakutia, Eastern Russia.

Isolated stegosaurian teeth from the Early Cretaceous high-latitude (palaeolatitude estimate of N 62°- 66.5°) Teete locality in Yakutia (Eastern Siberia, Russia) are characterized by a labiolingually compressed, slightly asymmetrical and mesiodistally denticulated (9-14 denticles) crown, a pronounced ring-like cingulum, as well as a "complex network of secondary ridges". The 63 teeth (found during on-site excavation in 2012, 2017-2019 and screen-washing in 2017-2019) most likely belong to one species of a derived (stegosaurine) stegosaur. Most of the teeth exhibit a high degree of wear and up to three wear facets has been observed on a single tooth. The prevalence of worn teeth with up to three wear facets and the presence of different types of facets (including steeply inclined and groove-like) indicate the tooth-tooth contact and precise dental occlusion in the Teete stegosaur. The microwear pattern (mesiodistally or slightly obliquely oriented scratches; differently oriented straight and curved scratches on some wear facets) suggest a complex jaw mechanism with palinal jaw motion. Histological analysis revealed that the Teete stegosaur is characterized by relatively short tooth formation time (95 days) and the presence of a "wavy enamel pattern". Discoveries of a "wavy enamel pattern" in the Teete stegosaur, in a Middle Jurassic stegosaur from Western Siberia, and in the basal ceratopsian Psittacosaurus, suggest that this histological feature is common for different ornithischian clades, including ornithopods, marginocephalians, and thyreophorans. A juvenile tooth in the Teete sample indicates that stegosaurs were year-round residents and reproduced in high latitudes. The combination of high degree of tooth wear with formation of multiple wear facets, complex jaw motions, relatively short tooth formation time and possibly high tooth replacement rates is interpreted as a special adaptation for a life in high-latitude conditions or, alternatively, as a common stegosaurian adaptation making stegosaurs a successful group of herbivorous dinosaurs in the Middle Jurassic-Early Cretaceous and enabeling them to live in both low- and high-latitude ecosystems.

Method for detection of mtDNA damages for evaluating of pesticides toxicity for bumblebees (Bombus terrestris L.).

Bumblebees are important for crop pollination. Currently, the number of pollinators is decreasing worldwide, which is attributed mostly to the widespread use of pesticides. The aim of this work was to develop a method for assessing the genotoxicity of pesticides for the Bombus terrestris L. bumblebee using long-range PCR of mitochondrial DNA fragments. We have developed a panel of primers and assessed the genotoxicity of the following pesticides: imidacloprid, rotenone, deltamethrin, difenocanozole, malathion, metribuzin, penconazole, esfenvalerate, and dithianon. All pesticides (except imidacloprid) inhibited mitochondrial respiration fueled by pyruvate + malate; the strongest effect was observed for rotenone and difenocanozole. Three pesticides (dithianon, rotenone, and difenocanozole) affected the rate of H2O2 production. To study the pesticide-induced DNA damage in vitro and in vivo, we used three different mtDNA. The mtDNA damage was observed for all studied pesticides. Most of the studied pesticides caused significant damage to mtDNA in vitro and in vivo when ingested. Our results indicate that all tested pesticides, including herbicides and fungicides, can have a toxic effect on pollinators. However, the extent of pesticide-induced mtDNA damage in the flight muscles was significantly less upon the contact compared to the oral administration.

Evaluation of the toxicity of fungicides to flight muscle mitochondria of bumblebee (Bombus terrestris L.).

Insects pollinate 75% of crops used for human consumption. Over the last decade, a substantial reduction in the abundance of pollinating insects has been recorded and recognized as a severe matter for food supply security. Many of the important food crops destined for human consumption are grown in greenhouses. A unique feature of greenhouse agriculture is the extensive use of fungicides to curb multiple fungal infections. The most widely used pollinating insects in greenhouses are commercially reared bumblebees. However, there is no data regarding the toxicity of fungicides to bumblebee mitochondria. To fill this gap in knowledge, we examined the effects of 16 widely used fungicides on the energetics of the flight muscles mitochondria of Bombus terrestris. We found that diniconazole and fludioxonil uncoupled the respiration of mitochondria; dithianon and difenoconazole inhibited it. By analyzing the action of these inhibitors on mitochondrial respiration and generation of reactive oxygen species, we concluded that difenoconazole inhibited electron transport at the level of Complex I and glycerol-3-phosphate dehydrogenase. Dithianon strongly inhibited succinate dehydrogenase and glycerol-3-phosphate dehydrogenase. It also strongly inhibited mitochondrial oxidation of NAD-linked substrates or glycerol 3-phosphate, but it had no effect on the enzymatic activity of Complex I. It may be suggested that dithianon inhibits electron transport downstream of Complex I, likely at multiply sites.

A new phylogeny for basal Trechnotheria and Cladotheria and affinities of South American endemic Late Cretaceous mammals.

The endemic South American mammals Meridiolestida, considered previously as dryolestoid cladotherians, are found to be non-cladotherian trechnotherians related to spalacotheriid symmetrodontans based on a parsimony analysis of 137 morphological characters among 44 taxa. Spalacotheriidae is the sister taxon to Meridiolestida, and the latter clade is derived from a primitive spalacolestine that migrated to South America from North America at the beginning of the Late Cretaceous. Meridiolestida survived until the early Paleocene (Peligrotherium) and early Miocene (Necrolestes) in South America, and their extinction is probably linked to the increasing competition with metatherian and eutherian tribosphenic mammals. The clade Meridiolestida plus Spalacotheriidae is the sister taxon to Cladotheria and forms a new clade Alethinotheria. Alethinotheria and its sister taxon Zhangheotheria, new clade (Zhangheotheriidae plus basal taxa), comprise Trechnotheria. Cladotheria is divided into Zatheria (plus stem taxa, including Amphitherium) and Dryolestida, including Dryolestidae and a paraphyletic array of basal dryolestidans (formerly classified as "Paurodontidae"). The South American Vincelestes and Groebertherium are basal dryolestidans.

An aegialodontid upper molar and the evolution of mammal dentition.

The most obvious key synapomorphy of the therian mammals is the tribosphenic pattern of their molars. Tribosphenic teeth are capable of both shearing and grinding, which substantially increase effectiveness of food processing and, in turn, permit evolution of a wide range of dietary specializations. Functional tribospheny developed repeatedly during mammalian evolution but was successful only in the Boreosphenida. The earliest stage in the development of boreosphenidan tribospheny has remained poorly understood, being documented only by lower molars of aegialodontids. Here, we report a known upper molar of an aegialodontid mammal, Kielantherium, from the Early Cretaceous of Mongolia.