Abstract Shell beds, or coquinas, have a complex origin, limiting their utility in paleoecology. However, such accumulations can serve as crucial paleoenvironmental indicators, since their bioestratinomic and diagenetic properties explain the physical-chemical and biological processes of their formation, as well as the ancient environments linked to their development. In 2016, the PALEOANTAR Project sampled coquinas from the James Ross Island (Antarctic Peninsula) in Passo São José (PSJ – San José Way) and Muro do Castelo (MDC – Castle Wall), two new localities with outcrops of the lower Lachman Crags Member, Santa Marta Formation, Marambio Group, Cretaceous of Larsen Basin. The paleontological content and sedimentary structures indicate a shallow marine depositional system. The PSJ coquina are composed by gastropods bioclasts, with predominantly dense/loose packing. The MDC presents a larger variety of bioclasts with bivalve dominance on a loose packing and conglomeratic horizons, that varies from granule to pebble. Sedimentary and biostratinomic features observed in samples from both localities indicate their genesis from high-energy events, characterized as a proximal tempestite. These descriptions allow a more accurate reconstruction of the depositional environments, highlighting the importance of these rocks in the geological record during the Cretaceous of Antarctica. beds origin paleoecology However indicators physicalchemical physical chemical formation development 2016 Antarctic Peninsula Way Wall, Wall , Wall) Member Formation Group Basin system denseloose dense horizons pebble highenergy high energy events tempestite Antarctica 201 20 2

Abstract This study investigates ichnoassemblages characterized by spreite trace fossils from the Upper Cretaceous Snow Hill Island Formation on Vega Island, Antarctica. The succession reveals alternating heterolithic beds of sandy siltstones to very fine- to fine-grained sandstones, suggestive of a deltaic depositional setting influenced by fluctuating energy conditions. The dominance of spreite structures, such as Paradictyodora antarctica and Euflabella, suggests the prevalence of a colonization window for deposit- or detritus-feeding activity. Notably, the prevalence of Euflabella towards the upper levels of the succession, in more proximal and impacted depositional setting, suggests an adaptive strategy for coping with varying food resources, corroborating its role as a trophic generalist. Additionally, the absence of distinct shifts between fully marine and stressed ichnofauna challenges a clear assignation to the Phycosiphon or Rosselia ichnofacies, although in vertical succession the Euflabella dominance in upper levels is related to a lower diverse ichnoassemblage than Paradictyodora in lower levels, suggesting some freshwater impact in the top. The occurrence of horizontal and vertical sessile deposit feeding structures would align with the Rosselia ichnofacies definition, but the presence of spreite burrows and high ichnodisparity better fits into the Cruziana ichnofacies. These spreite-dominated ichonoassemblages are here attributed to Cruziana ichnofacies. Antarctica fine finegrained grained sandstones conditions detritusfeeding detritus activity Notably resources generalist Additionally top definition spreitedominated dominated

Abstract A worldwide revision of the Cretaceous record of Neornithes (crown birds) revealed that unambiguous neornithine taxa are extremely scarce, with only a few showing diagnostic features to be confidently assigned to that group. Here we report two new neornithine specimens from Vega Island (López de Bertodano Formation). The first is a synsacrum (MN 7832-V) that shows a complex pattern of transversal diverticula intercepting the canalis synsacri, as in extant neornithines. Micro-CT scanning revealed a camerate pattern of trabeculae typical of neornithines. It further shows the oldest occurrence of lumbosacral canals in Neornithes, which are related to a balance sensing system acting in the control of walking and perching. The second specimen (MN 7833-V) is a distal portion of a tarsometatarsus sharing with Vegavis iaai a straight apical border of the crista plantaris lateralis. Osteohistologically the tarsometatarsus shows a thick and highly vascularized cortex that lacks any growth marks, resembling Polarornis gregorii. The cortex is osteosclerotic as in other extinct and extant diving neornithines. These new specimens increase the occurrences of the Cretaceous avian material recovered from the Upper Cretaceous strata of the James Ross Sub-Basin, suggesting that a Vegaviidae-dominated avian assemblage was present in the Antarctic Peninsula during the upper Maastrichtian. crown birds scarce group López Formation. Formation . Formation) MN 7832V V 7832 7832-V synsacri neornithines MicroCT Micro CT perching 7833V 7833 7833-V lateralis marks gregorii SubBasin, SubBasin Sub Basin, Basin Sub-Basin Vegaviidaedominated Vegaviidae dominated Maastrichtian 783 78 7

Abstract A study of macro and microfacies, palynoflora and palynofacies of the non-marine Cerro Negro Formation at President Head Peninsula, Snow Island, northwest of the Antarctic Peninsula, was developed. Two assemblages were recognized: Palynofacies assemblage 1 (P1) at the base of the section with a dominance of fern spores and conifer pollen grains, and facies association consisting of a clastic layer, with the predominance of mudstones; and Palynofacies assemblage 2 (P2) at the top of the section, with remarkable abundance of AOM/Pseudoamorphous particles, associated with facies that includes tuffs. The complete section shows in some levels the presence of freshwater algae and translucent phytoclasts. The integrated data characterizes a fluvial-lacustrine environment, what is reinforced by the occurrence of freshwater algae (Botryococcus) in some levels of P1 and P2. We could verify an increase in volcanic activity towards the top of the section that apparently has played an important role in the collapse of the palynoflora. The occurrence of the spore species Muricingulisporis annulatus, Sotasporites elegans, S. triangularis, Foraminisporis wonthaggiensis, and F. asymmetricus in the Cerro Negro Formation allows the correlation with sections in South America and Australia, suggesting an Aptian age for these deposits.

Esse trabalho investiga a porção média da Formação Mafra (Grupo Itararé) na região de Mafra(SC)-Rio Negro(PR). Uma sondagem com 40m testemunhados (PM-6), adjacente a uma grande pedreira com 70m de altura, fornece, em conjunto, quase 100m de seção, dominada por varvitos e diamictitos, representativa do Mafra-Médio. Recobrindo erosivamente esse intervalo, a mesma pedreira expõe 20m de arenitos sigmoidais, já caracterizando a unidade Mafra-Superior. A Formação Mafra-Médio consiste de ciclos de granocrescência ascendente (varvito a diamictito), recobertos por um complexo ciclo granodecrescente (arenito-diamictito-varvito), atribuído a eventos de deglaciação; esse evento culmina com a deposição de siltito fossilífero marinho, que, ao contrário das demais fácies, não tem clastos caídos (dropstones). As complexas relações laterais que marcam o ciclo/evento de deglaciação podem ser documentadas em uma seção estratigráfica com cinco afloramentos. A base do evento é erosiva, fornecendo calhas que acomodam localmente grandes espessuras; tal sucessão transgressiva, desenvolvida com a deglaciação, deve-se ao recuo progressivo das geleiras. O intervalo médio da Formação Mafra representa um trato de sistemas transgressivo/de nível de base alto de uma seqüência deposicional de 3ª ordem, junto com os arenitos e siltitos do Mafra-Inferior, estes constituindo o trato de sistemas de nível baixo.

The middle interval of Mafra Formation (Itararé Group) has been investigated in the Mafra-Rio Negro area, eastern margin of Paraná basin. The 40m-cored section of well PM-6, drilled at the foot of the 70m-high Motocross Quarry, provide a 90m-composite column representative of middle-Mafra Formation. This interval is unconformably overlain by sigmoidal sandstones of the upper part of Mafra Formation, as displayed in the same quarry. Two types of cycles are found in middle Mafra. Several coarsening-upward cycles composed of varvites, massive sandstones/siltstones (local) and diamictites, are followed by a major fining-upward cycle, formed by sandstone, diamictite and varvite. Pebble to boulder-size dropstones occur in all facies. The upper FU-cycle, designated as deglaciation facies/cycle, has a complex distribution of thickness and constituent lithofacies. Local depocenters of the cycle are related to lows escavated by glaciers; they were filled by sediments derived from the receeding ice, in a classical, transgressive setting related to deglaciation. The middle-Mafra Formation forms the upper, transgressive-highstand system tracts of a depositional sequence, together with sandstones and diamictites of the lower, lowstand system tracts of lower Mafra Formation.