Paleoecology and paleoenvironments of Podocarp trees in the Ameghino Petrified forest (Golfo San Jorge Basin, Patagonia, Argentina): constraints for Early Paleogene paleoclimate

During the Early Paleocene (Danian), Central Patagonia had a warm-temperate climate and was dominated by evergreen coniferous forests. Abundant permineralized conifer woods along with some dicot and palm leaf compressions were found in the Ameghino Petrified Forest, and provide evidence of this type of flora. All the permineralized wood and large trunks recovered were assigned to the species Podocarpoxylon mazzonii. An estimated tree height of 17-29m was calculated on the basis of diameter measurements. Based on 14 ring sequences, with a total of 169 rings, the mean ring width and Mean Sensitivity (MS) were 1.23 and 0.19mm respectively. The growth rings are moderately wide, extremely uniform and complacent, indicating that the environment was favourable and constant, and lacked significant stress factors limiting tree growth. Following the quantitative analysis for conifers outlined by Falcon-Lang, the growth ring anatomy of the Podocarpoxylon mazzonii suggests that these trees had an evergreen habit. The combination of the fossil flora, growth ring, and sedimentological analyses suggest that this mostly evergreen coniferous forest developed under warm-temperate conditions and without limiting factors

Paleoecology and paleoenvironments of Podocarp trees in the Ameghino Petrified forest (Golfo San Jorge Basin, Patagonia, Argentina): constraints for Early Paleogene paleoclimate

During the Early Paleocene (Danian), Central Patagonia had a warm-temperate climate and was dominated by evergreen coniferous forests. Abundant permineralized conifer woods along with some dicot and palm leaf compressions were found in the Ameghino Petrified Forest, and provide evidence of this type of flora. All the permineralized wood and large trunks recovered were assigned to the species Podocarpoxylon mazzonii. An estimated tree height of 17-29m was calculated on the basis of diameter measurements. Based on 14 ring sequences, with a total of 169 rings, the mean ring width and Mean Sensitivity (MS) were 1.23 and 0.19mm respectively. The growth rings are moderately wide, extremely uniform and complacent, indicating that the environment was favourable and constant, and lacked significant stress factors limiting tree growth. Following the quantitative analysis for conifers outlined by Falcon-Lang, the growth ring anatomy of the Podocarpoxylon mazzonii suggests that these trees had an evergreen habit. The combination of the fossil flora, growth ring, and sedimentological analyses suggest that this mostly evergreen coniferous forest developed under warm-temperate conditions and without limiting factors

The earliest burst of necrophagous dung beetles in South America revealed by the Cenozoic record of Coprinisphaera

New ichnological, sedimentological and palaeobotanical information from a Miocene palaeosol succession from Patagonia bearing abundant fossil brood balls of dung beetles (Coprinisphaera) allow inferring novel aspects of the evolutionary history, biology and feeding habits of Scarabaeinae, along with the palaeoenvironmental and palaeoclimatic conditions in which they nested. Coprinisphaera tonnii and Coprinisphaera akatanka, both attributed to necrophagous dung beetles, represent 40.2% of the specimens. Considering their scarce or null record in older Cenozoic units from South America, these high values reveal that the first burst of necrophagous Scarabaeinae took place during the Miocene. Some Coprinisphaera preserve characters that indicate the developmental stage of the ball occupant and the adult emergence success. Both ichnospecies show the egg chamber isolated from the provision chamber, which was associated with a higher preference of cleptoparasites for necrophagous balls. The comparison among the abundance of traces of nest intruders in Coprinisphaera attributed both to necrophagous and to coprophagous beetles from different units of South America indicates that the presence of such intruders would be independent of the nature of the organic matter contained within the balls. Phytolith analyses performed in Coprinisphaera and extant necrophagous and coprophagous balls indicate that the comparison between the relative abundance of phytoliths in the wall of the brood ball, their infilling and the bearing palaeosol is a useful tool for inferring the feeding behaviour of the trace makers and support the attribution of Coprinisphaera tonnii and Coprinisphaera akatanka to necrophagous Scarabaeinae. Sedimentary and palaeosol analyses indicate that the beetles would have nested in well-drained soils showing mollic-like features, in grass-dominated habitats, under a seasonal sub-humid, temperate–warm climate.Fil: Cantil, Liliana Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Bellosi, Eduardo Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Sánchez, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Gonzalez, Mirta Gladys. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Genise, Jorge Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin