Corncobs in the Campfire: Evidence of Cultivation of Zea mays at 44CH62, The Randy K Wade Site

In 20 years of excavation, the Randy K. Wade site (44CH62) has only produced indirect evidence of the cultivation of corn (Zea mays) in the Late Woodland village. This indirect evidence consists primarily of corncob impressions on Dan River pottery. In the summer of 2017, an intact hearth was excavated which contained the preserved remains of multiple charred corncobs- the first direct evidence of corn. The hearth also contained remains of other organic materials such as charred corn kernels, bark, sticks, bone fragments, and acorns. This paper will examine the direct evidence for corn cultivation at the Wade site and how this fits into the broader context of Dan River sites in the southern piedmont of Virginia

Functional attributes of epilithic diatoms for palaeoenvironmental interpretations in South-West Greenland lakes

Benthic diatoms are commonly used for palaeoenvironmental reconstruction in Arctic regions, but interpretation of their ecology remains challenging. We studied epilithic diatom assemblages from the shallow margins of 19 lakes from three areas (coast-inland-ice sheet margin) along a climate gradient in Kangerlussuaq, West Greenland during two periods; shortly after ice-off (spring) and in the middle of the growth season (summer). We aimed to understand the distribution of Arctic epilithic diatoms in relation to water chemistry gradients during the two seasons, to investigate their incorporation into lake sediments and to assess their applicability as palaeoenvironmental indicators. Diatoms were correlated with nutrients in the spring and alkalinity/major ions in the summer, when nutrients were depleted; approximately half of the variance explained was independent of spatial factors. When categorised by functional attributes, diatom seasonal succession differed among regions with the most obvious changes in inland lakes where summer temperatures are warmer, organic nutrient processing is prevalent and silicate is limiting. These conditions led to small, motile and adnate diatoms being abundant in inland lakes during the summer (Nitzschia spp., Encyonopsis microcephala), as these functional attributes are suited to living within complex mats of non-siliceous microbial biofilms. Seasonal succession in silica-rich lakes at the coast was less pronounced and assemblages included Tabellaria flocculosa (indicating more acidic conditions) and Hannaea arcus (indicating input from inflowing rivers). The nitrogen-fixing diatom Epithemia sorex increased from the coast to the ice sheet, negatively correlating with a gradient of reactive nitrogen. The presence of this diatom in Holocene sediment records alongside cyanobacterial carotenoids during arid periods of low nitrogen delivery, suggests that it is a useful indicator of nitrogen limitation. Nitzschia species appear to be associated with high concentrations of organic carbon and heterotrophy, but their poor representation in West Greenland lake sediments due to taphonomic processes limits their palaeoenvironmental application in this region. Proportions of epilithic taxa in lake sediment records of coastal lakes increased during some wetter periods of the Holocene, suggesting that snowpack-derived nutrient delivery may offer diatom taxa living at lake margins a competitive advantage over planktonic diatoms during the “moating” ice melt period. Thus, further research investigating linkages between epilithic diatoms, snowpack and nutrient delivery in seasonally frozen lakes is recommended as these taxa live on the ‘front-line’ during the spring and may be especially sensitive to changes in snowmelt conditions

The oldest frog crabs (Decapoda: Brachyura: Raninoida) from the Aptian of northern South America

Raninoida, also known as “frog crabs,” is a clade of extant true crabs (Brachyura) characterized by a fusiform carapace (raninid-type), narrow thoracic sternum, pleon partially exposed dorsally, and paddle-like limbs, all of which are well suited to their cryptic burrowing lifestyle. However, the most basal raninoids from the Cretaceous were morphologically different, with ornamented carapaces that were wider than long (necrocarcinid-type), a broader thoracic sternum, and the pleon fitting between the legs assisted by pleonal locking mechanisms. During Albian times (∼112 to 99.6 Ma.) both body plans flourished worldwide. In contrast, pre-Albian (older than ∼112 Ma.) fusiform families have not yet been reported. The discovery of Notopocorystes kerri n. sp., a fusiform crab from the upper Aptian (∼115 Ma.) of Colombia, South America, and the re-examination of Planocarcinus olssoni (Rathbun, 1937) n. comb., a necrocarcinid-like crab from the same age and locality, extend the record of the two body plans back into the Aptian of the equatorial Neotropics. Notopocorystes kerri is the oldest fusiform raninoid known to date, revealing that the morphological innovation of a fusiform carapace was already evolved in Raninoida before the rapid radiation experienced during Albian times. Our findings are suggestive of a still unresolved Palaeocorystidae, containing the rootstock for the post-Aptian Raninidae/Symethidae clade, with the most basal palaeocorystids lying in proximity to, and possibly derived from, a necrocarcinid-like ancestor.</p