Planktonic foraminiferal species identification is central to many paleoceanographic studies, from selecting species for geochemical research to elucidating the biotic dynamics of microfossil communities relevant to physical oceanographic processes and interconnected phenomena such as climate change. However, few resources exist to train students in the difficult task of discerning amongst closely related species, resulting in diverging taxonomic schools that differ in species concepts and boundaries. This problem is exacerbated by the limited number of taxonomic experts. Here we document our initial progress toward removing these confounding and/or rate-limiting factors by generating the first extensive image library of modern planktonic foraminifera, providing digital taxonomic training tools and resources, and automating species-level taxonomic identification of planktonic foraminifera via machine learning using convolution neural networks. Experts identified 34,640 images of modern (extant) planktonic foraminifera to the species level. These images are served as species exemplars through the online portal Endless Forams (endlessforams.org) and a taxonomic training portal hosted on the citizen science platform Zooniverse (zooniverse.org/projects/ahsiang/ endless-forams/). A supervised machine learning classifier was then trained with~27,000 images of these identified planktonic foraminifera. The best-performing model provided the correct species name for an image in the validation set 87.4% of the time and included the correct name in its top three guesses 97.7% of the time. Together, these resources provide a rigorous set of training tools in modern planktonic foraminiferal taxonomy and a means of rapidly generating assemblage data via machine learning in future studies for applications such as paleotemperature reconstruction.

The sculpture of scales and plates of articulated anaspids from the order Birkeniida is described and used to clarify the position of scale taxa previously left in open nomenclature. The dermal skeleton of a well-preserved squamation of Birkenia elegans Traquair, 1898 from the Silurian of Scotland shows a characteristic finely tuberculated sculpture over the whole body. Rhyncholepis parvula Kiær, 1911, Pterygolepis nitida (Kiær, 1911) and Pharyngolepis oblonga Kiær, 1911, from the Silurian of Norway show three other sculpture types. Northern Hemisphere disarticulated scales and plates are described here, supporting a new anaspid taxonomy that includes both articulated and disarticulated material. The diversity, distribution, evolutionary trends and biostratigraphy of anaspids are described in the context of this new taxonomy, which includes six families (two are new) subdivided into 16 genera (10 are new) and 22 species (15 are new).New taxa among Birkeniidae Traquair, 1898 are Birkenia robusta sp. nov. and Hoburgilepis papillata gen. et sp. nov.. Rhyncholepididae Kiær, 1924 includes Rhyncholepis butriangula sp. nov., Silmalepis erinacea gen. et sp. nov., Vesikulepis funiforma gen. et sp. nov., Maurylepis lacrimans gen. et sp. nov., and the previously described Schidiosteus mustelensis Pander, 1856 and Rytidolepis quenstedtii Pander, 1856. Tahulalepididae fam. nov. is represented by Tahulalepis elongituberculata gen. et sp. nov. and the revised T. kingi (Woodward, 1947). Septentrioniidae fam. nov. contains Septentrionia lancifera gen. et sp. nov., S. mucronata gen. et sp. nov., S. dissimilis gen. et sp. nov., S. seducta gen. et sp. nov., Liivilepis curvata gen. et sp. nov., Spokoinolepis alternans gen. et sp. nov. and Manbrookia asperella gen. et sp. nov. The family level position of Ruhnulepis longicostata gen. et sp. nov. is uncertain. Pterygolepididae Obruchev, 1964 and Pharyngolepididae Kiær, 1924 remain monogeneric.

Widely regarded as an imminent threat to our oceans, ocean acidification has been documented in all oceanic basins. Projected changes in seawater chemistry will have catastrophic biotic effects due to ocean acidification hindering biogenic carbonate production, which will in turn lead to substantial changes in marine ecosystems. However, previous attempts to quantify the effect of acidification on planktonic calcifying organisms has relied on laboratory based studies with substantial methodological limitations. This has been overcome by comparing historic plankton tows from the seminal HMS Challenger Expedition (1872-1876) with the recent Tara Oceans expedition material (2009-2016). Nano CT-scans of selected equatorial Pacific Ocean planktonic foraminifera, have revealed that all modern specimens had up to 76% thinner shells than their historic counterparts. The "Challenger Revisited" project highlights the potential of historic ocean collections as a tool to investigate ocean acidification since the early Industrial Revolution. Further analyses of such biotic archives will enable researchers to quantify the effects of anthropogenic climate change across the globe.

The size structure of plankton communities is an important determinant of their functions in marine ecosystems. However, few studies have quantified how organism size varies within species across biogeographical scales. Here, we investigate how planktonic foraminifera, a ubiquitous zooplankton group, vary in size across the tropical and subtropical oceans of the world. Using a recently digitized museum collection, we measured shell area of 3,799 individuals of nine extant species in 53 seafloor sediments. We first analyzed potential size biases in the collection. Then, for each site, we obtained corresponding local values of mean annual sea‐surface temperature (SST), net primary productivity (NPP), and relative abundance of each species. Given former studies, we expected species to reach largest shell sizes under optimal environmental conditions. In contrast, we observe that species differ in how much their size variation is explained by SST, NPP, and/or relative abundance. While some species have predictable size variation given these variables ( Trilobatus sacculifer, Globigerinoides conglobatus, Globigerinella siphonifera, Pulleniatina obliquiloculata, Globorotalia truncatulinoides ), other species show no relationships between size and the studied covariates ( Globigerinoides ruber , Neogloboquadrina dutertrei , Globorotalia menardii, Globoconella inflata ). By incorporating intraspecific variation and sampling broader geographical ranges compared to previous studies, we conclude that shell size variation in planktonic foraminifera species cannot be consistently predicted by the environment. Our results caution against the general use of size as a proxy for planktonic foraminifera environmental optima. More generally, our work highlights the utility of natural history collections and the importance of studying intraspecific variation when interpreting macroecological patterns.

ABSTRACT. Thelodont scales from the Middle Llandovery±lowermost Lochkovian of southern Britain are described with three new taxa, Loganellia? unispinata sp. nov., Nethertonodus prodigialis gen. et sp. nov. and Paralogania tarranti sp. nov. established, and Paralogania kaarmisensis Ma Èrss identi®ed for the ®rst time from Britain. Thelodonts are rare in the Llandovery and Wenlock series where predominantly Loganellia cf. aldridgei Turner, Loganellia scotica (Traquair) and Thelodus sp. are accompanied by coniform conodonts Panderodus Ethington, Decoriconus Cooper and Dapsilodus obliquicostatus (Branson and Mehl). The majority of the material has been recovered from the Ludlow and Pr Ïõ Âdolõ Â series. Thelodus laevis (Pander) and Paralogania martinssoni (Gross) occur in the lower Gorstian. Paralogania kaarmisensis and Phlebolepis elegans Pander come from the Upper Gorstian±Lower Ludfordian and are associated with the zonal conodont Polygnathoides siluricus Branson and Mehl in the upper Gorstian. Thelodus parvidens Agassiz and T. trilobatus Hoppe dominate in the Upper Ludfordian in association with the rarer zonal conodonts Ozarkodina snajdri (Walliser), O. crispa (Walliser) and O. remscheidensis eosteinhornensis (Walliser). The basal Pr Ïõ Âdolõ Â Series indicates a change to a thelodont fauna dominated by Paralogania ludlowiensis (Gross) and including Nethertonodus prodigialis. Higher in the Pr Ïõ Âdolõ Â Series, a succession in faunas includes Katoporodus cf. timanicus (Karataju Åte-Talimaa), Paralogania tarranti, Loganellia? unispinata and Goniporus alatus (Gross). In the highest Pr Ïõ Âdolõ Â beds Paralogania kummerowi (Gross) and Loganellia cuneata (Gross) can be traced before the incoming of the lowermost Devonian taxon Turinia pagei (Powrie) along with Nikolivia gutta Karataju Åte-Talimaa. Correlations with the Baltic are suggested from the Lower Ludlow, Upper Silurian, up to the Lower Lochkovian, Lower Devonian. Gross (1967) studied and described scales from the Ludlow and Temeside Bone Beds and the Psammosteus Limestone, and also scales from some other Devonian outcrops he obtained from O. Walliser of Go Èttingen and T. érvig (1917±1994). Gross (1967) also suggested that British thelodonts were useful for biostratigraphy and correlations with the Baltic and Oslo Region. Turner (1973) gave the distribution of thelodonts from a large number of localities in Britain, recognized a succession of assemblages, and suggested correlations with the Baltic, Scandinavia, Podolia, North Timan, Spitsbergen and Canada. As a result of this study, the distribution of thelodonts was considered when correlating Upper Silurian boundaries in Britain and the Siluro-Devonian boundary in particular (Turner 1977;White and Coppack 1977; Bassett et al. 1982). Thelodonts have been identi®ed from some British borehole studies and used in biostratigraphy (Turner 1973(Turner , 1984(Turner , 2000White and Coppack 1977). New thelodonts were [Palaeontology, Vol. 47, Part 5, 2004 q The Palaeontological Association described during collabo...