Mariano E. Malvé

Paleontology provides insights into the history of the planet, from the origins of life billions of years ago to the biotic changes of the Recent. The scope of paleontological research is as vast as it is varied, and the field is constantly evolving. In an effort to identify “Big Questions” in paleontology, experts from around the world came together to build a list of priority questions the field can address in the years ahead. The 89 questions presented herein (grouped within 11 themes) represent contributions from nearly 200 international scientists. These questions touch on common themes including biodiversity drivers and patterns, integrating data types across spatiotemporal scales, applying paleontological data to contemporary biodiversity and climate issues, and effectively utilizing innovative methods and technology for new paleontological insights. In addition to these theoretical questions, discussions touch upon structural concerns within the field, advocating for an increased valuation of specimen-based research, protection of natural heritage sites, and the importance of collections infrastructure, along with a stronger emphasis on human diversity, equity, and inclusion. These questions offer a starting point—an initial nucleus of consensus that paleontologists can expand on—for engaging in discussions, securing funding, advocating for museums, and fostering continued growth in shared research directions.

Biotic interactions—and predation in particular—are thought to follow a latitudinal gradient, increasing towards the tropics; yet empirical evidence remains contradictory and largely based on studies from the Northern Hemisphere. Moreover, the role of environmental variables shaping latitudinal gradients of predation intensity has seldom been tested. Here, we quantify predation by shell-breaking crabs on modern shells of the marine gastropod Trophon geversianus along a latitudinal gradient (40°–54° S) on the southwestern Atlantic coast. We further evaluate how intrinsic factors (four shell morphometric traits) and extrinsic factors (seven environmental variables and the biogeographic region) jointly influence predation patterns. Fragmentation from crushing predation affected 37% of the shells (544 out of 1480), with the most frequent damage types being major body whorl damage (28%), deep aperture chips (11%) and extensive aperture chips (6%). When analysed by biogeographic province, fragmentation increased significantly towards the south in the Magellan province. Notably, random forest modelling revealed that intrinsic factors—particularly shell size and thickness—were stronger predictors than extrinsic factors in driving latitudinal variability of shell-breaking crab predation. By highlighting the dominant influence of intrinsic factors over extrinsic ones, this study emphasizes the crucial role of species-specific traits in shaping predator–prey interactions across biogeographic regions.

The European green crab ( Carcinus maenas) is one of the most extensively studied decapod species worldwide, and it currently inhabits every continent except Antarctica. Its effects are observed across various spatio-temporal scales, impacting a wide range of taxa and environments. While extensive research has been conducted in the Northern Hemisphere, populations in the Southern Hemisphere (e.g., Argentina, Australia, and South Africa) have not been thoroughly investigated. This study has three main goals: (1) summarise and contextualise the invasion history of green crabs in the Southwest Atlantic since their initial detection in 2000, (2) present nine case studies identifying the potential ecological and economic impacts of green crabs on coastal ecosystems, and to highlight priority research areas, and (3) discuss appropriate management actions in response to the species' rapid spread in the region. Our findings suggest that green crabs are likely to impact foundation species along rocky shores, alter the physical characteristics of soft-bottom environments, and affect infaunal organisms in sandy shores. Most of these impacts are either occurring or expected to occur in numerous marine protected areas. We also examine green crab interactions with other key species, highlighting its dual role as both an invasive predator and prey for native species, thus serving as a novel food resource. Furthermore, we consider their effects on commercially important species, tourism, and implications for threatened native species. Finally, we recommend prioritising prevention and rapid response strategies for managing green crab invasions, emphasising the importance of early detection and prompt action to address new incursions.

This study aims at synthesizing the recent invasion history of Carcinus maenas in the SW Atlantic (~20 years), particularly the northward expansion, based on available published papers, technical reports, and new field surveys. Our analyses extend the known distribution range northwards ca. 330 km. totaling ~1000 km along the Argentinean coast since its last detection in Nuevo Gulf in 2015. The expansion rate appeared to slow down during the last 15 years (from 115km/yr. to 30 km/yr.) as the species continues moving northwards into the transition zone between the Magellan and Argentinean biogeographic provinces (41°–43°S). In addition, a species distribution model (SDM) is provided at a much finer spatial resolution than previous studies, which accurately foresees suitable areas of invasion in the southern San Jorge Gulf, and predicts a hotspot of invasibility around 40°–33°S° if the invasion continues northward. Potential impacts of C. maenas on native species, particularly economically important oyster beds are discussed.

Web site of the journal of the Argentinian Association of Paleontology

Broad-scale latitudinal morphological trends in gastropods along the southwestern Atlantic coast are scant, since the majority of studies have focused on local scales. Here, we evaluate biogeographic shell shape variation in the marine gastropod Trophon geversianus across most of its distributional range, covering 14 degrees of latitude. Samples come from death assemblages which have the potential to unveil biogeographic patterns along spatio-temporal scales and are not affected by short-term volatility in comparison with living assemblages. We performed morphometric analyses on shells from death assemblages, and compared shape variation between mid-Holocene and modern shells from one southern site. Multivariate analyses identified two morphotypes matching the biogeographic regions of the Argentine Sea that segregates a warm-temperate from a cold-temperate zone. The Magellan province morphotype is characterized by a larger shell, lower spire height, and higher aperture length than the Argentinean province morphotype. This change in shell shape is significantly correlated to sea surface temperature, even after accounting for spatial autocorrelation, which could be indirectly influencing intraspecific morphoclines via shifts in growth rates. On the other side, shell size and shape variations were also detected (size increase over recent geological time) between mid-Holocene and modern specimens at the Beagle Channel, which could be attributed to paleoenvironmental changes and to shifts in predator-prey relationships. Our study illustrates the usefulness of death assemblages for revealing large-scale patterns of shell-shape variability in mollusk species, and highlights the spatial coincidence of intraspecific morphological differentiation with the transition zone between biogeographic provinces of the Argentine Sea.