Pal(a)eoPERCS

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🌊🌍🐠🦎An international virtual Pal(a)eo EaRly Career Seminar series. Led by ECRs, feat. ECRs, open to all. Join us every Tuesday at 1600 UTC (Daylight Savings)/1500 UTC!🌍🌎🌏🌸🐚🦕🐙 https://paleopercs.com/

Talk title: Quantifying diachroneity of calcareous nannofossil datums across the western Pacific Ocean
Next week at #PalaeoPERCS we will be joined by Leticia Rezende de Oliveira from Federal University of Santa Maria, Brazil. Sign up here: https://paleopercs.com/participate/
Advances in molecular developmental biology have revealed that many occurrences of convergent evolution are better categorized as parallel evolution, the acquisition of a similar trait in closely related lineages through the co-option of ancestrally shared genetic, developmental, or morphological units. The concept of parallel evolution is still poorly formed in evolutionary biology, and major questions remain regarding the extent of its role in macroevolutionary patterns. One feature that may be an example of parallel evolution is heterodonty, the variation in tooth size and/or shape along a jaw. While heterodonty is often considered a mammalian feature, several non-mammalian taxa also exhibit varying degrees of heterodonty. Our ongoing research attempts to characterize heterodonty across reptiles and compare the mechanisms underlying heterodont tooth development in reptiles and mammals.
The Early Permian (Asselian–Kungurian) witnessed the peak and collapse of the late Paleozoic ice age (LPIA). Its demise was coeval with rising pCO2atm from estimated pre-industrial levels in the earliest Asselian (peak-glaciation) to doubling today’s concentrations at the end of the Kungurian (post-glaciation). Sea-level fluctuations caused by the waxing and waning of ice sheets during peak glaciation are recorded in Asselian cyclothems. These transgressive-regressive sequences have been extensively studied but the amplitude in sea-level change they record remains unclear. The first part of this presentation will discuss the amplitude of eustatic fluctuations represented in cyclothems in New Mexico, Austria, and South China. Contemporaneous to the peak and collapse of the LPIA, an aridification and seasonality trend associated with intensifying monsoonal circulation began across most of Pangea. In South China, a shift towards warm and humid conditions had a profound impact on sedimentation of carbonate platforms adjacent to emerged areas. Enhanced coastal upwelling driven by intensified monsoonal circulation affected sedimentation of platforms outboard. The second part of this presentation will investigate the effect of warm and humid conditions in carbonate platforms of South China and enhanced coastal upwelling on areas at low latitude.
Taxonomic work is the backbone of vertebrate paleontology and provides crucial scaffolding for our understanding of a fossil’s place in nearly any aspect of science: its evolutionary relationships, its paleoecology, evolutionary trends, biogeographic dispersal, and functional morphology. Furthermore, taxonomy is important in democratizing paleontology, as it provides detailed anatomical descriptions, photographs, and even 3D scans of specimens some workers may never get to see in person. Fossils that do not get proper taxonomic treatment often go understudied. One example is the toothed whale family the Squalodontidae. Despite being a transitional form between the earliest aquatic whales and modern toothed whales, the taxonomic practices of the 19th century rendered the Squalodontidae a “wastebasket taxon” and it has taken over a century for this family to be extensively revisited. Findings reveal the real diversity of this family, their ecological niches, their evolutionary relationships, and the implications for trait evolution in toothed whales. The Squalodontidae highlight the importance of revisiting historic specimens in a modern light and the value of taxonomy in the study of deep time.
Fossil vertebrates have been used in the literature as a source of information on past palaeogeographic settings in the Neotropics, although fishes have been less studied when compared to other groups such as mammals. Fishes and their fossil record are especially useful for studying past drainage and landmass configurations because of physical restriction to either freshwater or marine aquatic environment that most species present, and their comparatively limited dispersal capacities when compared to other vertebrate groups such as birds or large mammals. The goal of this presentation is to showcase the relevance of fossil fishes from Cenozoic strata in Northern South America to test hypotheses on palaeogeographic reconstructions, especially related to the timing of the Panama Isthmus closure, and the timing of drainage separation as a consequence of the Andean orogeny. We will discuss the implications of the freshwater fossil findings from the Castilletes, Sincelejo, and Ware Formations in Northern Colombia, in the middle Miocene to Pliocene time interval. We will also discuss the use of the fossil record in marine groups for calibrating molecular phylogenies and how this helps us understand the relationship between the Panama Isthmus closure and the evolution of Carangarian fishes. Finally, we will highlight how the need for statistical tools for better integrating and comparing information from the fossil record and molecular phylogenies have triggered the development and computational implementation of methods for estimating events in geological time, and to better use the available fossil record in divergence time estimation.
Stromatolites represent exceptional geochemical archives recording microbial metabolism and environmental evolution throughout Earth's history. High-resolution analytical techniques, particularly femtosecond laser ablation ICP-MS (FS-LA-ICP-MS), enable unprecedented micro-scale mapping of trace elements and isotopes within stromatolitic laminae. This seminar presents our integrated approach at Tongji University's Carbonate Geochemistry Laboratory, combining elemental mapping, rare earth element systematics, and redox-sensitive trace metals to reconstruct paleo-environmental conditions in Precambrian microbial habitats. Elemental maps reveal metal partitioning reflecting redox gradients, microbial processes, and diagenesis, while also guiding strategic sampling for isotope analysis and U-Pb dating where biostratigraphic markers are absent. Beyond scientific findings, this talk highlights collaborative research opportunities, funding mechanisms, and career pathways for early career researchers in China's dynamic geoscience community.
Tropical carbonate platforms are an important coastal ecosystem, comprising a series of shallow benthic habitats, including coral reefs, seagrass meadows, tidal flats and channels. The habitats on carbonate platforms are highly spatially heterogenous and dynamic. Assessing the change rate, change pattern, and understanding the causes of such changes (if there are any) is important, from both the ecological and geological points of view. However, the observations on the coastal systems have time biases: it either very short (few years) or very long (from cores, > 1000 years), and we lack observations acquired at an intermediate timescale (decades) to bridge habitat dynamics observed today with the rock records from the cores. In this study, we used one of the oldest aerial photos from 1945 to constrain the habitat dynamics and compare the habitat distributions with that of today.
The origin of mammals involved major reorganization of the locomotor system, from ‘sprawling’ to ‘erect’ limb postures. Yet, despite a rich fossil record, how this shift was achieved has remained challenging to decipher. This talk will summarize recent efforts to integrate the fossil record of mammals and their non-mammalian synapsid ancestors with modern animal anatomy and computational biomechanics. These have helped clarify evolutionary patterns of anatomical transformation, and the timing of major functional shifts. A fully erect limb posture evolved much later than originally thought, well within crown-group mammals. Far from being an orderly, linear narrative, the sprawling-to-erect transition in synapsids is becoming understood as a highly complex, nonlinear, and protracted event.
Marine phytoplankton play an important part within the global carbon cycle, removing great amounts of carbon from the atmosphere and producing around half of the atmospheric oxygen today. Furthermore, forming the largest part of the base of aquatic food chains, phytoplankton represent the starting point of biological activities in the oceans. Therefore, the study of ancient phytoplankton dynamics at regional and global scales can provide valuable insights into the evolution of marine ecosystems.
Ganoid scales and fish teeth can be found around the world and through deep time. By creating a classification of the preservation of these fossils, distinctive patterns were discovered. Analysing the abrasion of these objects can tell us more about the energy level of the environment and how far the fossils were transported post mortem. To verify my hypothesis, an experimental approach is now in the works using specimens from different geological epochs. If successful, aquatic paleoenvironments can be interpreted in high detail.
The South Pacific was the final frontier of human colonisation on Earth. Human migration across the Pacific occurred in two waves, the first starting around 3000 yr BP and then after a long pause of 2000 years, the second occurred at approximately 1000 yr BP. Reasons for these migrations are contested, but climate is increasingly thought to have been a factor. This work utilised a combination of multi-proxy palaeo records and socio-ecological modelling to investigate the role of climate in the timing of migration and colonisation in the tropical South Pacific. The key finding from the palaeoenvironmental records is evidence for a shift towards dry conditions around the second wave of human migration into Eastern Polynesia and again in the relatively early stages of colonisation. The model outputs suggest that drought has a greater impact on population dynamics the closer to the absolute carrying capacity the population gets and that severity of the drought rather than the frequency is the key factor determining the impact of a drought on agricultural outputs and population dynamics.
Dr. Peter Neff is an assistant professor at the University of Minnesota who specializes in ice core paleoclimatology, particularly recovering some of the newest and most difficult new ice core samples in the last decade, from challenging and remote parts of Antarctica as well as the Coast Mountains of British Columbia, Canada. Peter received his BSc and MSc from the University of Washington and his PhD from Victoria University of Wellington, New Zealand.
The Indian Summer Monsoon (ISM) winds drive upwelling-induced productivity in the western as well as the eastern Arabian Sea. The subsequent degradation of the organic matter is linked to the occurrence of the oxygen minimum zone (OMZ) and carbonate preservation. Using multiproxy data from the assemblage and stable isotope ratios of foraminifera (planktic and benthic), and the preservation state of pteropods, my research focused on reconstructing oceanographic variability in the eastern Arabian Sea since the late Marine Isotope Stage (MIS) 3. The results show that solar insolation, regional wind strength, sea-level, and continental influx of fresh water modulated productivity, carbon cycling, coastal hypoxia and OMZ dynamics in the eastern Arabian Sea, leaving distinct imprints on the microfaunal communities like foraminifera and pteropods.
The fossil record is our only direct source of evidence for how life on Earth has waxed and waned over its long history. However, the fossil record is also incomplete and biased in many ways, after passing through biological, geological, and socio-economic filters. Over the last fifty years, a wide variety of methods have been developed to try and elucidate macroevolutionary patterns by accounting for fossil record structure or bias, with varying levels of success. I will review the different approaches that have previously been applied to infer past biodiversity, and discuss their strengths and weaknesses, illustrating this with case studies. Finally, I will propose some ways in which we can move forward as a field, and develop stronger approaches for estimating biodiversity through deep time.