Subhronil Mondal

Bio: Subhronil Mondal is an academic researcher from University of Calcutta. The author has contributed to research in topics: Coastal erosion & Predation. The author has an hindex of 10, co-authored 33 publications receiving 251 citations. Previous affiliations of Subhronil Mondal include University of South Florida & Indian Institute of Science.

Naticid confamilial drilling predation through time

Abstract: Gastropod drilling predation in the fossil record is prevalent and has been documented by many workers; however, vivid documentation of confamilial naticid predation is poor. Here, data compiled from previously published sources, supplemented by unpublished museum collections, document different aspects of naticid confamilial predation (NCP) in a temporal-latitudinal context. Confamilial drilling frequency (DF) showed a Cretaceous low, a small rise to a stable plateau in the Eocene, followed by a peak in the Oligocene, and finally a drop to a stable level from the Miocene to the Holocene. The stepwise rise in DF is comparable with the overall history of drilling predation. However, the temporal increase in DF was visible only in the mid-latitudes, while in other latitudes, no temporal trend was observed. The frequency of failed attack has always been very low. In comparison, a decrease in prey effectiveness (PE) was observed in the Neogene relative to the Cretaceous and Paleocene–Eocene intervals. In case of site selectivity, either apertural or abapertural sites were targeted until the Oligocene, and subsequently became more random. Some of these trends may be biased based on insufficient site selectivity data as well as uneven sampling from different latitudes representing different time intervals. More data on quantification of predation intensities along with the behavioral aspects of NCP are required to properly document other aspects of this interaction.

The Effect of Taxonomic Corrections on Phanerozoic Generic Richness Trends in Marine Bivalves with a Discussion on the Clade's Overall History

Abstract: This study uses a comprehensive, revised, and updated global bivalve dataset combining information from two major databases available to study temporal trends in Phanerozoic bivalve richness: the Sepkoski Compendium and the Paleobiology Database. This compilation results in greater taxonomic and stratigraphic coverage than possible with either of the two databases alone. However, there are challenges in directly comparing these two sources due to differences in their taxonomic designations and stratigraphic range information. Moreover, both of these datasets are fraught with a number of taxonomic errors, which can significantly bias the overall richness estimate. Additionally, a substantial number of taxonomic corrections were made before a new Phanerozoic bivalve richness curve was produced. The new generic taxonomic curve is comparable with the trajectory of the Sepkoski’s modern fauna and shows rapid and substantial diversification through the Ordovician, followed by a Paleozoic plateau, a Mesozoic high, and Cenozoic diversification after a small reduction in richness associated with the K/Pg extinction. The steep Cenozoic rise documented in the raw richness curve derived from the new dataset is likely real, and reflects the overall robustness and completeness of the bivalve fossil record.

Repair scars on Mactra violacea from the eastern coast of India: A new classification and a model for describing shell breakage on bivalves

Abstract: Non-lethal shell damage, which is preserved as repair scars on the bivalve shell, can be predatory or non-predatory in origin. When the peeling crabs are the main predatory groups, non-predatory damages are produced by impact from the saltating clasts or by wear and tear during burrowing. In both cases, these repair scars almost look alike, and it is difficult to identify which factor is causally responsible. Because survival of an individual is related to the severity of the shell-break irrespective of the cause, here, we have developed a classificatory scheme to categorize the repaired traces on the basis of intensity of the damage. Moreover, we have provided a model to analyze how the severity of scars can be effectively used to study species’ adaptation against shell breaking causes, by using Mactra violacea as a studied species. Individuals who survive shell breakage may adapt to escalated morphological traits to resist damage in the long term. Subhronil Mondal. School of Geosciences, University of South Florida, 4202 E. Fowler Ave. NES107, Tampa, FL 33620-5250, USA. subhronil.m@gmail.com Subhendu Bardhan. Department of Geological Sciences, Jadavpur University, Kolkata-700032, India. sbardhan12@gmail.com Sumanta Mallick. Department of Geological Sciences, Jadavpur University, Kolkata-700032, India. sumanta.geol87@gmail.com Arindam Roy. Department of Geological Sciences, Jadavpur University, Kolkata-700032, India. addy.geol@gmail.com

The Miocene: The Future of the Past

Abstract: The Miocene epoch (23.03–5.33 Ma) was a time interval of global warmth, relative to today. Continental configurations and mountain topography transitioned towards modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhouse interval – the Miocene Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, pCO2, and ocean and atmospheric circulation mostly (but not ubiquitously) covaried with these large changes in climate. With higher temperatures and moderately higher pCO2 (∼400–600 ppm), the MCO has been suggested as a particularly appropriate analogue for future climate scenarios, and for assessing the predictive accuracy of numerical climate models – the same models that are used to simulate future climate. Yet, Miocene conditions have proved difficult to reconcile with models. This implies either missing positive feedbacks in the models, a lack of knowledge of past climate forcings, or the need for re‐interpretation of proxies, which might mitigate the model‐data discrepancy. Our understanding of Miocene climatic, biogeochemical, and oceanic changes on broad spatial and temporal scales is still developing. New records documenting the physical, chemical, and biotic aspects of the Earth system are emerging, and together provide a more comprehensive understanding of this important time interval. Here we review the state‐of‐the‐art in Miocene climate, ocean circulation, biogeochemical cycling, ice sheet dynamics, and biotic adaptation research as inferred through proxy observations and modelling studies.

Shaping the Latitudinal Diversity Gradient: New Perspectives from a Synthesis of Paleobiology and Biogeography.

Abstract: An impediment to understanding the origin and dynamics of the latitudinal diversity gradient (LDG)-the most pervasive large-scale biotic pattern on Earth-has been the tendency to focus narrowly on a single causal factor when a more synthetic, integrative approach is needed. Using marine bivalves as a model system and drawing on other systems where possible, we review paleobiologic and biogeographic support for two supposedly opposing views, that the LDG is shaped primarily by (a) local environmental factors that determine the number of species and higher taxa at a given latitude (in situ hypotheses) or (b) the entry of lineages arising elsewhere into a focal region (spatial dynamics hypotheses). Support for in situ hypotheses includes the fit of present-day diversity trends in many clades to such environmental factors as temperature and the correlation of extinction intensities in Pliocene bivalve faunas with net regional temperature changes. Support for spatial dynamics hypotheses includes the age-frequency distribution of bivalve genera across latitudes, which is consistent with an out-of-the-tropics dynamic, as are the higher species diversities in temperate southeastern Australia and southeastern Japan than in the tropical Caribbean. Thus, both in situ and spatial dynamics processes must shape the bivalve LDG and are likely to operate in other groups as well. The relative strengths of the two processes may differ among groups showing similar LDGs, but dissecting their effects will require improved methods of integrating fossil data with molecular phylogenies. We highlight several potential research directions and argue that many of the most dramatic biotic patterns, past and present, are likely to have been generated by diverse, mutually reinforcing drivers.