Chandipur intertidal flat in eastern coast of India is a killing field. The vast stretch of intertidal habitat opens up during the low tide, and is monopolized by a single naticid species which preys extensively on intertidal taxa. The predator, Natica tigrina, wades through the soft sediments and ambushes on epi- or infaunal prey.There were reports on naticid subaerial hunting, where the workers made vivid observations, but only in few instances quantified different aspects of predation. Detailed quantitative analyses of the present study revealed that N. tigrina attacks opportunistically on all infaunal and epifaunal intertidal bivalve and gastropod prey taxa. Drilling frequencies ranged from 9.70% to 67.67% with no apparent relation with relative abundances of the taxa. High drilling frequency on conspecific predation perhaps suggested elimination of the potential competitor as well as a profitable prey. Behavioral data of predation, i.e., stereotypy of site and size of drillholes on prey shells and low prey effectiveness indicated that the predator was highly efficient. © 2016 Elsevier B.V.

SUBHRONIL MONDAL

Geology

A PAHARI

S BARDHAN

D SARKAR

S SAHA

D BURAGOHAIN

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Palaeogeography, Palaeoclimatology, Palaeoecology

Despite an expectation that predation pressure decreases with increasing latitude, studies on latitudinal variation in gastropod drilling predation through space and time have revealed equivocal trends. Here, we study the latitudinal pattern of gastropod drilling predation from the late Early Cretaceous to the Pleistocene based on a new compilation of global data on mollusks mostly from the northern hemisphere. The study finds a mid-latitudinal (i.e., 21–408) peak in drilling predation intensity during the Miocene (the only time interval with sufficient data from all latitudinal bins), and a possible mid-latitudinal peak during the Cretaceous. For the Eocene, Pliocene, and Pleistocene the middle—and either the lower or higher latitudinal—bins show the highest drilling intensity, therefore suggesting a much flatter latitudinal gradient in drilling predation pattern; the Paleocene and Oligocene lack sufficient data for statistical comparison. The Miocene mid-latitudinal peak remains almost unchanged when analyses are restricted to certain ecological and taxonomic groups. Different abiotic (e.g., temperature) and biotic factors (e.g., generic abundances of the predatory gastropods) alone cannot explain the observed trend. The area of shallow shelf might have played a positive but statistically insignificant role in determining the observed pattern. © 2019, SEPM (Society for Sedimentary Geology).

Palaios

Latitudinal patterns of gastropod drilling predation intensity through time

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. Copyright © 2017, SEPM (Society for Sedimentary Geology).

Naticid confamilial drilling predation through time

Ecologic diversity within marine invertebrates has typically been reconstructed by examining three components: mobility, feeding habit, and tiering. Based on various combinations of these three features, a wide range of hypothetical ecospaces or "cubes" (the agglomeration of which forms a "Bambachian cube") can be delineated. Given the range of constraints on a specific Glade's morphologic diversity, however, only a relatively limited proportion of these possible combinations are actualized. Previous studies investigating Phanerozoic trends have documented the general pattern of ecologic diversity measured as the total number of filled cubes of all metazoan groups which displays a major increase in the range of ecospace inhabited. However, detailed, Glade-specific studies are limited. In this Phanerozoic-level study on the Class Bivalvia, a group with a very robust and virtually unparalleled fossil record, the Glade's ecologic diversity is reconstructed based on a set of newly compiled taxonomic and ecologic databases that were initially derived from a combination of the Sepkoski Compendium and the Paleobiology Database. These data have been binned into 94 intervals, from the Fortunian up to the Piacenzian. The ecologic position of each genus was determined relative to the 140 ecologic cubes that reflect the hypothetical range of ecospace bivalves may have inhabited (i.e. fundamental cubes or ecospaces) and which are based on a substantially modified version of the earlier Bambachain cube (Bambach et al., 2007). The overall results show several features: (1) given the various morphologic constraints, bivalves have only occupied 44 of the total, hypothetically available cubes which represents the Glade's realized ecospace; (2) the most significant and dramatic phase of increase in the range of ecologic types occurred during the Ordovician; following this event, new ecospace was exploited in a much more limited fashion; (3) most changes in ecospace utilization involved increased packing within a relatively limited suite of cubes; and (4) mass extinctions had a very limited impact on ecospace utilization despite their impacts on bivalve taxonomic richness; only the K-Pg extinction had significant effect on the overall ecologic diversity of bivalves, largely reflecting the demise of a novel reef-building group, the rudistids. (C) 2015 Elsevier B.V. All rights reserved.

Earth-Science Reviews

Phanerozoic trends in ecospace utilization: The bivalve perspective

Predator-prey interaction, especially drilling and shell-breaking predation pressure, caused significant evolutionary changes within these predator-prey communities. Although temporal trends are well understood in prey assemblages, studies to trace such changes within taxonspecific clades up to Recent times have been rare. Here, we studied both the drilling and shell-breaking predation on Recent terebrid gastropods from the Indian subcontinent and compared the results with a newly updated, global database. The major part of our data came from a large collection reposited in the archive of the Zoological Survey of India in Kolkata for more than 100 years. Detailed analyses of this study based on a newly raised, global database revealed the following findings: (1) Drilling frequency (DF) of Indian terebrids was low, but consistent with the DF of only available but limited data provided by Vermeij et al. (1980). In comparison, peeling frequency (PF) in Indian terebrids appeared to be highest in the world; (2) DF showed latitudinal variation, that is, higher incidence of drilling occurred in higher latitudes; no such pattern emerged from the PF data; (3) drillholes were site-stereotyped, which suggested that Recent naticid drillers were escalated; (4) shell ornaments failed to protect against durophagy; (5) shell shape and thickness had different impact against different modes of predation. While slender and thicker shells were almost immune to drilling predation, no such relation existed for peeling predation; (6) on the other hand, body size appears to have evolved as anti-predatory traits in Recent terebrids. Larger species had low DF and high PF values; (7) temporally, DF showed fluctuating pattern, with modern values showing declining trend. This was perhaps due to increase in body size and behavioural change of the terebrid gastropods. Unfortunately, no peeling frequency data for this clade was available from the fossil record.

Journal	Data powered by TypesetPalaeogeography, Palaeoclimatology, Palaeoecology
Publisher	Data powered by TypesetElsevier B.V.
ISSN	0031-0182
Open Access	No