Subhendu Bardhan

Jadavpur University | JU · Department of Geological Sciences

The present study reports the oldest occurrence of Seebachia bronni Krauss, 1850, the type species of the genus Seebachia, within the Astartidae from the ferruginous oolitic bands of the upper Tithonian (Jurassic) of Kutch, western India. Although Pruvostiella (Eoseebachia), previously known as Seebachia (Eoseebachia), has been reported from the sa...

We published a series of papers regarding the oldest turritellids, naticids, their paleoecological interaction, and gastropod biozonation, which are of Oxfordian in age, from the Jhura pond section, Kutch, western India. Recently, an Oxfordian age was challenged by Fürsich et al. (2023) and they argued for a Cenozoic age. The authors reproduced a l...

An organism’s body size is interlinked with several ecological and physiological parameters and, therefore, has been widely used to detect and describe long-term macroevolutionary trends. One of those long-term trends is Cope’s rule, a tendency to increase size over time. In the present study, we document long-term evolutionary trends in the body s...

In the post-Paleozoic communities, brachiopods are generally thought to be less attractive prey to predators than bivalves. However, recent studies have documented significant predation pressure on brachiopods throughout the Mesozoic and Cenozoic. The present study is aimed to document predation pressure on the Maastrichtian Rectithyris subdepressa...

Although empirical testing of Cope's rule, the tendency for size to increase over time, has received significant attention in the last few decades, there is no consensus about the applicability of this rule across taxonomic levels. In the present study, we investigate the distribution of body size of Trigoniida bivalves, at order-, family-, genus-...

Gastropod drillholes on prey shells provide an opportunity to test the importance of predation in an evolutionary context. Although records of drilling predation are widespread across the Phanerozoic, the temporal distribution and relative importance of this mode of predation is still controversial. Further, some studies indicate a decline of drill...

We document and quantify one of the oldest predator–prey interactions between naticid gastropods and molluscan prey, on the basis of drill holes in shells, from the Late Jurassic (Oxfordian) beds of Kutch, western India. Previously, many workers recorded naticid-like drill holes on prey taxa from the Triassic and the Jurassic, but in the absence of...

Unambiguous gastropod drilling predation has been reported in shells of Cretaceous age onwards. Global data suggest that the drilling intensity shows wide spatial variation throughout the Miocene. In order to understand the factors controlling geographic variability in drilling predation, data from many regions are needed. The present study include...

The study of drilling predation has been largely limited to molluscs. Herein, we report drilling predation on Recent acorn barnacles by gastropods from Chandipur, eastern India. The aspects of predator-prey relation dealt here are the size and site preference of the predator; the interrelationship between barnacle shell morphology (e.g., shape, ext...

Jurassic gastropods of Kutch

Naticid taxonomy is in a state of flux owing to non-descript shell morphology and frequent convergence. Inadequate preservation of naticid body fossils has further complicated the matter in determining the true affinity and the exact time of origin of the clade. As a result, a plethora of classificatory schemes of naticid phylogeny and times of ori...

Turritellid gastropods are important components of many Cretaceous–Recent fossil marine faunas worldwide. Their shell is morphologically simple, making homoplasy widespread and phylogenetic analysis difficult, but fossil and living species can be recognized based on shell characters. For many decades, it has been the consensus that the oldest defin...

The genus Hubertoceras was described under the subfamily Proplanulitinae from the middle to upper Callovian (Middle Jurassic) beds of Kutch. Recently we revisited the Kutch Proplanulitinae and proposed a new endemic subfamily Sivajiceratinae for them. The new subfamily consists of the genera Sivajiceras, Kinkeliniceras, Obtusicostites and Hubertoce...

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 t...

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...

Waagen (1875) was the first who dealt with the Jurassic ammonites of Kutch based on detailed taxonomic work. In his monograph, he described among many species Perisphinctes spirorbis Neumayr, 1870 and P . aberrans Waagen, 1875 from the Callovian of Kutch, but the figures mentioned in the description did not correspond to the actual species. For P ....

Drilling predation provides a rare opportunity to study and quantify prey-predator interactions in the fossil record. Records of drilling predation on scaphopod mollusc are rare. Here, we report naticid drilling predation on scaphopods from a “Turritelline-dominated assemblage” (TDA) stratigraphically just below the K-Pg boundary sections in Rajahm...

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 report...

The lower Miocene molluscan assemblages of Kutch, India are known for long. Previous studies suggested that gastropod diversity increased within the lower Miocene. However, a number of studies showed that species richness is dependent on sample volume or specimen number. In other words, the previously reported increase in gastropod species richness...

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...

The lower Miocene molluscan assemblages of Kutch, India are known for long. Previous studies suggested that gastropod diversity increased within the lower Miocene. However, a number of studies showed that species richness is dependent on sample volume or specimen number. In other words, the previously reported increase in gastropod species richness...

Although common, confamilial naticid predation intensity was not very high in the geological record. Here, we gathered modern confamilial predation data from the Indian coasts and showed that confamilial naticid predation on a naticid species, Natica gualteriana, is exceptionally high at Chandipur, one of our studied areas. We studied the different...

Traces of predation by drilling gastropods and peeling crabs provide important insights about predator-prey interaction in ecological as well as evolutionary times. Predation on turritelline gastropods, in this context, has been frequently discussed in literature. Here, we have estimated the intensity of predation (both drilling and peeling) on Rec...

bivalves and gastropods. This newly developed biological system thoroughly reorganised predator-prey interaction and was causally related to large scale evolutionary changes (i.e. co-evolution and escalation: see Vermeij, 1987). Interestingly, species of these two families are also reported by us from the present Infratrappean bed; they are Mammill...

Evidence of intense naticid drilling predation occurs on turritelline prey from a turritelline-dominated assemblage (TDA) which lies below the K-T boundary sections in Rajahmundry, India. Previously, it was believed that drilling frequency (DF) on turritelline taxa was low during the Cretaceous. Data from the study area indicates that the Cenozoic...

Perisphinctes Waagen, 1869 is an important genus of the Oxfordian. In many areas the taxon has been excessively and subjectively split. Based on the material collected in Kutch (India), including the type specimens, we have grouped eight species previously described as distinct into one biological species, Perisphinctes indogermanus Waagen, 1875. I...

The study of past biotic interactions is important not only to understand the paleoecological history of a community, but also to test the evolutionary role of such interactions. Drill holes in invertebrate exoskeletons provide one of the very few scenarios where biotic interaction could be studied directly and the related hypotheses could be teste...

The genus Choffatia (Siemiradzki) is an important Callovian ammonite in Kutch biostratigraphy. Several species of the genus were described by the early workers who did not recognize intraspecific variability and sexual dimorphism in terms of the modern concepts. We have described here three dimorphic species based on material reposited in the Geolo...

Barroisiceras de Grossouvre was hitherto unknown in India. B. onilahyense Basse, which elsewhere belongs exclusively to the Coniacian, has been recorded from the Bryozoan Limestone Formation of central India. This find, as well as the presence of another time-diagnostic Coniacian ammonite, Placenticeras kaffrarium Etheridge and two inoceramid bival...

Cymatonautilus is a new record from Kutch with precise stratigraphic background. Being a temporally restricted but geographically widely distributed genus, Cymatonautilus is considered as a fleeting taxon. It cryptically appeared during the latest early Callovian and survived only up to the middle Callovian, but dispersed rapidly through a long bel...

The identification of late Bathonian beds and the position of the boundary between the Bathonian and Callovian in Kutch, western India, continued to be elusive until recently. The dominant ammonite faunas show strong endemism and thus are of little value in worldwide age correlations. The present paper records Epistrenoceras Bentz from the Patcham...

The coastal areas of the world are undergoing severe erosion due to a rapid transgression starting 3000 years ago. The erosion leads to exhumation of an ancient marsh at many places along the eastern coast of India. This marsh supported rich mangrove vegetation and a monospecific bivalve community, Glauconome sculpta (Sowerby), typical of estuarine...

In 1981, Kitchell et al. envisaged a net energy maximization model that can rank different prey according to their preferences. Several workers tested the model both in experimental studies and in fossil records. In the present endeavor we have tried to analyze the nature, from a cost-benefit perspective, of naticid predation on two Recent prey biv...

An assemblage of Phlycticeras Hyatt from a precisely dated zone of Middle Callovian in Kutch, India has been analyzed. Systematic study reveals that this sample can be divided into two size groups. The larger set shows different adult modifications leading to ornamental polymorphism. Polymorphs are very similar, if not identical, to different chron...

Biological interaction between two ecologically related species in sympatry results mostly as character divergence, which is also known as ecological character displacement. However, there are reports of character convergence in areas of overlap. Here we present a case study of sympatric convergence and allopatric divergence in form between two spe...

Mesozoic gastropod assemblages currently emerged from Kutch, western India constitute one of the most diverse communities known during the Bathonian–Oxfordian worldwide. The present paper describes part of the Jurassic gastropod faunas of the family Pleurotomariidae from Kutch, comprising ten species belonging to three genera, of which eight specie...

Recently collected specimens of Umiaites from the latest Jurassic of Kutch, have facilitated a better understanding of this endemic genus. Two previously described species, Umiaites rajnathi and U. Minor, appear to be conspecific, and the former name is retained. An attempt has been made to characterize the sexual dimorphism between Proniceras and...

The subfamily Hecticoceratinae SPATH, 1925, belonging to the family Oppelidae, is an important faunal element during the Bathonian - Oxfordian. The present paper addresses sexual dimorphism in one of the species of the type genus, i.e. Hecticoceras giganteum SPATH, from Kutch, western India. Dimorphism within this species is marked by size and orna...

Three of Kitchin's (1903) trigomid species, Trigonia trapeziforms, T spissicosiata, and T cardiniiformis, have been frequently examined taxonomically, but their phylogenetic relationships remain uncertain. Taxonomic designations have ranged from grouping them within a single subgenus to separating them into different subfamilies. Principal factors...

The Bathonian ammonite assemblages have been previously poorly recorded in Kutch. The present study has unearthed a rich array of ammonite taxa ranging from the Middle to Upper Bathonian. While Oxycerites Rollier (1909) is a new record from Kutch, the oldest occurrence of Choffatia Siemiradzki (1898) has been found from the Middle Bathonian horizon...

Genetically controlled discontinuous variation within a single population is termed polymorphism (Ford, 1940). According to the McGraw Hill Encyclopedia (1984: 1364), genetic polymorphism is “A form of genetic variation, specifically a discontinuous variation, occurring within plant and animal species in which distinct forms exist together in the s...

The Late Tithonian ammonite-bearing horizons have very limited geographic occurrence in Kutch, being restricted only to the western part of the mainland. A 15 m thick sequence consisting mainly of oolite-shale alternations and coarse grained sandstone yields the terminal Tithonian faunal assemblages. The previous comprehensive report comes from Spa...

Kitchin first reported Trigonia ventricosa (Krauss) from Kutch in 1903. The populations he studied came from different localities and stratigraphic horizons, but erroneous information on Kutch geology initially led him to believe that all his material was obtained only from Late Tithonian strata. He noted, however, that populations of different are...

  The subfamily Eucycloceratinae Spath, 1928, belonging to the family Sphaeroceratidae, is an important Indo-Madagascan faunal element and is reported here from the Callovian of Kutch, India. Previously the subfamily was considered to consist of 14 morphospecies placed in four morphogenera. The present study is based on re-examination of the type m...

A new species of Erymnoceras, Erymnoceras washtawaensis sp. nov., from Wagad, eastern Kutch is described. The genus is a time-diagnostic fleeting taxon and is found elsewhere only from the upper Middle Callovian. This record allows a precise dating of the Middle Callovian sequence in this region, which in turn assists intra- and interprovincial cor...

The history of the taxonomy of the family Reineckeiidae Hyatt, 1900 recapitulates the history of classification of the Ammonoidea. The majority of the previous classifications were done in the analytical stage of taxonomy and the lower rank taxa were at best morphospecies or morphogenera. Use of population and stratigraphic data reveal that the gen...

The Kutch basin developed due to the fragmentation of Gondwana during the Middle Jurassic and hosted diverse endemic fauna, of which brachiopods are one of the chief constituents. The dominant brachiopod faunal element is the terebratulid genus Kutchithyris Buckman. The genus is represented throughout the exposed Middle Bathonian to Oxfordian seque...

India, once a member of the lost supercontinent Gondwana, broke away from it and made a solitary northward excursion and finally collided with Asia. During its long voyage, India remained isolated for 100 Ma and is expected to be characterized by stunning endemic biodiversity. But this is not recognized by the terrestrial faunal and floral content,...

Cryptorhynchia is a brachiopod genus, until recently known only from the late Bathonian. Two new species C. karuna and C. jhooraensis are here described from the middle Bathonian at Kutch, western India and record the earliest known occurrences of the genus. They constitute ancestor-descendant lineages with the two existing younger species C. pulch...

Ribs appeared cryptically in the Middle Jurassic nautiloid Paracenoceras. These ribs were produced by crowding of growth lirae as a corollary of change in body size during paedomorphic evolution. Initially, they had no direct functional significance. Some other contemporary genera are found to have similar ribbing patterns, partially developed on e...

Kheraiceras Spath reached its peak during the Late Bathonian-Early Callovia and achieved a wide biogeographic distribution during that interval. The genus speciated rapidly and is represented in the fossil record by many species. The present endeavour provides a full taxonomic account of six species, of which five are from Kutch, western India. The...

The Middle Jurassic sediments of Kutch have been known all over the world as a veritable storehouse of diverse fauna, particularly ammonites. The present investigation has brought to light a rich haul of gastropods hitherto unknown in Kutch. The present assemblage includes eleven new species belonging to nine genera. They are: Colpomphalus jumarens...

The phylogenetic position of Epimorphoceras decorum (WAAGEN) known only from a monotypic holotype is contentious. Some workers have placed it in the Reineckeiidae, others assigned it to the Morphoceratidae or the Parkinsoniidae. A reineckeiid affinity is contested mainly on the grounds of morphological and stratigraphic incompatibility. A restudy o...

The present note reports ornamental polymorphism in the nautiloid Paracenoceras prohexagonum from the Lower Chari Formation (Jurassic) of Kutch. The forms are described and the genetic significance discussed in detail.

Three forms of Paracenoceras are reported, two of them new species, the third a new record in Kutch. These species, together with two other species of Paracenoceras come from a single horizon at a single locality in Kutch. Besides omnipresent and extensively studied ammonites, the present nautiloids help in placing a more authentic Bathonian-Callov...

Three Oxfordian species belonging to Paracenoceras (Nautiloidea) are described here of which two are new records. Paracenoceras hexagonum and P. giganteum come from the Lower to Middle Oxfordian and the Upper Oxfordian beds respectively from elsewhere, but in Kutch, they are found in a single horizon, thus indicating condensation. Reports of sexual...

The general opinion is that hummocky cross-stratification is generated from superposition of storm waves on a unidirectional current. However, constraints on the type of the current field have not been clearly established. Sedimentary structures preserved in rocks of the Tithonian-Neocomian Umia Member, Kutch, India, indicate hummocky cross-stratif...

In marginal marine environments facies mosaics become complicated through time as and when the regular autocyclic changes are frequently intervened by allocyclic changes. The facies mosaic of the marginal marine Tithonian Ghuneri Member (476 m thick) exposed in western Kutch, India, is likewise fairly complex with frequent lateral as well as vertic...