The study, published in the journal Zitteliana, treats the Lakhapar assemblage not as a scattering of isolated curiosities but as a true biological population. Using multivariate statistics, the researchers measured shell diameter, whorl height, whorl thickness, and umbilical width across dozens of specimens, then subjected the data to hierarchical clustering, principal component analysis, and linear regression modelling. The verdict is striking: the ammonites show high phenotype instability, with transient forms blurring the boundaries between the two named morphospecies, Hildoglochiceras kobelli and H. kobelliforme. Rather than two separate species, the statistical evidence points to something far more elegant — a dimorphic pair, in which the smaller, wider-umbilicated kobelliforme is the microconch and the larger, tighter-coiled kobelli is the macroconch of one and the same biological species.

Dimorphism — the existence of two distinct adult body forms within one species — is a well-known phenomenon in ammonites, generally interpreted as the difference between male and female animals. But proving it requires large samples from a single horizon, something Late Jurassic rocks in Kachchh rarely provide. Dominant depositional conditions in the basin, which was steadily filling with siliciclastic sediment towards the Early Cretaceous, meant that ammonites were generally rare except at a few horizons. The Lakhapar bed, roughly 357 metres above the base of the Jhuran Formation, is one of those exceptions. It interrupts largely restrictive conditions for ammonites in the area, recording a transgressive pulse and a maximum flooding zone — a moment when rising seas briefly opened the shelf to these free-swimming cephalopod relatives of squid and cuttlefish.

The horizon itself is a palaeontological treasure chest. Apart from the Hildoglochiceras assemblage, it contains haploceratids, a taramelliceratin ammonite, a single specimen of Aulacosphinctoides, an incomplete virgatosphinctin, and a benthic macrofauna of more than sixty taxa, including bivalves, gastropods, brachiopods, belemnites, echinoids, crinoids, decapods, and sponges. Wood fragments are common, most of them bored by bivalves. Vertebrate remains include rib fragments, vertebrae, and an articulated flipper of a marine reptile, probably an ichthyosaur. The bed records a time of low net sedimentation, when the influx of coarse-grained siliciclastics gradually ceased and carbonate mud accumulated during extended low-energy periods, with intense bioturbation mixing the two sediment types into a poorly sorted, condensed unit.

The statistical analysis went further than simple clustering. Linear regression revealed that the diameter of the umbilicus — the coiled opening at the centre of the shell — is best predicted by the combined effect of shell diameter and whorl height, with a regression coefficient of 0.96 and a p-value below 0.0001. Whorl thickness, by contrast, contributes the least to umbilical formation, with p-values of 0.09 and 0.46 in the relevant models. This means that some variation in shell thickness is essentially irrelevant at the population level, and that the ammonites were constructionally constrained in how their shells could grow. The principal component analysis separated the assemblage into two distinct clusters corresponding to the microconch and macroconch morphs, but also revealed about eighteen specimens sitting halfway between the two — a character overlap that the authors interpret as evidence of a single palaeobiological population rather than a mixture of species.

The implications extend well beyond Kachchh. Hildoglochiceras has long been known from the Himalayas, Pakistan, Madagascar, Tanzania, and possibly Argentina, but always as scattered single specimens or small samples with imprecise stratigraphy. The new study confirms the genus is endemic to the shelf areas fringing the Trans-Erythraean Trough, the seaway that would eventually become the Indian Ocean. Its restriction to these palaeomargins explains why the ammonite never achieved the wide geographic range of its Tethyan cousins. The comprehensive review of biostratigraphic interpretations conducted by the authors shows that the assumed range of Hildoglochiceras has fluctuated wildly over the decades — from the uppermost Kimmeridgian to the lowermost Upper Tithonian — but most probably the genus was restricted to, or at least better represented in, Lower Tithonian horizons.

Part of the confusion stems from a misinterpretation inherited from the middle of the twentieth century. Arkell in 1956 wrongly assumed that Hildoglochiceras co-occurred with Pseudolissoceras in Mexico, based on a careless reading of Imlay’s work. Zeiss in 1968 accepted this error and promoted a correlation of Hildoglochiceras horizons with the Tethyan Semiforme Zone in Europe, an interpretation that was uncritically accepted for decades. The Mexican-Cuban forms were later correctly reinterpreted as the genus Salinites, which is Late Tithonian to Early Berriasian in age. The new study argues that the usual correlation with the Semiforme/Verruciferum Zone is not supported by published ammonite biostratigraphy, and instead correlates the Lakhapar Hildoglochiceras Horizon with the lower part of the Albertinum/Darwini Zone in the Secondary Standard Scale for European and West-Tethyan ammonite bio-chronostratigraphy.

The single taramelliceratin specimen in the assemblage, tentatively assigned to the Taramelliceras compsum–kachhense group or to Parastreblites sp. gr. hoelderi, provides a crucial biostratigraphic anchor. Its stratigraphic range in west-Tethyan areas extends to the lower part of the Lower Tithonian, and its co-occurrence with Hildoglochiceras in Kachchh and Madagascar suggests that the oldest records of the latter genus are older than usually interpreted. The specimen may have been reworked, suggesting that the emersion surface at the base of the Hildoglochiceras Horizon — marked by an irregular, iron-crusted top of the underlying calcareous sandstone — may represent a wide stratigraphical gap. The lowermost level of the horizon contains abundant juvenile Hildoglochiceras and haploceratids, hinting at a sudden colonisation event when conditions briefly became favourable.

What emerges from this study is a portrait of an ammonite genus that was environmentally restricted, phenotypically unstable, and stratigraphically elusive. Hildoglochiceras thrived during transgressive pulses on epicontinental shelves surrounding the Trans-Erythraean Trough, but its records are scattered across areas where ammonite-poor or barren siliciclastic deposits, stratigraphic gaps, and local tectonic forcing conspired to mask its true range. The authors favour a local rather than wide regional significance for Hildoglochiceras records before they can be used for precise correlation across the trough. Future research with bed-by-bed sampling is needed before inferring the age of the youngest records within the Tithonian, but variation in biostratigraphic ranges must be expected from separate areas, each of which should be interpreted with clear statements about data reliability.

For now, the Lakhapar assemblage stands as the most relevant record of Hildoglochiceras available anywhere in the world. It demonstrates that these ammonites, far from being a diverse array of species, were probably a single dimorphic species whose two adult forms had been mistaken for separate taxa for over a century. It confirms the genus as an endemic inhabitant of the shelves fringing the proto-Indian Ocean. And it shows that even a thin band of rock in a remote Indian basin, when subjected to modern multivariate analysis, can overturn assumptions that have persisted since the days of Oppel, Waagen, and Spath. The Hildoglochiceras Horizon of the Jara Dome is a reminder that the fossil record is not a tidy catalogue of species but a dynamic, environmentally driven story — one that palaeontologists are only now beginning to read with the statistical tools it deserves.

Subject of Research: First population-level study of the ammonite genus Hildoglochiceras Spath, and the Lower Tithonian record of the Hildoglochiceras Horizon in the Kachchh Basin, India

Article Title: First population-level study of the ammonite genus Hildoglochiceras Spath, and the Lower Tithonian record of the Hildoglochiceras Horizon in the Kachchh Basin, India

Article References: Pandey, D. K., Fürsich, F. T., Alberti, M., Das, R., & Olóriz Sáez, F. (2022). First population-level study of the ammonite genus Hildoglochiceras Spath, and the Lower Tithonian record of the Hildoglochiceras Horizon in the Kachchh Basin, India. Zitteliana, 96, 1-49. https://doi.org/10.3897/zitteliana.96.73892

Image Credits: AI Generated

DOI: 10.3897/zitteliana.96.73892

Keywords: First, population-level, ammonite, genus, Hildoglochiceras, Spath, Lower, Tithonian, record, Horizon, Kachchh, Basin

The Spiti Shale Formation is a package of black shales with minor sandstone intercalations that stretches from northern Pakistan through northern India and Nepal to southern Tibet. These rocks represent outer shelf to upper slope deposits on the southern margin of the Neotethys, and their macroinvertebrate assemblages are dominated by ammonites and belemnites that commonly occur in claystone concretions. Benthic macroinvertebrates such as bivalves, gastropods and brachiopods are restricted to a few widely spaced layers, while large parts of the formation contain no macrobenthos at all. This patchy distribution reflects unsuitable conditions at the sea floor, in particular a lack of oxygen that was partly caused by upwelling of cold, nutrient-rich waters onto the shelf.

More than 240 bivalve specimens were collected from localities across the Spiti Valley, including sites near Chichim, Langza, Kaza, Kibber, Komic and Demul, as well as a single locality near Zangla in the Zanskar Valley. Most fossils come from the lower member of the Spiti Shale Formation, where they weather out of soft shales or occur in thin shell beds. Very few specimens were recovered from the underlying Ferruginous Oolite Formation, a unit of variable lithology containing sandstones, shelly limestones and iron-ooid bearing limestones that hosts a much richer benthic macrofauna, although one that is usually difficult to extract from the well-cemented rocks. The Spiti Shale Formation of the Zanskar Valley proved almost barren of benthic fossils.

Preservation is a central challenge in working with this fauna. With few exceptions, the bivalves are poorly preserved. Apart from some large and comparatively thick-shelled forms such as Pruvostiella, bivalves are well preserved only in concretions, where they occur as composite moulds. Shells in unconsolidated sediment are usually strongly crushed and fragmented by compaction and tectonic stress, which in some cases renders identification difficult. The style of distortion depends on the final burial position of the shells: specimens buried in growth position became dorso-ventrally shortened, while shells reoriented by burrowers or excavated by currents after death became laterally flattened. All intermediate preservational stages occur, and this compactional history has shaped how palaeontologists have interpreted the fauna for more than a century.

Among the most abundant taxa is Palaeonucula cuneiformis, a thick-shelled, elongated-oval protobranch bivalve that dominates the lower member together with Grammatodon (Indogrammatodon) egertonianus and Pruvostiella (P.) hermanni. Early workers including Herbert in 1831, Everest in 1833, Blanford in 1864 and Stoliczka in 1866 regarded the common nuculid as the species figured by J. de C. Sowerby in 1840, a highly variable form occurring from the Bathonian to the Kimmeridgian in the Kachchh Basin. Holdhaus, however, placed the Spiti specimens in two new species, Nucula spitiensis and N. hyomorpha, and he related the diagnostic features of these species to their preservational state, arguing that one was always dorso-ventrally compressed while the other was laterally compressed. Cox in 1940 regarded the two as synonyms, and the present study confirms that the Spiti material belongs to P. cuneiformis, a species widespread in the Ethiopian faunal province from Madagascar to the Arabian Peninsula.

Grammatodon (Indogrammatodon) egertonianus is a large arcoid bivalve with a rhomboidal to trapezoidal outline, much longer than high, and ornamented with radial ribs that are more numerous on the right valve than on the left. The species is closely related to G. (I.) virgatus, which is widespread within the Ethiopian faunal province, but it differs by being more elongated, having fewer radial ribs on both valves, and showing a less pronounced difference in ribbing between right and left valves. Nearly all specimens from the Spiti area are distorted by compaction, with the dorso-ventral axis commonly shortened, suggesting that the individuals are preserved in growth position.

The study also elevates Pruvostiella to generic rank and revises the astartid fauna of the Himalayas. The moderately-sized astartids from the Spiti Shale Formation have been accommodated in several species in the past, including Astarte spitiensis, A. unilateralis, A. hiemalis, A. sowerbyana, A. hermanni and A. scytalis. Because intermediate forms exist between these species and because two to four of these morphotypes repeatedly co-occur within individual horizons, the authors regard these forms as representing a single species, Pruvostiella (P.) hermanni, on ecological grounds. It is highly unlikely that several closely related species with a more or less identical mode of life would repeatedly co-occur within a community. The Kachchh specimens, although closely related, are more than three times the size of the Himalayan forms and are thus unlikely to be conspecific.

Several faunal elements in the Spiti Shale Formation, such as Australobuchia, Malayomaorica and Retroceramus, are also known from the southeastern margin of the Neotethys, including New Zealand and Indonesia. The occurrence of these high-latitude southern taxa at relatively low palaeolatitudes, between 20 and 30 degrees south according to the palaeolatitude calculator of van Hinsbergen and colleagues, can be explained by their restriction to outer shelf and slope environments where, due to upwelling, lower water temperatures prevailed. Isothermal submergence may explain the way polar faunas were able to cross the tropics. The genus Malayomaorica is documented from the Indian Himalayas for the first time in this study.

By contrast, other taxa, in particular Pruvostiella (P.) hermanni and Grammatodon (Indogrammatodon) egertonianus, are closely related but not identical to forms from the Kachchh Rift Basin situated at the western margin of the Indian Craton. This comparison between the poorly known deep shelf benthic bivalve fauna of the Himalayas and the shallow shelf Jurassic fauna of Kachchh is one of the most significant contributions of the present study, offering a rare opportunity to contrast benthic communities across a bathymetric gradient on the same continental margin.

The Spiti Shale Formation spans the time interval between the Callovian and the earliest Cretaceous, and its thickness is difficult to establish, but judging from the sections measured, the formation is at least 110 metres thick. The stratigraphic subdivision of the Jurassic strata of the Indian Himalayas has a long history, beginning with Stoliczka in 1866 and continuing through Diener in 1895, Krishna in 1983, Pathak in 1993 and Pandey and colleagues in 2013. The intensively folded and faulted succession has made it virtually impossible to measure a single continuous section, which nearly a hundred years later led to disputes over the correct lithostratigraphic composition of the formation. The present study follows the recognition of three informal members named the lower, middle and upper member.

In the lower member, the bivalve Bositra is abundant at the base, followed by a low-diversity fauna dominated by Palaeonucula, Pruvostiella and Indogrammatodon. Bositra buchii is a very widespread opportunistic byssate bivalve able to tolerate dysoxic conditions, and it occurs profusely in black silty shales at the base of the lower member at Langza, where it forms near-monospecific assemblages. In the middle member, bivalves are very scarce and usually found in mudrock concretions where they commonly form small clusters. In the upper member, bivalves locally form loosely packed concentrations in which the fossils are poorly preserved, composed of Australobuchia, Retroceramus and Malayomaorica.

The new taxonomic account revises the bivalve fauna recorded by earlier studies wherever possible. Stoliczka described 17 bivalve taxa from the two formations in 1866, of which only 13 remain valid after taxonomic revision. Holdhaus described 37 bivalve taxa from the Indian Himalayas in 1913, of which around 30 remain after sorting out synonymies. The present study describes 24 taxa from the Spiti Shale Formation and six additional ones from the Ferruginous Oolite Formation, providing a revised framework for understanding the benthic fauna that inhabited the mid to outer shelf regions of the southern Neotethys during the Jurassic.

The material has been deposited in the collections of the Bayerische Staatssammlung für Paläontologie und Geologie in Munich, ensuring that the specimens remain available for future research. As palaeoecological work on the Spiti Shale Formation continues, this revised taxonomy will serve as a foundation for reconstructing the structure and dynamics of benthic communities along the southern margin of the Neotethys, a region whose deep shelf faunas remain very poorly known compared with the shallow shelf faunas of the Kachchh Basin and other parts of the Ethiopian faunal province.

Subject of Research: Taxonomic revision of Jurassic bivalve fauna from the Spiti Shale and Ferruginous Oolite formations in the Indian Himalayas

Article Title: Jurassic bivalves from the Spiti area of the Himalayas, northern India

Article References: Fürsich, F. T., Alberti, M., Pandey, D. K., & Ayoub-Hannaa, W. S. (2022). Jurassic bivalves from the Spiti area of the Himalayas, northern India. Zitteliana, 96, 153-178. https://doi.org/10.3897/zitteliana.96.87253

Image Credits: AI Generated

DOI: 10.3897/zitteliana.96.87253

Keywords: Jurassic, bivalves, Himalayas, Spiti, palaeontology, Neotethys, Kachchh, palaeoecology, area, northern, India, scientific research

The research team, led by Rahul Dev of ICAR-NBPGR together with colleagues from ICAR-CSSRI and ICAR-CAZRI, conducted field surveys during February and March 2019 across five talukas of arid Kachchh: Bhuj, Mandvi, Nakhatrana, Bhachau and Rapar. The collection zone stretched across roughly 170 kilometres, mapping the Central and Western Kachchh ber-growing belt, with geographic extremes running from 23.0347 to 23.6881 degrees north latitude and 69.2051 to 70.7156 degrees east longitude. Bhuj taluka contributed the largest share of accessions with 17 samples, followed by Nakhatrana with 8, Mandvi with 4 and Abdasa with a single accession. Each collection was geo-referenced, and passport data on site conditions, associated vegetation and conservation status were recorded in the field.

The Indian jujube, Ziziphus mauritiana, is an evergreen tree of the Rhamnaceae family cultivated for thousands of years across the Indo-Pak subcontinent and much of Asia and Africa. The genus Ziziphus encompasses roughly 50 to 170 species, though only a handful, notably Z. mauritiana, Z. jujuba and Z. nummularia, are grown for their edible drupes. Ber earns its nickname, the poor man’s apple, from its dense nutritional profile: the fruits are rich in carbohydrates, sugars, dietary fibre, vitamins C and A, and minerals such as calcium and phosphorus, while also containing appreciable phenolic compounds, flavonoids and other antioxidants. Its deep taproot and ability to dormant during drought allow the tree to endure scorching temperatures and saline or alkaline soils, making it a staple of arid agriculture in Rajasthan, Gujarat and beyond.

To capture the full phenotypic breadth of the Kachchh germplasm, the researchers measured seventeen morphological and quality traits on each accession, spanning plant height, canopy spread, branch number, stem girth, leaf area, fruit dimensions, fruit weight and total soluble solids. Fruit measurements were taken with digital calipers accurate to 0.01 millimetres, and derived morphometric indices, including a Fruit Size Index calculated as length multiplied by width, a Shape Index of length divided by width, and roundness ratios, quantified fruit geometry. Canopy volume was estimated using the contour method, treating each crown as a geometric solid, while approximate fruit volume and surface area were computed from ellipsoidal formulas. The team then applied principal component analysis, hierarchical clustering with Ward’s minimum variance algorithm and Pearson correlation analysis, using Python-based tools including scikit-learn, SciPy, Matplotlib and Seaborn.

The descriptive statistics alone tell a striking story of phenotypic dispersion. Plant height ranged from 144 centimetres in the compact Ber_Bhuj_1 to 455 centimetres in the towering Ber_Bhuj_30, with a coefficient of variation of 30.36 percent. Canopy volume proved the most variable vegetative trait of all, spanning 0.58 to 8.34 cubic metres with a coefficient of variation of 66.24 percent. Primary branch counts diverged from just 2 to as many as 20 per plant, and leaf area ranged from 1.38 to 9.76 square centimetres, signalling highly diverse photosynthetic capacity across the population. Ber_Abda_20 displayed the widest horizontal footprint, while Ber_Bhuj_30 dominated in height and canopy volume.

Fruit traits revealed equally compelling variation, though with a different structure. Mean fruit length was 10.67 millimetres, ranging from 8.29 to 13.05 millimetres, and mean width was 11.27 millimetres, with both dimensions showing moderate variability of around 10 percent. Weight and volume parameters varied more dramatically: five-fruit weight spanned 1.54 to 7.48 grams, fruit volume ranged from 353.20 to 1332.10 cubic millimetres, and test weight ranged from 308 to 1496 grams, all with coefficients of variation between 29 and 32 percent. Ber_Abda_20 consistently topped every weight and volume parameter. Most striking of all was total soluble solids, the key biochemical marker of sweetness, which ranged from a modest 3.40 degrees Brix to an exceptional 17.50 degrees Brix, a coefficient of variation of nearly 38 percent, with the highest sugar accumulation recorded in accession Ber_Bhuj_21. Fruit roundness, surface area and shape index, by contrast, emerged as the most stable traits across the population.

The multivariate statistics distilled this complexity into an elegant framework. Principal component analysis compressed the seventeen traits into four components with eigenvalues above 1, together explaining 85.55 percent of total variance. The first component alone accounted for 50.14 percent and was heavily loaded with fruit dimensions, five-fruit weight, size index, fruit volume, surface area, test weight and total soluble solids, effectively isolating the high-yielding, high-sugar genotypes Ber_Abda_20 and Ber_Bhuj_30. The second component, explaining 20.50 percent, mathematically contrasted vegetative vigour, captured by plant height, canopy spread, stem girth and branch count, against fruit shape characteristics, cleanly separating large vegetative trees from compact, fruit-dominant plants. The third and fourth components, contributing 8.62 and 6.29 percent respectively, were tied to fruit symmetry parameters and to leaf area and stem girth modifications.

Hierarchical clustering then sorted the 30 accessions into four distinct phenotypic groups. Cluster 1 contained five high-vigour, large-fruited accessions including Ber_Bhuj_21, Ber_Nakh_22, Ber_Bhuj_24, Ber_Bhuj_29 and Ber_Bhuj_30, characterised by tall plants, broad canopies and large fruits. Cluster 2 was a unique single-accession group containing only Ber_Abda_20, an ideotype combining moderate vegetative vigour with exceptionally large fruits and maximum sugar content. Cluster 3 comprised eight compact accessions such as Ber_Bhuj_1 and Ber_Bhuj_2, defined by low vigour and small, round fruits, while the remaining 16 intermediate accessions formed Cluster 4. Correlation analysis reinforced the picture: plant height correlated strongly with canopy volume at r equal to 0.91, fruit weight correlated tightly with size index at r equal to 0.58, and total soluble solids rose with plant spread and canopy volume, confirming that larger architectures favour greater photosynthetic accumulation and sweeter fruit. Notably, stem girth showed no association with fruit weight, hinting that quality traits can be selected independently of tree size.

The implications extend well beyond taxonomy. Four accessions, Ber_Abda_20, Ber_Bhuj_21, Ber_Bhuj_29 and Ber_Bhuj_30, stand out as elite candidates for cultivar development and field trials, with potential roles either as candidate varieties or as robust rootstocks tailored for hyper-arid, saline environments. The strong correlation patterns between structural traits and fruit quality indices also offer reliable selection proxies that could accelerate early-stage seedling culling in future breeding programmes. Just as importantly, the study sounds a conservation alarm: wild ber diversity across India remains poorly characterised and is threatened by habitat loss, overgrazing and the spread of improved cultivars. By demonstrating that Kachchh’s under-studied germplasm ranks among the most resilient and variable ber populations yet reported, the research makes a persuasive case that the genetic resources of India’s harshest landscapes are not a curiosity but a strategic asset for food security in the climate era.

Subject of Research: Agro-morphological and biochemical diversity of wild ber (Ziziphus spp.) germplasm from the Kachchh region of Gujarat, India

Article Title: Multivariate analysis of agro morphological and biochemical variation in ber germplasm from the Kachchh region of Gujarat India

Article References: Dev, R., Singh, T., Kumar, C., Tetarwal, A., & Dayal, D. (2026). Multivariate analysis of agro morphological and biochemical variation in ber germplasm from the Kachchh region of Gujarat India. Discover Plants, 3(1), Article 373. https://doi.org/10.1007/s44372-026-00808-5

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00808-5

Keywords: Ziziphus mauritiana, ber, germplasm diversity, Kachchh, Gujarat, principal component analysis, cluster analysis, fruit quality, total soluble solids, arid horticulture, climate resilience, plant breeding