The oldest birotule-bearing freshwater sponges from the Upper Cretaceous–lower Paleocene Deccan volcanic-associated sediments of India

A new fossil occurrence of freshwater sponges (Porifera: Demospongiae) is reported from the Deccan volcanic associated Naskal intertrappean locality, deposited in an interval of <100 kyr across the Cretaceous/Paleogene (K/Pg) boundary. This is the oldest record of siliceous fossil birotule spicules (gemmuloscleres) belonging to asexual resting stages typical of the order Spongillida. The analysis supports the ascription of these fossils to the family Palaeospongillidae. The diagnosis and description of Longibirotula Pronzato and Manconi gen. nov. and its type species Longibirotula antiqua Manconi and Samant sp. nov. from the Naskal intertrappean is based on skeletal and gemmular spicular morphotraits. The findings have provided evidence of the presence of diversified groups of freshwater sponges during the Late Cretaceous on the Indian subcontinent and Gondwanaland. From the biogeographic context, the findings track the evolutionary trends of the oldest continental sponges in the Asian and Australasian/Insular Pacific regions

Palynoflora from Lakshmipur intertrappean deposits of Kutch, Gujarat: age implications

A diverse spore and pollen assemblage is reported for the first time from the northwesternmost Deccan intertrappeans exposed near Lakshmipur, District Kutch, in the western Indian state of Gujarat. The assemblage is indicative of distinct variations within the Maastrichtian intertrappean palynofloras occurring in different sections across the Deccan province. The flora is significant as it helps to establish a palynological basis for ascertaining temporal differences between the widely separated individual parts of the Deccan volcano-sedimentary province

Deccan Volcanism: a main trigger of environmental changes leading to the K/Pg mass extinction?

Recent studies indicate that the bulk (80%) of Deccan trap eruptions occurred over a relatively short time interval in magnetic polarity C29r, whereas multi-proxy studies from central and southeastern India place the Cretaceous-Paleogene (K/Pg) mass extinction near the end of this main phase of Deccan volcanism suggesting a cause-and-effect relationship. Beyond India multi-proxy studies also place the main Deccan phase in the uppermost Maastrichtian C29r below the K/Pg (planktic foraminiferal zones CF2-CF1), as indicated by a rapid shift in ¹⁸⁷Os/¹⁸⁸Os ratios in deep-sea sections from the Atlantic, Pacific and Indian Oceans, coincident with rapid climate warming, coeval increase in weathering, a significant decrease in bulk carbonate indicative of acidification due to volcanic SO2, and major biotic stress conditions expressed in species dwarfing and decreased abundance in calcareous microfossils (planktic foraminifera and nannofossils)

A review of small-bodied theropod dinosaurs from the Upper Cretaceous of India, with description of new cranial remains of a noasaurid (Theropoda: Abelisauria)

Small-bodied theropod dinosaurs are rare on southern landmasses but have been known from India for a century. Excavations by Charles Matley and Durgansankar Bhattacharji in uppermost Cretaceous sediments at Bara Simla, central India in 1917–1919 recovered small theropod vertebral and limb elements originally interpreted as coelurosaurians and separated into at least three species (Compsosuchus solus, Laevisuchus indicus, Jubbulpuria tenuis) based on features that can now be attributed to their serial position in the vertebral column. The comparatively recent discoveries of Noasaurus leali and Masiakasaurus knopfleri from similar-aged rocks in South America and Madagascar, respectively, and advances in basal theropod systematics led to a revised interpretation of most small-bodied Indian theropods as noasaurid abelisauroids. Here we review and redescribe Laevisuchus, Jubbulpuria, and Compsosuchus, including several elements that until now were thought lost, and describe a new partial noasaurid dentary from central India. The dentary bears the characteristic procumbent dentition of Masiakasaurus, which apparently is absent in Noasaurus. Likewise, cervical vertebrae of Laevisuchus more closely resemble those of Masiakasaurus than those of Noasaurus. Despite these similarities, phylogenetic analyses indicate that the balance of character data supports the Indian noasaurid species outside the sister-taxon pairing of South American and Malagasy species. Bones of small-bodied theropods have been recovered exclusively from the youngest Mesozoic localities in India (e.g., Pisdura, Bara Simla); to date they have not been reported from the slightly older localities in western and central India, from southern Indian sites in the Cauvery Basin, nor from the Vitakri Formation of Pakistan.</p

Palynology of the uppermost Cretaceous to lowermost Paleocene Deccan volcanic associated sediments of the Mandla Lobe, Central India

Palynological study of the uppermost Cretaceous–lowermost Paleocene sequences of the Deccan volcanic province in the Mandla Lobe of central India was carried out to understand floral diversity, paleoecology and paleoclimate during Deccan volcanic activity (67. 4–62.5 Ma). The study involved 17 intertrappean sedimentary beds at 13 stratigraphic levels. The analysis shows the presence of a rich and diverse palynoflora represented by 47 genera and 61 species of pteridophytes, gymnosperms, algae, and fungi. Amongst these, we recognized three new genera and 10 new species. At the lower stratigraphic levels, (582–602 meters above sea level), Late Cretaceous (Maastrichtian) age marker palynomorphs, namely Azolla cretacea, Farabeipollis minutus, Jiangsupollis striatus and J. intertrappea sp. nov. and dominance of Gabonisporis vigourouxii and Aquilapollenites bengalensis were recorded. At the higher stratigraphic levels, (698–858 meters above sea level) Early Paleocene (Danian) age marker palynoassemblages, such as Haloragacidites amolosus, Longapertites vaneendenburgi, Mulleripollis bolpurensis, Palmaepollenites nadhamunii, and P. eocenicus were recorded. Palynoassemblage and associated clay minerals indicate deposition of intertrappean beds in a fluctuating climate, ranging from humid and semiarid to arid and the prevalence of estuarine to freshwater depositional environments at the time of deposition. Palynofloral assemblages suggests prevalence of warm humid tropical climate with high precipitation during the deposition of intertrappean beds.</p

New mammals from the Naskal intertrappean site and the age of India's earliest eutherians

The first Cretaceous mammals described from India were recovered from the Naskal locality, on the southeastern edge of the Deccan Traps Volcanic Province (DTVP), where it is preserved between two basalt flows. Because the DTVP eruptions spanned the Cretaceous-Paleogene boundary (KPB), it is often unknown whether trap-associated fossil sites are latest Cretaceous (Maastrichtian) or early Paleocene in age. The Naskal locality accounts for nearly half of published mammal records from DTVP-associated sediments as well as a host of other vertebrate microfossils. Its age takes on singular importance in the context of mammalian evolution in India and the effects of the end-Cretaceous mass extinction and subsequent evolutionary radiation of placentals. Here we describe two new mammal species, Indoclemensia naskalensis gen. et sp. nov. and I. magnus sp. nov., from Naskal and present evidence from 40Ar/39Ar geochronology, magnetostratigraphy, and chemostratigraphy of the over- and underlying basalt flows to refine the age of the Naskal locality and nearby Rangapur locality. In conjunction with palynostratigraphy and vertebrate biostratigraphy, these sites can be confidently restricted to a <100 kyr interval spanning the KPB. The most probable 40Ar/39Ar age is latest Cretaceous (66.136–66.056 Ma), but an earliest Paleogene age cannot be ruled out. We explore the implications of this age assignment for Deccan chemostratigraphy and Deccan volcanism, Cretaceous-Paleogene (K/Pg) mass extinction, Indian mammalian faunal evolution, and the timing of the origin of placental mammals