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Numerous isolated teeth recovered from the Upper Triassic Tiki Formation of India have high, cylindrical, triangular to conical crowns with serrated mesial and distal carinae, and oval/subcircular and elliptical crown bases. Within this overall morphology, the teeth are subdivided into six morphotypes based on crown proportions, nature of carinae and serration and crown-base ratios. These ziphodont teeth are compared with those of other dominant Late Triassic carnivores of India to show similarity with that of the phytosaurs based on their shape, recurved nature, crown proportions, the presence of carina(e), nature of serrations and serration density. The different morphotypes reflect positional heterodonty, and three upper jaw dental sets are identified. This finding is corroborated by PCA, where the morphotypes form distinctly separate clusters, though partial overlapping of these convex hull polygons suggests that these teeth belonged to a single phytosaur taxon. As tripartite dentition is a derived condition; it may be concluded that these isolated teeth belonged to a more derived phytosaur, yet to be recovered from the Tiki Formation. The study highlights the importance of examining isolated teeth in order to identify the fossil forms which are yet to be discovered. [ABSTRACT FROM AUTHOR]

A new Mystriosuchinae phytosaur, Colossosuchus techniensis, is described from the Upper Triassic Tiki Formation of India. Colossosuchus is diagnosed by multiple apomorphies, including a strongly downturned terminal rosette (c. 70°), closely spaced mediolateral band‐like ornamentation on dorsal surface of the nasal, dorsolaterally oriented supratemporal fenestra, ventrolaterally inclined postorbital–squamosal bars depressed below the skull table, dorsally convex parietal–squamosal bar that descends ventrolaterally below the skull roof, dome‐shaped skull in lateral view, prominent neural arch laminae and fossae, three sacral vertebrae, robust proximal end of the tibia, and fibula with high anteroposterior flaring of the distal end. The total body length of the largest individual recovered from the bonebed is estimated to be more than 8 m, suggesting that Colossosuchus is one of the largest phytosaurs known. Phylogenetic analysis nests Colossosuchus and other undescribed specimens from India within Mystriosuchinae. These form a distinct clade and represent the earliest record of endemism among Gondwanan phytosaurs. This clade is recovered as sister taxa to ((Volcanosuchus + Rutiodon) + Leptosuchomorpha), where the depressed supratemporal fenestra first appeared in the phytosaur lineage, a feature previously used to diagnose the derived leptosuchomorphs. Early‐diverging phytosaur diversification may have coincided with the final stages of the Carnian Pluvial Event with their possible migratory routes along the circum‐Tethyan coastline. The lineage continued to evolve mostly through endemic radiations and experienced an extinction event during early Norian, which marked the disappearance of most of the non‐leptosuchomorph taxa. This is attributed to post‐CPE aridification, although more study is required. [ABSTRACT FROM AUTHOR]

A monotaxic bonebed containing numerous phytosaur specimens is reported from the Upper Triassic Tiki Formation of India. The comprehensive minimum number of individuals is estimated to be 21, which includes multiple juveniles and subadults, and only a few adults. Such intraspecific aggregation of juvenile-dominated phytosaurs is explained here by parental care and juveniles living in cohorts, as are evident from extant phylogenetic bracketing of either lepidosaurs or crocodiles and birds. The cause of this mass death is probably disease related, after which the carcasses bloated, floated, and disarticulated at the site of death, resulting in an autochthonous assemblage. The carcasses remained submerged under shallow, slow-moving or standing water for a prolonged time and later were subaerially exposed after the recession of water. Subsequently, flooding events resulted in their burial under the overbank fines. Comparison of biostratinomic variables with those of a rhynchosaur-dominated bonebed recovered previously from the same stratigraphic horizon showed distinct differences in their causes of death and fossilization pathways. The latter may be attributed to their habitat differences because the phytosaurs lived in the low-lying areas or ponds and the rhynchosaurs resided on relatively higher and drier areas of the Tiki floodplain. [ABSTRACT FROM AUTHOR]

Detailed description and phylogenetic assessment of a phytosaur skull collected from the Tiki Formation of the Rewa Gondwana Basin of India and earlier diagnosed as Parasuchus hislopi, show that it pertains to a new genus and species, Volcanosuchus statisticae. The new taxon is characterized by marginal overlapping of the nostrils by the antorbital fenestrae, external nares situated on a bulbous and raised dome, the lateral surface of the jugal ornamented by a prominent ridge defined by multiple tubercles and radiating thread‐like structures, and distinct ornamentation patterns on the rostrum and skull table. Phylogenetic analysis nests Volcanosuchus within Mystriosuchinae, where it forms a sister taxon to (Rutiodon + Leptosuchomorpha) and marks the transition between the basal Parasuchidae and more derived Mystriosuchinae phytosaurs. Evolution of the phytosaur skulls resulted in changes from non‐overlapping nostril and antorbital fenestra to an overlapping state, anteroposterior elongation of the exoccipital–supraoccipital shelf, appearance of a median ridge on the basioccipital, and reduction of the supratemporal fenestra. Considerable faunal overlap of the Tiki Formation is evident with the lower Maleri Formation, which is late Carnian based on the occurrence of Hyperodapedon, Parasuchus and Exaeretodon. The Tiki Formation correlates with the Ischigualasto Formation of Argentina, the upper part of the Santa Maria Formation, and the overlying lower Caturrita Formation of Brazil, the Isalo II Beds of Madagascar, Lossiemouth Sandstone of Scotland, and the lower Tecovas Formation of the Chinle Group of North America, and ranges from late Carnian to early/middle Norian. [ABSTRACT FROM AUTHOR]

A new bonebed recovered from the Late Triassic of India contains various macro- and microfossils, unionid bivalves and coprolites. The macrofossils include more than 700 identifiable skeletal specimens of 27 metoposaurid, four phytosaur and two rhynchosaur individuals whereas the microfossils comprise about 500 isolated teeth of varied chondrichthyans, dipnoans, actinopterygians, archosauriforms, and several non-mammalian cynodonts. The bonebed is a monodominant, multitaxic, parautochthonous, time-averaged, attritional assemblage. The Tiki floodplain was populated by highly diverse animal communities occupying terrestrial, semi-aquatic and aquatic realms, where scavenging and/or predation were common. Two distinct biostratinomic modes deduced are – (i), natural death, decomposition, and differential pre-burial modifications of the large terrestrial and semi-aquatic animals, and (ii) breaching of banks during flooding events, mass death, and high energy deposition of sediment load including various aquatic fishes and unionids. Similar REE patterns of a representative sample set of bone specimens and their encasing matrices suggest same diagenetic condition and a single burial event. The MREE enrichment, cerium and uranium content indicate reducing burial microenvironment for the studied fossil specimens. The Late Triassic scenario comprised highly dynamic animal communities that had different mortality dynamics and fossilisation pathways depending on the habitats and palaeobehaviour of the animals. [ABSTRACT FROM AUTHOR]

Allokotosauria, a clade of non-archosauriform archosauromorphs with a broad diversity of body plans, plays a crucial role in better understanding the evolutionary history of early diverging stem-archosaurs. Here we provide a detailed redescription of Malerisaurus robinsonae, a malerisaurine allokotosaur from the middle Carnian-lowermost Norian lower Maleri Formation, Pranhita-Godavari Basin, India. The new anatomical information available from recently discovered and well-preserved skeletons of various allokotosaurs, such as Azendohsaurus madagaskarensis, Shringasaurus indicus, Puercosuchus traverorum, and Malerisaurus-like taxa, and their comparison with Malerisaurus robinsonae enriches our understanding of the anatomy of this species. To reassess the phylogenetic relationships of Malerisaurus robinsonae, we revised its scorings and included eight additional allokotosaurian species to the already most comprehensive phylogenetic dataset focused on Permo-Triassic archosauromorphs. We modified 70 scorings for Malerisaurus robinsonae and the new analysis recovered this species at the base of Malerisaurinae and this group as the earliest branch of Azendohsauridae. Pamelaria dolichotrachela is found as the earliest diverging non-malerisaurine azendohsaurid and sister taxon to the Shringasaurus indicus + Azendohsaurus spp. clade. Trilophosaurid interrelationships are well resolved, with Teraterpeton hrynewichorum, Coelodontognathus ricovi, and Rutiotomodon tytthos as their successive earliest-branching species. The position of Anisodontosaurus greeri as a sister taxon to Variodens inopinatus bolsters long ghost lineages in the Late Triassic trilophosaurid record. A disparity analysis of tooth crown morphology shows that Allokotosauria is the most disparate Permo-Triassic archosauromorph clade, exploring the almost complete range of basic crown morphologies. Trilophosaurids occupy an area of the dental morphospace unique among archosauromorphs., (© 2024 American Association for Anatomy.)

A new, partially preserved skull of chigutisaurid amphibian (temnospondyli) has been reported for the first time from the Late Triassic Tiki Formation of India. Chigutisaurids are now known to occur in Australia’s Early and Late Triassic, the Late Triassic in India, Argentina, and Brazil, the Jurassic of South Africa and Australia, and the Cretaceous of Australia. In India, the first appearance of chigutisaurids marks the Carnian—middle Carnian/Norian Boundary. This work also attempts to correlate, again for the first time, the advent of chigutisaurids and the occurrence of Carnian Pluvial Episodes (CPE) in the Late Triassic Maleri and Tiki Formation of Central India. The new specimen belongs to the genus Compsocerops prevalent in the Late Triassic Maleri Formation occurring 700 km south. However, the chigutisaurid specimen recovered from the Tiki Formation is a new species when compared to that of the Maleri Formation. It has the presence of an inward curved process of the quadratojugal as opposed to the straight downward trending process of the quadratojugal, the presence of vomerine foramen, shorter and wider interpterygoid vacuities, wider subtemporal vacuities, and the base of the interpterygoid vacuities at the same level with the base of the subtemporal vacuity. It proves that the Tiki Formation is coeval with the Lower Maleri Formation and a part of Upper Maleri. [ABSTRACT FROM AUTHOR]

Multiple spiral and non‐spiral cylindrical coprolites with profuse bone inclusions were recovered from a metoposaurid‐dominated bonebed in the Upper Triassic Tiki Formation of India. The spiral coprolites are assigned to two new ichnotaxa based on amphipolar and heteropolar micropolar coilings. The non‐spiral coprolites are internally devoid of any spiral structure, mostly cylindrical, except for a few, which are ellipsoidal. All of these coprolites contain randomly scattered inclusions of partly digested and undigested skeletal fragments. Based on external and internal morphology, and the type of inclusions, the probable producers of these coprolites are considered to have been carnivorous and/or piscivorous, and included different types of chondrichthyans, dipnoans and actinopterygians, as well as various semiaquatic and terrestrial tetrapods. A web‐like interconnectedness is evident, which highlights dynamic and highly diverse animal communities inhabiting the terrestrial, semiaquatic and aquatic realms and dissolution of the inter‐realm boundaries in the Upper Triassic Tiki palaeoecosystem. [ABSTRACT FROM AUTHOR]

The radiation of archosauromorph reptiles in the Triassic Period produced an unprecedented collection of diverse and disparate forms with a mix of varied ecologies and body sizes. Some of these forms were completely unique to the Triassic, whereas others were converged on by later members of Archosauromorpha. One of the most striking examples of this is with Triopticus primus, the early dome‐headed form later mimicked by pachycephalosaurid dinosaurs. Here we fully describe the cranial anatomy of Triopticus primus, but also recognize a second dome‐headed form from a Upper Triassic deposit in present‐day India. The new taxon, Kranosaura kuttyi gen. et sp. nov., is likely the sister taxon of Triopticus primus based on the presence of a greatly expanded skull roof with a deep dorsal opening (possibly the pineal opening) through the dome, similar cranial sculpturing, and a skull table that is expanded more posterior than the posterior extent of the basioccipital. However, the dome of Kranosaura kuttyi gen. et sp. nov. extends anterodorsally, unlike that of any other archosauromorph. Histological sections and computed tomographic reconstructions through the skull of Kranosaura kuttyi gen. et sp. nov. further reveal the uniqueness of the dome of these early archosauromorphs. Moreover, our integrated analysis further demonstrates that there are many ways to create a dome in Amniota. The presence of 'dome‐headed' archosauromorphs at two localities on the western and eastern portions of Pangea suggests that these archosauromorphs were widespread and are likely part of more assemblages than currently recognized. [ABSTRACT FROM AUTHOR]

A new rich and varied assemblage of archosauriform teeth is reported from the Upper Triassic Tiki Formation of India. Twelve morphotypes are identified based on their distinctive morphology, crown proportions, nature of serrations/denticles and serration density. Morphotypes I and II show similarity with that of Galtonia and Protecovasaurus, respectively, whereas morphotypes III–VI have low, subtriangular or leaf-shaped, asymmetrical, labiolingually compressed crowns with lenticular-subcircular bases and are diagnosed as belonging to different indeterminate archosauriforms. Morphotype VII shows similarity with aetosaur teeth, whereas morphotypes VIII–XII are ziphodont teeth having high, cylindrical, recurved crown with labiolingual compression, serrated carinae and subrectangular serrations, and are theropod-like. Variation in dental histology is noted between these morphotypes based on extent of pulp cavity, dentinal tubules and von Ebner lines of incremental growth. In multivariate analyses, there is considerable overlapping of convex hull polygons with morphospaces of other known archosauriforms such as Protecovasaurus, Crosbysaurus and Tecovasaurus known from the lower Tecovas Formation of the Chinle Group, USA. Such similarity correlates the two horizons despite wide geographic separation, suggesting that the age of the Tiki Formation may be younger than that previously suggested. Based on the known fossil flora and fauna, a mid-late Carnian age is proposed for the Tiki Formation. [ABSTRACT FROM AUTHOR]

Multiple, small, cylindrical scroll coprolites having rounded and tapering ends and pertaining to a new ichnotaxon have been recovered from the Upper Triassic Tiki Formation of India. This is the first record of scroll coprolites from the Mesozoic. Based on cross‐sectional geometry, external surface textures, and internal morphology, these coprolites are subdivided into three morphotypes. The coprolites contain several kinds of undigested food material in the form of ganoid fish scales, teeth, lower jaw and skeletal remains of various osteichthyans, chondrichthyans, archosauriforms and indeterminate reptiles. These inclusions are embedded in the groundmass separated by thin mucosal layers. The groundmass contains abundant gas vesicles, and secondarily‐filled shrinkage cracks. EDS analysis shows that the overall composition of the coprolites reflects Ca, P, C and O, suggesting calcium phosphate mineralogy, though other elements such as Fe, Mn, Al, Si are present in lesser proportions. Based on their similarity with the scrolled faeces of extant euryhaline hammerhead sharks, it is deduced that these coprolites were produced by euryhaline hybodontid sharks. At least two hybodontid taxa, Lonchidion and Pristrisodus, show high prevalence in the Tiki vertebrate fauna, suggesting that these were the possible producers. As the coprolite inclusions contain remains of other aquatic animals, these carnivorous hybodonts constituted the dominant predators of the Tiki aquatic ecosystem. [ABSTRACT FROM AUTHOR]

The current work attempts to address a century old problem regarding the stratigraphic disposition of the Upper Gondwana succession of the Rewa basin based on geological mapping and litholog preparation along well exposed transects. The proposed Upper Gondwana stratigraphy of the Rewa basin comprises a continuous and thick package of Triassic sediments unconformably overlain by the Jurassic Parsora Formation. The Triassic succession consists of a basal Pali Formation, an intermediate and newly designated Karki Formation and the overlying mud-dominant Tiki Formation. These formations are well defined based on physical attributes such as lithology, textures and sedimentary structures, and are easily distinguishable in the field. Based on stratigraphic correlation and fossil content, a Lower-Middle Triassic age has been assigned for the Pali and Karki formations, while the Tiki Formation is Upper Triassic (Carnian) in age. Preliminary observations based on lithological characteristics, sand body geometry and sand: mud ratios suggest that within a fluvial setting there were considerable changes in environments of deposition through time, especially during Triassic to Jurassic transition. [ABSTRACT FROM AUTHOR]