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Metoposaurids are an important Late Triassic temnospondyl family known from nonmarine sediments of Europe, North-America, North Africa and India. Indian taxon Metoposaurus maleriensis became Buettneria maleriensis. “Metoposaurus” was thereafter restricted to encompass only M. diagnosticus from Germany and M. bakeri from North America, whose lacrimals are excluded from the orbital margin. However, some specimens of M. diagnosticus also exhibit lacrimals contributing to the orbital margins, as in Buettneria. Also, the generic name Buettneria was preoccupied, and Koskinonodon represents the senior synonym. Hence, the taxonomic status of the Indian metoposaurids became questionable. Metoposaurids being extremely conservative in nature, no single character could be assigned to distinguish them at the species level and there is no alpha level taxonomy available. Assigning a taxonomic status of the Indian taxon along with alpha taxonomy of all the other metoposaurids viewed through the lights of morphometry and morphospace is the main purpose of this paper. All genera were studied first hand from different museums of the world. Detailed measurements of skull bones and morphological properties are critically appraised. Biometric studies were done to analyse the variation between different taxa. Morphospace of different bones are constructed after conducting elliptical Fourier analysis and PCA using R. Cladogram using TNT and comparison of the cranial morphology is provided. Fourteen parsimonious trees, 50% majority rule consensus, Bremer support value and bootstrap resampling all reveals that Indian taxon occupies a distinct position somewhere between the European Metoposaurus and North American Koskinonodon. This fact corroborates with the morphospace analysis. There is also a strong bio geographic correlation in the fact that the Indian taxon was widely separated from the main cluster of the European and the North American taxa. Panthasaurus gen. nov. maleriensis is erected for the Indian taxon of metoposaurids. Biometry and morphospace studies supports Indian Metoposaurus to be a separate taxon.

Metoposaurids are representatives of the extinct amphibian clade Temnospondyli, found on almost every continent exclusively in the Late Triassic deposits. Osteohistologically, it is one of the best-known temnospondyl groups, analyzed with a wide spectrum of methods, such as morphology, morphometry, bone histology or computed modelling. The least known member of Metoposauridae isPanthasaurus maleriensisfrom the Pranhita-Godavari basin in Central India, being geographically the most southern record of this family. For the first time the bone histology of this taxon was studied with a focus on the intraspecific variability of the histological framework and the relationship between the observed growth pattern and climatic and/or environmental conditions. The studied material includes thin-sections of five long bones, a rib, an ilium and an intercentrum belonging most likely to eight individuals ranging from different ontogenetic stages. All bones have a large medullary region with progressively increasing remodeling, surrounded by a lamellar-zonal tissue type. The primary cortex consists of parallel-fibered matrix showing various degrees of organization, less organized collagen fibers in the zones and higher organized in the annuli. Growth marks occur in the form of alternating zones and annuli in every bone except the ilium and the intercentrum. The vascularity becomes less dense towards the outermost cortex in all sampled limb bones. Towards the outermost cortex the zone thickness is decreasing, in contrast to the avascular annuli, that become thicker or are of the same thickness. The growth pattern ofP. maleriensisis uniform and represents changes in ontogenetic development. Multiple resting lines are prominent in the outer annuli of the limb bones and the rib and they presumably indicate climatic and environmental influence on the growth pattern. Therefore, a prolonged phase of slowed-down growth occurred during the unfavorable phase, but a complete cessation of growth indicated by Lines of Arrested Growth (LAGs) is not recorded in the studied samples. Based on the histological framework we conclude that the climate had an impact on the growth pattern. As we do not see any LAGs in the Indian metoposaurid, we assume that the local climate was relatively mild in India during the Late Triassic. A similar prolonged phase of slowed down growth without the occurrence of LAGs was observed inMetoposaurus krasiejowensisfrom the Late Triassic of Krasiejów (Poland). This is in contrast to Moroccan metoposauridDutuitosaurus ouazzouifrom the Late Triassic of Argana Basin, where LAGs are regularly deposited throughout ontogeny indicating most likely harsher climatic conditions.