Mass Extinction Research Articles

Multiple Speciation and Extinction Rate Shifts Shaped the Macro-Evolutionary History of the Genus Lycium Towards a Rather Gradual Accumulation of Species Within the Genus

The Neotropics are the most species-rich region on Earth, and spectacular diversification rates in plants are reported in plants, mostly occurring in oceanic archipelagos, making Neotropical and island plant lineages a model for macro-evolutionary studies. The genus Lycium in the Solanaceae family, originating from the Neotropics and exhibiting a unique disjunct geography across several islands, is therefore expected to experience exceptional diversification events. In this study, we aimed to quantify the diversification trajectories of the genus Lycium to elucidate the diversification events within the genus. We compiled a DNA matrix of six markers on 75% of all the species in the genus to reconstruct a dated phylogeny. Based on this phylogeny, we first revisited the historical biogeography of the genus. Then, we fitted a Compound Poisson Process on Mass Extinction Time model to investigate the following key evolutionary events: speciation rate, extinction rate, as well as mass extinction events. Our analysis confirmed that South America is the origin of the genus, which may have undergone a suite of successive long-distance dispersals. Also, we found that most species arose as recently as 5 million years ago, and that the diversification rate found is among the slowest rates in the plant kingdom. This is likely shaped by the multiple speciation and extinction rate shifts that we also detected throughout the evolutionary history of the genus, including one mass extinction at the early stage of its evolutionary history. However, both speciation and extinction rates remain roughly constant over time, leading to a gradual species accumulation over time.

Habitat Association Predicts Population Connectivity and Persistence in Flightless Beetles: A Population Genomics Approach Within a Dynamic Archipelago.

Habitat association has been proposed to affect evolutionary dynamics through its control on dispersal propensity, which is considered a key trait for lineage survival in habitats of low durational stability. The Habitat Constraint hypothesis predicts different micro- and macroevolutionary patterns for stable versus dynamic habitat specialists, but the empirical evidence remains controversial and in insects mostly derives from winged lineages. We here use genome-wide SNP data to assess the effect of habitat association on the population dynamics of two closely related flightless lineages of the genus Eutagenia (Coleoptera: Tenebrionidae), which are co-distributed across the Cyclades islands in the Eastern Mediterranean but are associated with habitat types of different presumed stability: the psammophilous lineage is associated with dynamic sandy coastal habitats, while the geophilous lineage is associated with comparatively stable compact soil habitats. Our comparative population genomic and demographic analyses support higher inter-island gene flow in the psammophilous lineage, presumably due to the physical properties of dynamic sand-dune habitats that promote passive dispersal. We also find consistent bottlenecks in the psammophilous demes, suggesting that lineage evolution in the dynamic habitat is punctuated by local extinction and recolonisation events. The inferred demographic processes are surprisingly uniform among psammophilous demes, but vary considerably among geophilous demes depending on historical island connectivity, indicating more stringent constraints on the dynamic habitat lineage. This study extends the Habitat Constraint hypothesis by demonstrating that selection on dispersal traits is not the only mechanism that can drive consistent differences in evolutionary dynamics between stable versus dynamic habitat specialists.

Functional diversity and resilience of bivalves after the Permian-Triassic mass extinction

The Permian-Triassic mass extinction was the largest extinction event in the Phanerozoic eon, with profound taxonomic and ecological effects on the ecosystem function. Functional diversity, a facet of biodiversity, could reflect the ecosystem function and stability. Although previous studies have shown that the functional richness of global marine organisms was decoupled from their taxonomic diversity during the mass extinctions, the evolution of functional diversity during the Permian-Triassic mass extinction and its aftermath is still under debate. The ecologically diverse clade bivalves may be more representative for understanding the evolution of functional diversity. To investigate the evolutionary dynamics of the functional diversity of bivalves, a global bivalve dataset of 8929 occurrences from the latest Permian to the Late Triassic was constructed. Functional richness, functional evenness, and functional redundancy were calculated to reflect the functional diversity in this study. Our results showed that the functional richness of bivalves was slightly affected by the Permian-Triassic mass extinction, decoupled from the significant decrease in taxonomic diversity. Meanwhile, a decrease in functional redundancy and an increase in functional evenness were observed after the mass extinction. In addition, bivalves showed high resilience to the mass extinction by maintaining the ecospace and reducing the functional redundancy. The high taxonomic diversity, high functional richness, high functional redundancy and relatively higher proportion of infaunal bivalves during the Late Triassic indicate that the Mesozoic marine revolution was already underway.

Insight into the Phylogenetic Relationships of Phasmatodea and Selection Pressure Analysis of Phraortes liaoningensis Chen & He, 1991 (Phasmatodea: Lonchodidae) Using Mitogenomes

Stick and leaf insects are a group among the Insecta that are famous for their extraordinary mimicry ability. Since the establishment of the Phasmatodea, their internal classification has been constantly revised. Mitochondrial genes as molecular markers have been widely used for species classification, but the phylogenetic relationships within the Phasmatodea remain to be thoroughly discussed. In the present study, five mitogenomes of Phasmatodea ranging from 15,746 bp to 16,747 bp in length were sequenced. Bayesian inference (BI) and maximum likelihood (ML) analyses were carried out based on a 13 PCGs data matrix (nt123) and a combined matrix of 13 PCGs and two rRNA genes (nt123_rRNA). The present study supports the conclusion that Phylliidae was the basal group of Neophasmatodea and confirms the monophyly of Lonchodinae and Necrosciinae, but it shows that Lonchodidae was polyphyletic. A sister group of Bacillidae and Pseudophasmatidae was also recovered. The phylogenetic tree based on the nt_123 dataset showed higher node support values. The construction of a divergent time tree in this study supported the conclusion that extant Phasmatodea originated in the Jurassic (170 Mya) and most lineages diverged after the Cretaceous–Paleogene extinction event. To explore whether the mitochondrial genes of Phraortes liaoningensis collected from high latitudes where low temperatures occur for eight months of the year are under selection pressure, this study used the branch-site model and the branch model to analyze the selection pressure on the 13 mitochondria protein-coding genes (PCGs). We found that both ND2 and ND4L of Ph. liaoningensis exhibited positive selection sites using the branch-site model. This study shows that a low-temperature environment causes mitochondrial genes to be selected to meet the energy requirements for survival.

Stoichiometric theory in optimal foraging strategy.

Understanding how organisms make choices about what to eat is a fascinating puzzle explored in this study, which employs stoichiometric modeling and optimal foraging principles. The research delves into the intricate balance of nutrient intake with foraging strategies, investigating quality and quantity-based food selection through mathematical models. The stoichiometric models in this study, encompassing producers and a grazer, unveils the dynamics of decision-making processes, introducing fixed and variable energetic foraging costs. Analysis reveals cell quota-dependent predation behaviors, elucidating biological phenomena such as "compensatory foraging behaviors" and the "stoichiometric extinction effect". The Marginal Value Theorem quantifies food selection, highlighting the profitability of prey items and emphasizing its role in optimizing foraging strategies in predator-prey dynamics. The environmental factors like light and nutrient availability prove pivotal in shaping optimal foraging strategies, with numerical results from a multi-species model contributing to a comprehensive understanding of the intricate interplay between organisms and their environment.

Extinction training suppresses activity of fear memory ensembles across the hippocampus and alters transcriptomes of fear-encoding cells.

Contextual fear conditioning has been shown to activate a set of "fear ensemble" cells in the hippocampal dentate gyrus (DG) whose reactivation is necessary and sufficient for expression of contextual fear. We previously demonstrated that extinction learning suppresses reactivation of these fear ensemble cells and activates a competing set of DG cells-the "extinction ensemble." Here, we tested whether extinction was sufficient to suppress reactivation in other regions and used single nucleus RNA sequencing (snRNA-seq) of cells in the dorsal dentate gyrus to examine how extinction affects the transcriptomic activity of fear ensemble and fear recall-activated cells. Our results confirm the suppressive effects of extinction in the dorsal and ventral dentate gyrus and demonstrate that this same effect extends to fear ensemble cells located in the dorsal CA1. Interestingly, the extinction-induced suppression of fear ensemble activity was not detected in ventral CA1. Our snRNA-seq analysis demonstrates that extinction training markedly changes transcription patterns in fear ensemble cells and that cells activated during recall of fear and recall of extinction have distinct transcriptomic profiles. Together, our results indicate that extinction training suppresses a broad portion of the fear ensemble in the hippocampus, and this suppression is accompanied by changes in the transcriptomes of fear ensemble cells and the emergence of a transcriptionally unique extinction ensemble.

The “Lochkovian-Pragian Event” re-assessed: New data from the low latitude shelf of peri-Gondwana

In the late Lochkovian a regression is documented in several areas of the world, followed by a transgression in the early Pragian. Connected with the eustatic variation, a minor extinction event occurred (“Lochkovian-Pragian Event”), affecting several fossil groups, a strong reduction of carbonate production and sedimentary facies changes. The Carnic Alps are a key area for studying this event, because lower Devonian rocks are widely exposed, representing diverse sedimentary environments from shallow water to relatively deep shelf. Fourteen sections were measured along the Carnic Alps across the Lochkovian-Pragian boundary. In the shallower part of the basin, both the Polinik and the Seekopf formations span the boundary, but evident erosional surfaces are observable in the field at the Lochkovian-Pragian boundary. Above the unconformity, at places the so-called megaclast horizon is present in the Seekopf Formation. In intermediate settings the Rauchkofel Fm. Is unconfomably followed by the Kellerwand Fm., and different parts of the upper Lochkovian and lower Pragian are missing in the various sections. In the deeper parts of the basin the transition from the La Valute Fm. To the Findenig Fm. Is slightly diachronous from the latest Lochkovian to the earliest Pragian; however, conodonts and tentaculitids are rare in the marly boundary beds, preventing a precise chronostratigraphic calibration of these levels. At places, evidence of subaerial exposure at the formational boundary is documented. In general, the hiatus seems to be larger in the western part of the Carnic Alps, in correspondence with the shallower parts of the succession, suggesting a sea level drop in the late Lochkovian, followed by a transgression in the Pragian. Data from the Carnic Alps are compared with those of other regions of North Gondwana to demonstrate that the sea-level variation at the Lochkovian-Pragian boundary are of global importance

Seasonal trends and light extinction effects of PM2.5 chemical composition from 2021 to 2022 in a typical industrial city of central China

Seasonal trends and light extinction effects of PM2.5 chemical composition from 2021 to 2022 in a typical industrial city of central China

Cretaceous stratigraphy in the Songliao Basin, NE China

The Songliao Basin is one of the largest non-marine oil- and gas-bearing basins that developed during the Cretaceous period, recording an almost complete Cretaceous stratigraphy. With oil and gas exploration, as well as the Continental Scientific Drilling Project of Cretaceous Songliao Basin (CCSD-SK) (2006–21), significant progress has been made on the stratigraphy of the Songliao Basin. The Songliao Basin is therefore important for understanding the non-marine Cretaceous system. Based on lithostratigraphy, sequence stratigraphy, biostratigraphy, geochronology, magnetostratigraphy and cyclostratigraphy, a comprehensive stratigraphical framework of the Songliao Basin has been established in this study. The Lower Cretaceous strata (Hauterivian–Albian) of the basin are dominated by volcanic–sedimentary deposits, while the lower-middle Upper Cretaceous (Cenomanian mid-Campanian) strata are dominated by lacustrine deposits. The upper Upper Cretaceous strata (late Campanian–Maastrichtian) are dominated by fluvial–lacustrine deposits. Fossils are very abundant in the Songliao Basin, and three biotas – the Jehol Biota sensu lato , the Songhuajiang Biota and the Mingshui Biota – are recognized in the Songliao Basin. Furthermore, several important geological events, such as lake anoxic events, seawater incursion events and the K/Pg boundary extinction events are all recorded in the Songliao Basin.

Rethinking the Anthropocene: Not a time-transgressive event but a sudden rupture on the geologic time scale

The recent decision by the International Commission on Stratigraphy to reject the Anthropocene as an Epoch has reignited the debate on its definition. Some scholars have argued for interpreting the Anthropocene as an Event with no specific point of onset, but this argument has its shortcomings, including the fact that the term event has multiple connotations. This Viewpoint adds important insight to the ongoing debate by positing that (i) deliberations on the Anthropocene’s definition should not be confined to geological and historical viewpoints and must include ecological insights, and (ii) there is widespread evidence of anthropogenic reconfiguration of the planetary biosphere which translates to an accelerating sixth mass extinction as well as a conspicuous rise in the Human Appropriation of Net Primary Productivity (HANPP) at an unprecedented rate during the past few decades. When considered together with rapid anthropogenic climate change, these trends mark a major departure from previous trends on the geologic timescale, and they clearly show that the planetary biosphere has recently undergone a sudden and abrupt shift into a novel state, which cannot be adequately described by a temporally diffuse, gradual event; and must be conceptualized as a rupture—a geologically sudden major departure from prevalent trends; which in turn justifies the conceptualization of the Anthropocene as a separate chronostratigraphic unit. Understanding the catastrophic nature of the recent anthropogenic impact on the planetary biosphere is crucial for interpreting the Anthropocene and geologists must be cautious not to dilute its magnitude.

A Phylogenomic Backbone for Acoelomorpha Inferred from Transcriptomic Data.

Xenacoelomorpha are mostly microscopic, morphologically simple worms, lacking many structures typical of other bilaterians. Xenacoelomorphs -which include three main groups: Acoela, Nemertodermatida, and Xenoturbella- have been proposed to be an early diverging Bilateria, sister to protostomes and deuterostomes, but other phylogenomic analyses have recovered this clade nested within the deuterostomes, as sister to Ambulacraria. The position of Xenacoelomorpha within the metazoan tree has understandably attracted a lot of attention, overshadowing the study of phylogenetic relationships within this group. Given that Xenoturbella includes only six species whose relationships are well understood, we decided to focus on the most speciose Acoelomorpha (Acoela + Nemertodermatida). Here, we have sequenced 29 transcriptomes, doubling the number of sequenced species, to infer a backbone tree for Acoelomorpha based on genomic data. The recovered topology is mostly congruent with previous studies. The most important difference is the recovery of Paratomella as the first off-shoot within Acoela, dramatically changing the reconstruction of the ancestral acoel. Besides, we have detected incongruence between the gene trees and the species tree, likely linked to incomplete lineage sorting, and some signal of introgression between the families Dakuidae and Mecynostomidae, which hampers inferring the correct placement of this family and, particularly, of the genus Notocelis. We have also used this dataset to infer for the first time diversification times within Acoelomorpha, which coincide with known bilaterian diversification and extinction events. Given the importance of morphological data in acoelomorph phylogenetics, we tested several partitions and models. Although morphological data failed to recover a robust phylogeny, phylogenetic placement has proven to be a suitable alternative when a reference phylogeny is available.

Is Gamma-Ray Burst 221009A Really a Once-in-10,000 yr Event?

Gamma-ray bursts (GRBs) brighter than the GRB 221009A, the brightest yet observed, have previously been estimated to occur at a rate of one per 10,000 yr, based on the extrapolation of the distribution of fluences of the long-GRB population. We show that bursts this bright could instead have a rate as high as approximately one per 200 yr if they are from a separate population of narrow-jet GRBs. This population must have a maximum redshift of about z ≈ 0.38 in order to avoid overproducing the observed rate of fainter GRBs. We show that it will take ≳100 yr to confirm this new population based on observing another GRB from it with a γ-ray detector; observing an orphan optical afterglow from this population with Vera Rubin Observatory or an orphan radio afterglow with the Square Kilometer Array will also take similarly long times to observe, and it is unclear if they could be distinguished from the standard GRB population. We show that the nearby narrow-jet population has more favorable energetics for producing ultra-high-energy cosmic rays than standard GRBs. The rate of bursts in the Milky Way bright enough to cause mass extinctions of life on Earth from the narrow-jet population is estimated to be approximately one per 500 Myr. This GRB population could make life in the Milky Way less likely, with implications for future searches for life on exoplanets.

Trade-offs between receptor modification and fitness drive host-bacteriophage co-evolution leading to phage extinction or co-existence.

Parasite-host co-evolution results in population extinction or co-existence, yet the factors driving these distinct outcomes remain elusive. In this study, Salmonella strains were individually co-evolved with the lytic phage SF1 for 30days, resulting in phage extinction or co-existence. We conducted a systematic investigation into the phenotypic and genetic dynamics of evolved host cells and phages to elucidate the evolutionary mechanisms. Throughout co-evolution, host cells displayed diverse phage resistance patterns: sensitivity, partial resistance, and complete resistance, to wild-type phage. Moreover, phage resistance strength showed a robust linear correlation with phage adsorption, suggesting that surface modification-mediated phage attachment predominates as the resistance mechanism in evolved bacterial populations. Additionally, bacterial isolates eliminating phages exhibited higher mutation rates and lower fitness costs in developing resistance compared to those leading to co-existence. Phage resistance genes were classified into two categories: key mutations, characterized by nonsense/frameshift mutations in rfaH-regulated rfb genes, leading to the removal of the receptor O-antigen; and secondary mutations, which involve less critical modifications, such as fimbrial synthesis and tRNA modification. The accumulation of secondary mutations resulted in partial and complete resistance, which could be overcome by evolved phages, whereas key mutations conferred undefeatable complete resistance by deleting receptors. In conclusion, higher key mutation frequencies with lower fitness costs promised strong resistance and eventual phage extinction, whereas deficiencies in fitness cost, mutation rate, and key mutation led to co-existence. Our findings reveal the distinct population dynamics and evolutionary trade-offs of phage resistance during co-evolution, thereby deepening our understanding of microbial interactions.

Exceptionally preserved burrows of ichnogenus Asterosoma from the lower Silurian of South China: systematic ichnology, palaeoecology and implications for ecosystem recovery following the late Ordovician mass extinction

Exceptionally preserved complex burrows are described from the lower Silurian of South China, and they are identified as Asterosoma ludwigae Schlirf, 2000, which is characterized by the straight or curved bulbs that bud from an axial, vertical or horizontal, cylindrical burrow following a dichotomous or fan-like pattern. Striae and concentric lamination of burrow fills indicate that the special mining behaviour of the tracemaker reflects appendages that imprinted the burrow wall during their activities, speculating that polychaetes or holothuroides could be strong candidates of the tracemaker of A . ludwigae . Abundant organic-matter-rich peloids and muddy matrix in burrow fills may consist of tracemaker's secretions or excrement. Abundant extracellular polymeric substance (EPS) and clay minerals in filling sediment indicate the possible presence of microbes, implying that Asterosoma is not a simple fodinichnion, but rather created a beneficial symbiosis between tracemakers and microbes in burrows. Phanerozoic spatiotemporal distributions indicate that Asterosoma was distributed in broad habitats from deep sea to delta, but showed a strong preference for the shallow sea. Compilation of new ichnofossils and previously reported ichnotaxa from South China reveals that ichnospecies richness, burrow size and complexity all increased significantly during the late Aeronian, indicating a full recovery after the late Ordovician mass extinction.

Surprisingly wide climatic niche breadth of a relict mountain species raises hope for survival under climate change

AbstractAimsWe assessed the juvenile climatic niche breadth of a relict mountain species by comparing field observations and transplant experiments within and beyond the elevational limits of its distribution range.LocationLebanon – Near East – Mediterranean region.MethodsWe studied the survival and growth of the Cedar of Lebanon (Cedrus libani) to determine the lower and upper elevational range limits of its juvenile stage through an experimental setup with and without water supplementation and with potentially competing species as a control. The experiment included eight common gardens at elevations ranging from 110 to 2330 m, within and far beyond the warm and cold limits of Cedar distribution observed under natural conditions.ResultsWe observed unexpectedly high survival and growth rates of Cedar at elevations well below the range of its natural distribution in Lebanon. Below the observed warm limit, water stress at very low elevations and competition at low and medium elevations limited juvenile survival. In contrast, cold temperature and water stress limited survival at elevations slightly above the observed upper natural limit. The experimental setup demonstrated that the elevation range suitable for Cedar growth and survival was twice as wide as the range within which Cedar is observed under natural conditions.Main ConclusionsHigh survival rates experimentally observed beyond the warm limit of the natural distribution range of the Cedar of Lebanon raise hope for its resilience to ongoing climate warming. If this pattern were frequent among montane species, it would challenge predictions of massive extinction with climate change and pave the way for promoting adaptive actions such as competition management to improve their survival.

Rugose Coral Biogeography of the Western Palaeotethys During the Mississippian

The Mississippian was an epoch of strong earth system changes, both tectonic and climatic. During the Mississippian, the marine faunas experienced a recovery after the late Devonian mass extinctions, and the rugose corals are a conspicuous example. This study tries to give a general view of the utility of rugose coral to reconstruct the palaeogeography in the Western Palaeotethys during the Mississippian. The methodology includes a database with the genera and species recorded in that area and time period, compiled using more than 700 articles and revisions of several collections in Europe. We worked with the six sub-provinces defined in previous studies for the Western Palaeotethys. A generic-level analysis was performed using paired group hierarchical clustering, building clusters for the Tournaisian, early Visean, late Visean and Serpukhovian. With that information, palaeomaps for those intervals have been illustrated and discussed. The rugose corals have some deficits for the reconstruction of the biogeography because of their strong palaeoecologic control and their insufficient and unequal record, but they provide important information that improves the knowledge on the palaeogeography of the studied region.

ExoLyn: A golden mean approach to multispecies cloud modeling in atmospheric retrieval

Clouds are ubiquitous in exoplanets' atmospheres and play an important role in setting the opacity and chemical inventory of the atmosphere. Understanding clouds is a critical step in interpreting exoplanets' spectroscopic data. The aim is to model the multispecies nature of clouds in atmospheric retrieval studies. To this end, we developed -- a 1D cloud model that balances physical consistency with computational efficiency. solves the transport equation of cloud particles and vapor under cloud condensation rates that are self-consistently calculated from thermodynamics. is a standalone, open source package capable of being combined with optool to calculate solid opacities and with petitRADTRANS to generate transmission or emission spectra. With we find that the compositional structure of clouds in hot Jupiter planets' atmospheres is layered with a cloud dominated by magnesiumsilicates on top of an iron cloud. This finding is consistent with more complex cloud formation models but can be obtained with in only a few seconds. The composition of the cloud particles can be constrained from the spectrum, for example MgSiO3 and Mg2SiO4 components give rise to an absorption feature at $8-10\ m $. We investigate the dependence of the cloud structure on the bulk elemental composition of the planet and find that SiO2 -dominated clouds form on metal-rich planets and Fe clouds with a strong extinction effect form on C-rich planets. Designed toward maximum flexibility can also be used in retrieval analysis of sub-Neptunes and self-luminous planets. The efficiency of opens the possibility of joint retrieval of exoplanets' gas and cloud components.

Characterization of genome-wide phylogenetic conflict uncovers evolutionary modes of carnivorous fungi.

Mass extinction has often paved the way for rapid evolutionary radiation, resulting in the emergence of diverse taxa within specific lineages. The emergence and diversification of carnivorous nematode-trapping fungi (NTF) in Ascomycota have been linked to the Permian-Triassic (PT) extinction, but the processes underlying NTF radiation remain unclear. We conducted phylogenomic analyses using 23 genomes that represent three NTF lineages, each employing distinct nematode traps-mechanical traps (Drechslerella spp.), three-dimensional (3D) adhesive traps (Arthrobotrys spp.), and two-dimensional (2D) adhesive traps (Dactylellina spp.), and the genome of one non-NTF species as the outgroup. These analyses revealed multiple mechanisms that likely contributed to the tempo of the NTF evolution and rapid radiation. The species tree of NTFs based on 2,944 single-copy orthologous genes suggested that Drechslerella emerged earlier than Arthrobotrys and Dactylellina. Extensive genome-wide phylogenetic discordance was observed, mainly due to incomplete lineage sorting (ILS) between lineages. Two modes of non-vertical evolution (introgression and horizontal gene transfer) also contributed to phylogenetic discordance. The ILS genes that are associated with hyphal growth and trap morphogenesis (e.g., those associated with the cell membrane system and polarized cell division) exhibited signs of positive selection.IMPORTANCEBy conducting a comprehensive phylogenomic analysis of 23 genomes across three NTF lineages, the research reveals how diverse evolutionary mechanisms, including ILS and non-vertical evolution (introgression and horizontal gene transfer), contribute to the swift diversification of NTFs. These findings highlight the complex evolutionary dynamics that drive the rapid radiation of NTFs, providing valuable insights into the processes underlying their diversity and adaptation.

The biogeographic history of the allokotosaurian archosauromorphs in the Triassic of Pangaea

ABSTRACT Allokotosauria (Trilophosauridae + Azendohsauridae) is a clade of Early – Late Triassic quadruped, sprawling archosauromorphs with diverse dietary habits, known from Madagascar, India, Morocco, North America, and Europe. We conducted the first quantitative biogeographic analysis of the clade to reconstruct its ancestral areas and dispersal events. The results estimated the India + Tanzania area as ancestral for Allokotosauria. Eastern North America was reconstructed as the ancestral area of Trilophosauridae, implying an Early Triassic Southern to Northern Hemisphere dispersal. Subsequently, trilophosaurids were restricted to the Northern Hemisphere, and at least two dispersal events from Europe to western North America are estimated during the early Anisian and probably during the early Carnian, respectively. Azendohsauridae retained the ancestral area of India + Tanzania during much of its evolutionary history. Two dispersal events to western and eastern North America, respectively, are reconstructed during the Carnian – early Norian, likely during or in the aftermath of the Carnian Pluvial Episode (CPE). This pattern mirrors that of early dinosaurs, which were restricted to the Southern Hemisphere with dispersals to the Northern Hemisphere not recorded until the end of the CPE. This study informs about biogeographic patterns involved in the biotic recovery after the end-Permian mass extinction and the early evolutionary radiation of Archosauromorpha.

The Permian – Triassic boundary in Peninsular India and the extinction of the Glossopteridales

The Glossopteridales was a distinctive order of gymnospermous seed-plants that occurred widely in the Permian of Gondwana. Some authors have suggested that they may also have occurred in the Triassic and so had survived the catastrophic Permian – Triassic extinction event. This suggestion was mainly based on records from peninsular India such as from the Panchet Formation, which traditionally was regarded as Triassic in age. This paper reviews the evidence for a Triassic age for these floras and it is argued that they are in fact late Permian. There is no clear evidence that the Glossopteridales survived the P/T biotic crisis in India and only unequivocal evidence is in China that they survived into the Triassic.