Review of the marsupials (Mammalia: Metatheria) from the late Paleogene (Chadronian–Arikareean: late Eocene–late Oligocene) of North America

The taxonomy of marsupials from the late Paleogene of North America (Chadronian to Arikareean North American land mammal ages: late Eocene–late Oligocene) is reviewed based on new and previously undescribed fossil material as well as reevaluation of previously described material. Two families are recognized, the Herpetotheriidae and Peradectidae. Nine species of herpetotheriids are recognized within two genera: Herpetotherium Cope, 1873a and Copedelphys Korth, 1994, including one new species, H. tabrumi. The greatest diversity of herpetotheriids was in the Chadronian (four species). By the late Arikareean, only a single species is recognized. The range of Copedelphys is extended into the early Whitneyan (previously limited to Chadronian–Orellan). Among species of Herpetotherium, the ranges of two species have been extended: H. valens (Lambe, 1908) from the Chadronian is reported from the Orellan, and H. marsupium (Troxell, 1923) from the Uintan and Duchesnean is reported from the early Chadronian. The range of H. merriami (Stock and Furlong, 1922), previously only known from the Arikareean of Oregon, is expanded geographically eastward to Montana. Within the Peradectidae only three species are recognized: Peradectes cf. californicus (Stock, 1936) and Didelphidectes pumilis Hough, 1961 from the Chadronian, and Nanodelphys hunti (Cope, 1873b) from the Orellan to early Arikareean. Specimens previously identified as an unnamed new species of Nanodelphys from the Whitneyan and Arikareean are referred here to N. hunti.     

BIODIVERSITY RESEARCH: Nestedness for different reasons: the distributions of birds,lizards and small mammals on islands of an inundated lake

Aim We examined whether the community compositions of birds, lizards and small mammals were nested in a fragmented landscape in the Thousand Island Lake, China. We also assessed whether the mechanisms influencing nestedness differed among these taxonomic groups. Location Thousand Island Lake, China. Methods Presence/absence matrices were compiled for birds (42 islands) and lizards (42 islands) using line‐transect methods, and for small mammals (14 islands) using live‐trapping methods from 2006 to 2009. Nestedness was analysed using BINMATNEST, and statistical significance was assessed using the conservative null model 3. We used Spearman rank correlations and partial Spearman rank correlations to examine associations of nestedness and habitat variables (area, isolation, habitat diversity and plant richness) as well as life‐history traits (body size, habitat specificity, geographical range size and area requirement) related to species extinction and immigration tendencies. Results The community compositions of birds, lizards and small mammals were all significantly nested, but the causal factors underlying nestedness differed among taxonomic groups. For birds, island area, habitat specificity and area requirement were significantly correlated with nestedness after controlling for other independent variables. For lizards, habitat heterogeneity was the single best correlate of nestedness. For small mammals, island area, habitat heterogeneity and habitat specificity were significantly correlated with nestedness. The nested patterns of birds, lizards and small mammals were not attributable to passive sampling or selective colonization. Main conclusions The processes influencing nested patterns differed among taxonomic groups. Nestedness of bird assemblages was driven by selective extinction, and lizard assemblage was caused by habitat nestedness, while nestedness of small mammals resulted from both selective extinction and habitat nestedness. Therefore, we should take taxonomic differences into account when analysing nestedness to develop conservation guidelines and refrain from using single taxa as surrogates for others.     

EXTINCTION SPACE—A METHOD FOR THE QUANTIFICATION AND CLASSIFICATION OF CHANGES IN MORPHOSPACE ACROSS EXTINCTION BOUNDARIES

Three main modes of extinction are responsible for reductions in morphological disparity: (1) random (caused by a nonselective extinction event); (2) marginal (a symmetric, selective extinction event trimming the margin of morphospace); and (3) lateral (an asymmetric, selective extinction event eliminating one side of the morphospace). These three types of extinction event can be distinguished from one another by comparing changes in three measures of morphospace occupation: (1) the sum of range along the main axes; (2) the sum of variance; and (3) the position of the centroid. Computer simulations of various extinction events demonstrate that the pre‐extinction distribution of taxa (random or normal) in the morphospace has little influence on the quantification of disparity changes, whereas the modes of the extinction events play the major role. Together, the three disparity metrics define an “extinction‐space” in which different extinction events can be directly compared with one another. Application of this method to selected extinction events (Frasnian‐Famennian, Devonian‐Carboniferous, and Permian‐Triassic) of the Ammonoidea demonstrate the similarity of the Devonian events (selective extinctions) but the striking difference from the end‐Permian event (nonselective extinction). These events differ in their mode of extinction despite decreases in taxonomic diversity of similar magnitude.     

Global Taxonomic Diversity of Anomodonts (Tetrapoda,Therapsida) and the Terrestrial Rock Record Across the Permian-Triassic Boundary

The end-Permian biotic crisis (∼252.5 Ma) represents the most severe extinction event in Earth''s history. This paper investigates diversity patterns in Anomodontia, an extinct group of therapsid synapsids (‘mammal-like reptiles’), through time and in particular across this event. As herbivores and the dominant terrestrial tetrapods of their time, anomodonts play a central role in assessing the impact of the end-Permian extinction on terrestrial ecosystems. Taxonomic diversity analysis reveals that anomodonts experienced three distinct phases of diversification interrupted by the same number of extinctions, i.e. an end-Guadalupian, an end-Permian, and a mid-Triassic extinction. A positive correlation between the number of taxa and the number of formations per time interval shows that anomodont diversity is biased by the Permian-Triassic terrestrial rock record. Normalized diversity curves indicate that anomodont richness continuously declines from the Middle Permian to the Late Triassic, but also reveals all three extinction events. Taxonomic rates (origination and extinction) indicate that the end-Guadalupian and end-Permian extinctions were driven by increased rates of extinction as well as low origination rates. However, this pattern is not evident at the final decline of anomodont diversity during the Middle Triassic. Therefore, it remains unclear whether the Middle Triassic extinction represents a gradual or abrupt event that is unique to anomodonts or more common among terrestrial tetrapods. The end-Permian extinction represents the most distinct event in terms of decline in anomodont richness and turnover rates.     

Severe extinction and rapid recovery of mammals across the Cretaceous–Palaeogene boundary,and the effects of rarity on patterns of extinction and recovery

The end‐Cretaceous mass extinction ranks among the most severe extinctions of all time; however, patterns of extinction and recovery remain incompletely understood. In particular, it is unclear how severe the extinction was, how rapid the recovery was and how sampling biases might affect our understanding of these processes. To better understand terrestrial extinction and recovery and how sampling influences these patterns, we collected data on the occurrence and abundance of fossil mammals to examine mammalian diversity across the K‐Pg boundary in North America. Our data show that the extinction was more severe and the recovery more rapid than previously thought. Extinction rates are markedly higher than previously estimated: of 59 species, four survived (93% species extinction, 86% of genera). Survival is correlated with geographic range size and abundance, with widespread, common species tending to survive. This creates a sampling artefact in which rare species are both more vulnerable to extinction and less likely to be recovered, such that the fossil record is inherently biased towards the survivors. The recovery was remarkably rapid. Within 300 000 years, local diversity recovered and regional diversity rose to twice Cretaceous levels, driven by increased endemicity; morphological disparity increased above levels observed in the Cretaceous. The speed of the recovery tends to be obscured by sampling effects; faunas show increased endemicity, such that a rapid, regional increase in diversity and disparity is not seen in geographically restricted studies. Sampling biases that operate against rare taxa appear to obscure the severity of extinction and the pace of recovery across the K‐Pg boundary, and similar biases may operate during other extinction events.     

Pattern and process in the geographical ranges of freshwater fishes

North American freshwater fishes were studied to determine whether they displayed the same relationships between log (geographical range size) and log (body size) and the same pattern of range shape as found among North American birds and mammals. The forces that produce these patterns were also investigated. The log (geographical range size) : log (body size) relationship was analysed for 121 North American freshwater fish species. Thirty‐two imperilled species were compared with 89 non‐imperilled species to determine if the overall relationship could result from differential extinction. Range geometries were analysed, within and among habitat guilds, to determine if general patterns could be detected. The log (geographical range size) : log (body size) pattern among freshwater fish species was triangular and qualitatively similar to that found for North American birds and mammals. The results suggest that below a minimum geographical range, the likelihood of extinction increases dramatically for freshwater fishes and that this minimum range size increases with body size. The pattern of fish species’ range shapes differs from that found for other North American vertebrate taxa because, on average, fish possess much smaller ranges than terrestrial species and most fish species’ geographical ranges extend further on a north–south axis than on an east–west axis. The log (geographical range size) : log (body size) pattern reveals that fish species’ geographical ranges are more constrained than those of terrestrial species. The triangular relationship may be caused by differential extinction of species with large bodies and small geographical ranges as well as higher speciation rates of small‐bodied fish. The restricted geographical ranges of freshwater fishes gives them much in common with terrestrial species on oceanic islands. Range shape patterns within habitat guilds reflect guild‐specific historical and current ecological forces. The overall pattern of range shapes emerges from the combination of ecologically different subunits.     

Five hundred million years of extinction and recovery: a phanerozoic survey of large‐scale diversity patterns in fishes

Abstract: Fishes include more than half of all living animals with backbones, but large‐scale palaeobiological patterns in this assemblage have not received the same attention as those for terrestrial vertebrates. Previous surveys of the fish record have generally been anecdotal, or limited either in their stratigraphic or in their taxonomic scope. Here, we provide a broad overview of the Phanerozoic history of fish diversity, placing a special emphasis on intervals of turnover, evolutionary radiation, and extinction. In particular, we provide in‐depth reviews of changes during, and ecological and evolutionary recovery after, the end‐Devonian (Hangenberg) and Cretaceous–Palaeogene (K–Pg) extinctions.     

Early Cenozoic increases in mammal diversity cannot be explained solely by expansion into larger body sizes

A prominent hypothesis in the diversification of placental mammals after the Cretaceous–Palaeogene (K/Pg) boundary suggests that the extinction of non-avian dinosaurs resulted in the ecological release of mammals, which were previously constrained to small body sizes and limited species richness. This ‘dinosaur incumbency hypothesis’ may therefore explain increases in mammalian diversity via expansion into larger body size niches, that were previously occupied by dinosaurs, but does not directly predict increases in other body size classes. To evaluate this, we estimate sampling-standardized diversity patterns of terrestrial North American fossil mammals within body size classes, during the Cretaceous and Palaeogene. We find strong evidence for post-extinction diversity increases in all size classes. Increases in the diversity of small-bodied species (less than 100 g, the common body size class of Cretaceous mammals, and much smaller than the smallest non-avialan dinosaurs (c. 400 g)) were similar to those of larger species. We propose that small-bodied mammals had access to greater energetic resources or were able to partition resources more finely after the K/Pg mass extinction. This is likely to be the result of a combination of widespread niche clearing due to the K/Pg mass extinctions, alongside a suite of biotic and abiotic changes that occurred during the Late Cretaceous and across the K/Pg boundary, such as shifting floral composition, and novel key innovations among eutherian mammals.     

Permian–Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution

The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end‐Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian–Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian–Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, ‘Palaeopterygii’, ‘Subholostei’, Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end‐Guadalupian crisis is not evident from our data, but ‘palaeopterygians’ experienced a significant body size increase across the Guadalupian–Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian–Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, ‘palaeopterygians’, ‘subholosteans’) and a second one during the Middle Triassic (‘subholosteans’, neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle–Late Permian, resulted in a profound change within global fish communities, from chondrichthyan‐rich faunas of the Permo‐Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.     

What really happened in the late Triassic?

Major extinctions occurred both in the sea and on land during the Late Triassic in two major phases, in the middle to late Carnian and, 12–17 Myr later, at the Triassic‐Jurassic boundary. Many recent reports have discounted the role of the earlier event, suggesting that it is (1) an artefact of a subsequent gap in the record, (2) a complex turnover phenomenon, or (3) local to Europe. These three views are disputed, with evidence from both the marine and terrestrial realms. New data on terrestrial tetrapods suggests that the late Carnian event was more important than the end‐Triassic event. For tetrapods, the end‐Triassic extinction was a whimper that was followed by the radiation of five families of dinosaurs and mammal‐like reptiles, while the late Carnian event saw the disappearance of nine diverse families, and subsequent radiation of 13 families of turtles, crocodilomorphs, pterosaurs, dinosaurs, lepidosaurs and mammals. Also, for many groups of marine animals, the Carnian event marked a more significant turning point in diversification than did the end‐Triassic event.     

Taxonomic diversity of the terrestrial bird and mammal fauna in temperate and boreal biomes of the northern hemisphere

Abstract. Using comprehensive range information of northern Hemisphere birds and mammals, we assessed the taxonomic diversity of these two groups in four different regions: Europe, east Asia, and western and eastern North America. East Asia is the richest region in the number of bird and mammal species, genera, families and orders, except that mammal species richness is highest in western North America. Eastern North America is taxonomically the poorest region, but when only forest-associated taxa were considered in mammals taxonomic diversity is equally low in Europe and in eastern North America, and in birds, Europe is the least diverse region. Patterns in endemic taxa follow overall taxonomic diversity. The proportion of shared taxa between regions is higher among boreal species and genera than among all taxa. A comparison with tree species diversity underpins the role of east Asia as the most diverse of all northern biota. Largely congruent patterns at different taxonomic levels emphasizes the role of historical processes, such as differential extinction rate in response to paleoenvironmental fluctuations, in producing these patterns, but we stress the need for more research on the coevolution of species diversity and habitat diversity.     

Interactions within and between clades shaped the diversification of terrestrial carnivores

A longstanding debate in evolutionary biology and paleontology is whether ecological interactions such as competition impose diversity dependence on speciation and extinction rates. Here, we analyze the fossil record of terrestrial mammalian carnivores in North America and Eurasia using a Bayesian framework to assess whether their diversity dynamics were affected by diversity dependence within and between families (12 in Eurasia, 10 in North America). We found eight instances of within‐clade diversity dependence suppressing speciation rates and detected between‐clade effects increasing extinction rates in six instances. Diversity dependence often involved lineages that migrated between continents and we found that speciation was more responsive to diversity changes within the clade, whereas extinction responded to diversity of taxa in other clades. The analysis of the fossil record of Carnivora suggests that interactions within and between clades are associated with different speciation and extinction regimes, opening room for a broader theory of diversity dependence.     

Exploring the phylogenetic history of mammal species richness

Aim At broad geographical scales, species richness is a product of three basic processes: speciation, extinction and migration. However, determining which of these processes predominates is a major challenge. Whilst palaeontological studies can provide information on speciation and extinction rates, data are frequently lacking. Here we use a recent dated phylogenetic tree of mammals to explore the relative importance of these three processes in structuring present‐day richness gradients. Location The global terrestrial biosphere. Methods We combine macroecological data with phylogenetic methods more typically used in community ecology to describe the phylogenetic history of regional faunas. Using simulations, we explore two simple phylogenetic metrics, the mean and variance in the pairwise distances between taxa, and describe their relationship to phylogenetic tree topology. We then use these two metrics to characterize the evolutionary relationships among mammal species assemblages across the terrestrial biome. Results We show that the mean and variance in the pairwise distances describe phylogenetic tree topology well, but are less sensitive to phylogenetic uncertainty than more direct measures of tree shape. We find the phylogeny for South American mammals is imbalanced and ‘stemmy’ (long branches towards the root), consistent with recent diversification within evolutionarily disparate lineages. In contrast, the phylogeny for African mammals is balanced and ‘tippy’ (long branches towards the tips), more consistent with the slow accumulation of diversity over long times, reflecting the Old World origin of many mammal clades. Main conclusions We show that phylogeny can accurately capture biogeographical processes operating at broad spatial scales and over long time periods. Our results support inferences from the fossil record – that the New World tropics are a diversity cradle whereas the Old World tropics are a museum of old diversity.     

The evolution of aquatic feeding in seals: insights from Enaliarctos (Carnivora: Pinnipedimorpha), the oldest known seal

The development of pierce‐feeding and loss of oral processing represented major adaptations for underwater feeding in marine mammals. We examined the evolution of pierce‐feeding and its association with changes in tooth spacing and tooth size to determine whether pierce‐feeding was practiced by the earliest known pinnipeds. Data on crown size and spacing in postcanine dentition were collected and 1) analysed by principal components analysis (PCA) to determine the tooth morphospace of arctoid carnivores, 2) analysed by least squares (LS) regression and phylogenetic independent contrasts (PIC) to determine what morphological variables were associated with increases in tooth spacing, and 3) used to reconstruct the evolution of feeding related traits within a phylogenetic context. The PCA analysis revealed that within arctoid carnivores, the greatest differences in morphospace were associated with pierce‐feeding, and the early‐diverging seal Enaliarctos was placed within the pinniped morphospace. Increased tooth spacing within Pinnipedia is a result of decreased postcanine crown size. When the evolution of dental characters is reconstructed, ‘enaliarctines’ were found to represent an intermediate stage in evolution between ‘fissiped’ and pinniped carnivores. They retained the limited tooth spacing of terrestrial carnivores, possessed postcanine crown lengths intermediate in size between pinnipeds and fissipeds, and possessed reduced heterodonty characteristic of crown pinnipeds. Our study indicated that pierce‐feeding evolved early within pinnipeds. This suggested either that pierce‐feeding evolved prior to the loss of mastication, or that pierce‐feeding evolved at the same time as loss of mastication, and well before simplification of the dentition was completed.     

Rise and fall of the phacopids: the morphological history of a successful trilobite family

Phacopidae were a successful family of the Silurian–Devonian period. Although their diversity trends are well identified, their shape evolution is unknown; their morphology often considered to be conservative. We have quantified these morphologies using geometric morphometrics (landmarks) and investigated their evolution using morphological disparity indices. Results identified morphological variations between the genera, and through time. Phacopids differ from each other by the position of the facial suture linked to the size of the visual complex, the shape of the genal angle and the elongation of both cephalon and pygidium. The morphological disparity of cephala was high from the Silurian, contrary to that of pygidia. Subsequently, the morphological disparity increased in the Early Devonian with the development of narrow cephala and triangular pygidia. Morphological disparity was greater in the Emsian for both cephala and pygidia, more than 50 myr after the origination of phacopids. It constituted a perfect example illustrating that a peak of biodiversity does not necessarily happen in the early history of a clade. Subsequently, a strong decrease of morphological disparity occurred in the Middle Devonian, in conjunction with sea-level changes and anoxic events. Taxonomic richness and morphological disparity declined strongly in the Givetian, in a non-random extinction affecting particularly blind genera. The morphological disparity remained low in the Frasnian despite progressive eye reduction influenced by environmental changes. An extensive recovery occurred in the Famennian with an important increase of both taxonomic and morphological diversity. The Hangenberg event caused the final extinction of phacopids.     

Decoupling of taxonomic diversity and morphological disparity during decline of the Cambrian trilobite family Pterocephaliidae

Although discordance between taxonomic diversity and morphological disparity is common, little is known about the underlying dynamics that drive this decoupling. Early in the history of the Cambrian trilobite family Pterocephaliidae, there was an increase in taxonomic diversity and morphological diversity. As taxonomic diversity declined in the later history of the clade, range of variation stayed high and disparity continued to increase. However, per‐branch rates of morphological evolution estimated from a recent phylogeny decreased with time. Neither within‐trait nor within‐species variation increased or decreased, suggesting that the declining rates of morphological evolution were more likely related to ecological opportunity or niche partitioning, rather than increasing intrinsic constraints. This is further supported by evidence for increased biofacies associations throughout the time period. Thus, the high disparity seen at low taxonomic diversity late in the history of this clade was due to extinction – either random or targeting mean forms – rather than increased rates of morphological evolution. This pattern also provides a scenario that could account for instances of low taxonomic diversity but high morphological disparity in modern groups.     

A palaeobotanical perspective on the great end-Permian biotic crisis

Mass extinctions are crucial to understanding changes in biodiversity through time. However, it is still disputed whether extinction dynamics in the marine and terrestrial biotas followed comparable trajectories. For instance, while marine realms have suffered five strong depletions in diversity, the so-called ‘Big Five’ mass extinctions, only the end-Permian event appears to have also resulted in a major abrupt reduction in continental diversity. However, recent evidence based on the diversity dynamics of vegetation has suggested the presence of two major episodes of extinction in the terrestrial environments, at the end-Carboniferous and the end-Permian times. This apparent contradiction is addressed in the present study. Here, we show that while the end-Carboniferous plant extinction was focused on particular environments (e.g. tropical wetlands) and affected mainly the free-sporing plant diversity (i.e. lycopsids, ferns and progymnosperms), only the end-Permian mass extinction had devastating effects on vegetation on a global scale. If we take the biosphere as a whole, the results highlight that the end-Permian biotic crisis was the only genuine global mass extinction event, affecting widely both the marine and terrestrial environments.     

Human pressures predict species’ geographic range size better than biological traits

Geographic range size is the manifestation of complex interactions between intrinsic species traits and extrinsic environmental conditions. It is also a fundamental ecological attribute of species and a key extinction risk correlate. Past research has primarily focused on the role of biological and environmental predictors of range size, but macroecological patterns can also be distorted by human activities. Here, we analyse the role of extrinsic (biogeography, habitat state, climate, human pressure) and intrinsic (biology) variables in predicting range size of the world's terrestrial mammals. In particular, our aim is to compare the predictive ability of human pressure vs. species biology. We evaluated the ability of 19 intrinsic and extrinsic variables in predicting range size for 4867 terrestrial mammals. We repeated the analyses after excluding restricted‐range species and performed separate analyses for species in different biogeographic realms and taxonomic groups. Our model had high predictive ability and showed that climatic variables and human pressures are the most influential predictors of range size. Interestingly, human pressures predict current geographic range size better than biological traits. These findings were confirmed when repeating the analyses on large‐ranged species, individual biogeographic regions and individual taxonomic groups. Climatic and human impacts have determined the extinction of mammal species in the past and are the main factors shaping the present distribution of mammals. These factors also affect other vertebrate groups globally, and their influence on range size may be similar as well. Measuring climatic and human variables can allow to obtain approximate range size estimations for data‐deficient and newly discovered species (e.g. hundreds of mammal species worldwide). Our results support the need for a more careful consideration of the role of climate change and human impact – as opposed to species biological characteristics – in shaping species distribution ranges.     

Niche width impacts vertebrate diversification

Aim The size of the climatic niche of a species is a major factor determining its distribution and evolution. In particular, it has been proposed that niche width should be associated with the rate of species diversification. Here, we test whether species niche width affects the speciation and extinction rates of three main clades of vertebrates: amphibians, mammals and birds. Location Global. Methods We obtained the time‐calibrated phylogenies, IUCN conservation status, species distribution maps and climatic data for 2340 species of amphibians, 4563 species of mammals and 9823 species of birds. We computed the niche width for each species as the mean annual temperature across the species range. We estimated speciation, extinction and transition rates associated with lineages with either narrow (specialist) or wide (generalist) niches using phylogeny‐based birth–death models. We also tested if current conservation status was correlated with the niche width of species. Results We found higher net diversification rates in specialist species than in generalist species. This result was explained by both higher speciation rates (for the three taxonomic groups) and lower extinction rates (for mammals and birds only) in specialist than in generalist species. In contrast, current specialist species tended to be more threatened than generalist species. Main conclusions Our diversification analysis shows that the width of the climatic niche is strongly associated with diversification rates and may thus be a crucial factor for understanding the emergence of diversity patterns in vertebrates. The striking difference between our diversification results and current conservation status suggests that the current extinction process may be different from extinction rates estimated from the whole history of the group.