It has been proposed that Otodus megalodon exhibits a Bergmann-like size pattern, with individuals growing larger in cooler waters, an interpretation used to challenge the existence of fossil nursery assemblages. Here, we reanalyse the dataset used to support this claim, restricting analyses to upper anterior teeth to control for dental positional effects. We test for temporal stability in body size across the Miocene and Pliocene and evaluate global-scale correlations between body size and sea-surface temperature. Using ordinary least squares and linear mixed-effects models in both frequentist and Bayesian frameworks, we find no statistically significant relationship between temperature and body size. Most regressions yield positive slopes, directly contradicting the negative trend predicted by Bergmann's rule. In contrast, nursery designation explains a substantially greater proportion of body size variation, showing a consistent and significant negative effect across all models. Furthermore, we develop an expanded modelling framework that relates temperature directly to tooth crown height while accounting for jaw and positional heterodonty and explicitly incorporating nursery designation and locality-level palaeotemperature uncertainty. Results from this approach likewise provide no support for a temperature-size relationship, while reinforcing the dominant influence of nursery assemblages on size variation. We identify conceptual and methodological limitations in the previous study, including biologically implausible size predictions and uncertain palaeotemperature estimates. Overall, our findings refute the proposed temperature-size pattern and support the interpretation of small-bodied fossil assemblages as juvenile-dominated nurseries, underscoring the importance of rigorous quantitative testing in macroecological analyses based on fossil data.
A new lace bug, Paleoanomala decapitata sp. nov. (Tingidae, Tingiometrinae), is described from Lower Cretaceous (upper Albian) amber of Pe & ntilde;acerrada I (Burgos, Spain). The genus Paleoanomala was previously known only from Cenomanian Kachin amber of Myanmar, and the discovery of this new species significantly expands its palaeogeographical range as well as the known diversity of lace bugs from Spanish amber deposits. Furthermore, the description of the new species urged us to undertake a reinterpretation of forewing venation in early lace bugs, finding nearly identical venation patterns in the extinct genera Paleoanomala and Tingiometra (Tingiometrinae), and Hispanocader (Hispanocaderidae). Based on this revised interpretation and other shared morphological characters, the extinct tingid subfamily Tingiometrinae and the family Hispanocaderidae are synonymized with Ebboidae, which is here treated as the subfamily Ebboinae stat. nov. within Tingidae. Additionally, Paleoanomala aptenus Poinar & Vega is recognized as a junior synonym of Tingiometra yuripopovi Golub & Heiss, and the latter species is transferred to Paleoanomala as Paleoanomala yuripopovi comb. nov. The affinities of the male paratype previously assigned to this species remain uncertain and it is tentatively treated as Ebboinae indet. Finally, a synthesis of the palaeobiogeographical affinities of arthropods from Cretaceous Spanish amber suggests extensive faunal connections between Iberia, Myanmar and the Middle East during the Early Cretaceous, reflecting the widespread distribution of resiniferous forest ecosystems across Laurasia.
Abstract Early Eocene birds from the British London Clay have been known for two centuries, but a comprehensive understanding of the avifauna of the London Clay Formation is still in its infancy. In the present study, the bird assemblage of the Walton Member is reviewed, which represents one of the oldest subdivisions of the formation. With more than 80 currently recognized species, it is one of the most comprehensive early Cenozoic avifaunas known to date. Some taxa are unknown from middle Eocene sites, while others have undergone few morphological changes over several million years, which may constitute evidence for niche conservatism in balanced ecosystems. The fossils show a high taxonomic concordance with coeval bird assemblages in North America, but the extent to which early Eocene avifaunas were similar on a global scale is unknown owing to the limited fossil record from the southern continents. The avian diversity of Walton‐on‐the‐Naze is not evenly distributed across neornithine phylogeny, and taxa of the Telluraves predominate. Other clades that produced arboreal birds are conspicuously absent. The occurrence of stem group representatives of multiple telluravian taxa suggests an initial diversification of the clade on the northern continents, which conflicts with biogeographic scenarios derived from the extant taxa. A notable feature of the avifauna of Walton‐on‐the‐Naze is the very small size of many species of the Telluraves and Strisores, which is attributed to the fact that these birds were at the beginning of an adaptive radiation.
A revision of fossil leaflets previously attributed to Mimosa or Mimosites from Palaeogene basins in southwestern Europe resulted in the establishment of three new combinations: Parvileguminophyllum norica, P. oblita and P. deperdita. These fossil-species coexisted under a relatively uniform climate during the Oligocene but differed in their distribution: P. deperdita grew across southern Europe, P. norica occurred in southwestern and Central Europe, and P. oblita in southwestern Europe. Morphological comparison with extant species shows strong similarities with certain Mimosa and Senegalia species that today inhabit seasonally dry tropical climates (Aw/As K & ouml;ppen climate types), contrasting with the humid subtropical conditions (Cfa/Cwa) inferred for the fossil localities containing the fossil-species. Integration of palaeoclimatic and palaeobiogeographic evidence suggests that P. norica, P. oblita and P. deperdita became extinct because of declining temperatures. Parvileguminophyllum deperdita appears to have persisted until the Late Miocene in Crete and Sicily, possibly due to their southerly positions and the 'island buffer effect', which may have mitigated the impacts of global cooling. These findings challenge the long-standing assumption that Palaeogene legumes from Europe necessarily indicate arid conditions.
Hexactinellids are sponges with a unique syncytial organization of soft tissues and siliceous six-rayed spicules. According to skeletal morphological synapomorphies, including siliceous spicules with axial filaments, the Hexactinellida are considered the sister group to the Demospongiae, the largest class of sponges, which have a ubiquitous cellular organization as well as monaxon and tetraxon spicules. This fundamental morphological difference between the classes raises an important question about the origins of crown-group hexactinellids and silicean sponges as a whole. An intact spiculate sponge Botomospongia sphaeroides gen. et sp. nov. from the lower Cambrian Stage 3/4 Sinsk Lagerst & auml;tte of the Siberian Platform provides new data on this issue. The new sponge possesses specialized anchor spicules and thick wall differentiated into distinct dermal and choanosomal skeletons. Intact preservation of tentative soft tissues points to features of its syncytial organization. In total, morphological features of B. sphaeroides indicate its stem-group hexactinellid affinities and suggest that its close relationships with possible early crown-group hexactinellids appeared in the Ordovician. A resulting combination of the most primitive and advanced hexactinellid features, observed in B. sphaeroides, can serve to differentiate new early Palaeozoic stem- and crown-group siliceans.
Nearly half of all living vertebrate diversity can be traced back to a single lineage of lobe-finned fishes (piscine sarcopterygians) that radiated during the Palaeozoic Era. In recent years, the phylogenetic framework of tetrapodomorph fishes has largely stabilized, with the exception of the 'Osteolepiformes', the interrelationships of which are still under debate. To resolve these uncertainties, expanded taxonomic sampling and new morphological data are essential to refine our understanding of their evolutionary history. Emerging tomography imaging techniques are providing much of this new anatomical information, including that pertaining to cranial endocasts. Endocasts can serve as proxies for gross brain morphology, and thus have the added benefit of shedding light on palaeoneurological evolution in long-extinct lineages. Here, using a combination of synchrotron, neutron and micro-computed tomography, we generate high-resolution 3D virtual models of ethmosphenoids and their associated cranial endocast and sensory (lateral) line canal systems in 13 stem tetrapods. Using principal components analysis for incomplete data we identify distinct patterns of morphospace occupation among the different families. While the 'Tristichopteridae' usually occupy a wholly distinct region, the 'Osteolepididae' and Megalichthyidae exhibit partial overlap, but with 'Osteolepididae' always showing a broader range of variation. Our findings demonstrate that ethmosphenoids and their endocasts retain morphological features of shared phylogenetic affinity that can aid in resolving phylogenetic placement of fragmentary or enigmatic taxa. Furthermore, palaeoneurobiological evidence from these 'Osteolepiformes' suggests that these fishes retained a more conservative sensory umwelt prior to the rapid emergence of enhanced visual acuity in the earliest tetrapods.
In this study we describe a corrosion pattern, interpreted as having been produced by digestion, on a hatchling Allosaurus maxilla from the former Guimarota coal mine fossil site. This site, located near Leiria in the west-central region of Portugal, is recognized as one of the most significant Upper Jurassic microvertebrate fossil localities worldwide. It is particularly renowned for its abundant and diverse fossil record of early mammalians, but a wide array of other vertebrates, including theropod dinosaurs, were also collected. The maxilla bears teeth that have been heavily corroded on the crowns, above the gum line, whereas the rest of the bone shows no signs of corrosion, suggesting a regurgitated partially digested animal. This represents the first record of a partially digested theropod fossil from the Upper Jurassic of Portugal and one of the few non-avian dinosaur specimens with such marks documented worldwide. Based on the fossil record from Guimarota and the observed corrosion pattern and preservation of the specimen, we suggest that the most likely consumer responsible for these marks was probably a non-avian theropod, although a pterosaur or crocodyliform producer also cannot be completely excluded. This study emphasizes that similar corrosion patterns may be more common in the Mesozoic fossil record than previously recognized and, when considered alongside additional evidence (e.g. fossil disarticulation and taphocenoses), can provide valuable insights into trophic interactions and ecosystem dynamics in ancient environments.
We describe a new large-sized paracrocodylomorph pseudosuchian, Shakajlura riojanensis gen. et sp. nov., from the Tarjadia Assemblage Zone (AZ) levels (upper Ladinian to lower Carnian) of the Cha & ntilde;ares Formation, La Rioja Province, northwestern Argentina. The specimen consists of several disarticulated cranial, and a few postcranial, bones and was collected from stratigraphic levels seemingly coeval with those where Luperosuchus fractus, a loricatan of similar size, was found. The general morphology and stratigraphic occurrence of Shakajlura riojanensis suggests the possibility of close affinities with Luperosuchus fractus, but considerable differences in key features between the two holotypes (e.g. Shakajlura riojanensis lacks the following: ornamentation on the lateral side of the maxilla, a prominent curvature of the dorsal portion of the nasals, and a knob-like structure on the postorbital) and a unique combination of character states among pseudosuchians enabled us to erect a new genus and species. Shakajlura riojanensis can be distinguished by the presence of a prominent shelf on the medial surface of the jugal, an incision on the ventral portion of the ascending process of the quadrate, and an enlarged prearticular compared with the preserved jaw elements. Shakajlura riojanensis is recovered as an early-diverging paracrocodylomorph, but the possibility that it represents an early-diverging member of Loricata cannot be discarded. This new species expands the current knowledge of the paracrocodylomorphs of the Tarjadia AZ and introduces a new component to the top predators of the Cha & ntilde;ares Formation.
Dinosaur eggs were recovered from the Dadaepo Basin in Busan (south-east Korea), which is early Late Cretaceous in age and is close to Japan, but the eggs have not been studied. Among East Asian egg-bearing basins, the Dadaepo Basin is characterized by exceptionally high thermal maturity (c. 310 degrees C), providing a unique opportunity to examine the influence of thermal maturation on the microstructural preservation of fossil eggs. In this study, we describe at least two distinct oogenera recovered from the Dadaepo Formation. The first is identified as Mosaicoolithus, an ootaxon indigenous to East Asia, while the second corresponds to Macroelongatoolithus, an ootaxon widely distributed across the lower Upper Cretaceous deposits of East Asia and North America. Notably, the microstructural preservation of eggshells from the Dadaepo Formation is nearly identical to that observed in specimens from less thermally mature basins in East Asia. This indicates that elevated thermal maturity does not necessarily result in the alteration of eggshell microstructure during fossilization. Microscopy and geochemistry assessments of fluid-mediated alteration may insufficiently screen thermally matured eggshells for clumped isotope analysis, which remain susceptible to geothermal heating. The Dadaepo Macroelongatoolithus refines the global chronological range for Macroelongatoolithus to the Cenomanian-Turonian. It indirectly supports an early Late Cretaceous age for the controversial age of the Iren Dabasu (or Erlian) Formation (Inner Mongolia, China), known for giant oviraptorosaurs. Furthermore, this global age constraint highlights Cenomanian-Turonian deposits in the Bering Strait region as promising targets for future Arctic Macroelongatoolithus discoveries.
The Cerro de Las Cabras Formation preserves one of the richest Triassic palynofloras in southwestern Gondwana, although detailed studies have focused only on its type section. To expand this view, we performed a palynological study in the Estancia La Obligaci & oacute;n area and contrasted findings with Potrerillos locality. This study identifies six genera and 28 species of palynomorphs not previously recorded here, raising the total diversity of the unit to 102 genera and 203 species. Assemblages are largely dominated by non-striate bisaccate pollen, while striate and monosulcate pollen appear in lower and increasing frequencies, respectively; spore abundance, although limited, is notable in the lower stratigraphic levels. The species accumulation curve indicates substantial potential for the discovery of new palynotaxa. Rarefaction analysis supports overall comparability among assemblages, despite observed differences in diversity patterns and slight variations in slope. The stratigraphic arrangement of palynological assemblages suggests a possible temporal control on their taxonomic composition; however, taxonomical differences among localities hinder reliable biostratigraphic correlation. The common presence of typical European taxa and joint occurrence of other palynostratigraphic markers from elsewhere, most of them already recorded in the type section, constrains the age of the unit in Estancia La Obligaci & oacute;n locality to the upper Anisian to lower Ladinian.
Dysalotosaurus lettowvorbecki (Ornithopoda, Dinosauria) is a small-sized dryosaurid iguanodontian known from various isolated remains collected from the Tendaguru Formation (Upper Jurassic, Tanzania). Micro-computed tomography of a small individual encased in a block offered a unique opportunity to describe c. 40 associated elements and clarify previously undocumented anatomical details of this species. The preserved material includes cranial elements, an almost complete cervical series, four dorsal vertebrae, and part of the appendicular skeleton. A comprehensive assessment of the individual, based on qualitative features and morphometric analyses, indicates an early ontogenetic stage and an absolute age of 4-5 years. Notably, the cervical vertebrae predominantly exhibit partially closed neurocentral sutures, whereas the two more posterior dorsal vertebrae have open sutures, along with disarticulated neural arches. This finding challenges the simple 'tail-to-head' fusion pattern typically assumed for the vertebral series of Ornithopoda, and suggests a potential cervical locus of neurocentral fusion within this clade. Phylogenetic comparative methods indicate a complex distribution of these neurocentral fusion patterns within Archosauria.
Cochlichnus anguineus is an ichnotaxon recognized for its distinctive regular wavy morphology. It is a characteristic trace fossil typically associated with aquatic and marginal aquatic environments. However, in this study we examine its unusual occurrence in the aeolian sandstones of the Botucatu Formation (Lower Cretaceous, Paran & aacute; Basin, Brazil). Drawing on neoichnological evidence from modern dune environments in Brazil and Namibia, we propose that stiletto fly larvae (Diptera, Therevidae) are the most likely tracemakers of these fossils. This represents the earliest known occurrence of Therevidae in the fossil record, supporting evidence from molecular analyses. Furthermore, we compare these traces with similar ones from other aeolian units, discussing ichnotaxonomic implications. A key focus is the nuanced distinction between trails and burrows. In light of this, we propose an emended diagnosis for ichnogenus Cochlichnus, restricting it to shallow trails made in the substrate and on its surface, reflecting a behavioural pattern distinct from Cymataulus. While Cymataulus also has a similar wavy pattern, it represents dwelling burrows rather than surface trails.
The Early Triassic is typically described as an interval of poor fossil preservation and low diversity in the aftermath of the Permian-Triassic mass extinction. For radiolarians, very little information is available due to the lack of known radiolarian-yielding locations. However, well-preserved radiolarians, including the oldest (Griesbachian, Early Triassic) occurrence of fossilized central capsule membranes, have been recovered from a shallow marine Permian/Triassic boundary succession at Lusitaniadalen (Svalbard) and described herein. Eleven species from seven genera of Radiolaria have been found, including three new species (?Entactinia sengeri, Archaeocenosphaera plankei and Thaisphaera ullarinmanae) and two new subspecies (?Entactinia meishanensis smyraksikorae and Grandetortura nipponica stepheni). Combined with the unexpectedly high diversity of other organisms from the Permian/Triassic boundary in Svalbard, these new data further indicate that Svalbard represents either a previously unknown refuge or a locality of exceptional preservation in the aftermath of the mass extinction event.
The notoungulate genus Puelia has a complex taxonomic history marked by uncertain familial placement and misidentified specimens. Examination of the holotype of Puelia plicata and unpublished upper and lower tooth material from several fossil localities provided new knowledge of both the genus and species. This study refines the diagnosis of P. plicata and expands our understanding of its anatomical and neuroanatomical variation. Puelia ranks among the smallest known toxodonts (12-17 kg) and displays a mosaic of cranio-dental traits found in 'notohippids', 'isotemnids' and leontiniids. A virtual 3D brain endocast reveals a mix of primitive and derived characteristics typical of both Toxodontia and Typotheria. Features such as a large neocortex, bulging temporal lobes, and developed piriform lobes suggest enhanced sensory integration, particularly for olfaction and audition. A low encephalization quotient (EQ approximate to 0.4) aligns with broader notoungulate trends. Endocranial traits, including a triangular telencephalon, enlarged olfactory bulbs, and reduced sulcal complexity, resemble those of early Eocene taxa such as Periphragnis and Notostylops, but also some later Typotheria. These similarities should be interpreted as results of allometric scaling linked to small body size rather than close phylogenetic relationships. This underscores the role of size-related convergence in shaping cranial and brain anatomy within Notoungulata. While the precise phylogenetic position of Puelia remains unresolved, its unique anatomical attributes offer key insights into early toxodontian evolution and the broader diversification of notoungulates. Integration of palaeoneurological and morphometric data proves essential for interpreting these evolutionary patterns.
The Cangxi Formation of the Sichuan Basin, southwestern China provides important insights into how palaeoenvironmental conditions influenced the evolution of biota during the Early Cretaceous greenhouse period. However, the application of ostracods from the Sichuan Basin remains highly limited to date. Here, we present a detailed taxonomic analysis of 20 non-marine ostracod species belonging to seven genera (Jingguella, Deyangia, Pinnocypridea, Cypridea, Damonella, Cypridoidea gen. indet. and Alicenula?, including Deyangia rhodopetra sp. nov.) from the Cangxi Formation, along with age constraints and palaeogeographic interpretations. The Cangxi Formation is distinguished from the underlying strata by the presence of Jingguella, Deyangia and Pinnocypridea, and notably represents one of the earliest occurrences of Cypridea in East Asia. This indicates a transitional phase from the non-Cypridea fauna to the Cypridea-dominated fauna. A comparable faunal transition occurred in northeastern China, although the southwestern region is dominated by jingguellids (Jingguella and Deyangia), whereas Luanpingella prevailed in the northeast. The morphological similarity between jingguellids and Luanpingella suggests a close phylogenetic affinity among these taxa. Based on these data, the Cangxi Formation is assigned a Valanginian-Hauterivian age (minimum range of late Valanginian to early Hauterivian). The ostracod fauna dominated by jingguellids closely resembles those from basins along the eastern margin of the Tethys Ocean in Asia and corresponds to the palynofloral province boundary indicative of arid climatic conditions. Therefore, the Cangxi ostracods are crucial for advancing our understanding of the evolution and distribution of biota influenced by palaeogeographic setting and climatic zonation during the Early Cretaceous.
South American hystricognath rodents (Caviomorpha) are a dynamic and important group of mammals with a rich fossil record that spans nearly every continental ecosystem. The oldest records come from the Palaeogene of the Peruvian Amazonia. They are well-documented in the Early Miocene assemblages from extratropical Patagonia. In this work, we describe the first Early Miocene caviomorph assemblage (AMD-45) from the tropics that is both abundant and taxonomically rich, enabling us to evaluate early biogeographic patterns and dispersal events influencing this clade. Nine taxa belonging to the four caviomorph superfamilies, as well as a caviomorph incertae sedis are recognized. These rodents have brachydont and generalized molars (Atalayamys incertum gen. et sp. nov., Matsigenkamys ericius gen. et sp. nov., Acarechimys manumanta sp. nov.), protohypsodont and more derived molars (Ricardomys antiqua sp. nov., Manumys materdei gen. et sp. nov., Marianamys altadens gen. et sp. nov., Luantus silbamanta sp. nov. and Maquiamys precursor), and even euhypsodont teeth (Peruchinchilla prima gen. et sp. nov.). The AMD-45 fauna represents a mix of generalized and derived taxa, with chinchilloids and pan-octodontoids being the most taxonomically diverse and abundant. Comparison with other South American rodent assemblages supports the hypothesis that the equatorial tropics acted as a taxonomic incubator (long-lasting lineages) and provides evidence for in situ evolution and migration waves. The AMD-45 rodents also represent the oldest occurrence of high-crowned caviomorphs in low-latitude faunas, with the evolution of hypsodonty proposed to follow distinctive latitudinal and temporal trajectories.
The most complete record of the earliest dinosaur lineages is from the Carnian from the higher latitudes of Pangea (e.g. present-day Brazil, Argentina), but dinosaurian assemblages from the upper stages of the Upper Triassic are better known from the low latitudes of Pangea (present day southwestern USA). How early carnivorous dinosaurian diversity matches or mismatches at various latitudes remains to be documented because of uncertainty around the spatio-temporal ranges and phylogenetic relationships of early dinosaur lineages. We examine low-latitude diversity patterns through the lens of the saurischian dinosaur Tawa hallae and close relatives, including a new species, Ptychotherates bucculentus gen. et sp. nov. The new taxon is known from an incomplete but well-preserved skull (CM 31368) from the uppermost Triassic Coelophysis Quarry in northern New Mexico. The new taxon clearly shares synapomorphies with Tawa hallae, such as distinctive fossae on the quadrate and otoccipital and a dorsoventrally tall and laterally flat jugal. However, the new taxon is distinguishable from all other coeval ornithodirans by a combination of many character states, including the proportionally dorsoventrally deepest jugal known for any Triassic-aged dinosaur. Higher-palaeolatitude ecosystems across Pangea show a complete turnover of carnivorous dinosaurs by neotheropods in the Norian and Rhaetian, but the 'Chindesaurus-Tawa' clade (Morphoraptora clade nov.) coexisted with neotheropods possibly until the End-Triassic Extinction Event. This suggests a low-latitude 'museum' where early-diverging lineages survived much longer than at higher latitudes, and that the End-Triassic Extinction Event affected dinosaur diversity more than previously hypothesized.
Terror birds comprise an iconic group of apex predator birds from America, with a rich fossil record that is one of the longest among birds for a Neoaves family, ranging from the middle Eocene to the latest Pleistocene. Here, we report the discovery of a new genus and species of Phorusrhacidae, based on an incomplete tibiotarsus recovered from an Upper Pleistocene (25 326-25 733 cal yr BP) cave deposit in Bahia, northeastern Brazil, and previously interpreted as a New World vulture. The preserved morphology exhibits unique diagnostic features that support the recognition of a new species belonging to the small-size phorusrhacids, the Psilopterinae, a clade that probably had poor flying abilities. In addition to the systematic assignment, we discuss aspects of its palaeoecology (isotopic habitat and body mass estimate), providing new insights into the diversity and evolutionary history of the last known terror birds.
The fossil record of coelacanths (Actinistia) is diminished by several nominal gaps that obscure vital information pertaining to the clade's evolutionary history. Latimeriidae, the family that includes the extant coelacanth Latimeria, in addition to the Cenozoic, has an outstanding missing gap of 50 myr during the Mesozoic, with no records of this family from the Lower Cretaceous. Upper Cretaceous latimeriids are morphologically derived and show close anatomical similarities with Latimeria, although an understanding of their macroevolutionary trends, timings of key character acquisitions, and gross patterns in their skeletal evolution are largely obscured by a lack of diagnosed Lower Cretaceous taxa. Using x-ray computed tomography (XCT), we here report the first diagnostic latimeriid from the Lower Cretaceous: Macropoma gombessae sp. nov. based on an articulated cranium and associated fragments of the post-cranial skeleton from the Albian Gault Formation of southern England. The new species demonstrates a drastic shift in dermal ornamentation between the Lower and Upper Cretaceous, including an unusual narrowing and change in placement of the supraorbital sensory canal within the supraorbitals, and increased reduction in the dentary leading towards the morphologies present in Latimeria. Phylogenetic analysis resolves the new species as sister to Macropoma, and together are sister to a clade containing Swenzia and Latimeria. We additionally reappraise 'Macropoma' willemoesii (Upper Jurassic, Germany) as not belonging to Macropoma, indicating M. gombessae as the stratigraphically oldest species of this historic and evolutionarily novel genus.
Although the evolutionary history of conulariids has been widely studied, previous works have focused mostly on limited time intervals. In this paper, we examine the diversity dynamics of the group throughout its entire history, using various mathematical approaches. An updated occurrences database was compiled to estimate the genus-level richness throughout the fossil record and to calculate diversity and evolutionary rate. For a better understanding of the group's macroevolutionary dynamics, two additional analyses were applied to check for age dependency on extinction and to infer whether any environmental factors may explain the variations in origination and extinction rates. The analyses show that Conulariida diversity behaviour is characteristic of the Palaeozoic evolutionary fauna. The decline after the Late Ordovician and subsequent disappearance of the group throughout the Palaeozoic and Triassic is due not so much to an increase in extinction rate, but to a significant decrease in origination rate. The analysis of potential influences from environmental factors, such as sea level, continental break-up, continental scatter, global average temperatures, deep ocean temperatures and atmospheric oxygen level, resulted in no clear correlation. Higher extinction risk was associated with genera having a shorter evolutionary history. The genera Conularia and Paraconularia, often used as catch-all taxa, require systematic revision to clarify the true diversity of the group. Overall, the main drivers of Conulariida diversity remain uncertain.
