The magnitude and ontogenetic patterns of intraspecific variation can provide important insights into the evolution and development of organisms. Understanding the intraspecific variation of organisms is also a key to correctly pursuing studies in major fields of palaeontology. However, intraspecific variation has been largely overlooked in ectocochleate cephalopods, particularly nautilids. Furthermore

The Cambrian coral Cambroctoconus occurs selectively in the crypts of calcimicrobe Epiphyton reefs of the Zhangxia Formation (Miaolingian) in Shandong Province, North China. These cryptobionts preferentially grow laterally and/or downward, in some cases showing pendent growth from the ceilings of the reef framework. The upside‐down growth is clearly shown by the downward‐oriented aperture and the presence

We test for the presence of evolutionary stasis in a species of Late Cretaceous ammonoid cephalopod, Hoploscaphites nicolletii, from the North American Western Interior Seaway. A comprehensive dataset of morphological traits was compiled across the entire spatial and temporal range of this species. These were analysed in conjunction with sedimentologically and geochemically derived palaeoenvironmental

The tetraradial or pentaradial fossil embryos and related hatched individuals from the early Cambrian Kuanchuanpu Formation are of great interest for understanding the early evolution of medusozoans. The phylogenetic and evolutionary significance of their external and internal characters (e.g. manubrium, tentacles, septa and claustra) is still controversial. Here we describe a new pentamerous medusozoan

The Great Ordovician Biodiversification Event (GOBE) refers to one of the greatest increases in biodiversity during the Phanerozoic. Recent studies have shown that this taxonomic increase can be attributed to elevated origination rates around the Dapingian–Darriwilian boundary in the Middle Ordovician, while extinction rates stayed relatively constant throughout the Ordovician. Even though this global

Turtles are key components of modern vertebrate faunas and their diversity and distributions are likely to be affected by anthropogenic climate change. However, there is limited baseline data on turtle taxonomic richness through time or assessment of their past responses to global environmental change. We used the extensive Triassic–Palaeogene (252–223 Ma) fossil record of terrestrial and freshwater

Conspicuously few body‐fossil taxa are known to span the Ediacaran–Cambrian boundary, a pattern usually taken to signal either a terminal Proterozoic mass extinction, or taphonomic failure. We draw attention to the emerging record of small carbonaceous fossils (SCFs), which exhibit continuous preservation spanning this critical interval. Here we focus on the enigmatic SCF Cochleatina, a morphologically

Morphological variation (disparity) is almost invariably characterized by two non‐mutually exclusive approaches: (1) quantitatively, through geometric morphometrics; and (2) in terms of discrete, ‘cladistic’, or categorical characters. Uncertainty over the comparability of these approaches diminishes the potential to obtain nomothetic insights into the evolution of morphological disparity and the few

Silicification is the most important process of fossilization resulting in the preservation of internal tissues in plants, thereby providing essential information on the anatomy, life history, and evolution of land plants. However, fundamental knowledge of silica uptake, precipitation, and contribution to in situ plant fossilization is limited. To identify the cellular pathway of aqueous silica and

Exceptionally well‐preserved impressions of two bundles of bristles protrude from the apertures of small, spiral shells of Pelagiella exigua, recovered from the Kinzers Formation (Cambrian, Stage 4, ‘Olenellus Zone’, c. 512 Ma) of Pennsylvania. These impressions are inferred to represent clusters of chitinous chaetae, comparable to those borne by annelid parapodia and some larval brachiopods. They

Modern elasmobranchs have a long evolutionary history and an abundant fossil record that consists mainly of teeth. Many fossil taxa have living representatives. However, the representation of extant taxa in the fossil record is unknown. To begin to understand the geological history of extant elasmobranchs, we here assess the quality of their fossil record. We do so by assessing the Pull of the Recent

There are few cases where numbers or types of possible phenotypes are known, although vast state spaces have been postulated. Rarely applied in this context, graph theory and topology enable enumeration of possible phenotypes and evolutionary transitions. Here, we generate polyhedral calyx graphs for the Late Cretaceous, stemless crinoids Marsupites testudinarius and Uintacrinus socialis (Uintacrinoidea

Despite their importance for understanding phylogeny, character evolution and classification, well‐constrained homology relationships for posterior plating in crinoids have only recently been attempted. Here, we re‐evaluate posterior plate homologies in all major crinoid lineages using development, fossil ontogenies and phylogenetic evidence. Based on these lines of evidence, we change terminology

Iterative evolution has proved a difficult evolutionary phenomenon to study and interpret. Inferences of causality vary from study to study and quantitatively based phylogenetic reconstruction has never been attempted. In an effort to better understand iterative evolution we employed stratocladistics, gap analysis and disparity analysis to study the case of the Monograptidae in the aftermath of the

Duck‐billed dinosaurs (Hadrosauridae) were the most common ornithopods of the Late Cretaceous. Second only to sauropods and in many cases exceeding the sizes of the largest land mammals (such as indricotheres or proboscideans), they are among the largest terrestrial herbivores to have walked the Earth. Despite their gigantic size, diversity and abundance, their growth strategies remain poorly understood

Terrestrial insects are often remarkably well preserved in lacustrine Konservat Lagerstätten. However, the assumption that carcasses should sink fast through the water column seems contradictory as this scenario is unlikely due to excessive buoyancy and surface tension. The mechanisms that promote rapid and permanent emplacement onto the sediment surface (RPESS) of such terrestrial animal remains are

The carditid genus Cyclocardia is currently the most diverse genus of the family, including nearly 180 nominal species encompassing wide stratigraphical (Cretaceous–Recent) and geographical (Antarctica, South and North America, Europe, Africa, Alaska, Russia, Japan and New Zealand) ranges. Due to the lack of autapomorphies in the diagnosis of the genus and its large account of species, we re‐evaluate

Herein, we describe Alatochelon myrteum gen. et sp. nov., a large tortoise from the post‐Messinian (lower Pliocene) of the area of Puerto de la Cadena (Region of Murcia), Spain. The new taxon cannot be attributed to Titanochelon, which represented the only lineage of large tortoises previously recognized in the Neogene record of Europe. Alatochelon myrteum shows African affinities, especially with

Although extensive research has been carried out in recent years on the origin and evolution of human bipedalism, a full understanding of this question is far from settled. Miocene hominoids are key to a better understanding of the locomotor types observed in living apes and humans. Pierolapithecus catalaunicus, an extinct stem great ape from the middle Miocene (c. 12.0 Ma) of the Vallès‐Penedès Basin

Collagens are the most abundant proteins in the animal kingdom. They form the structural framework of connective tissues such as bones, tendons and skin, and play important biomechanical role in supporting tissue functions. The preservation of collagen in deep time is a topic of intense debate. Here we provide indisputable evidence for the presence of collagen in early Eocene fish vertebrae using online

The most commonly preserved soft tissues associated with ornithischian dinosaurs are skin remains. The apparent resistance of hadrosaur skin to decay, and its abundance in the fossil record relative to that of other tetrapods, has been attributed to factors such as thickness and composition. Here we report additional intrinsic factors within hadrosaur skin: 3D‐preserved eumelanin‐bearing bodies, dermal

Lophialetidae is an extinct group of endemic Asiatic tapiroids that are widely distributed in the Eocene sediments of Asia. Schlosseria magister and Lophialetes expeditus are the most abundant species in this family. However, their dietary and ecological characteristics are largely unknown. For the first time, we reconstruct the palaeodiet and habitat of these two lophialetids using a combination of

Shell decollation is a growth strategy that has been adopted by a number of invertebrate taxa to offset the metabolic and ecological disadvantages of shell growth. However, little is known about the origin and evolution of this process. We here describe well‐preserved specimens of the hyolith Cupitheca decollata sp. nov. preserving the decollation process, from the early Cambrian Yu'anshan Formation

Echimyidae is a species‐rich clade of Neotropical rodents, which diversified in association with forested biomes. Since the late Miocene, a few lineages from southern South America have been adapted to open environments. Eumysops is one of these southern echimyids, and its peculiar craniomandibular morphology has been assumed to be a result of adaptation to open environments. We performed a geometric

The Triassic to Recent fossil record of the dinoflagellates is represented overwhelmingly by geologically resistant, organic‐walled, non‐motile resting cysts; such cysts are formed following the sexual phase in the life cycle. Very few confirmed records exist of the motile stage being preserved in the fossil record. This paper reports the occurrence of two very unusual dinoflagellate taphofacies, one

The study of the global mass extinction event at the Cretaceous–Palaeogene (K/Pg) boundary can aid in understanding patterns of selective extinction, and survival and dynamics of ecosystem recovery. Outcrops in the Maastrichtian type area (south‐east Netherlands, north‐east Belgium) comprise a stratigraphically expanded K/Pg boundary succession that offers a unique opportunity to study marine ecosystem

The origin of the unique body plan of turtles has long been one of the most intriguing mysteries in evolutionary morphology. Discoveries of several new stem‐turtles, together with insights from recent studies on the development of the shell in extant turtles, have provided crucial new information concerning this subject. It is now possible to develop a comprehensive scenario for the sequence of evolutionary

Variation in preservation and sampling probability clouds our estimates of past biodiversity. The most extreme examples are Lagerstätten faunas and floras. Although such deposits provide a wealth of information and represent true richness better than other deposits, they can create misleading diversity peaks because of their species richness. Here, we investigate how Lagerstätten formations add to

Species diversity patterns are governed by complex interactions among biotic and abiotic factors over time and space, but are essentially the result of the diversification dynamics (differential speciation and extinction rates) over the long‐term evolutionary history of a clade. Previous studies have suggested that temporal variation in global temperature drove long‐term diversity changes in Crocodylia

Proterosuchids are an important group of carnivorous basal archosauriforms characterized by a bizarre and enigmatic downturned premaxilla that overhangs the lower jaw. They are particularly significant because they radiated in the immediate aftermath of the Permian–Triassic mass extinction and represent one of the best known ‘disaster taxa’ following that event. While traditionally considered to be

In the last few decades, hook‐like structures have been reported in the Mesozoic ammonite family Scaphitidae. Despite their exceptional preservation and debates about their function, no detailed reconstruction has been available until now. For the first time, we describe the composition and details of the morphology of these structures found in the body chambers of six specimens of the Campanian ammonite

Konservat‐Lagerstätten are seen as snapshots of past biodiversity for a given location and time. However, processes leading to the exceptional morphological preservation of fossils in these deposits remain incompletely understood. This results in a deficient assessment of taphonomic biases and limits the robustness/relevance of palaeobiological reconstructions. Here, we report the mineralogical characterization

Featherstars, comatulid crinoids that shed their stalk during their ontogeny, are the most species‐rich lineage of modern crinoids and the only ones present in shallow water today. Although they are of considerable palaeontological interest as a ‘success story’ of the Mesozoic Marine Revolution, their fossil record is relatively species‐poor and fragmentary. New Spanish fossils of the Cretaceous featherstar

Evolutionary transitions between quadrupedal and bipedal postures are pivotal to the diversification of amniotes on land, including in our own lineage (Hominini). Heterochrony is suggested as a macroevolutionary mechanism for postural transitions but understanding postural evolution in deep time is hindered by a lack of methods for inferring posture in extinct species. Dinosaurs are an excellent natural

Disparity, the diversity of form and function of organisms, can be assessed from cladistic or phenetic characters, and from discrete characters or continuous characters such as landmarks, outlines, or ratios. But do these different methods of assessing disparity provide comparable results? Here we provide evidence that all metrics correlate significantly with each other and capture similar patterns

A major uncertainty in estimating energy budgets and population densities of extinct animals is the carrying capacity of their ecosystems, constrained by net primary productivity (NPP) and its digestible energy content. The hypothesis that increases in NPP due to elevated atmospheric CO 2 contributed to the unparalleled size of the sauropods has recently been rejected, based on modern studies on herbivorous

Stem-group gnathostomes reveal the sequence of character acquisition in the origin of modern jawed vertebrates. The petalichthyids are placoderm-grade stem-group gnathostomes known from both isolated skeletal material and rarer articulated specimens of one genus. They are of particular interest because of anatomical resemblances with osteostracans, the jawless sister group of jawed vertebrates. Because

Fossil taxa are critical to inferences of historical diversity and the origins of modern biodiversity, but realizing their evolutionary significance is contingent on restoring fossil species to their correct position within the tree of life. For most fossil species, morphology is the only source of data for phylogenetic inference; this has traditionally been analysed using parsimony, the predominance

Understanding how regional ecosystems respond to sea-level and environmental perturbations is a main challenge in palaeoecology. Here we use quantitative abundance estimates, integrated within a sequence stratigraphic and environmental framework, to reconstruct benthic community changes through the 13 myr history of the Jurassic Sundance Seaway in the western United States. Sundance Seaway communities

A new chroococcalean cyanobacterium is described from approximately 1-billion-year-old non-marine deposits of the Torridonian Group of Scotland and the Nonesuch Formation of Michigan, USA. Individual cells of the new microfossil, Eohalothece lacustrina gen. et sp. nov., are associated with benthic microbial biofilms, but the majority of samples are recovered in palynological preparations in the form

Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy of melanin and melanosomes, however, is incompletely understood. In particular, the chemical processes responsible for melanosome preservation have not been investigated. As a result, the origins of sulfur-bearing compounds in fossil melanosomes

As the sister lineage of all other actinopterygians, the Middle to Late Devonian (Eifelian-Frasnian) Cheirolepis occupies a pivotal position in vertebrate phylogeny. Although the dermal skeleton of this taxon has been exhaustively described, very little of its endoskeleton is known, leaving questions of neurocranial and fin evolution in early ray-finned fishes unresolved. The model for early actinopterygian

Pterosaurs, a Mesozoic group of flying archosaurs, have become a focal point for debates pertaining to the impact of sampling biases on our reading of the fossil record, as well as the utility of sampling proxies in palaeodiversity reconstructions. The completeness of the pterosaur fossil specimens themselves potentially provides additional information that is not captured in existing sampling proxies

Cyanobacteria are among the most ancient of evolutionary lineages, oxygenic photosynthesizers that may have originated before 3.0 Ga, as evidenced by free oxygen levels. Throughout the Precambrian, cyanobacteria were one of the most important drivers of biological innovations, strongly impacting early Earth's environments. At the end of the Archean Eon, they were responsible for the rapid oxygenation

Sedimentary rocks of the Scotia Group, Prins Karls Forland, Svalbard, have been metamorphosed to lower greenschist facies. Yet Scotia chert nodules contain abundant organic-walled microfossils belonging to at least seventeen taxa. Their black colour indicates that the fossils underwent substantial thermal alteration. However, it is suggested that preservation in a matrix of early diagenetic silica

Four neocatastrophist claims about mass extinction are currently being debated; they are that: 1, the late Cretaceous mass extinction was caused by large body impact; 2, as many as five other major extinctions were caused by impact; 3, the timing of extinction events since the Permian is uniformly periodic; and 4, the ages of impact craters on Earth are also periodic and in phase with the extinctions

The functional anatomy of the hindlimb of bipedal dinosaurs has been intensively studied. Yet, surprisingly little work has been done concerning functional adaptation of digits for terrestrial locomotion. While complete and articulated pes skeletons are scarce, pes shape is abundantly recorded by fossil footprints. We elucidate the significance of footprint shape and size for locomotion using a large

Fossils are a key source of data on the evolution of feather structure and function through deep time, but their ability to resolve macroevolutionary questions is compromised by an incomplete understanding of their taphonomy. Critically, the relative preservation potential of two key feather components, melanosomes and keratinous tissue, is not fully resolved. Recent studies suggesting that melanosomes