Sam Giles

University of Birmingham · School of Geography, Earth and Environmental Sciences

A complex brain is central to the success of backboned animals. However, direct evidence bearing on vertebrate brain evolution comes almost exclusively from extant species, leaving substantial knowledge gaps. Although rare, soft-tissue preservation in fossils can yield unique insights on patterns of neuroanatomical evolution. Paleontological eviden...

Decay experiments are ever increasing in complexity to better understand taphonomic processes. However, adding new variables, such as sediment, can create methodological biases, such as artificial anatomical character loss during exhumation. Non-invasive in situ imaging techniques such as X-ray computed tomography (XCT scanning) could mitigate this...

Teleost fishes comprise more than 36,000 living vertebrate species and occupy a wide range of aquatic ecosystems. Despite their overwhelming success, extinct taxa outside of the living radiation-stem teleosts-remain poorly understood. Dorsetichthys bechei is an Early Jurassic stem teleost of historic importance. Although D. bechei is well described...

Attempts to explain the origin and diversification of vertebrates have commonly invoked the evolution of feeding ecology, contrasting the passive suspension feeding of invertebrate chordates and larval lampreys with active predation in living jawed vertebrates. Of the extinct jawless vertebrates that phylogenetically intercalate these living groups...

There is a well-documented racial and ethnic diversity crisis in Geography, Earth and Environmental Sciences (GEES) subjects in the Global North that leads to inequities in who does environmental research. The Equator project set out to increase participation and retention of UK-domiciled Black, Asian and minority ethnic students in GEES research b...

Polyploidy or whole-genome duplication (WGD) is a major event that drastically reshapes genome architecture and is often assumed to be causally associated with organismal innovations and radiations. The 2R hypothesis suggests that two WGD events (1R and 2R) occurred during early vertebrate evolution. However, the timing of the 2R event relative to...

The early Eocene fossil assemblage of the London Clay (Southeastern England) is a key window to the early Paleogene diversification of teleost fishes in the open ocean. Despite their three-dimensional preservation that offers unique insight into skeletal anatomy, the London Clay fossils are still poorly described for the most part. †Whitephippus ta...

The neurocranium is an integral part of the vertebrate head, itself a major evolutionary innovation1,2. However, its early history remains poorly understood, with great dissimilarity in form between the two living vertebrate groups: gnathostomes (jawed vertebrates) and cyclostomes (hagfishes and lampreys)2,3. The 100 Myr gap separating the Cambrian...

Attempts to explain the origin and diversification of vertebrates have commonly invoked the evolution of feeding ecology, contrasting the passive suspension feeding of invertebrate chordate and larval lampreys with active predation in living jawed vertebrates. Of the extinct jawless vertebrates that phylogenetically intercalate these living groups,...

The early Eocene fossil assemblage of the London Clay (Southeastern England) is a key window to the early Palaeogene diversification of teleost fishes in the open ocean. Despite their three-dimensional preservation that offers unique insight into skeletal anatomy, the London Clay fossils are still poorly described for the most part. Whitephippus ta...

Whole genome duplications (WGDs) are major events that drastically reshape genome architecture and are causally associated with organismal innovations and radiations. The 2R Hypothesis suggests that two WGD events (1R and 2R) occurred during early vertebrate evolution. However, the veracity and timing of the 2R event relative to the divergence of g...

Whole genome duplications (WGDs) are major events that drastically reshape genome architecture and are causally associated with organismal innovations and radiations ¹ . The 2R Hypothesis suggests that two WGD events (1R and 2R) occurred during early vertebrate evolution 2,3 . However, the veracity and timing of the 2R event relative to the diverge...

Morphological evolution of the vertebrate skull has been explored across a wide range of tetrapod clades using geometric morphometrics, but the application of these methods to teleost fishes, accounting for roughly half of all vertebrate species, has been limited. Here we present the results of a study investigating three-dimensional morphological...

In the last few decades, Geology courses, particularly in the Global North have seen a decline in student enrolment. Geologists have linked this downturn to a lack of exposure to the subject at school and college level. This work seeks to understand the public’s relationship with Geology and draws on over 5000 open-ended question responses to a sur...

The origin of jaws and teeth remains contentious in vertebrate evolution. ‘Placoderms’ (Silurian-Devonian armoured jawed fishes) are central to debates on the origins of these anatomical structures. ‘Acanthothoracids’ are generally considered the most primitive ‘placoderms’. However, they are so far known mainly from disarticulated skeletal element...

Brain anatomy provides key evidence for the relationships between ray-finned fishes¹, but two major limitations obscure our understanding of neuroanatomical evolution in this major vertebrate group. First, the deepest branching living lineages are separated from the group’s common ancestor by hundreds of millions of years, with indications that asp...

Morphological evolution of the vertebrate skull has been explored across a wide range of tetrapod clades, but teleost fishes, accounting for roughly half of all vertebrate species, have largely been overlooked. Here we present the results of a study investigating three-dimensional morphological evolution across 114 species of Pelagiaria, a morpholo...

Pachycormiformes is a diverse clade of stem-teleost actinopterygian fishes with a stratigraphic range from the Lower Jurassic (Toarcian) to Upper Cretaceous (Maastrichtian). The Toarcian Posidonienschiefer Formation in SW Germany records the earliest occurrence of †Pachycormiformes in the fossil record, offering unique and crucial insight into the...

Many accounts of the early history of actinopterygians (ray-finned fishes) posit that the end-Devonian mass extinction had a major influence on their evolution. Existing phylogenies suggest this episode could have acted as a bottleneck, paring the early diversity of the group to a handful of survivors. This picture, coupled with increases in taxono...

Geoscience is one of the least diverse science disciplines in the Global North in terms of ethnic minority representation. Over recent years, efforts to improve access and participation in the geosciences have increased, with funding bodies recognizing the need to invest in this work. This article discusses the research undertaken within the EQUATO...

Extant ray-finned fishes (Actinopterygii) dominate marine and freshwater environments, yet spatio-temporal diversity dynamics following their origin in the Palaeozoic are poorly understood. Previous studies investigate face-value patterns of richness, with only qualitative assessment of biases acting on the Palaeozoic actinopterygian fossil record....

Actinopterygii makes up half of living vertebrate diversity, and study of fossil members during their Palaeozoic rise to dominance has a long history of descriptive work. Although research interest into Palaeozoic actinopterygians has increased in recent years, broader patterns of diversity and diversity dynamics remain critically understudied. Pas...

Geography, Earth and Environmental Science (GEES) research will play a vital role in addressing the grand challenges of the 21st century, contributing to many of the UN sustainable development goals and the global energy transition. However, geoscience knowledge cannot be successfully applied to global problems that impact people from all walks of...

Brain anatomy provides key evidence for ray-finned fish relationships, but two key limitations obscure our understanding of neuroanatomical evolution in this major vertebrate group. First, the deepest branching living lineages are separated from the group's common ancestor by hundreds of millions of years, with indications that aspects of their bra...

The actinopterygian crown group (comprising all living ray-finned fishes) originated by the end of the Carboniferous. However, most late Paleozoic taxa are stem actinopterygians, and broadly resemble stratigraphically older taxa. The early Permian † Brachydegma caelatum is notable for its three-dimensional preservation and past phylogenetic interpr...

Extant ray-finned fishes (Actinopterygii) dominate marine and freshwater environments, yet their spatiotemporal diversity dynamics following their origin in the Palaeozoic are poorly understood. Previous studies investigate face-value patterns of richness, with only qualitative assessment of potential biases acting on the Palaeozoic actinopterygian...

The teeth of sharks famously form a series of transversely organized files with a conveyor-belt replacement that are borne directly on the jaw cartilages, in contrast to the dermal plate-borne dentition of bony fishes that undergoes site-specific replacement. A major obstacle in understanding how this system evolved is the poorly understood relatio...

Actinopterygian (ray-finned) fishes represent the principal vertebrate group in aquatic settings. This dominance is often attributed to their apparent success in the aftermath of the end-Devonian extinction. Increases in taxonomic and morphological diversity in the early Carboniferous, coupled with phylogenetic hypotheses implying the survival of f...

Ensuring taught fieldwork is a positive, generative, collective, and valuable experience for all participants requires considerations beyond course content. To guarantee safety and belonging, participants’ identities (backgrounds and protected characteristics) must be considered as a part of fieldwork planning and implementation. Furthermore, getti...

Actinopterygii are the most speciose living vertebrate clade, and study of fossil members during their Palaeozoic rise to dominance has a long history of descriptive work. Although research interest into Palaeozoic actinopterygians has increased in recent years, broader patterns of diversity and diversity dynamics remain critically understudied. Pa...

Geoscientists will play key roles in the grand challenges of the twenty-first century, but this requires our field to address its past when it comes to diversity and inclusion. Considering the bleak picture of racial diversity in the UK, we put forward steps institutions can take to break down barriers and make the geosciences equitable.

Our understanding of the earliest evolution of jawed vertebrates depends on a credible phylogenetic framework for the jawed stem gnathostomes collectively known as “placoderms”.¹ However, their relationships, and whether placoderms represent a single radiation or a paraphyletic array, remain contentious.2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 This u...

Endochondral bone is the main internal skeletal tissue of nearly all osteichthyans—the group comprising more than 60,000 living species of bony fishes and tetrapods. Chondrichthyans (sharks and their kin) are the living sister group of osteichthyans and have primarily cartilaginous endoskeletons, long considered the ancestral condition for all jawe...

The redescription of Cimolichthys lewesiensis leidy, 1857 (Aulopiformes: Cimolichthyidae) based on computed tomography specimens

Geoscientists have a key role to play in the great challenges of the 21st Century, but solving these problems requires diverse collaborations and engagement with stakeholders from all backgrounds, both in the fundamental science and its implementation. How can we break down the barriers that have made Geoscience amongst the worst for racial minorit...

Our understanding of the earliest evolution of jawed vertebrates depends on a credible phylogenetic assessment of the jawed stem gnathostomes collectively known as ‘placoderms’. However, their relationships, and even whether ‘placoderms’ represent a single radiation or a paraphyletic array, remain contentious. Here we describe the endocranial cavit...

The teeth of sharks famously form a series of parallel, continuously replacing files borne directly on the mandibular cartilages. In contrast, bony fishes possess site-specific shedding dentition borne on dermal plates. Understanding how these disparate systems evolved is challenging, not least because of poorly understood relationships and the pro...

Vegrandichthys coitecus gen. et sp., nov., is described as a basal member of the subfamily Eurypholinae, within family Enchodontidae. This new species is based on a single specimen from the Early Cenomanian marine deposits exposed in the El Chango quarry, Chiapas, Southern Mexico. Although this fish exhibits osteological features to support its ins...

Endochondral bone is the main internal skeletal tissue of nearly all osteichthyans(1,2)--the group comprising more than 60,000 living species of bony fishes and tetrapods. Chondrichthyans (sharks and their kin) are the living sister group of osteichthyans and have cartilaginous endoskeletons, long considered the ancestral condition for all jawed ve...

Porolepiforms represent a clade of Devonian stem lungfishes, divided into the cosmine-bearing and probably paraphyletic 'Porolepidae' (e.g. Porolepis, Heimenia) and the cosmine-free and stratigraphically younger Holoptychiidae (e.g. Holoptychius, Glyptolepis, Laccognathus). Data on the dermoskeleton are available for both groups, but are more limit...

We examine whether the proportion of women publishing in palaeontology is approaching parity, using data from the journal Palaeontology as a proxy for the discipline. This work was motivated by the sense that, despite increased representation of women, articles on palaeontological subjects almost never appear to have 50% female authorship, regardle...

Fieldwork is an integral part of geoscience subjects, but changing career pathways and student demographics have major implications for the future of compulsory fieldwork. The ways in which fieldwork is taught and the learning outcomes it fulfils urgently need updating.

Many institutions do not have guidelines surrounding toilet stops on field trips, and the topic is rarely discussed. This document is intended to educate staff and students about toilet stops and menstruation in the field. This document also contains a set of recommendations for field work and field trips with the aim of minimising stress and anxie...

Our understanding of the earliest evolution of jawed vertebrates depends on a credible phylogenetic framework for the jawed stem gnathostomes collectively known as "placoderms".(1) However, their relationships, and whether placoderms represent a single radiation or a paraphyletic array, remain contentious.(2-13) This uncertainty is compounded by an...

Fieldwork is an integral part of Geoscience, but changing career pathways and student demographics have major implications for the future of fundamental geoscience fieldskills.

Our understanding of the ecology and phylogenetic relationships of Pachycormiformes, a group of Mesozoic stem teleosts including the iconic Leedsichthys, has often been hindered by a lack of comprehensive morphological information. Micro‐CT scanning of an articulated, although flattened, cranium of the edentulous Martillichthys renwickae from the M...

The study of early actinopterygians (ray‐finned fishes) from the Devonian has been hampered by imperfect preservation in the majority of taxa. The Late Devonian (early Frasnian) Gogo Formation of north‐western Western Australia is notable in producing complete fossil actinopterygians with exceptional three‐dimensional preservation of both the derma...

The Permo-Carboniferous eurynotiforms show conspicuous modifications to postcranial and cranial morphology relative to primitive actinopterygian conditions, and represent an important early example of functional experimentation within ray-finned fishes. Although eurynotiforms are represented by abundant articulated fossil material, the internal ana...

BACKGROUND: †Saurichthyiformes were a successful group of latest Permian-Middle Jurassic predatory actinopterygian fishes and constituted important, widely-distributed components of Triassic marine and freshwater faunas. Their systematic affinities have long been debated, with †saurichthyiforms often being aligned with chondrosteans, a group today...

A new Triassic neopterygian is described on the basis of a large three-dimensional neurocranium from the Rhaetian (Late Triassic) of the Kössen Formation (Schesaplana, Grisons, Switzerland). CT scanning reveals neurocranial features similar to Dapedium, suggesting that this new genus, Scopulipiscis saxciput gen. et sp. nov., was deep-bodied and pot...

‘Gempylids’ (snake mackerels) and trichiurids (cutlassfishes) are pelagic fishes characterized by slender to eel‐like bodies, deep‐sea predatory ecologies, and large fang‐like teeth. Several hypotheses of relationships between these groups have been proposed, but a consensus remains elusive. Fossils attributed to ‘gempylids’ and trichiurids consist...

The skull of 'Ligulalepis' from the Early Devonian of Australia (AM-F101607) has significantly expanded our knowledge of early osteichthyan anatomy, but its phylogenetic position has remained uncertain. We herein describe a second skull of 'Ligulalepis' and present micro-CT data on both specimens to reveal novel anatomical features, including crani...

Discoveries of putative stem sarcopterygians from the late Silurian and Early Devonian of South China have increased our knowledge of the initial diversification of osteichthyans while also highlighting incongruities in character evolution in this major jawed vertebrate group. Character-rich endocrania are incompletely preserved for early bony fish...

This corrects the article DOI: 10.1038/nature23654.

Gill skeletons provide a rich source of character information for inferring the relationships among extant fishes. However, the difficulties in accessing branchial structures in fossils have limited the use of gill-arch anatomy in phylogenetic studies of extinct fishes. Here we apply micro-computed tomography (µCT) to visualize and describe gill-ar...

The Dipnomorpha include the extinct Porolepiformes, in addition to Powichthys and Youngolepis and the extant Dipnoi (lungfish). As sister group to the Tetrapodomorpha, the Dipnomorpha hold a valuable place in our understanding of early sarcopterygian evolution. With complete cranial endocasts now known from most other stem sarcopterygian groups inc...

The Dipnomorpha include the extinct Porolepiformes, in addition to Powichthys and Youngolepis and the extant Dipnoi (lungfish). As sister group to the Tetrapodomorpha, the Dipnomorpha hold a valuable place in our understanding of early sarcopterygian evolution. With complete cranial endocasts now known from most other stem sarcopterygian groups inc...

Modern ray-finned fishes (Actinopterygii) comprise half of extant vertebrate species and are widely thought to have originated before or near the end of the Middle Devonian epoch (around 385 million years ago). Polypterids (bichirs and ropefish) represent the earliest-diverging lineage of living actinopterygians, with almost all Palaeozoic taxa int...

The affinity of Tullimonstrum gregarium, a pincer-mouthed, soft bodied bilaterian, has been subject to debate since its recovery from Carboniferous coal deposits at Mazon Creek, Illinois. After decades of impasse focused on mollusc, arthropod and annelid attributes, two recent, yet conflicting, high-profile studies concluded that the ‘Tully Monster...

Living ray-finned fishes number approximately 30,000 species, roughly equal to modern lobe-finned fishes plus tetrapods combined. The fossil record of ray-finned fishes extends to the Early Devonian (ca. 415 Ma), although the oldest taxa for which the morphology of the otic region is known in any great detail are 35 million years younger. Early act...

Osteichthyans comprise two divisions, each containing over 32,000 living species [1]: Sarcopterygii (lobe-finned fishes and tetrapods) and Actinopterygii (ray-finned fishes). Recent discoveries from China highlight the morphological disparity of early sarcopterygians and extend their origin into the late Silurian [2–4]. By contrast, the oldest unam...

Endocasts of the osseous labyrinth have the potential to yield information about both phylogenetic relationships and ecology. Although bony labyrinth morphology is well documented in many groups of fossil vertebrates, little is known for early Neopterygii, the major fish radiation containing living teleosts, gars and the bowfin. Here, we reconstruc...

Actinopterygians (ray-finned fishes) are the most diverse living osteichthyan (bony vertebrate) group, with a rich fossil record. However, details of their earliest history during the middle Palaeozoic (Devonian) 'Age of Fishes' remains sketchy. This stems from an uneven understanding of anatomy in early actinopterygians, with a few well-known spec...

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-f...

The phylogeny of Silurian and Devonian (443-358 million years ago [Ma]) fishes remains the foremost problem in the study of the origin of modern gnathostomes (jawed vertebrates). A central question concerns the morphology of the last common ancestor of living jawed vertebrates, with competing hypotheses advancing either a chondrichthyan-¹⁻³ or oste...

Cranial endocasts, infillings of the skeletal void that once contained the brain and associated soft tissues, represent detailed anatomical structures that have long been the focus of paleontological investigation. We applied computed tomographics (CTs) in order to generate endocast models for the Paleozoic actinopterygian fishes Mimipiscis and Ken...

Synopsis A nearly complete mandible of a large tetrapodomorph sarcopterygian from the Frasnian Alves Beds is studied with the aid of computed tomography. The absence of cosmine, a small parasymphysial dental plate bearing dentition that is discontinuous with that of the coronoids, and the presence of an elongated posterior coronoid that bears two f...

The vertebrate dermal skeleton has long been interpreted to have evolved from a primitive condition exemplified by chondrichthyans. However, chondrichthyans and osteichthyans evolved from an ancestral gnathostome stem-lineage in which the dermal skeleton was more extensively developed. To elucidate the histology and skeletal structure of the gnatho...

Traditional hypotheses posit that teeth evolved from dermal scales, through the expansion of odontogenetically competent ectoderm into the mouth of jawless vertebrates. The discovery of tooth-like scales inside thelodonts, an extinct group of jawless vertebrates, led to the alternative hypothesis that teeth evolved from endodermal derivatives and t...