In 1952, Erik Jarvik diagnosed and offered a brief description of the large-bodied, highly nested tristichopterid taxon Eusthenodon, and its type species E. wangsjoi, from fossils recovered from the Britta Dal Formation (Famennian) of Gauss Halvø ( = Peninsula) and Ymer Ø ( = Island) in East Greenland. The original diagnosis for Eusthenodon only needed to distinguish the tristichopterid taxon from the two others known at the time, Eusthenopteron and Tristichopterus, both of them small-bodied forms with anatomy now recognised to be primitive within the clade. Following that publication, no new large-bodied tristichopterids with Eusthenodon-like characteristics would be introduced until the description of Mandageria fairfaxi in 1997. In the 45 interim years, the limited descriptive details and insufficient diagnosis of Eusthenodon turned the name into a broadly applicable taxonomic label for large-bodied tristichopterid discoveries. Recent efforts to rediagnose the taxon and reconsider its global distribution of referred materials have improved the taxonomic utility of the name. However, no complete description of type species E. wangsjoi has yet been written. This is despite a type series of specimens that includes complete and articulated skulls that remain available for study in the collections of the Natural History Museum of Denmark (NHMD). The work presented here fulfils the need for a complete comparative description of E. wangsjoi in the context of the many highly nested tristichopterid species that have been described in the last three decades. New figures of the E. wangsjoi type series of specimens are the first to offer views of the fossils unobscured by the superimposition of interpretive line drawings. The new description is accompanied by a descriptive inventory of all the potential E. wangsjoi fossils at the NHMD and a new phylogenetic analysis of clade Tristichopteridae that includes revised character data for E. wangsjoi and adds one recently described species.

The fossil record of dinosaurs in Scotland mostly comprises isolated highly fragmentary bones from the Great Estuarine Group in the Inner Hebrides (Bajocian–Bathonian). Here we report the first definite dinosaur body fossil ever found in Scotland (historically), having been discovered in 1973, but not collected until 45 years later. It is the first and most complete partial dinosaur skeleton currently known from Scotland. NMS G.2023.19.1 was recovered from a challenging foreshore location in the Isle of Skye, and transported to harbour in a semi-rigid inflatable boat towed by a motor boat. After manual preparation, micro-CT scanning was carried out, but this did not aid in identification. Among many unidentifiable elements, a neural arch, two ribs and part of the ilium are described herein, and their features indicate that this was a cerapodan or ornithopod dinosaur. Histological thin sections of one of the ribs support this identification, indicating an individual at least eight years of age, growing slowly at the time of death. If ornithopodan, as our data suggest, it could represent the world's oldest body fossil of this clade.

Rhadinichthys is one of the most wide-ranging and speciose genera of Palaeozoic actinopterygians. A classic variety of ‘palaeoniscoid’, Rhadinichthys species are generally small (~10–15 cm) and known mostly from dermal skeletal remains that show features commonplace among early ray-finned fishes. For this reason, the genus has long been considered a poorly diagnosed wastebasket taxon in need of revision and rarely included in systematic analyses. In the present work, syntypes of Rhadinichthys ornatissimus, the type species, are re-examined and supplemented with better-preserved material from other localities in the Scottish Midland Valley. A neotype is nominated and a more precise diagnosis presented with a suite of genus-level apomorphies. Unexpectedly, these traits are also evident in the monotypic Lower Carboniferous actinopterygian genus Woodichthys, which the neotype of R. ornatissimus closely resembles. As a result, the genus Woodichthys is subsumed within the redefined Rhadinichthys, and the single Woodichthys species is reassigned as R. bearsdeni, comb. nov., bringing with it a set of endoskeletal data. Some of these data are new, derived from μCT scans of the skull of the R. bearsdeni holotype, yielding renderings that update the original description of its skull table, parasphenoid, neurocranium, and otoliths. Further new data concerning the hyoid arch are obtained from a new specimen of R. bearsdeni from a site close by the original Bearsden locality. Redefined in this way, Rhadinichthys presents a data-rich operational taxonomic unit better suited for systematic studies. However, in so doing, it also releases a cluster of fossil species no longer anchored to a genus and now in need of rediagnoses.

A number of early tetrapods occur in different localities from the Ballagan Formation in Scotland. These localities are within the 12 Myr time duration of the Tournaisian so it is important to be able to place them within a chronology to better understand the evolutionary relationships of the tetrapods. Palynology is used to recognise distinct assemblages in the Norham West Mains Farm borehole and the Burnmouth coastal section which become a composite standard. The Willie's Hole tetrapods (Koilops, Mesanerpeton and Perittodus) come from the lower part of the Ballagan Formation with Auchenreoch Glen (Pederpes) somewhat higher. The oldest tetrapods are from the Harbour beds at Burnmouth with the Ross end cliffs tetrapods (Aytonerpeton, Diploradus and Ossirarus) the youngest assemblage. It is not possible to place the Coldstream tetrapods as the spore assemblage is low diversity. Tantallognathus from Tantallon is early Viséan in age. Occidens portlocki, an isolated partial tetrapod jaw from a historic collection in Northern Ireland, is not of Tournaisian age and hence not from within Romer's Gap, but it can be dated as Brigantian (latest Viséan) age. The other significant Romer's Gap locality from Blue Beach, Nova Scotia, Canada, is different in age span and palaeoenvironment.

The Early Mississippian site of Willie's Hole in south-eastern Scotland hosts some of the earliest terrestrial tetrapods. This study reports on the palaeoenvironment, micropalaeontology and palaeoecology of this important locality. The 8 m thick section comprises saline–hypersaline lake facies (dolostones, evaporites), fluvial facies (conglomerate lags, rippled, planar-laminated, and cross-bedded sandstones and siltstones) and overbank facies (laminated grey siltstones, sandy siltstones, very fine sandstones and palaeosols). Numerous exposure surfaces characterised by rooting, desiccation or brecciation indicate the repeated wetting and drying of the floodplain. Vertebrate, invertebrate and plant fossils are concentrated in the overbank facies association, particularly in sandy siltstones. Macro- and microfossils present are tetrapods, rhizodonts, actinopterygians, gyracanthids, dipnoans, chondrichthyans (Ageleodus), bivalve molluscs, eumalacostracans, myriapods (diplopods), eurypterids, scorpions, branchiopods, ostracods, Spirorbis, Serpula, Calcitarcha, Monocraterion trace fossils, plant stems, arborescent lycopsids (Stigmaria, Lepidodendron) and megaspores of the creeping lycopsid Oxroadia conferta. Various palaeoenvironments coexisted on a tropical, coastal, low-lying floodplain: evaporitic saline lakes, small meandering river channels, brackish salinity temporary lakes, wet marshes and sub-aerial dry land with scrubby vegetation and trees. Tetrapods inhabited waterlogged floodplain marshes and were transported post-mortem by meteoric flooding events into brackish lakes and pools. The abundance of tetrapod and other fossils is attributed to taphonomic concentration and preferential preservation during rapid burial. The Willie's Hole succession gives a window into the rich ecology and habitats on coastal floodplains after life recovered from the end-Devonian extinction and tetrapods walked on land.

The braincase and middle ear region underwent a dramatic reconfiguration during the fish–tetrapod transition, involving the loss of the intracranial joint and associated structures, as well as the loss of the lateral commissure and the transformation of the hyomandibula into a stapes. The earliest examples of the tetrapod condition are seen in Devonian stem tetrapods. Complete otoccipital regions have only been described from two genera, Ichthyostega and Acanthostega, which differ greatly from each other. Here we present the first complete otoccipital region of Ventastega, together with new data on Acanthostega that modify the published reconstruction. In lateral view, both braincases are similar in shape, with large fenestrae vestibuli and anteroposteriorly short, but tall, exoccipitals. However, in occipital view the exoccipital-basioccipital complex of Ventastega resembles that of Eusthenopteron and differs substantially from Acanthostega. Remarkably, both braincases contain an arcual plate, a sarcopterygian fish characteristic known in taxa with an intracranial joint, such as Eusthenopteron and Latimeria, but never before seen in a tetrapod. The hypophysial region of Acanthostega contains an interorbital foramen similar to that in post-Devonian tetrapods, contrasting with Ventastega which has a solid braincase wall with small foramina similar to the condition in Eusthenopteron. The suture pattern of the skull roof of Ventastega is fully resolved and the presence of an intertemporal bone is confirmed.

Porolepiforms represent one of the key lineages of early lobe-finned fishes. They include two taxonomic groupings: the paraphyletic ‘porolepidids’, characterised by rhombic scales and extensive development of cosmine on dermal bones; and the monophyletic, more nested holoptychiids, characterised by round scales and lack of cosmine. Braincases and endocasts represent important sources of information bearing on sarcopterygian interrelationships, but the level of detail available for these structures is highly uneven. Among porolepiforms, the braincase and endocast is best known for the Middle Devonian holoptychiid Glyptolepis groenlandica, but even here there is lack of detail compared to the most completely understood examples from other sarcopterygian lineages. Here we address this deficiency through micro-computed tomographic study of the intact neurocranium of Durialepis edentatus and Early Devonian (Emsian) ‘porolepidid’-grade porolepiforms from the Eifel region of Germany. We present some revisions to external details of the braincase reported by a prior study, the most significant of which is identification of the occipital arch. Scans reveal substantial new data on internal structure of the braincase. The endocranial cavity of the ethmosphenoid division closely agrees with details reported for Glyptolepis and Powichthys, and we agree with past studies that argue for a close relationship between the latter genus and porolepiforms. Durialepis edentatus shows a dense network of canals in the snout comparable to the rostral tubuli of several other sarcoptergians. We also provide the first model of the posterior cranial endocast in a porolepiform. Drawing on additional tomographic data for Glyptolepis paucidens and an unnamed Scottish holoptychiid, we review patterns of character distribution in porolepiform braincases and endocasts, amplifying support for clades including Porolepiformes + Powichthys and for Holoptychiidae.

The Southern Uplands-Down-Longford Terrane (SUDLT) saw exploration for coal in Ordovician-Silurian marine rocks for several centuries, including well after it was understood that land plant coals would not occur in such rocks. Some lithologies were so carbonaceous that a fuel of sorts was mined. The record of this exploration and mining activity is mostly forgotten, but there are diverse sources to show that it was widespread. Exploration was mostly inspired by outcrops of Moffat Shale, in which deformation and hydrocarbon generation left coal-like products. The hydrocarbon origin conferred high calorific value to the fuel, so it did burn and encouraged exploration. The deposits show that an accretionary prism can be a reservoir of locally abundant carbon.

The descriptions of two co-occurring cardioid crustaceans from the Ballagan Formation (Tournaisian, Lower Carboniferous) of Chirnside, Scottish Borders, help to resolve the taxonomy of the genus Tealliocaris. Tealliocaris robusta Peach, 1908 is assigned to Schramocaris to form S. robusta (Peach, 1908) comb. nov. on the basis of morphological characters such as the rugosity and position of the branchial carinae as well as the nature of the pleon, and becomes the earliest representative of this genus in Scotland. A new species of Tealliocaris is also recognised from this locality and is described as T. briggsi sp. nov., based on the smooth carapace, lack of pleonic grooves and the number of spines on the scaphocerite and lateral margin of the anterior carapace. The systematic position of the Pendleian specimens identified by Peach (1908) as ‘Tealliocaris robusta var.’ is finally resolved and described as T. weegie sp. nov.

The early tetrapod Eoherpeton watsoni is known from the mid- to late Carboniferous (late Viséan to Namurian, approximately 346–313 Ma) of Scotland. The holotype is made up of a nearly complete but crushed skull with postcranial fragments. The skull anatomy of Eoherpeton was first described over 40 years ago; however, many details are obscured due to deformation of the specimen, including internal bone surfaces, the palatal bones and dentition, and suture morphology. Most phylogenetic analyses place Eoherpeton as an embolomere/reptilomorph on the lineage leading to amniotes, making it a key taxon for understanding anatomical changes during the fish-tetrapod transition. In this paper, we scanned the holotype using micro-computed tomography and digitally prepared the specimen. Based on these data, we present a revised description of the skull, including sutural morphology, that supplements and amends previous descriptions. New anatomical findings include the presence of a previously unknown tooth-bearing vomer, additional information on the shape of the basipterygoid processes and jaw joint, the ability to visualise the full extent of the pterygoid, and confirmation of the arrangement of the coronoid series. We also note the size of the pterygoid flange, which is larger than previously described for Eoherpeton. The pterygoid flange is widely considered to be characteristic of amniotes and serves as the origin of the medial pterygoideus muscle. The differentiation of the adductor muscles and appearance of medial pterygoideus are thought to have permitted a static pressure bite in amniotes, potentially resulting in greater bite forces and increased dietary range. Thus, the presence and extent of the pterygoid flange in Eoherpeton suggests this feature (and associated changes in feeding mechanism) may have evolved earlier than previously thought. Finally, the skull was digitally repaired and retrodeformed to create a new, hypothetical three-dimensional reconstruction of the skull of Eoherpeton.

The non-archosauriform archosauromorph Dinocephalosaurus orientalis was first described from the Upper Member of the Guanling Formation (late Anisian, Middle Triassic) of Guizhou Province by Li in 2003 on the basis of a complete articulated skull and the first three cervical vertebrae exposed in dorsal to right lateral view. Since then, additional specimens have been discovered in southwestern China. Here, five newly discovered specimens are described for the first time, and redescriptions of the holotype IVPP V13767 and another referred specimen, IVPP V13898, are provided. Together, these permit the description of the complete skeleton of this remarkable long-necked marine reptile. The postcranial skeleton is as much as 6 metres long, and characterised by its long tail and even longer neck. The appendicular skeleton exhibits a high degree of skeletal paedomorphosis recalling that of many sauropterygians, but the skull and neck are completely inconsistent with sauropterygian affinities. The palate does not extend back over the basisphenoid region and lacks any development of the closed condition typical of sauropterygians. The arrangement of cranial elements, including the presence of narial fossae, is very similar to that seen in another long-necked archosauromorph, Tanystropheus hydroides, which at least in part represents a convergence related to an aquatic piscivorous lifestyle. The long and low cervical vertebrae support exceptionally elongate cervical ribs that extend across multiple intervertebral joints and contribute to a ‘stiffening bundle of ribs’ extending along the entire ventral side of the neck, as in many other non-crocopodan archosauromorphs. The functional significance of the extraordinarily elongate neck is hard to discern but it presumably played a key role in feeding, and it is probably analogous to the elongate necks seen in pelagic, long-necked plesiosaurs. Dinocephalosaurus orientalis was almost certainly a fully marine reptile and even gave birth at sea.

Photogrammetry was used to elucidate complex strata relationships between isolated outcrops of the Palaeocene lava fields of SW Mull, part of the North Atlantic Igneous Province. Subsequent sampling for lava geochemistry and palynology was undertaken based on interpretation of these photogrammetry models. Coherent units of Plateau- and Staffa-type lavas were identified using lava geochemistry, in particular using rare earth elements (REEs), divisions supported by multivariate statistics. Lavas with three different REE compositional clusters were identified within the Staffa magma type and four within the Plateau type of SW Mull. Understanding the distribution of these lava types was achieved using the interpreted photogrammetry models and analysis of prominent interbedded sedimentary rock units and their correlative unconformities. Probably the most renowned rocks of SW Mull are the thick columnar jointed lavas, including those of the Isle of Staffa. REE geochemistry reveals that lavas of both Staffa- and Plateau-type geochemistry occur as columnar jointed facies associated with what has previously been attributed to the Staffa Lava Formation. Instead, the SW Mull Lava Field was initiated by eruption of Plateau-type lava into a fault-controlled valley. Subsequent eruptions of Staffa-type lavas partially infilled this structure, which was finally overfilled by a thick succession of younger Plateau-type lavas. The geochemical characteristics of this Plateau–Staffa–Plateau lava succession indicate that magma reservoirs deep in the crust were succeeded by shallow melts during a period of crustal extension. This phase of shallow melting induced topographical instability and formation of sedimentary interbeds and correlative unconformities that characterise the Staffa-type lava succession. Subsequent compressive tectonics forced a return to deep crustal melts. Interbed palynofloral compositional data indicate that eruption of the later Plateau-type lavas likely took place within a period of ~2.5 million years during the Selandian to early Thanetian period.

Drillholes on shells provide a useful way to investigate prey and predator relationships. The current study documents predator–prey interactions exemplified by a faunal assemblage of the fossil gastropod Turritella cingulifera from the Pleistocene Szekou Formation in Hengchun Peninsula, Taiwan. All recognisable skeletal and shell fragments that are larger than 3 mm in size were collected and recorded. Processed bulk sediments (5.24 kg) contained 1462 molluscan shells, including 824 specimens of T. cingulifera, and 27 non-molluscan invertebrates. In the current study, approximately 41.6% (609/1462) of molluscs are drilled with at least one hole. Drilling intensities (DIs) regardless of shell completeness in all gastropods, bivalves and the turritelline gastropod T. cingulifera are 0.546, 0.060 and 0.413, respectively. DI on turritellids is significantly lower than that on other gastropods (χ2= 21.039, P < 0.001). Furthermore, the percentage of drillholes that occur in multiply drilled specimens is 34.7% (95/275) for turritelline gastropods based on complete to nearly complete specimens (n = 588). Our study shows no significant preference of drillhole position either on the suture or on the whorl (χ2= 0.055, P = 0.814). Most drillholes are located in whorls two to four proximal to the aperture. Drillhole diameters of the shells with one drillhole and ones with multiple drillholes are 1.0 and 0.5 mm on average, and the results of Mann–Whitney tests indicate that they are significantly different (P < 0.001). The first turritelline gastropod shell with an incomplete drillhole from Taiwan is documented here. The dominant drilling predators were naticids based on the drillhole morphology and the presence of naticids in the same assemblage. No apparent prey size selectivity is observed, so a ‘size refugium’ does not exist for the turritellids in the current study.

Methodologies that analyse the colouration and external appearance of extant species are very useful tools when facing one of the greatest challenges in the palaeoartistic reconstructions of extinct fauna: inferring the colour patterns. Earlier works have applied this methodology, for example, in the reconstruction of the Miocene bovid Tethytragus, proving that the maximum likelihood (ML) analysis to infer ancestral states has promising potential. This study offers a proposal for the reconstruction of the external appearance of Heteroprox moralesi Azanza 1989, an early cervid of the Middle Miocene present in several fossil sites of Central Spain. For the reconstruction of the external appearance, the colour patterns of all the extant species of the family Cervidae were studied with the method of ML analysis, as well as recent works about their phylogeny. The results show the most probable basal colour pattern of the cervids: dark shades on the limbs, dorsal section, and head of the animal, and, in contrast, lighter colours on the neck and perianal region. This basal pattern can be used as a basis for reconstructing colouration and to hypothesise about the external appearance of extinct taxa. Furthermore, the inferred forest habitat of H. moralesi has been taken into consideration in order to adjust the colour pattern, comparing the final results of the analysis performed in this study with that of the pattern observed in extant forest deer as well as with previous works employing this methodology.

In the last decade, the identification of bone fragments by peptide mass fingerprinting or zooarchaeology by mass spectrometry is developing as a powerful tool in Quaternary palaeontology. The sequence of amino acids that make up the bone collagen molecule shows slight variations between taxa, which can be studied by mass spectrometry for taxonomic purposes. This requires reference databases that allow peptide identification. Although the cave bear (Ursus spelaeus Rosenmüller, 1794) is a common component in many European Pleistocene cave sites, no peptide fingerprint taxonomic study has paid special attention to this species up to now. For peptide markers in Ursidae, the most recent proposal is based on collagen obtained from a modern brown bear sample. In this work we attempt to cover this gap by studying bone collagen of cave and brown bear samples from different origins and different chronology, applying matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI TOF). We also performed an in-silico study of ursid bone collagen sequences published in databases. In our results we detected some discrepancies between the peptides obtained from both in silico and MALDI TOF analysis of fossil collagen and those published in the literature, in which we conclude that there are some misidentified peptides. The identification of skeletal remains by means of their peptide fingerprint is proving to be a powerful tool in palaeontology, which will bear greater fruit once the limitations of a technique that is in its initial stages have been overcome.

Permian fishes and their isolated microremains are known from many localities in the Zechstein Basin. However, up to date the vertebrates have never been revealed in the southeasternmost part of this ancient sea. The new material consists of euselachian-type dermal denticles,?Listracanthus sp. dermal denticle,?Omanoselache sp. tooth, actinopterygian scales and actinopterygian teeth. Here, the detailed study of euselachian and actinopterygian remains, their stratigraphic distribution and geographical contexts is presented. Based on the qualitative analysis of teeth shapes several ecomorphotypes were described as well as the probable dietary preferences of fishes were reconstructed. These finds confirmed existence of small predators who fed on soft bodied prey as well as durophagous forms which were feeding on small shelly crustaceans or molluscs. The analysis of stratigraphic distribution of microremains, and their comparison with neighbouring sections revealed a spatially correlatable trend in increasing abundance of fishes in the more clayey parts of sections, interpreted to be positively associated with a sea level transgression event.

Byronids are problematic fossils of possible cnidarian affinity, only rarely reported from the Devonian, but never previously studied in the Barrandian area, Czech Republic. Two new species Prestephanoscyphus branzovensis sp. nov. and Prestephanoscyphus robustus sp. nov. are erected from the Lochkovian and the Eifelian, respectively. Four poorly known species referred to Byronia are described in open nomenclature from the Emsian and Eifelian. The new genus Parabyronia gen. nov. with the type species Parabyronia elegans sp. nov. is closely related to other sphenothallids but is distinguished by transverse ridges on its theca and short spines at the apertural end of the theca. Definite identification of phosphatic rings as the attachment structure of byronids was proved by new material of the Lochkovian age. A dwarf conularia Pidiconularia gen. nov. with the type species Pidiconularia tubulata sp. nov. is remarkable by its minute size and very fine ornament; its conulariid affinity is proved by subrectangular cross-section and four internal carinae. Microstructure of theca of Prestephanoscyphus is characterised by alternation of compact laminae of aligned columnar microcrystallites and chambered laminae with isometric microcrystallites of apatite. Accretionary growth of byronid theca and structure of the holdfast with basal opening for the adhesive pedal disc support their cnidarian affinity although they likely display the bilateral instead of tetramerous symmetry. The protective function of bilaterally symmetrical whorls of internal apophyses in Prestephanoscyphus is suggested and their role in strengthening of thecal wall or supporting function of gastric septa are disputed. The byronids are regarded as epibionts rather than attached to the rocks. They are representatives of benthic groups with phosphatic shells that declined with decreasing availability of phosphorus in seas and oceans.

The Lower Pleistocene Karnezeika locality, lies in the Peloponnese, southern Greece, and its fauna corresponds to the Middle Villafranchian biochronological unit (MN17). The recovered mammal assemblage includes, among others, a few remains of a large Cercopithecid. Herein, we describe this material, including an upper second molar, a partially preserved proximal radius and, possibly, an upper first incisor. The teeth show advanced stages of wear but retain their typical papionin characters, such as a strong lingual cleft and four bilophodont cusps in the molar. The general morphology and wear pattern of the teeth rules out the possibility that the remains belong to the genus Theropithecus, while the general size of the corresponding material excludes the possibility of a Macaca representative as well. On the contrary, the studied material better fits the size range of Paradolichopithecus. Even though this genus is likely represented in the Villafranchian of Europe by a single species, Par. arvernensis, the scarcity of the studied material imposes reservations and thus the Karnezeika papionin is referred at the moment to cf. Paradolichopithecus sp. As in the rest of Europe, the Paradolichopithecus record is rare in Greece, having been found in only two localities, Vatera and Dafnero. Despite its scarcity, the new material from Karnezeika indicates a wide distribution of this important taxon in the Greek peninsula.

A small lot of fossil whale barnacles from the Upper Pleistocene of California and the Middle Pleistocene (Chibanian) of Oregon (United States West Coast), described in a 1972 unpublished MA thesis, are formally described and illustrated herein. In that thesis, a new genus and species name were proposed; however, according to the International Code of Zoological Nomenclature, they have no taxonomic standing and are thus unavailable. Based on our reappraisal, two specimens in this lot belong to a new, extinct species that can be assigned to the purportedly extant genus Cetopirus. Cetopirus polysyrinx sp. nov. differs from congeners in that its secondary T-shaped flanges are multitubiferous internally, that is, they are perforated by a high number of irregularly-sized and irregularly-spaced tubules that result in a spongy aspect in transverse section. Whether or not this peculiar condition had any adaptive significance is difficult to determine. Considering that Cetopirus is currently known as an obligate epibiont of right whales (including the North Pacific form Eubalaena japonica (Lacépède 1818)), the host of C. polysyrinx sp. nov. was E. japonica or some other species of Eubalaena. The Plio-Pleistocene deposits of the Pacific coast of North America have yielded a rather idiosyncratic fossil whale barnacle fauna, inclusive of the genera Cetolepas, Cryptolepas and now Cetopirus, which seemingly contrasts with all other coeval assemblages worldwide, the latter being in turn dominated by Coronula spp.

Brachiopod taxonomy is based on descriptions of shell morphology and key characters, but diagenesis generally modifies or erases some of them, hindering brachiopod identification. Brachiopods that are taxonomically related usually present shells with similar appearance but can differ in size (i.e., Rhynchonellata). Some aspects of morphology – for example the angular measurement of the curvature of the shell or details of shell microstructure – could aid taxonomic identification. Gigantoproductids, which lack a robust taxonomy, have the largest shells among brachiopods and are ideal for this kind of study because of their gigantic size and morphological variability. Furthermore, they have a great abundance and worldwide distribution during the mid-Carboniferous. More than 700 samples have been collected from Sierra Morena (Spain), Montagne Noire (France) and Adarouch (Morocco) identifying up to six gigantoproductid genera: Globosoproductus, Semiplanus, Kansuella?, Latiproductus, Gigantoproductus and Datangia. Microstructural features from 170 thin sections belonging to gigantoproductid ventral valves have been studied, and six crystal morphologies have been distinguished within the tertiary layer: subhorizontal, imbricated, crenulated, acicular, short and long columnar morphologies. Moreover, 23 complete shells from all genera have been selected to investigate shell size and curvature. Results from this study emphasise that shell size, curvature and crystal shape are taxa-related. Finally, a remarkable morphological change in the gigantoproductid populations from the western Palaeo-Tethys occurred during the Viséan–Serpukhovian, from thin-shelled genera with subhorizontal morphology (Viséan) to thick-shelled genera with a tertiary layer consisting of long columnar crystals (Serpukhovian). This study proves that microstructure, maximum thickness and shell spiral characterisation are robust characters when applied to gigantoproductid taxonomy, but also have great potential in other brachiopod groups.