Categorical versus geometric morphometric approaches to characterizing the evolution of morphological disparity in Osteostraci (Vertebrata, stem Gnathostomata)

Morphological variation (disparity) tends to be evaluated through two non-mutually exclusive approaches: (i) quantitatively, through geometric morphometrics, and (ii) 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 benchmarking studies conducted so far show contrasting results. Here, we apply both approaches to characterising morphology in the stem-gnathostome vertebrate clade Osteostraci, in order to assess congruence between these alternative methods as well as to explore the evolutionary patterns of the grou…

The palaeontological virtual collection of the University of Valencia’s Natural History Museum: a new tool for palaeontological heritage outreach

The rise of new digitalization technologies is changing the way to access to the fossil collections for palaeontology outreach, providing new tools to preserve our important palaeontological heritage. In this sense, museums and palaeontological institutions,aware of the advantages of applying these new technologies for the accomplishment of their functions, have started to develop their own online repositories to facilitate the access to the most representative fossil of their collections. Following this trend, the aim of this work is to present the creation of the new “Virtual 3D Collection” of the University of Valencia’s Natural History Museum, showing, as an example, the “Ichnofossil Co…

Late Devonian (Famennian) chondrichthyes from Mexico

The Paleozoic vertebrate fossil record from Mexico is very scarce and strongly biased by rock exposure, composed mainly of upper Paleozoic (Carboniferous and Permian) outcrops (e.g., Sánchez-Zavala et al., 1999; Poole et al., 2005; González- Rodríguez et al., 2013). In particular, the Mexican Paleozoic fish fossil record comprises a few isolated chondrichthyan scales and some semiarticulated symphysial tooth whorls belonging to the iconic shark Helicoprion, with ages ranging from the Late Carboniferous to the early Permian. The first reported Paleozoic fish from Mexico belongs to a semiarticulated symphysial tooth whorl of Helicoprion mexicanus from the Permian of Coahuila, near Las Delicia…

First occurrence of fossil vertebrates from the Carboniferous of Colombia

Data concerning Paleozoic vertebrates from the South American continent are still scarce. In Colombia, occurrences were until now restricted to the Late Devonian fish assemblage from Floresta and, ...

First Perigondwanan record of actinolepids (Vertebrata: Placodermi: Arthrodira) from the Lochkovian (Early Devonian) of Spain and its palaeobiogeographic significance.

Different palaeogeographic models have been proposed for the position of Laurussia ( including Baltica) and Gondwana-derived microcontinents ( including Ibero-Armorica) during Ordovician to Late Carboniferous times. Principal differences concern the presence and duration of a large ocean, the Rheic Ocean, acting as a faunal barrier between these areas. The timing of the collision of Laurussia with Gondwana and/or Gondwana-derived terranes continues to be debated. Here we present new faunal data revealing close biogeographical relations between Ibero-Armorica ("Perigondwanan" or Gondwanan derivate terranes) and Podolia (SE margin of Baltica, in Laurussia). The placoderm assemblage found in t…

Middle Triassic conodont apparatus architecture revealed by synchrotron X-ray microtomography

Abstract The composition of conodont apparatuses is crucial for understanding the feeding mechanisms of these early vertebrates. However, the multielement apparatus reconstructions of most species remain equivocal because they have been inferred from loose element collections, guided by knowledge from rare articulated ‘bedding plane assemblages’ and fused clusters, often from distantly related taxa. Even these natural assemblages can be difficult to interpret because the component elements can be closely juxtaposed or embedded in matrix, making it hard to discern the morphology of each element and their relative positions within the architecture of the feeding apparatus. Here we report five…

Late Paleozoic microfaunas in the pebbles of the Podlipoglav conglomerate, Central Slovenia

Abstract The Paleozoic conglomerate at Podlipoglav in the transitional area between the External and Internal Dinarides of Slovenia contains limestone pebbles that have been examined micropaleontologically. The recovered conodont faunas are marked by the obvious absence of shallow-water taxa. The Lower to Middle Devonian faunas are characterized by relatively abundant polygnathids that are assigned to the Emsian and early Eifelian excavatus-nothoperbonus, laticostatus and costatus Zones. The Pennsylvanian conodont faunas contain relatively deep-water Neolochriea or gondolellids indicating an early Bashkirian and Moscovian age. A presence of the radiolarian species Pseudoalbaillella nodosa s…

Life in the Palaeozoic: an overview of land and sea ecosystems

The Palaeozoic Era, lasting from 541-252 million years ago, was a time of dramatic geographical, climatic, and evolutionary changes. During this Era, life experienced a tremendous transformation and many critical macroevolutionary events took place, including important biotic radiations and diversifications, and three of the five major mass extinctions on the Earth history (Raup&Sepkoski 1982). The advent and diversification of most modern metazoan phyla occurred during the Cambrian and Ordovician periods, in the so-called Cambrian Explosion and Great Ordovician Biodiversification Event (GOBE) (Servais et al. 2010). During the Ordovician, tectonic movements lead to a global cooling that cul…

Lonchidion derenzii, sp. nov., a new lonchidiid shark (Chondrichthyes, Hybodontiforms) from the Upper Triassic of Spain, with remarks on lonchidiid enameloid

Lonchidiidae Herman, 1977, represents one of the most diverse and controversial families of Hybodontiformes, the sister group of Neoselachii (i.e., modern sharks, skates, and rays). It was initially erected as a monogeneric family including only Lonchidion Estes, 1964, a genus of small euryhaline hybodonts from the Mesozoic. Recently, Cappetta (2012) recognized up to eight genera within the family: Baharyodon, Diplolonchidion, Vectiselachos, Hylaeobatis, Isanodus, Parvodus,Lissodus, andLonchidion, although the content of the family is still under discussion (see, e.g., Rees, 2008; Khamha et al., 2016). Major discrepancies concern the phylogenetic relationships between Lonchidion and Lissodu…

Biomechanics of Machaeracanthus pectoral fin spines provide evidence for distinctive spine function and lifestyle among early chondrichthyans

Acanthodians are a major group of Paleaozoic jawed vertebrates that constitute a paraphyletic assemblage of stem-chondrichthyans (Brazeau and Friedman, 2015). Representatives of this group are characterized, among other traits, by the presence of bony spines in front of all paired and median fins except the caudal (Denison, 1979), which has given rise to their colloquial name of 'spiny sharks'. The occurrence of pectoral fin spines is recognized as a potential gnathostome synapomorphy (Miller et al., 2003) or symplesiomorphy (Coates, 2003), being also present in other major groups of Paleaozoic jawed vertebrates, including placoderms (Young, 2010), 'non-acanthodian' chondrichthyans (Miller …

New Lower Devonian Polygnathids (Conodonta) from the Spanish Central Pyrenees, with comments on the early radiation of the group

The comprehensive study of six Pragian-lower Emsian (Lower Devonian) sections from the Spanish Central Pyrenees has yielded a rich assemblage of conodont faunas, highlighting an important succession of Polygnathus species. Among them, the presence of the biostrati­graphical markers P. pireneae , P. kitabicus, P. excavatus excavatus and P. exc. 114 stands out. This conodont succession allows the identification of the Pragian/Emsian boundary and the early Emsian zones and subzones: the kitabicus Zone and the Lower and Middle excavatus subzones. It is also remarkable the presence of three new polygnathid species: P. aragonensis n. sp., P. carlsi n. sp. and P. ramoni n. sp. Additionally, P. pan…

Open data and digital morphology

International audience; Over the past two decades, the development of methods for visualizing and analysing specimens digitally, in three and even four dimensions, has transformed the study of living and fossil organisms. However, the initial promise that the widespread application of such methods would facilitate access to the underlying digital data has not been fully achieved. The underlying datasets for many published studies are not readily or freely available, introducing a barrier to verification and reproducibility, and the reuse of data. There is no current agreement or policy on the amount and type of data that should be made available alongside studies that use, and in some cases…

Critical appraisal of tubular putative eumetazoans from the Ediacaran Weng'an Doushantuo biota

Molecular clock analyses estimate that crown-group animals began diversifying hundreds of millions of years before the start of the Cambrian period. However, the fossil record has not yielded unequivocal evidence for animals during this interval. Some of the most promising candidates for Precambrian animals occur in the Weng'an biota of South China, including a suite of tubular fossils assigned to Sinocyclocyclicus, Ramitubus, Crassitubus and Quadratitubus, that have been interpreted as soft-bodied eumetazoans comparable to tabulate corals. Here, we present new insights into the anatomy, original composition and phylogenetic affinities of these taxa based on data from synchrotron radiation …

Trending topics in Spanish Palaeontology: Contributions from the XI Encuentro de Jóvenes Investigadores

The present volume represents a series of synthetic works presented at the “XI Encuentro de Jóvenes Investigadores en Paleontología”, which took place in Atarfe (Granada, Spain) on April 2013. During this meeting, more than thirty contributions were presented, offering a representative sample of the palaeontological state-of-the-art research currently developed in Spain. A small selection of these contributions is here presented, highlighting than most of them are first-authored by early-stage Spanish researcher who attended the aforementioned meeting. As stated above, our planet has evolved since its origin, in a similar wat that Palaeontology has evolved during the las decades. This evolu…

X-ray nanotomography and electron backscatter diffraction demonstrate the crystalline, heterogeneous and impermeable nature of conodont white matter

Conodont elements, microfossil remains of extinct primitive vertebrates, are commonly exploited as mineral archives of ocean chemistry, yielding fundamental insights into the palaeotemperature and chemical composition of past oceans. Geochemical assays have been traditionally focused on the so-called lamellar and white matter crown tissues; however, the porosity and crystallographic nature of the white matter and its inferred permeability are disputed, raising concerns over its suitability as a geochemical archive. Here, we constrain the characteristics of this tissue and address conflicting interpretations using ptychographic X-ray-computed tomography (PXCT), pore network analysis, synchro…

Supplementary methods, figures, tables and information from Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)

Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatun, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from Kernel probability density functions and Gaussian mixture models. Our analyses support the presence of fiv…

Balance training versus balance training and foot and ankle mobilization: a pilot randomized trial in community-dwelling older adults

Background: Balance limitations and foot and ankle problems are common in older adults. Objective: To determine the impact of augmented balance training with foot and ankle mobilizations (FAMs) on ...

Discovery of a Lochkovian flora (Lower Devonian) in the Iberian Peninsula

ABSTRACT The Lower Devonian represents an important episode in plant life history, which was marked by the diversification of land plants. Unfortunately, remains of early Devonian plants in the Iberian Peninsula are scarce. In the present paper, we describe a small assemblage of early land plants from the Lochkovian (Lower Devonian) of the Teruel Province in Spain. The main element consists of Taeniocrada-like sterile stems that are predominandy dichotomous and ribbon-like with a narrow central strand. An unidentified fossil formed by dichotomous axes together with an uncertain globular structure were also observed. This finding increases our knowledge of the palaeogeographical distribution…

Ichnological evidence of semi-aquatic locomotion in early turtles from eastern Iberia during the Carnian Humid Episode (Late Triassic)

Abstract Some of the earliest European records of fossil turtle footprints (Late Triassic, Middle Carnian, ~ 227–237 Ma) are interpreted from 46 footprints from three outcrops, Domeno, Quesa and Cortes de Pallas, located in the Iberian Range (eastern Spain). The samples were obtained from Upper Triassic rocks in Keuper Facies. They are characterized in the studied area by two well-defined evaporitic sequences, separated by a detrital stratigraphic interval, constituting the Manuel Sandstones Formation in which the studied fossil footprints were recorded. These fluvial deposits are correlatable with the Carnian Humid Episode. The footprints are tridactyl and tetradactyl, mainly digitigrade, …

Microstructure of Triassic conodont Pseudofurnishius murcianus van den Boogaard: Functional implications

Pseudofurnishius murcianus van den Boogaard is a Triassic conodont with a very characteristic morphology, a blade with a rostral platform heavily denticulated, that makes it easily distinguishable from other coeval species. It is a well-know taxon that has been the object of several palaeobiological works, focused on their apparatus reconstruction, ontogeny and, recently, their P 1 element function. In order to increase our palaeobiology knowledge of this taxon we undertook a histological analysis to corroborate the functional hypothesis established for this conodont. The histological study demonstrated the presence of different microstructural types, suggesting that they are functional ada…

Supplementary methods, figures, tables and information from Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)

Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatun, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from Kernel probability density functions and Gaussian mixture models. Our analyses support the presence of fiv…

Supplementary material from Functional assessment of morphological homoplasy in stem-gnathostomes

The Osteostraci and Galeaspida are stem-gnathostomes, occupying a key phylogenetic position for resolving the nature of the jawless ancestor from which jawed vertebrates evolved more than 400 million years ago. Both groups are characterized by the presence of rigid headshields that share a number of common morphological traits, in some cases hindering the resolution of their interrelationships and the exact nature of their affinities with jawed vertebrates. Here, we explore the morphological and functional diversity of osteostracan and galeaspid headshields using an innovative approach that combines geometric morphometrics and computational fluid dynamics, thereby constraining the underlyin…

Functional assessment of morphological homoplasy in stem-gnathostomes

Osteostraci and Galeaspida are stem-gnathostomes, occupying a key phylogenetic position for resolving the nature of the jawless ancestor from which jawed vertebrates evolved more than 400 million years ago. Both groups are characterized by the presence of rigid headshields that share a number of common morphological traits, in some cases hindering the resolution of their interrelationships and the exact nature of their affinities with jawed vertebrates. Here, we explore the morphological and functional diversity of osteostracan and galeaspid headshields using an innovative approach that combines geometric morphometrics and computational fluid dynamics, thereby constraining the underlying fa…

An enigmatic marine reptile, Hispaniasaurus cranioelongatus (gen. et sp. nov.) with nothosauroid affinities from the Ladinian of the Iberian Range (Spain)

An incomplete skull of a marine reptile with an atypical elongation of the postorbital region is described. The find comes from the Muschelkalk facies (Cañete Formation) of the Villora section (Iberian Range, Cuenca Province, Spain), characterised by a shallow marine (intertidal) environment and dated as Ladinian in age. The small skull has a rectangular shape, lacking, as preserved, upper temporal openings and a parietal foramen. The upper temporal openings might be secondarily closed. However, the absence of a parietal foramen and squamosals in the preserved part and the incompleteness of the pterygoids make a posteriorly postponed location of the upper temporal openings also conceivable.…

Enameloid microstructure in the oldest known chondrichthyan teeth

Botella, H., Donoghue, P.C.J and Martinez-Perez, C. 2009. The enameloid microstructure of the oldest known chondrichthyan teeth. — Acta Zoologica (Stockholm) 90 (Suppl. 1): 103‐108 Previous studies on tooth enameloid microstructure in several chondrichthyan taxa spanning the phylogeny of the group provided support for the homology of chondrichthyan tooth enameloid. This hypothesis requires that a single crystallite enameloid (SCE) monolayer must be present in the teeth of the most primitive chondrichthyan. However, the dental microstructure of the earliest sharks has yet to be investigated. We have studied the tooth enameloid microstructure of the two oldest tooth-bearing shark species curr…

First fossil record (Middle Miocene) of the viper shark Trigonognathus Mochizuki and Ohe, 1990, in the Mediterranean realm

The genus Trigonognathus Mochizuki and Ohe, 1990, is a monospecific taxon of `lantern sharks¿ (i.e., family Etmopteridae), a group of small-sized bioluminescent deep-sea chondrichthyans, ranging in mature male specimens between 42¿47 cm total length, and at least 52 cm for females (Ebert et al., 2021). This shark inhabits the upper continental slopes as well as the uppermost slope of seamounts, often at the bottom, at depths ranging between 250¿1000 m, but has been caught at 150 m and 270 m in deep open waters (Mochizuki and Ohe, 1990; Compagno et al., 2005; Ebert et al., 2021). Only two species have been described thus far, the extant species Trigonognathus kabeyai Mochizuki and Ohe, 1990,…

Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)

Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatún, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from kernel probability density functions and Gaussian mixture models. Our analyses support the presence of fi…

Ecomorphological inferences in early vertebrates: reconstructing Dunkleosteus terrelli (Arthrodira, Placodermi) caudal fin from palaeoecological data

Our knowledge about the body morphology of many extinct early vertebrates is very limited, especially in regard to their post-thoracic region. The prompt disarticulation of the dermo-skeletal elements due to taphonomic processes and the lack of a well-ossified endoskeleton in a large number of groups hinder the preservation of complete specimens. Previous reconstructions of most early vertebrates known from partial remains have been wholly based on phylogenetically closely related taxa. However, body design of fishes is determined, to a large extent, by their swimming mode and feeding niche, making it possible to recognise different morphological traits that have evolved several times in no…

New insights into Late Devonian vertebrates and associated fauna from the Cuche Formation (Floresta Massif, Colombia)

New vertebrate remains are reported from the Late Devonian (?Frasnian) Cuche Formation of northeastern Colombia, including a new taxon of antiarch placoderm (Colombialepis villarroeli, gen. et sp. nov., previously reported as Asterolepis) and a new taxon of arthrodiran placoderm (Colombiaspis rinconensis, gen. et sp. nov.). We also report evidence of a stegotrachelid actinopterygian, a diplacanthid acanthodian (cf. Florestacanthus morenoi), a second antiarch placoderm (Bothriolepis sp.), a putative megalichthyid, and a putative tristichopterid. The absence of typical Euramerican markers, e.g., Asterolepis and Strepsodus, in this assemblage suggests that faunal interchange between Euramerica…

Patterns of ecological diversification in thelodonts

Here we explore the spatial, temporal and phylogenetic patterns of ecological diversification for the entire clade of thelodonts, one of the earliest groups of vertebrates and longest lasting of the Palaeozoic agnathans in the fossil record. Parsimony and maximum-likelihood methods are used to reconstruct ancestral states of their geographical distributions, habitats and lifestyles. Our results support the concept that thelodonts originated during the Middle?-Late Ordovician probably in marine open waters of Laurasia, with a demersal lifestyle on hard substrates being the ancestral condition for the whole clade. Later, thelodonts underwent a complex ecological diversification and palaeobiog…

Assessing metabolic constraints on the maximum body size of actinopterygians: locomotion energetics of Leedsichthys problematicus (Actinopterygii, Pachycormiformes)

Maximum sizes attained by living actinopterygians are much smaller than those reached by chondrichthyans. Several factors, including the high metabolic requirements of bony fishes, have been proposed as possible body‐size constraints but no empirical approaches exist. Remarkably, fossil evidence has rarely been considered despite some extinct actinopterygians reaching sizes comparable to those of the largest living sharks. Here, we have assessed the locomotion energetics of Leedsichthys problematicus, an extinct gigantic suspension‐feeder and the largest actinopterygian ever known, shedding light on the metabolic limits of body size in actinopterygians and the possible underlying factors th…

Sucesión de Polygnátidos (Conodontos) del Emsiense (Devónico Inferior) en los Pirineos Centrales Españoles

A comprehensive conodont study of five sections of Emsian age, carried out in the Spanish Central Pyrenees, has revealed an important succession of polygnathids that can be used for identifying basal boundaries of globally recognized biozones. This succession consists of Polygnathus excavatus excavatus, Po. gronbergi, Po. nothoperbonus, Po. mashkovae, Po. laticostatus, and the new species Polygnathus luciae that allows the identification of the excavatus, nothoperbonus and laticostatus Zones. The nothoperbonus Zone is further subdivided into Lower and Upper nothoperbonus subzones, relying upon the lowest occurrence of Po. mashkovae. These biostratigraphic data from the Spanish Central Pyren…

New data on the Lower Devonian chondrichthyan fauna from Celtiberia (Spain)

Lower Devonian microvertebrate remains from Spain, including localities in Celtiberia and Cantabrian Mountains, have been extensively studied during recent decades (e.g., Mader, 1986; Wang, 1993; ...

Caracterización electroquímica del proceso de degradación de materiales piritosos en colecciones geológicas y paleontológicas: propuestas de tratamiento y conservación

Este trabajo analiza los problemas de conservación y tratamiento de ejemplares paleontológicos y geológicos en los museos centrándonos en ejemplares piritizados, destacando los principales factores que afectan la preservación de este tipo de colecciones. Se ha realizado una intervención en ejemplares paleontológicos y geológicos en la cual han sido tratados para su adecuada conservación. Para caracterizar el proceso de degradación se ha realizado un estudio electroquímico sobre diversos ejemplares conservados en pirita y, de este modo, poder identificar estadios de la degradación presente de los ejemplares (producida en el curso del almacenamiento y conservación). La identificación de estos…

Machaeracanthus goujetin. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

ABSTRACT We describe here a new machaeracanthid acanthodian (Machaeracanthus goujeti n. sp.), based on isolated spines, scales and scapulocoracoids from the Lower Devonian (Lochkovian-Pragian) of the Nogueras Formation, Celtiberia, Spain. The new taxon also includes a fragmentary spine and isolated scales from the Lower Devonian of northern Spain (Palencia and Cantabrian Mountains) and western France (Saint-Cenere) originally assigned to Machaeracanthus sp. The spines of M. goujeti n. sp. comprise two morphotypes in agreement with the morphofunctional model of a pair of pectoral spines articulating with the pectoral girdle already indicated for M. hunsrueckianum Sudkamp & Burrow, 2007, M. l…

Bioluminescent-like squamation in the galeomorph shark Apristurus ampliceps (Chondrichthyes: Elasmobranchii)

Galeomorph sharks constitute the most taxonomically and ecologically diverse superorder of living selachians. Despite comprising several typically deep-water taxa, no bioluminescent species have been reported in this group so far. Interestingly, the study of shark squamation has been revealed in recent years to be a good proxy for inferring some ecological aspects of poorly known species. In particular, the high morphological specificity of the dermal denticles and the squamation patterns of all currently-known bioluminescent sharks could constitute a potential tool for predicting bioluminescence in both fossil and living taxa. Following this idea, we provide the first evidence supporting t…

Translating taxonomy into the evolution of conodont feeding ecology

Conodont research has long been divided between utilitarian applications to solve geological problems versus analysis of their palaeobiology. However recent advances in conodont functional analysis allow these independent stands of research to be unified, decoding the functional implications of their morphological variation. We demonstrate this using synchrotron tomography and Finite Element Analysis, informed by occlusal and microwear analyses, to analyze functionally the classic evolutionary sequence of the genus Polygnathus. Our study shows that the evolution of the platform in Polygnathus occurred to accommodate and dissipate the stress accumulation derived from the tooth-like function …

Evolutionary convergence in conodonts revealed by Synchrotron-based Tomographic Microscopy

Obruchevacanthus ireneae gen. et sp. nov., a new ischnacanthiform (Acanthodii) from the Lower Devonian of Spain

New disarticulated material of typically ischnacanthid scales, tooth whorls, and ?dentigerous jaw bones that occur recurrently together at many levels of the Lower Devonian of the Iberian Chain (Spain) is described. Based on their stratigraphical occurrence, histological evidence and comparison with similar ischnacanthid assemblages from other localities, we suggest including all of these remains in a unique natural assemblage, Obruchevacanthus ireneae gen. et sp. nov. This new taxon shares some features with Trundlelepis cervicostulata from the Lower Devonian of New South Wales (Australia), as for example the presence of a poorly developed pore canal system in their scales. This feature su…

Pre-Messinian ecological diversity of Mediterranean sharks revealed by the study of their dermal denticles

The Messinian salinity crisis (~5.59 Ma) is regarded as one of the most determining events for the recent evolutionary and palaeobiogeographic history of the Mediterranean biota. The impact of such episode has usually been assessed by evaluating the associated taxonomic turnover, however its consequences have rarely been interpreted from an ecological perspective. Here we assess the functional diversity of shark dermal denticles in a Serravallian locality from southeast Spain, providing a primary view into the pre-Messinian ecological diversity of shark communities from the Western Mediterranean. Our results reveal a high diversity of functional types of dermal denticles including dermal de…

Visual memory dysfunction as a neurocognitive endophenotype in bipolar disorder patients and their unaffected relatives. Evidence from a 5-year follow-up Valencia study.

BACKGROUND: Scarce research has focused on Visual Memory (VM) deficits as a possible neurocognitive endophenotype of bipolar disorder (BD). The main aim of this longitudinal, family study with healthy controls was to explore whether VM dysfunction represents a neurocognitive endophenotype of BD. METHODS: Assessment of VM by Rey-Osterrieth Complex Figure Test (ROCF) was carried out on a sample of 317 subjects, including 140 patients with BD, 60 unaffected first-degree relatives (BD-Rel), and 117 genetically-unrelated healthy controls (HC), on three occasions over a 5-year period (T1, T2, and T3). BD-Rel group scores were analyzed only at T1 and T2. RESULTS: Performance of BD patients was sig…

Table S1 from Open data and digital morphology

Summary of main online repositories for 3D digital morphological data.

New insights into the diversity dynamics of Triassic conodonts

International audience; In this paper, we examine the diversity trends and the evolutionary patterns of Triassic conodonts through a newly powered large-scale data-set compiled directly from the primary literature. Paleodiversity dynamics analyses have been undertaken by working at the species level and using a system of time units based on biozone subdivisions for a fine temporal level resolution. The role of heterogeneous duration of taxa in diversity estimates has been evaluated through the probabilistic profiles. Results reveal three different stages in the diversity behaviour of Triassic conodonts from standing metrics delimited by two inflections at the mid-Anisian and mid-Carnian. Su…

Exploring the major depletions of conodont diversity during the Triassic

International audience; In this paper, we show that the Triassic fossil record reflects just two great depletions of conodont diversity before the Rhaetian, which occurred in the Smithian (Olenekian, Early Triassic) and in the Julian (Carnian, Late Triassic). By exploring this context, our results highlighted that they respond to different origination?extinction dynamics. Thus, while the Smithian diversity depletion can be interpreted as a consequence of elevated extinction, the Julian diversity depletion was triggered by fluctuations in origination regime. This evidence suggests that, despite the role of extinction on diversity losses, conodonts suffered crucial changes on the origination …

The evolution of gigantism in active marine predators

A novel hypothesis to better understand the evolution of gigantism in active marine predators and the diversity of body sizes, feeding strategies and thermophysiologies of extinct and living aquatic vertebrates is proposed. Recent works suggest that some aspects of animal energetics can act as constraining factors for body size. Given that mass-specific metabolic rate decreases with body mass, the body size of active predators should be limited by the high metabolic demand of this feeding strategy. In this context, we propose that shifts towards higher metabolic levels can enable the same activity and feeding strategy to be maintained at bigger body sizes, offering a satisfactory explanatio…

Middle Triassic sharks from the Catalan Coastal ranges (NE Spain) and faunal colonization patterns during the westward transgression of Tethys

Abstract Palaeogeographic changes that occurred during the Middle Triassic in the westernmost Tethyan domain were governed by a westward marine transgression of the Tethys Ocean. The transgression flooded wide areas of the eastern part of Iberia, forming new epicontinental shallow-marine environments, which were subsequently colonized by diverse faunas, including chondrichthyans. The transgression is recorded by two successive transgressive–regressive cycles: (1) middle–late Anisian and (2) late Anisian–early Carnian. Here, we describe the chondrichthyan fauna recovered from several Middle Triassic stratigraphic sections (Pelsonian-Longobardian) located at the Catalan Coastal Basin (western…

There is no general model for occlusal kinematics in conodonts

Knowledge of conodont element function is based largely on analysis of morphologically similar P-1 elements of few comparatively closely related species known from abundant articulated remains. From these, a stereotypical pattern of rotational occlusion has been inferred, leading to the suggestion that this may represent a general model for ozarkodinin P-1 elements at the very least. We test the generality of this occlusal model through functional analysis of Pseudofurnishius murcianus P-1 elements which, though superficially similar to homologous elements in gnathodids, evolved their platform morphology independently, through a different mode of morphogenesis, and in a different topologica…

Tooth replacement rates in early chondrichthyans: a qualitative approach

The continuous replacement of teeth throughout their lifetime is a common characteristic of most chondrichthyans. This process was already present in the earliest representatives of the group. It has been well established that different species of extant sharks show rapid tooth replacement rates; however, some authors have suggested that in early chondrichthyans this rate might have been much slower. Here we present a qualitative approach to analyse tooth replacement rates in the Early Devonian shark Leonodus carlsi, the earliest tooth-bearing shark known to date. For this, we have examined 1,103 isolated teeth from Celtiberia, Spain. Our study provides strong evidences of an extremely slow…

Morphometric Discriminant Analysis of isolated chondrichthyan scales for palaeoecological inferences: the Middle Triassic of the Iberian Chain (Spain) as a case of study

[EN] Palaeontological studies on exosqueletal disarticulated remains of chondrichthyans have focused on teeth and only less interest has been paid to scales due their limited taxonomic and systematic significance. However, classical works linking the morphology and the function of the squamation in extant sharks suggest that, despite their limited taxonomic value, the study of isolated scales can be a useful tool for palaeoenvironmental and palaeoecological inferences. Following this idea, we have analyzed the fossil record of shark scales from two Middle Triassic sections of the Iberian Chain (Spain), identifying different functional types by means of a morphometric discriminant analysis. …

Tiburones de aguas profundas en el Mioceno medio de Alicante: implicaciones para la recuperación de los ecosistemas abisales mediterráneos después de la crisis mesiniense

El estudio de la localidad clásica de El Chorrillo del Mioceno Medio (Serravaliense) en la Provincia de Alicante, ha permitido la recuperación de una interesante asociación de microrestos de tiburones caracterizada por al menos siete taxones (Deania calcea, ¿Isistius triangulus, ¿Squaliolus cf. schaubi, ¿Paraetmopterus sp., Pristiophorus sp., Scyliorhinus sp. y un Squaliforme indeterminado) pertenecientes a tres órdenes diferentes (Squaliformes, Pristiophoriformes y Carcharhiniformes). Asociados a estos microrestos se han identificado también macrodientes pertenecientes a Cosmopolitodus hastalis, Isurus sp., Hemipristis serra, Odontaspis sp., Carcharhinus spp. y ¿Otodus (Megaselachus) megal…

Computational Fluid Dynamics Suggests Ecological Diversification among Stem-Gnathostomes.

Summary The evolutionary assembly of the vertebrate bodyplan has been characterized as a long-term ecological trend toward increasingly active and predatory lifestyles, culminating in jawed vertebrates that dominate modern vertebrate biodiversity [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. This contrast is no more stark than between the earliest jawed vertebrates and their immediate relatives, the extinct jawless, dermal armor-encased osteostracans, which have conventionally been interpreted as benthic mud-grubbers with poor swimming capabilities and low maneuverability [ 9 , 10 , 11 , 12 ]. Using computational fluid dynamics, we show that osteostracan headshield morphology is compatible with a dive…

A Serravallian (Middle Miocene) shark fauna from Southeastern Spain and its palaeoenvironment significance

The study of a new Serravallian (Middle Miocene) locality from the Southeastern Spain has yielded a shark assemblage characterized by microremains of at least seven taxa (Deania calcea, ¿Isistius triangulus, ¿Squaliolus cf. S. schaubi, ¿Paraetmopterus sp., Pristiophorus sp., Scyliorhinus sp. and a cf. Squaliformes indet) of three different orders (Squaliformes, Pristiophoriformes and Carcharhiniformes). In addition, associated macroremains have also been found, including teeth of ¿Cosmopolitodus hastalis, Isurus sp., Hemipristis serra, Odontaspis sp., Carcharhinus spp. and ¿Otodus (Megaselachus) megalodon. The assemblage contains taxa with disparate environmental preferences including not o…

Supplementary methods, figures, tables and information from Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)

Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatun, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from Kernel probability density functions and Gaussian mixture models. Our analyses support the presence of fiv…

Biomechanics of Machaeracanthus pectoral fin spines provide evidence for distinctive spine function and lifestyle among early chondrichthyans

Biomechanics of Machaeracanthus pectoral fin spines provide evidence for distinctive spine function and lifestyle among early chondrichthyans

R scripts of performed analyses from Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)

Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatun, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from Kernel probability density functions and Gaussian mixture models. Our analyses support the presence of fiv…

Data from: Patterns of ecological diversification in thelodonts

Here we explore the spatial, temporal and phylogenetic patterns of ecological diversification for the entire clade of thelodonts, one of the earliest groups of vertebrates and longest lasting of the Palaeozoic agnathans in the fossil record. Parsimony and maximum-likelihood methods are used to reconstruct ancestral states of their geographical distributions, habitats and lifestyles. Our results support the concept that thelodonts originated during the Middle?–Late Ordovician probably in marine open waters of Laurasia, with a demersal lifestyle on hard substrates being the ancestral condition for the whole clade. Later, thelodonts underwent a complex ecological diversification and palaeobiog…

Table S1. from X-ray nanotomography and electron backscatter diffraction demonstrate the crystalline, heterogeneous and impermeable nature of conodont white matter

Quantification and pore distribution derived from the Pore Network analysis of a cross section of the cusp of the eucondont Teriodontus nakamurai.

New insights into the diversity dynamics of Triassic conodonts

In this paper, we examine the diversity trends and the evolutionary patterns of Triassic conodonts through a newly powered large-scale data-set compiled directly from the primary literature. Paleodiversity dynamics analyses have been undertaken by working at the species level and using a system of time units based on biozone subdivisions for a fine temporal level resolution. The role of heterogeneous duration of taxa in diversity estimates has been evaluated through the probabilistic profiles. Results reveal three different stages in the diversity behaviour of Triassic conodonts from standing metrics delimited by two inflections at the mid-Anisian and mid-Carnian. Survivorship analysis supp…

Illustration for social media and potential cover image from Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)

Credits: Hugo Salais (Metazoa Studio)

Data from: There is no general model for occlusal kinematics in conodonts

Knowledge of conodont element function is based largely on analysis of morphologically similar P1 elements of few comparatively closely related species known from abundant articulated remains. From these, a stereotypical pattern of rotational occlusion has been inferred, leading to the suggestion that this may represent a general model for ozarkodinin P1 elements at the very least. We test the generality of this occlusal model through functional analysis of Pseudofurnishius murcianus P1 elements which, though superficially similar to homologous elements in gnathodids, evolved their platform morphology independently, through a different mode of morphogenesis, and in a different topological p…