Challenging Darwin: Evolution of Triassic Conodonts and Their Struggle for Life in a Changing World

Abstract The phylogeny and distribution of Triassic conodonts reveal many aspects of their natural history. Conodonts incorporate the morphologic response to temperature as well as to eustatic cycles. Speciation, radiation, and extinction are not fortuitous and evolution uses heterochrony (progenesis and neoteny) in response to stress-generating events. Proteromorphosis (reappearance of ancestral morphs) and paedomorphosis (retention of juvenile traits) is a reaction to sublethal environmental stress. This often follows radiation of fully developed forms in the recovery stage after extinction that timely matches transgressions. Evolutionary retrogradation (neoteny) during eustatic high stan…

Conodonts versus Triassic Climatic and Eustatic Changes

Kılıç, Ali Murat (Balikesir Author)

Middle Triassic carbonate platforms in eastern Iberia: Evolution of their fauna and palaeogeographic significance in the western Tethys

Abstract This article reports the first integrated study of the Middle Triassic of Iberia, based on the stratigraphy, sedimentology, and fossil fauna of Muschelkalk facies of the Iberian Ranges and the Catalan Coastal Ranges in Spain. On the basis of this study, new palaeogeographic reconstructions of the westernmost Tethys are proposed, and the evolution of the different palaeogeographic domains of Iberia (e.g., Iberian, Mediterranean, and Levantine–Balearic) are described. In these domains, Muschelkalk facies record the development of wide carbonate platforms that were the consequence of the first two broad marine transgressions of the Mesozoic in Iberia, respectively, late Pelsonian–earl…

Évolution rétrograde de Neospathodus au cours de la crise Permo - Triasique

The Permian - Triassic evolution of platform conodonts (Gondolellidae) consists mainly in developing the carina and the platform. During the sublethal environmental stress conditions subsequent to the Permian - Triassic extinction, the Wuchiapingian - Griesbachian Clarkina lineage is replaced by the primitive looking platform-lacking Dienerian - Aegean Neospathodus kummeli - Kashmirella timorensis lineage. Moreover, above Jinogondolella denticulata, end of the Capitanian Jinogondolella lineage, “Neospathodus” arcucristatus, an atavistic blade-like homeomorph that lacks a platform, underlies Protoclarkina crofti, of the base of the anagenetic Clarkina lineage. These primitive-looking forms a…

A database of Triassic conodonts from a comprehensive revisión of literature

The revision of a comprehensive amount of bibliography has made possible the development of a database containing the stratigraphic ranges of the conodont species from the uppermost Permian and the Triassic, with a total of 336 species in 52 genera. This database is aimed at biostratigraphy and studies related to biological, evolutional and palaeodiversity dynamics. La revisión de una amplia cantidad de bibliografía ha hecho posible el desarrollo de una base de datos en la que figuran los rangos estratigráficos de las especies de conodontos presentes desde el Pérmico superior y el Triásico, con un total de 336 especies y 52 géneros. Esta base de datos está dirigida a la bioestratigrafía y a…

Pseudodalatias henarejensisnov. sp. a new pseudodalatiid (Elasmobranchii) from the Middle Triassic of Spain

ABSTRACT Pseudodalatiids, a chondrichthyan family of uncertain phylogenetic affinities, have been hitherto exclusively known from the tooth-based species Pseudodalatias barnstonensis (Sykes, 1971), which has a stratigraphic range restricted to the Upper Triassic of Europe. Pseudodalatias presents a characteristic dentition which allows it to hold and cut its prey, showing a neoselachian design, but lacking the triple-layered enameloid microstructure of neoselachian teeth. The discovery of Pseudodalatias henarejensis nov. sp. in the Ladinian of Spain extends the stratigraphical range and the palaeogeographical distribution of this family. This new species also demonstrates that a cutting-clu…

The evolutionary trend of platform denticulation in Middle Triassic acuminate Gondolellidae (Conodonta)

Kılıç, Ali Murat (Balikesir Author)

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…

On the ontogeny and orientation of the Triassic Conodont P1-element in Pseudofurnishius murcianus Van den Boogaard, 1966

Successive growth stages of P1-elements in the Middle to early Late Triassic species Pseudofurnishius murcianus allows the observation of a detailed ontogeny. Besides the gradual enlargement of its curved blade and the growing number of its denticles, a small internal platform develops, eventually followed by an external one, both bearing denticles. The number of denticles on the blade and internal platform increases from five and one in the smallest specimens, respectively, to 14 and 9 in fully developed ones, whereby the distribution pattern of platform-denticles, on the inner one in particular, is of great morphological variety. For the orientation of the P1-element of P. murcianus, the …

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.…

Discussion about the stratigraphic range of "Pseudofurnishius murcianus" van den Boogaard (Conodonta) in the Iberian Peninsula, from the Calasparra section (Murcia, Spain)

The biostratigraphy of Calasparra Section is well-estabished with an ammonoid biozonation and ranges from Lower to Upper Ladinian. The continuous presence of Pseudofurnishius murcianus van den Boogaard, a characteristic conodont species of the Sephardic realm, along the section makes it one of the most important sections in the Iberian Peninsula for the study of the species. The first apparition of P. murcianus in the section corresponds with the first of Eoprotrachyceras curionii taxon, which is the principal marker for the base of the Ladinian stage in the GSSP of the Anisian-Ladinian boundary, and the age of the youngest conodonts, based on ammonoids (Epigonus Zone) is Lower Ladinian (up…

Permian-Triassic Rifting Stage

International audience; The Permian-Triassic rifting represents the first of the two Mesozoic rifting stages recorded in the Iberian Peninsula. Its first phases of development started during the Early Permian, and were linked to the beginning of the break-up of Pangea, the large, unique and rheologically unstable supercontinent that mainly resulted from the collision of Gondwana and Laurussia. This chapter analyzes this first rifting stage in Iberia in two separate phases, an initial or tectonic phase, and a later mature phase. This analysis focuses on the main Permian-Triassic basins of the Iberian Peninsula: the Pyrenean, Iberian, Catalan, Ebro and Betic basins, as well as the basins loca…

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 …

Taxonomy and evolution of the Triassic conodont Pseudofurnishius

Pseudofurnishius is a late Anisian (Pelsonian)—early Carnian (Cordevolian) conodont genus of gondolellid stock, characteristic for the Sephardic Province and restricted to the “Southern Tethys” region of the northern margin of Gondwana. Its most commonly found species, Pseudofurnishius murcianus, appears at the base of the Ladinian (Fassanian). The Ladinian material of Spain reveals its ontogeny characterised by initial lateral protrusions from the carina that may develop first mono-platform and later bi-platform units, finally evolving into elaborated multi-denticulated forms. The late Anisian—early Carnian phylogenesis of Pseudofurnishius priscus → P. shagami → P. murcianus is proposed. A…

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…

Comments on: A review of the evolution, biostratigraphy, provincialism and diversity of Middle and early Late Triassic conodonts

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…

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…