Philippe Janvier

Muséum National d'Histoire Naturelle · Département Origines et Evolution

L’étude des tissus minéralisés des premiers vertébrés est essentielle pour mieux comprendre l’origine et l’évolution de notre squelette. Par exemple, les Ptéraspidomorphes (gnathostomes souches) présentent certains des plus anciens restes connus de tissus osseux et « dentaires ». Cependant, l’identification de ces tissus reste débattue en raison de...

Lampreys, the oldest living jawless vertebrates, represent an iconic model in evolutionary biology and are always intriguing for their bizarre feeding behavior of sucking blood or gouging out tissues from their victims. They seemingly underwent few changes in morphology and feeding habit since their first appearance in the Late Devonian. However, t...

history of the discovery of the earliest known vertebrate with a mineralised dermal skeleton

For more than a century, scientists have pondered over mysterious fossils of an aquatic vertebrate, and argued about the type of creature this species represents. Newly analysed specimens might help to solve this puzzle. Specimens shed light on what type of creature Palaeospondylus was.

L’adaptation à la vie hors de l’eau a été l’un des événements majeurs de l’histoire évolutive des vertébrés. La transformation des nageoires en membres locomoteurs pourvus de doigts, jointe à la présence de poumons et à diverses adaptations physiologiques ont permis aux tétrapodes de conquérir l’ensemble des terres émergées et, de là, s’adapter à l...

The anatomy of the visceral skeleton of a Carboniferous holocephalan, the iniopterygian Iniopera, is studied here from 3D-preserved fossils from Kansas. For comparison and interpretation, the visceral skeleton and head circulatory system of the Recent holocephalan Callorhinchus milii are also described. Iniopera and modern holocephalans both displa...

Lampreys, one of the remaining two living jawless vertebrates, carry great weight in the study of vertebrate evolution. They have a long history dating back to the Devonian but left a scarce fossil record. So far, only five unequivocal fossil lampreys have been described, of which four are Paleozoic. Mesomyzon Chang, Zhang & Miao, 2006, the only kn...

This chapter is a brief review of the histological structures of the skeleton of early vertebrates, with particular reference to the mineralised tissues. The numerous taxa are considered in a temporal framework, from the earliest vertebrates from the Cambrian to the earliest land vertebrates, or tetrapods, from the Late Devonian. The evolutionary t...

Agnathans are an ensemble of jawless (nongnathostome) vertebrates, some of which are more closely related to the gnathostomes than others. Living agnathans fall into two groups, hagfishes (Hyperotreta) and lampreys (Hyperoartia), united into a higher group, the cyclostomes (Cyclostomi). Key Concepts • Phylogenomics now demonstrates that cyclostom...

An isolated pterygoid tooth plate of a lungfish from the Lower Devonian (Lochkovian–Pragian) of Vietnam is described. The material is negatively preserved and lacks associated jawbones to assign a reliable taxonomic status and phylogenetic position. The tooth plate is composed of five main tooth rows radially arranged, separated by several interrow...

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...

The neurocranium of sarcopterygian fishes was originally divided into an anterior (ethmosphenoid) and posterior (otoccipital) portion by an intracranial joint, and underwent major changes in its overall geometry before fusing into a single unit in lungfishes and early tetrapods¹. Although the pattern of these changes is well-documented, the develop...

Evolution and Development of Fishes - edited by Zerina Johanson January 2019

Modern lampreys (Petromyzontiformes) are one of two lineages of surviving jawless fishes (agnathans), and are thus of critical importance to understanding the evolution of the vertebrates. Although their fossil record is meager, it appears they have remained morphologically conserved for at least 360 million years, but the origin of their multi-stag...

A brief review of the recently published new data on the structure, sedimentary context and biogeography of the Ordovician arandaspid jawless vertebrate Sacabambaspis is provided, and some prospects are suggested for further findings. New data on the Silurian and Devonian vertebrates from Bolivia are reviewed, with comments on the question of the e...

The presence of a pulmonary organ that is entirely covered by true bone tissue and fills most of the abdominal cavity is hitherto unique to fossil actinistians. Although small hard plates have been recently reported in the lung of the extant coelacanth Latimeria chalumnae, the homology between these hard structures in fossil and extant forms remain...

Doliodus problematicus (NBMG 10127), from the Lower Devonian of New Brunswick, Canada (approx. 397-400 Mya) is the earliest sharklike jawed vertebrate (gnathostome) in which the pectoral girdle and fins are well preserved. Its pectoral endoskeleton included sharklike expanded paired coracoids, but Doliodus also possessed an "acanthodian-like" array...

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...

Acanthomorpha (spiny-rayed fishes) is a clade of teleosts that includes more than 15 000 extant species. Their deep phylogenetic intrarelationships, first reconstructed using morphological characters, have been extensively revised with molecular data. Moreover, the deep branches of the acanthomorph tree are still largely unresolved, with strong dis...

1. Introduction2. Systematic and Phylogenetic Framework of Chondrichthyan Diversity 2.1. Names, Taxa, and Characters2.2. Chondrichthyan Diversity and Interrelationships3. Environments and Adaptations4. Conclusion Current views about chondrichthyan phylogeny and systematics are briefly reviewed, with particular reference to the living and fossil tax...

Coelacanths are lobe-finned fishes known from the Devonian to Recent that were long considered extinct, until the discovery of two living species in deep marine waters of the Mozambique Channel and Sulawesi. Despite extensive studies, the pulmonary system of extant coelacanths has not been fully investigated. Here we confirm the presence of a lung...

The study of Devonian Colombian trilobites and inarticulate brachiopods allows to recognize two biostratigraphic levels within the Floresta Formation. The first level, in the lower part of the formation, is late Emsian in age, and yields 14 distinct trilobite taxa, including Colombianaspis carvalhoaegen. et sp. nov. The second one, in the upper par...

The interrelationships between major living vertebrate, and even chordate, groups are now reasonably well resolved thanks to a large amount of generally congruent data derived from molecular sequences, anatomy and physiology. But fossils provide unexpected combinations of characters that help us to understand how the anatomy of modern groups was pr...

The skull roof growth of Arabosteus variabilis (Acanthothoraci), from the Pragian-Early Emsian of Saudi Arabia is studied on the basis of well-preserved growth lines on the dermal plates. A clear tendency towards growth in length, i.e. allometry in length, can be observed for all studied skull roof plates of Arabosteus variabilis as well as for the...

With over 17 000 extant species (one third of the extant vertebrates), Acanthomorpha is a highly diverse marine teleost clade characterized by spines on the unpaired fins. In the last decade, large-scale molecular analyses helped to shape the acanthomorph tree, upturning some older views on their intrarelationships. However, major uncertainties rem...

Le Dévonien (Frasnien) de Colombie a livré des informations importantes sur la diversité taxonomique et les relations paléobiogéographiques des faunes de vertébrés marins d’Amérique du Sud (marge nord-ouest du Gondwana) au Dévonien terminal. Parmi ces faunes, composées majoritairement de taxons gondwaniens, figurent deux taxons trouvés également en...

Lampridiformes is a peculiar clade of pelagic marine acanthomorph (spiny-rayed) teleosts. Its phylogenetic position remains ambiguous, and varies depending on the type of data (morphological or molecular) used to infer interrelationships. Because the extreme morphological specializations of lampridiforms may have overwritten the ancestral features...

Le réexamen du myxiniforme présumé Myxineidus gononorum du Carbonifère supérieur de Montceau-les-Mines au moyen de la microtomographie par rayonnement X synchrotron en contraste de phase de propagation confirme la présence de deux séries de denticules non minéralisés et disposés en chevrons dans la cavité orale. Il indique également la présence pos...

Sophisticated microscopy analysis of conodont elements suggests that these mysterious fossil structures are not, as has been previously suggested, evolutionary precursors to vertebrate teeth. See Letter p.546

Silurian and Devonian deposits in Viet Nam are present in several zones and regions, including Quang Ninh, East Bac Bo, and West Bac Bo Zones of the Bac Bo Region, the Dien Bien-Nghe An and Binh Tri Thien Zones of the Viet-Lao Region, and the South Trung Bo, and Western Nam Bo Zones of the South Viet Nam Region (Fig. 1). The main lithological featu...

Background The pituitary gland is formed by the juxtaposition of two tissues: neuroectoderm arising from the basal diencephalon, and oral epithelium, which invaginates towards the central nervous system from the roof of the mouth. The oral invagination that reaches the brain from the mouth is referred to as Rathke’s pouch, with the tip forming the...

The vertebrate body plan is characterized by an increased complexity relative to that of all other chordates and large-scale gene amplifications have been associated with key morphological innovations leading to their remarkable evolutionary success. Here, we use compound full Hox clusters deletions to investigate how Hox genes duplications may hav...

Hagfish embryos show developmental features that contradict the idea that these jawless fish are the most primitive living vertebrates. The findings also help to trace the evolution of vertebrate cranial structure. See Article p.175

We present a redescription of Megalocoelacanthus dobiei, a giant fossil coelacanth from Upper Cretaceous strata of North America. Megalocoelacanthus has been previously described on the basis of composite material that consisted of isolated elements. Consequently, many aspects of its anatomy have remained unknown as well as its phylogenetic relatio...

Data matrix used in the phylogenetic analysis. (DOC)

Nexus file of the second phylogenetic analysis. (TXT)

Nexus file of the first phylogenetic analysis. (TXT)

Character list. (DOC)

Diagnostic information for the node and terminal taxa of the strict consensus tree illustrated Figure 22 . (DOC)

The origin of osteichthyans (bony fishes and tetrapods) dates back to the Late Silurian, but the early evolution of the group is poorly understood. Andreolepis is one of the oldest known osteichthyans, but exclusively documented by detached and fragmentary dermal microremains. A large data-set of Andreolepis scales from the Silurian of Gotland has...

Several outcrops of the Late Silurian and Devonian of the Ngoc Vung Series, northern Vietnam, yielded plant remains. The Late Silurian localities delivered the earliest known flora of the South China block. Although the fossils are fragmentary, they complement our knowledge about the global composition of the flora. The major components of the flor...

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...

Data Matrix used for the phylogenetic analysis. (DOC)

List of Characters and character states used for the phylogenetic analysis. (DOC)

The relationships of cartilaginous fishes are discussed in the light of well preserved three-dimensional Paleozoic specimens. There is no consensus to date on the interrelationship of Paleozoic chondrichthyans, although three main phylogenetic hypotheses exist in the current literature: 1. the Paleozoic shark-like chondrichthyans, such as the Symmo...

In contrast to lampreys and jawed vertebrates, hagfishes were thought to lack vertebrae. Now, long overlooked vertebral rudiments have been analysed in hagfish, suggesting that vertebrae existed in the last common ancestor of all vertebrates.

Most living vertebrates are jawed vertebrates (gnathostomes), and the living jawless vertebrates (cyclostomes), hagfishes and lampreys, provide scarce information about the profound reorganization of the vertebrate skull during the evolutionary origin of jaws. The extinct bony jawless vertebrates, or 'ostracoderms', are regarded as precursors of ja...

The acanthothoracid Hagiangella goujeti Janvier, 2005, has been described exclusively on the basis of isolated thoracic plates from the Lochkovian (Lower Devonian) Khao Loc Formation of Tung Vai, Ha Giang Province, northern Vietnam. It is characterized by a very high, triangular median crest on the median dorsal plate, and has been referred to the...