Ronan Allain

DISCOVERY OF MEGALOSAUR (DINOSAURIA, THEROPODA) IN THE MIDDLE BATHONIAN OF NORMANDY (FRANCE) AND ITS IMPLICATIONS FOR THE PHYLOGENY OF BASAL TETANURAE

Abstract I report here on the discovery of the most complete megalosaurid skull known to date, from the Calcaire de Caen Formation of northwesten France. The specimen, which represents a new species is questionably referred to Poekilopleuron. It includes a nearly complete, unornamented skull, characterized by its low lateral profile. In addition to its historical significance, it provides additional characters that are crucial for reconstructing the phylogeny and biogeography of basal theropods. Poekilopleuron? valesdunensis new species is closely related to Eustreptospondylus and Afrovenator, and is united with Torvosaurus in the family of Megalosauridae. The Megalosauridae appear less derived than the Allosauroidea but resemble the Spinosauridae, with which they form the sister-group to the Neotetanurae. The proposed phylogenetic analysis hypothesizes two previously unrecognized major radiations of carnivorous dinosaurs.

Découverte d’un dépôt paralique à bois fossiles, ambre insectifère et restes d’Iguanodontidae (Dinosauria, Ornithopoda) dans le Cénomanien inférieur de Fouras (Charente-Maritime, Sud-Ouest de la France)

Resume Un gisement paralique inedit, d’âge Cenomanien inferieur, avec du bois fossile, de l’ambre insectifere et des restes de vertebres, a ete decouvert sur l’estran de la presqu’ile de Fouras (Charente-Maritime, France), a la suite d’une tempete qui a temporairement ote du littoral les nappages de cordons sableux et de vasieres. L’assemblage de bois fossiles contient trois taxons de coniferes ( Agathoxylon , Podocarpoxylon , Brachyoxylon ) et un Ginkgoxylon . Les insectes de l’ambre correspondent a des Dipteres, des Hymenopteres et des Homopteres. Les restes de vertebres sont principalement representes par des carapaces de tortues terrestres (Solemydidae), des vertebres de serpents ( Simoliophis ) et des ossements de dinosaures, appartenant probablement au genre Iguanodon . Pour citer cet article : D. Neraudeau et al., C. R. Palevol 2 (2003).

Dinosaurs of France

Abstract The French dinosaur record is one of the most extensive in Europe; it ranges stratigraphically from the Late Triassic to the Latest Cretaceous. All major clades of dinosaurs but marginocephalians are known. About 20 species are based on significant material; the theropods are the best represented. Most of these taxa have been described or revised in recent years. Important specimens have been discovered in the Late Triassic of eastern France, the Middle Jurassic of Normandy, and the Late Cretaceous of Provence and Languedoc. The ichnological record is good for the Late Triassic-Early Jurassic, and the Late Cretaceous egg sites are among the richest in the world. To cite this article: R. Allain, X.P. Suberbiola, Palevol 2 (2003) 27–44.

A new genus of Dromaeosauridae (Dinosauria, Theropoda) from the Upper Cretaceous of France

Dromaeosaurid dinosaur remains are extremely rare in Europe and hitherto provide very poor taxonomic information. They are known in the Lower Maastrichtian of Portugal (Antunes and Sigogneau, 1992), in the Maastrichtian of Romania (Weishampel and Jianu, 1996) and in the Campanian–Maastrichtian of France (Buffetaut et al. 1986; Le Loeuff et al., 1992; Le Loeuff et Buffetaut, 1998). Since 1993, new discoveries of Upper Campanian to Lower Maastrichtian dinosaur remains at La Boucharde locality in the Arc Basin of southeastern France include some well-preserved, disarticulated postcranial elements of a single individual referred to the theropod family Dromaeosauridae. These fossils are the first from Europe which provide good taxonomic information and diagnostic characters for this dinosaur family. The first dromaeosaurid remains ever found in France were initially referred by Lapparent (1947:fig. 10) to Megalosaurus pannoniensis. Recently, a new dromaeosaurid, Variraptor mechinorum was named on the basis of poorly preserved material from the Upper Cretaceous of southern France. The holotypic specimen consists of the last dorsal vertebra and the sacrum discovered at the Bastide Neuve locality. However, no distinguishing features has been recognized on this holotypic material. Furthermore, the most part of the diagnosis is based on a cervico-dorsal vertebra found in another locality; Roques-Hautes. We therefore regard Variraptor mechinorum as a nomen dubium.

The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos

Spinosaurids are among the largest and most specialized carnivorous dinosaurs. The morphology of their crocodile-like skull, stomach contents, and oxygen isotopic composition of the bones suggest they had a predominantly piscivorous diet. Even if close relationships between spinosaurids and Middle Jurassic megalosaurs seem well established, very little is known about the transition from a generalized large basal tetanuran to the specialized morphology of spinosaurids. Spinosaurid remains were previously known from the Early to Late Cretaceous of North Africa, Europe, and South America. Here, we report the discovery of a new spinosaurid theropod from the late Early Cretaceous Savannakhet Basin in Laos, which is distinguished by an autapomorphic sinusoidal dorsosacral sail. This new taxon, Ichthyovenator laosensis gen. et sp. nov., includes well-preserved and partially articulated postcranial remains. Although possible spinosaurid teeth have been reported from various Early Cretaceous localities in Asia, the new taxon I. laosensis is the first definite record of Spinosauridae from Asia. Cladistic analysis identifies Ichthyovenator as a member of the sub-clade Baryonychinae and suggests a widespread distribution of this clade at the end of the Early Cretaceous. Chilantaisaurus tashouikensis from the Cretaceous of Inner Mongolia, and an ungual phalanx from the Upper Jurassic of Colorado are also referred to spinosaurids, extending both the stratigraphical and geographical range of this clade.

Un nouveau genre de dinosaure sauropode de la formation des Grès supérieurs (Aptien-Albien) du Laos

The partly-articulated postcranial remains of two sauropod skeletons recently found in Tang Vay (Savannakhet Province, Laos) are assigned to the species Tangvayosaurus hoffeti (nov. gen., nov. sp.). The derived characters present in the new material confirm the presence of titanosaurs in South East Asia at the end of the Early Cretaceous, but are not consistent with its placement within Titanosaurus genus as first done by Hoffet in 1942. All of the material relative to this species is therefore referred to a new genus: Tangvayosaurus. Tangvayosaurus and the Thai genus Phuwiangosaurus have strong affinities and are considered as primitive titanosaurs.

Earliest known European mammals: a review of the Morganucodonta from Saint-Nicolas-de-Port (Upper Triassic, France)

The Rhaetian locality of Saint-Nicolas-de-Port (France) has yielded the most abundant and diverse mammalian assemblage known from the Late Triassic. Most of the material remains undescribed. We review here the morganucodonts from Saint-Nicolas-de-Port. We identify the upper and lower molariforms of the genus Brachyzostrodon. We also identify in the site Morganucodon peyeri, previously known from the Late Triassic of Hallau (Switzerland), as well as the genera Paceyodon and Paikasigudodon. The description of the new species Megazostrodon chenali sp. nov. extends the stratigraphical and geographical range of the genus, previously known from the Early Jurassic of southern Africa. Finally, another new morganucodont, Rosierodon anceps gen. et sp. nov., is described. The Morganucodonta is recognized as the most diverse order of Late Triassic mammals. Current fossil data suggest that Europe was the centre of initial diversification of morganucodonts at the end of the Triassic, and that morganucodonts were not much affected by the extinction event at the Triassic/Jurassic transition. http://zoobank.org/urn:lsid:zoobank.org:pub:0D30F723-7D65-49B7-8375-BF916BFA0BBA

A reconstruction of Tazoudasaurus naimi (Dinosauria, Sauropoda) from the late Early Jurassic of Morocco

The basal sauropod Tazoudasaurus naimi from the late Early Jurassic of Morocco is represented by at least ten juvenile to adult individuals. Over the past seven years, the Toundoute continental series of Ouarzazate Province, a lateral equivalent of the Azilal and Wazzant Formations of the central High Atlas mountains (Toarcian to Early Aalenian age), produced over 600 skeletal elements pertaining to Tazoudasaurus. About a fifth of the available material has been prepared and studied. Except for the skull, the osteology of Tazoudasaurus is completely known. Superb preservation and the abundance of osteological data from the presently known Tazoudasaurus individuals make it possible to provide a detailed skeletal reconstruction for the first time.

Convergent Evolution of Jaws between Spinosaurid Dinosaurs and Pike Conger Eels

Spinosaurs represent a group of peculiar theropod dinosaurs that have often been described as “crocodile-mimic”, predominantly fish-eating predators, and recently claimed to have been semi-aquatic animals. Here we report a suite of craniodental characters unexpectedly shared by spinosaurs and pike conger eels. Pike conger eels are predatory, mainly piscivorous bottom-dwelling anguilliform fishes that inhabit marine and brackish environments. These two groups of dinosaurs and fishes show a mediolaterally compressed, elongated rostrum, a terminal “rosette” bearing enlarged teeth in both upper and lower jaws, and a notch posterior to the premaxillary “rosette” characterized by the presence of reduced teeth. The morphological convergence observed in the jaws of these two distantly related groups of vertebrates may result from similar feeding behaviours. This typical jaw morphology likely represents an effective biomechanical adaptation for biting and grabbing elusive prey items in low-light aquatic environments. Associated with this specialized snout morphology, numerous integumentary mechanoreceptors involved in prey detection are present in both spinosaurs and pike congers. Our new observations provide an additional convincing argument regarding the decades-long and widely debated lifestyle of spinosaurs.

A new Lepisosteiformes (Actinopterygii: Ginglymodi) from the Early Cretaceous of Laos and Thailand, SE Asia

A new genus and new species of ginglymodian is described from the Aptian Grès supérieurs Formation of the Savannakhet Basin, Laos (Lao Peoples Democratic Republic), found at the Ban Lamthouay locality. The fish is known from a single isolated head, which shows enough diagnostic characters to characterize a new taxon. It represents the first named actinopterygian fish from the Mesozoic of Laos. Among the derived characters are a very short and deep head, a series of very deep anterior infraorbitals, and a mosaic arrangement of the suborbitals. Recognition of this new form led us to identify isolated bones previously found in the Thai Khok Kruat Formation in Thailand, a lateral equivalent of the Grès supérieurs Formation. Two localities, Ban Saphan Hin and Khok Pha Suam, have yielded remains, in particular bones of the skull roof and of the circumorbital series as well as a partial postcranial body, assignable, with caution, to the new genus. When included in a cladistic analysis, the new taxon is placed at the base of the lepisosteoid lineage, together with Isanichthys known from an older formation in Thailand. The phylogenetic pattern obtained differs in some details from previous analyses and points out the pivotal role that some taxa play in the reconstruction of the phylogenies of ginglymodians. This new taxon enriches the diverse Late Jurassic–Early Cretaceous ginglymodian assemblage in South-east Asia, which surprisingly shows no evidence of teleosts. http://zoobank.org/urn:lsid:zoobank.org:pub:70564BE0-939C-4217-9D82-9E51AA298A8C