The vertebral pachyostosis of Carentonosaurus mineaui (a varanoid squamate from the Cenomanian) : from morphological analysis to functional, ontogenic and phylogenic implications.
The vertebral pachyostosis of Carentonosaurus mineaui
, an ″aigialosaurid″ (Mosasauroidea, Squamata) from the Cenomanian (late Cretaceous) of Charente-maritime (S-W of France) corresponds to an osteosclerosis, caused by a slowing or a pause of the chondroclastic and osteoclastic activities. This characteristic, observed also in the other Cretaceous squamates Pachyvaranus crassispondylus
and Simoliophis rochebrunei
, cannot be observed in any extant squamate. On the contrary, their vertebrae present a very strong porosity linked to the intensity of the osseous reworking accompanying their growth. This particularity of the osseous structure may be regarded as a heterochronic phenomenon, more specifically neoteny. Its link with an adaptation to shallow marine environment appears to be confirmed by the supposed ecology of C. mineaui
. Nevertheless, the polarity, plesiomorphic or derived
, of this character state within squamates remains unknown. The histological analysis of the periostic bone tissue of the vertebrae of this taxon gives information
(asymmetry, rate, cyclic growth) about its way of growth which may be compared to that of P. crassispondylus
and S. rochebrunei
. The pachyostosis strictly speaking, morphologically observed at the level of the lateral edges of the centrum and maybe at the base of the neural canal, could not be determined histologically on the performed cross sections and seems to be restricted to these vertebral zones.
philippe JANVIER1 & JOHN G. MAISEY2
1 UMR 5143, Département Histoire de la Terre, Muséum national d'Histoire Naturelle, 8 rue Buffon, 75005 Paris, France. (firstname.lastname@example.org)
2 Department of Vertebrate Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA. (email@example.com)
An enigmatic gnathostome skull and new chondrichthyan braincases from the Devonian of Bolivia.
The vertebrate faunas from Lower and Middle Devonian concretion-bearing beds of Bolivia essentially yield chondrichthyans and acanthodians, whereas placoderms and osteichthyans are virtually lacking. This unusual faunal composition is a thought to be linked to the circumpolar, cool water environments of the “Malvinokaffric Realm”. New braincase material now shows that these chondrichthyans fall into at least two major types, elasmobranch-like and Pucapampella
-like, respectively. Pucapampella
, a presumed basal chondrichthyan with a complete ventral fissure and a palatobasal articulation, now seems to have had a hitherto unsuspected specific diversity, and new material allows the reconstruction of its complete mandibular arch. In addition a complete, articulated gnathostome braincase recently discovered in the top part of the Emsian-Eifelian Icla Formation (Subandean zone, Sucre area) displays a peculiar character assemblage. Although its braincase morphology is rather chondrichthyan-like, it is not lined with prismatic calcified cartilage, and its mandibular arch elements are covered with denticle-bearing platelets. Its snout ends anteriorly with a pair of sigmoid, denticle-bearing elements that recall the tenacula of the Carboniferous presumed holocephalimorph Harpacanthus
. Various interpretations are proposed for this enigmatic skull. It may actually be a Harpacanthus
-like form, predating the earliest known evidence of the taxon by 65 Myr, but the lack of prismatic calcified cartilage raises the question of whether it is a holocephalimorph, or even a chondrichthyan. It also bears some resemblance to the equally enigmatic stensioellids, from the Emsian of Germany
, long thought to be primitive placoderms, but now tentatively reinterpreted as possible basal holocephalimorphs
Michael S. Jensen
Geological Museum, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark, (Michaelsj@snm.ku.dk)
Fossil birds from the Palaeocene of Menat, France.
As early as 1908, Launay mentioned that fossil birds had been found in the Palaeocene of central France. These fossils came from the Menat locality (Puy-de-Dôme). However, these birds were only briefly described and never re-described in detail. Of the three birds mentioned in the literature, one is currently held in the collection of the University Claude Bernard Lyon 1, and another in the collection of the Natural History Museum in Paris (MNHN). The third one appears to be lost. In addition, three new fossils have been recovered from the original site of Menat - one isolated foot, one isolated humerus, and a nearly complete forelimb – in addition to an old, never before described specimen that was ‘found’ in the collection of the MNHN. These fossils are described - although their exact phylogenetic affinities are difficult to decipher due to poor preservation, they certainly represent some of the oldest records of ‘landbirds’ known from the fossil record.
Oxford University Museum of Natural History, Parks Road, Oxford OX1 3JP (firstname.lastname@example.org )
Acoustic function in a non-mammalian eucynodont.
Allin’s theory that the reduced postdentary bones and quadrate of non-mammalian cynodonts were not only the morphological homologues, but also the functional equivalents of the mammalian tympanic bone and ear ossicles is tested on the basis of detailed new information of a specimen of Chiniquodon
. The anatomy is shown to be a compromise between the respective functional requirements for a persistent, though reduced, stress transmission function of a jaw articulation, and an acoustic transformation function of a middle ear. There was a sound pressure level transformer ratio of about 30, but the mass and compliances of the elements restricted sensitivity to low frequencies, up to perhaps 2kHz. Neither an air-filled tympanic cavity, nor a specialised tympanic membrane were present; snakes and other modern reptiles lacking a tympanic cavity offer a better mechanical analogy than modern mammals for the ear function of a cynodont.
The sensitivity to high frequency sound characteristic of the mammalian acoustic transformer system, with tympanic cavity and tympanic membrane, could only have evolved after the origin of the dentary-squamosal jaw articulation, and was correlated with miniaturisation in the lineage leading to basal mammaliaforms.
SANDRINE LADEVÈZE & CHRISTIAN DE MUIZON
Muséum National d'Histoire Naturelle, USM 0203 - UMR 5143 CNRS, Paléobiodiversité et paléoenvironnements, 8 rue Buffon, CP 38, F-75005 PARIS, France (email@example.com)
The auditory region of early Paleocene Pucadelphydae (Mammalia, Metatheria) from Tiupampa, Bolivia, with phylogenetic implications.
New petrosal bones, assigned to Pucadelphys
from the early Paleocene of Tiupampa (Bolivia) are here described, and provide supplementary information concerning the anatomy of the ear region of those taxa. The re-examination of characters from the petrosal and basicranium usable for a parsimony analysis, shed light on the phylogenetic relationships of the three Tiupampan genera known by complete cranial remains (i.e., Mayulestes
). The combination of dental, general cranial, and basicranial characters led to two alternative hypotheses. The first hypothesis states that borhyaenoids (including Mayulestes
) are nested within Notometatheria. Pucadelphyds (i.e., Pucadelphys
) are the sister group of a clade comprising MHNC 8369 (one isolated petrosal from Tiupampa) and Marsupialia. The second hypothesis favours the paraphyly of "borhyaenoids" (i.e., the exclusion of Mayulestes
from borhyaenoids) and the polyphyly of "Notometatheria". In this case, Mayulestes
and borhyaenids represent the stem group of a clade including Asiatic
, American and Australian metatherians.
This analysis, conducted with combined datasets (i.e., dental, general cranial, and basicranial), highlighted contradictory information brought by dental and cranial characters. This emphasizes the importance of considering a large anatomical complex (here the entire skull) for systematic purposes, that is likely to reflect the mosaic evolution of the characters among metatherians.
Pascaline Lauters1, Yuri L. Bolotsky², Jimmy Van Itterbeeck³, and Pascal Godefroit1
1Institut royal des Sciences naturelles de Belgique, Département de Paléontologie, rue Vautier, 29, B-1000 Bruxelles, (firstname.lastname@example.org and email@example.com)
²Geological and Nature exploration Institute, Far Eastern Branch of the Russian Academy of Sciences, per. Relochny 1, 675000 Blagoveschensk, Russia
³Afdeling Historische Geologie, Laboratorium voor stratigrafie, Katholieke Universiteit Leuven, Redingenstraat 16, 3000 Leuven
Taphonomy and age profile of a latest Cretaceous dinosaur bonebed in Far Eastern Russia.
Recent excavations of a Late Cretaceous dinosaur bonebed at Blagoveschenk (Far Eastern Russia) bring new information about its taphonomy and the age profile of its lambeosaurine population. The observed mixture of both fine and coarse sediments, without stratification, is typical for sediment gravity flow deposits. It can therefore be postulated that sediment gravity flows, originating from the uplifted areas at the border of the Zeya-Bureya Basin, concentrated the bones. The fossils form a monodominant bonebed: bones of the lambeosaurine Amurosaurus riabinini
form 90% of the recovered fossils, suggesting a herding behaviour for this lambeosaurine. The small number of associated skeletal elements indicates that the carcasses would have been disarticulated well before the transportation of the bones. Less than 2% of the bones exhibit potential tooth marks: scavenging activity was therefore limited, or scavengers had not to actively seek out the bones for nutrient intake. The under-representation of small and light skeletal elements, the dislocation of the dental batteries and the numerous fractured long bones suggest that most of the fossils were transported along a relatively important distance. The random orientation of the bones might indicate a sudden end of transport before its stability can be reached. The size-frequency distributions of some bones suggest an attritional mortality profile for the Amurosaurus
population. Predators preferentially killed younger specimens. The absence of fossils that may be attributed to nestling to early juvenile individuals indicate that they were segregated from the adults
, and could join the herd only when they were half-grown.
Jean Le Loeuff1, Tida Saenyamoon2 and Varavudh Suteethorn2
1 Musée des Dinosaures, 11260 Espéraza, France (firstname.lastname@example.org)
2 Department of Mineral Resources, Bangkok, Thailand
Mesozoic vertebrate footprints from Thailand.
The first mention of fossil footprints from Thailand was made in 1854 by Jean-Baptiste Pallegoix (1805-1862), a French priest, Titular Bishop of Mallus, who was the Vicar Apostolic of Siam between 1841 and 1862. Pallegoix, who was also the author of a useful Thai-French-Latin-English dictionary, mentioned footprints of antediluvian animals seen by him at Phrabat (or Phra Phuttabat, Saraburi Province) in Central Thailand. This discovery was evoked in 1868 by the French explorer Henri Mouhot (1826-1861), who travelled in Siam and Laos between 1858 and 1861. In 1883 the French geographer Elisée Reclus noticed that these footprints had not yet been studied by geologists. 122 years later we went to Phrabat and we could conclude that these Siamese footprints were erosional figures in marine Permian limestones mistakenly considered as fossil footprints.
In the meantime Triassic and Cretaceous vertebrate footprints have been discovered in Thailand. Triassic track makers from Nam Nao (Phetchabun province) were wide-gauge plantigradous animals (high pace angulation, large track width, large metatarsal impression) with tetradactyl mesaxonic pes and tetradactyl ectaxonic manus, using an asymmetrical gait. The systematic affinities of the track makers are not yet clear but they could be some primitive archosauromorphs such as phytosaurs. A new Cretaceous tracksite at Tha Uthen (Nakhon Phanom province) has recently been discovered and now belongs to the Department of Mineral Resources. It has revealed an impressive assemblage of small theropods, crocodiles and ornithopods.
BENT E. K. LINDOW1,2
1School of Biology and Environmental Science, University College Dublin, Ireland & 2Geological Museum, Natural History Museum of Denmark, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark. (email@example.com)
Taxonomic status of the Lithornithidae (Aves: Palaeognathae) from the Lower Eocene North Sea Basin.
The extinct family Lithornithidae constitutes the earliest, well-known clade of palaeognathous birds. They were an important and diverse constituent of the Northern Hemisphere avifauna in the Palaeocene – Lower Eocene. Three genera with a total of eight species are currently recognised from deposits in North America and the North Sea Basin.
The holotype of the type taxon for the family, Lithornis vulturinus Owen 1841, was destroyed during the Second World War. Subsequently, a neotype for this taxon and several new species of Lithornis were described by Houde (1988). However, recent re-analysis of lithornithid material from the North Sea Basin reveals that there is little or no osteological overlap between material preserved in the holotype and the neotype. The original differential diagnoses of the six species placed within Lithornis are founded on extremely weak criteria of relative size and not on osteological characters. For example, recent re-examination of the original holotype of the species L. nasi and new fossil material from the Danish Fur Formation, revealed a number of osteological characters, which are not present in other lithornithids from the North Sea Basin, but are present in the much larger lithornithid Paracathartes howardae from the Lower Eocene of North America. This suggests that the species is probably not referable to the genus Lithornis .
Finally, many specimens, some of them holotypes, previously referred to various species of Lithornis, consist of incomparable or non-diagnostic material. The genus Lithornis , and possibly the entire family is in need of revision and re-diagnosis.
Department of Palaeontology, Natural History Museum, London SW7 5BD, England (A.Longbottom@nhm.ac.uk)
The use of morphometric techniques in the analysis of intra- and inter-specific variation in recent and fossil catfish.
New catfish remains from the Paleogene of Mali, North Africa are described and compared with known species of Nigerium from the Paleogene of Nigeria. The shape and interrelationships of skull bones preserved in the numerous crania have been studied and analysed using various morphometric techniques. The results from the fossils are compared with those from recent bagrid catfish species in order to investigate intra-and inter- specific variation and to see if morphometric analyses can help determine how many species might be present within the Mali and Nigeria catfish faunas.
Jackson School of Geosciences, The University of Texas, Austin, USA (firstname.lastname@example.org)
Re-examination of cranial anatomy of Herpetotherium using High-Resolution MicroCT.
is a long-lived fossil marsupial genus from North America and Europe, and it is common in the fossil record anywhere from Early Eocene to Late Oligocene. Most of the specimens attributed to the genus are dental fragments. One particular specimen (AMNH 22304) of the genus is among the few well-preserved fossil marsupial crania known from the Cenozoic. Gabbett (1994) described the external basicranial anatomy of the genus with emphasis on the auditory region of this particular specimen.
Here, I re-examine the same specimen by utilizing a high-resolution microCT technology. MicroCT scan allows me to digitally remove the matrix and study the otherwise inaccessible cranial regions, and complements the previous work. This study investigates the anatomy of the endocranium and the nasal regions, and compares them to various extant didelphids and fossil marsupials.
SUSANNAH C. R. MAIDMENT
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom
Systematics and phylogeny of Stegosauria (Dinosauria, Ornithischia).
Stegosauria is a clade of ornithischian dinosaurs characterised by a bizarre array of dorsally projecting dermal plates or spines extending from the cervical region to the distal end of the tail. Although the first stegosaur was discovered in Swindon, U.K., in 1875, and numerous remains have since been recovered from North America, Tanzania and China, as well as locations throughout Europe, taxonomy and relationships within the group are largely unstudied. The first cladistic analysis of Stegosauria based upon direct observation of specimens is presented. In contrast to previous analyses, the resulting cladogram is well resolved
, and although relationships are not strongly supported by statistical tests, groupings accord well with the current understanding of palaeogeography during the Upper Jurassic and Lower Cretaceous: North American and British genera are closely related, and the African genus Kentrosaurus
is more distantly related. Chinese genera are basal and imply a relict primitive fauna in China during the Middle and Upper Jurassic.
OLIVIER MARIDET 1,3, KURT HEISSIG 2 & MARGUERITE HUGUENEY 3
1Laboratoire de Planétologie et Géodynamique, UMR CNRS 6112 - University of Nantes (email@example.com); 2Department für Geo- und Umwelt-wissenshaften, Section Paläontologie- Ludwig-Maximilians University, Munich; 3UMR 5125 PEPS - University Claude-Bernard, Lyon
New Eomyids from the Early Oligocene of Southern Germany and Southeastern France : evolutionary and paleoecological implications.
At the beginning of the Oligocene in Europe, following the global climatic change known as Stehlin’s “Grande Coupure”, mammalian communities present a deep change due to the arrival of new exotic taxa. Among small mammals the eomyids (Mammalia, Rodentia), that are already known from the American and Asian Eocene fossil record, appear in the European fossil record with the single species Eomys antiquus
. Previous studies (Comte & Vianey-Liaud 1989; Fahlbusch 1975) have proposed that the diversification known for this family from the Late Oligocene and the Miocene onward is the result of an evolution from this Early Oligocene species.
New material from Southern Germany and Southeastern France, especially two new taxa from the Early Oligocene, evidences that the diversity of this family is more deeply rooted and that the principal forms of eomyids known in the Late Oligocene were already present in Europe at the beginning of the Oligocene, as hinted by Engesser (1990) based on some lineage recognized within Swiss localities. A preliminary quantitative study based on rodent communities from Bavaria, including this new material, also emphasizes this drastic faunal change at the beginning of the Oligocene.
Comte, B. & Vianey-Liaud, M. (1989) Eomyidae (Rodentia) de l'Oligocène d'Europe Occidentale. Palaeontographica , 209A: 33-91.
Engesser, B. (1990) Die Eomyidae (Rodentia, Mammalia) der Molasse der Schweiz und Savoyens. Systematik und biostratigraphie. Schweizerische Paläontologische Abhandlungen , 112: 1-144.
Fahlbusch, V. (1975) Die Eomyiden (Rodentia, Mammalia) der Oberen Süßwasser-Molasse Bayerns. Mitteilungen der Bayerischen Staatssammlung für Paläontologie und histotische Geologie , 15: 63-90.
Grégoire Métais 1, Tao Qi 2, Jianwei Guo 2 & K. Christopher Beard 1
(1) Carnegie Museum of Natural History, Section of Vertebrate Paleontology, 4400 Forbes Avenue, Pittsburgh PA 15213, USA. (firstname.lastname@example.org, email@example.com)
(2) Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P. O. Box 643, Beijing 100044, China.
Diversity of Cetartiodactyls in the middle Eocene of China.
The Shanghuang fissure-fillings (Jiangsu Province) and the Heti Formation (Shanxi Province) have yielded unique middle Eocene mammal assemblages including “dichobunoids” and early ruminant artiodactyls. Most of the dental and post-cranial material from the Shanghuang fissure filling D are referable to the dichobunid Elaschitotherium qii
, and to three new forms of Selenodontia more poorly documented. Elaschitotherium qii
shows greatest affinities with two other poorly known Asian “dichobunoids” (Lantianius
, from the middle Eocene of China, and Eolantianius
from the early Eocene of Kyrgyzstan). These forms may be related to Gujaratia pakistanensis
, but they do not seem to be closely related to other basal forms known from the early-middle Eocene of the Indo-Pakistani region. Relationships with North American homacodonts and European dichobunids are still unclear.
The Irdinmanhan assemblage of the Shanghuang fissure D is particularly critical as it represents one of the rare windows into the Eocene evolution of artiodactyls in Asia. The complete analysis of this key fossil material suggests that bunoselenodont artiodactyls radiated synchronously in Asia, Europe, and North America. The diversity of “early ruminants” from both the lower member of the Heti Formation and the Shanghuang fissure filling D confirms the early diversification of the suborder as early as middle middle Eocene. Preliminary phylogenetic analysis suggests that the selenodont grade was probably acquired independently in several lineages of dichobunids inhabiting the three northern landmasses during the middle Eocene.
ANGELA C. MILNER & STIG A. WALSH
Department of Palaeontology, The Natural History Museum, London, England. (a.milner @nhm.ac.uk)
New data on avian brain evolution from fossil birds from the Lower Eocene of England.
Recently discovered Cretaceous bird fossils, particularly from Liaoning in China
, have provided important insights into the theropod-avialan transition and the evolution of flight. Nonetheless, little is known about how the avian brain evolved in response to the development of flight, largely because very few avian fossil endocranial casts are known. CT and 3D-based analysis of two Lower Eocene neornithines from the London Clay of England, Odontopteryx toliapica
and Prophaethon shrubsolei,
demonstrate that they
possessed brains comparable in size and shape to those of living seabirds, indicating that the bird brain had reached an evolutionary level close to that of Recent species by that time. However, poor development of the eminentia saggitalis (which is responsible for many advanced functions including binocular vision) in both species, especially in Odontopteryx
, shows that important telencephalic features characteristic of extant clades had not developed fully by the Eocene. These data nevertheless represent the earliest evidence of the avian eminentia saggitalis in the fossil record and have important implications for the evolution of avian cognitive ability. Our results support earlier hypotheses of a general increase in avian brain size over time, but indicate a trend toward diversification in telencephalic architecture that culminated in the extreme cerebrotypes today seen in, for example, Psittaciformes, Strigiformes and some Passeriformes.
Aurélie Pinton, Olga Otero, Patrick Vignaud, Michel Brunet
Laboratoire de Géobiologie, Biochronologie et Paléontologie Humaine, UMR 6046 du CRNS, Université Poitiers, SFA, avenue du recteur Pineau, F-86000 Poitiers, France (firstname.lastname@example.org)
The Synodontis (Mochokidae, Siluriformes) from Toros-Menalla (Late Miocene, Chad), Diversity and Paleoenvironmental implications.
(Mochokidae, Siluriformes) is a diverse freshwater catfish genus living in Africa. It is represented in all the ichtyological provinces except Maghreb and South Africa. Like other Siluriformes Synodontis
fish are characterised by their pectoral and dorsal spines and by the presence of maxillary and mandibular barbells. The Synodontis
fossil record starts in the Middle Miocene (Tunisia) and continues in the Mio-Pliocene mainly in East Africa (e.g. Kenya, Uganda). These fossils are rarely identified at a specific level. In fact, criteria of identification of the species are based on characters which are not preserved in the fossil (e.g. morphology of the barbells).
Here, we present the Synodontis fishes associated with the oldest known hominid, Sahelanthropus tchadensis (Brunet et al ., 2002). They were collected by the Mission Paléoanthropologique Franco-Tchadienne in the Late Miocene of Toros-Menalla, Chad (Vignaud et al ., 2002). This first Synodontis assemblage from Central Africa consists of abundant and well-preserved specimens. To identify this material, we have constructed the first identification key at a specific level. It is based on osteological characters and addressed to the well-preserved bones of the fossil record i.e. cleithrum, pectoral and dorsal spine, nucal plate, supraoccipital and frontal. The Synodontis fishes from Chad show a high taxonomic diversity including both living and fossil species. Moreover, this study reveals specific associations depending on the localities; this could testify to environmental particularity of these localities. Such diversity has never been revealed in the Synodontis fossil record.
Brunet M., Guy F., Pilbeam D. et al . 2002 - The earliest Hominid: Upper Miocene, Chad, Central Africa. Nature , 418 (6894): 145-151
Vignaud P., Duringer P., Mackaye H.T. et al . 2002 - Geology and Palaeontology of the Upper Miocene Toros-Menalla fossiliferous area, Djurab Desert, Northern Chad. Nature , 418 (6894): 152-155.
Department of Paleontology, Eötvös University, Budapest, Hungary