Le Crocodilien Diplocynodon (Eusuchia,Alligatoridae) dans la«série du gypse d'Aix à Venelles (Bouches-du-Rhône,France)

A crocodilian skeleton from the «série du gypse d'Aix (basal Aquitanian) at Venelles (Bouches-du-Rhône) is described and referred to Diplocynodon cf. rateli. The specimen seems to have been mutilated by scavengers before burial. The occurrence of the freshwater crocodilian Diplocynodon in the «série du gypse d'Aix is in agreement with recent reconstructions of the depositional environment, which suggest a basin with a fluctuating, but usually low, salinity.     

Pterosaur Stance and Gait and the Interpretation of Trackways

The tracks ascribed to pterosaurs from the Late Jurassic limestones at Crayssac, France, must be pterosaurian because the manus prints are so far outside those of the pes, the pes print is four times longer than wide, and the manus prints appear to preserve distinct traces of a posteromedially directed wing-finger. These tracks are different in important ways from previously described Pteraichnus trackways, which have been variably considered pterosaurian, crocodilian, or indeterminate. No Pteraichnus (sensu stricto: those not from Crayssac) tracks have diagnostic features of pterosaurs and in none can a complete phalangeal or digital formula be reconstructed; however, all published Pteraichnidae tracks fulfill the criteria of poor preservation, and some have some diagnostic features of crocodile tracks. Reconstructions of pterosaurs walking in pteraichnid tracks do not fit those tracks well, but crocodiles do. In contrast, the Crayssac tracks demonstrate the erect stance and parasagittal gait previously reconstructed for pterosaurs. They also demonstrate that the footfall pattern was not as in typical reptiles (LH-RF-RH-LF), but that the manus must have been raised before the next forward step of the ipselateral foot (LH-LF-RH-RF), suggesting that the quadrupedal pattern was secondary. The metatarsus in pterosaurs was set low at the beginning of a stride, as it is in crocodilians and basal dinosaurs. The diagnosis of the Ichnofamily Pteraichnidae comprises features of possible crocodilian trackmakers, but not of possible pterosaurian trackmakers. Trackways considered for attribution to pterosaurs should show (1) manus prints up to three interpedal widths from midline of body, and always lateral to pes prints, (2) pes prints four times longer than wide at the metatarso-phalangeal joint, and (3) penultimate phalanges longest among those of the pes.     

Voices of the past: a review of Paleozoic and Mesozoic animal sounds

Here, I present a review and synthesis of fossil and neontological evidence to find major trends in the pre-Cenozoic evolution of animal acoustic behaviour. Anatomical, ecological and phylogenetic data support the following scenario. Stridulating insects, including crickets, performed the first terrestrial twilight choruses during the Triassic. The twilight chorus was joined by water boatmen in the Lower Jurassic, anurans in the Upper Jurassic, geckoes and birds in the Lower Cretaceous, and cicadas and crocodilians in the Upper Cretaceous. Parallel evolution of defensive stridulation took place multiple times within Malacostraca, Arachnida and Coleoptera. Parallel evolution of defensive and courtship-related sound production took place in Actinopterygii, possibly as early as the Devonian. Defensive vocalisations by tetrapods probably did not appear until their predators acquired tympanic ears in the Permian. Tympanic ears appeared independently in Diadectomorpha, Seymouriamorpha, Parareptilia, Diapsida and derived Synapsida. Crocodilians and birds acquired vocal organs independently, and there is no anatomical evidence for vocal ability in bird-line archosaurs basal to the avian clade Ornithothoraces. Acoustic displays by non-avian dinosaurs were therefore probably non-vocal. Other aspects of the evolution of acoustic behaviour in these and other lineages are also discussed.     

On a cranial bony nodular protuberance on Mourasuchus pattersoni Cidade et al. 2017 (Crocodylia,Alligatoroidea) from the late Miocene of Venezuela

Mourasuchus pattersoni, from the late Miocene Urumaco Formation of Venezuela, is the fourth and most recent species described for the genus. The holotype, and only known specimen, is comprised of an almost complete skull with both mandibular rami and several postcranial remains. In ventral view, the right palatine bone has a spherical, nodular bony protuberance located on the anterior portion, near the suture with the maxilla. Unfortunately, we cannot assign a specific diagnosis based only on macroscopic inspection. Its appearance, form and location are compatible with three conditions: torus palatinus, a common benign intraoral bone overgrowth; osteoma, a benign neoplasical overgrowth of the bone; and hamartoma, an overgrowth of normal bone tissue that can only be differed from an osteoma by histological features. While occurrences of torus palatinus or hamartomas are not yet known in the nonhominid vertebrate fossil record, there are previous records of osteomas in fossil vertebrates, including in crocodylians, such as a specimen assigned to ‘Crocodylus sp.’ from the Eocene, aside from several records for living crocodylians. Future studies are needed to uncover an accurate diagnosis of this unusual structure and help increase our knowledge of paleopathology in fossil crocodylomorphs in general, especially in the Caimaninae clade.     

Jaw mechanism and dental function in the late cretaceous basal eusuchian Iharkutosuchus

Iharkutosuchus makadii is a basal eusuchian crocodylian with multicusped teeth discovered from the Upper Cretaceous of Hungary. Skull and dentition morphology indicates an active food processing for this crocodylian. First among crocodylians, a combination of different analyses, including cranial adductor muscle reconstruction, tooth wear pattern, and enamel microstructure studies, is applied here to support this hypothesis. Data provide unambiguous evidence for significant dental occlusion that was a result of a unique, transverse mandibular movement. Reconstruction of the jaw adductors demonstrates strong muscles responsible for slow but active jaw closure as the motor of transverse jaw movement; nevertheless muscles producing rapid jaw closure were reduced. Macrowear orientations show a dominantly transverse movement of the mandibles completed by a slight anteroposterior component. Along with quadrate morphology, macrowear further indicates that this motion was accomplished by alternate rotation of the mandibles about the quadrate condyles. Dental morphology and wear patterns suggest two types of power stroke: a slicing–crushing stroke associated dominantly with anterior tooth–food–tooth contact (with a low degree of transverse mandibular movement) during in the early stage of mastication, and a grinding stroke with significant posterior tooth–tooth contact and a dynamic transverse movement occurring later. The patterns of microwear show a diverse diet for Iharkutosuchus including both soft and hard items. This is also supported by the microstructure of the thick, wrinkled enamel built up mostly by poorly developed columnar units. Based on wear patterns, ontogenetic variation in feeding habits of Iharkutosuchus is also recognized. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

SYSTEMATICS AND TAXONOMY OF EOCENE TOMISTOMINE CROCODYLIANS FROM BRITAIN AND NORTHERN EUROPE

Abstract:  The holotype of Dollosuchus dixoni (Owen) from the Early–Middle Eocene Bracklesham Beds of England is a set of mandibular fragments that cannot be distinguished from corresponding parts of other longirostrine crocodylians. An isolated humerus from the Bracklesham Beds is consistent with a gavialoid, but it cannot be referred to the holotype of D. dixoni . The name Dollosuchoides densmorei is established for the well-preserved skull and skeleton of a tomistomine from the Middle Eocene of Belgium that had been referred to D. dixoni . It can be clearly distinguished from the basal tomistomine ' Crocodilus ' spenceri Buckland from the Lower Eocene of England, which cannot be referred to Dollosuchoides and is provisionally referred to Kentisuchus Mook. Although basal within Tomistominae, Dollosuchoides is more closely related to Tomistoma than to Kentisuchus .     

Tertiary crocodylians from Puerto Rico: Evidence for Late Tertiary endemic crocodylians in the West Indies?

Fragmentary fossils from northwestern Puerto Rico document the existence of crocodyliforms during the Late Oligocene and Early Miocene. The remains are insufficient to establish new named species, but they are inconsistent with any other crocodylian known from the western hemisphere during the Cenozoic, including extant Alligator and Crocodylus. They are thus consistent with the hypothesis that Crocodylus is a comparatively recent immigrant into the West Indies and suggest that, as with Australasia and Africa, the Antilles hosted an endemic clade of crocodylians during the Tertiary, later replaced by Crocodylus.     

Early Miocene vertebrates from Montagna della Maiella,Italy

Vertebrate remains from the lower Burdigalian (early Miocene) carbonates of Montagna della Maiella, central Italy, are described. These remains mostly consist of teeth belonging to 11 elasmobranch taxa (Carcharias acutissima, Carcharias cuspidata, Carcharodon subauriculatus, Isurushastalis, Isurus oxyrinchus, Isurus sp., Parotodus benedeni, Hemipristis serra, Galeocerdo aduncus, Galeocerdo contortus, Negaprion cf. eurybathrodon), eight teleost taxa (Diplodus sp. and two indeterminate sparids, Labrodon sp., Trigonodon jugleri, Sphyraena sp., Chilomycterus sp., Diodon sp.), an indeterminate crocodile, and two odontocete cetaceans (Squalodon sp. and an indeterminate kentriodontid). Paleoenvironmental and paleogeographical implications are discussed.     

Intraspecific variation in the skull morphology of the black caiman Melanosuchus niger (Alligatoridae,Caimaninae)

Melanosuchus niger is a caimanine alligatorid widely distributed in the northern region of South America. This species has been the focus of several ecological, genetic and morphological studies. However, morphological studies have generally been limited to examination of interspecific variation among extant species of South American crocodylians. Here, we present the first study of intraspecific variation in the skull of M. niger using a two‐dimensional geometric morphometric approach. The crania of 52 sexed individuals varying in size were analysed to quantify shape variation and to assign observed shape changes to different types of intraspecific variation, that is, ontogenetic variation and sexual dimorphism. Most of the variation in this species is ontogenetic variation in snout length, skull depth, orbit size and the width of the postorbital region. These changes are correlated with bite force performance and probably dietary changes. However, a comparison with previous functional studies reveals that functional adaptations during ontogeny seem to be primarily restricted to the postrostral region, whereas rostral shape changes are more related to dietary shifts. Furthermore, the skulls of M. niger exhibit a sexual dimorphism, which is primarily size‐related. The presence of non‐size‐related sexual dimorphism has to be tested in future examinations.