Evidence of osteomyelitis in the dentary of the late Triassic rhynchocephalian Clevosaurus brasiliensis (Lepidosauria: Rhynchocephalia) from southern Brazil and behavioural implications

Clevosaurus was a cosmopolitan Rhynchocephalia genus restricted to the Late Triassic and the Early Jurassic. In Brazil, C. brasiliensis is one of the most conspicuous species collected from the Candelária Sequence (Riograndia Assemblage Zone, Norian age) of the Santa Maria Supersequence. Several jaws of C. brasiliensis are housed in the Laboratório de Paleontologia de Vertebrados of the Instituto de Geociências-UFRGS. Some of these jaws bear a relatively small protuberant bony callus on the anterolateral margin of the dentary, evidenced by a different tissue pattern incorporating small pits and discrete grooves. This pattern closely resembles a common bone infection known in the mandible of the extant Sphenodon punctatus. Although this similarity, the infection may be the result of two possible processes: as consequence of orthal jaw shearing movements during feeding at the moments that the dentary impacts with the enlarged premaxillary tooth or due to injuries produced after fights between conspecific individuals (as is the case for S. punctatus). If the second hypothesis is correct, the same pathological processes probably occurred in the Late Triassic C. brasiliensis indicating that similar ethological conditions were already present at the beginning of the Mesozoic, during the initial radiation of the lepidosaurian clade.     

A new juvenile specimen of Yunnanosaurus robustus (Dinosauria: Sauropodomorpha) from Early to Middle Jurassic of Chuxiong Autonomous Prefecture,Yunnan Province,China

An almost complete skeleton with partial cranial material (ZMNH-M8739) is recovered from the Early or Middle Jurassic of southwest China. ZMNH-M8739 is identified as a juvenile individual of basal sauropodomorph dinosaur, Yunnanosaurus robustus Young, 1951. The revised diagnoses are as follows: absence of anteroposterior expansion on the medial end of astragalus and dorsoventrally compressed medium shaft of the metatarsal IV. Unfused neural arch and finely grooved long bone surface texture indicate that this individual is in the immature growth stage. ZMNH-M8739 possesses the tooth–tooth wear facet on its mesial maxillary and dentary teeth. However, the distal maxillary teeth have coarse serrations. Such a characteristic dentition could represent a unique feeding mechanism of this animal. Finally, ZMNH-M8739 constitutes a monophyletic group with Y. robustus (holotype), and Y. huangi is nesting this clade in the phylogenetic tree of the present analysis. Comparison of juvenile and adult specimen reveals distinctive growth changes of Y. robustus. This clade is positioned in an unnamed clade at a sister taxon of Sauropoda. Finally, some members of the so-called prosauropod dinosaurs constitute a monophyletic group in the present result.     

Influence of feed provisioning prior to digesta sampling on precaecal amino acid digestibility in broiler chickens

A regression approach was applied to determine the influence of feed provisioning prior to digesta sampling on precaecal (pc) amino acid (AA) digestibility in broiler chickens. Soybean meal was used as an example test ingredient. Five feed-provisioning protocols were investigated, four with restricted provision and one with ad libitum provision. When provision was restricted, feed was provided for 30 min after a withdrawal period of 12 h. Digesta were sampled 1, 2, 4 and 6 h after feeding commenced. A diet containing 300 g maize starch/kg was prepared. Half or all the maize starch was replaced with soybean meal in two other diets. Average pc digestibility of all determined AA in the soybean meal was 86% for the 4 and 6-h protocols and 66% and 60% for the 2 and 1-h protocols, respectively. Average pc AA digestibility of soybean meal was 76% for ad libitum feed provision. Feed provisioning also influenced the determined variance. Variance in digestibility ranked in magnitude 1 h > ad libitum > 2 h > 6 h > 4 h for all AA. Owing to the considerable influence of feed-provisioning protocols found in this study, comparisons of pc AA digestibility between studies applying different protocols prior to digesta sampling must be treated with caution. Digestibility experiments aimed at providing estimates for practical feed formulation should use feed-provisioning procedures similar to those used in practice.     

An early juvenile specimen of Bolong yixianensis (Ornithopoda: Iguanodontia) from the Lower Cretaceous of Ningcheng County,Nei Mongol,China

We describe an early juvenile specimen (ZMNH M8812) of Bolong yixianensis from the Yixian Formation (Lower Cretaceous) of Ningcheng County, Nei Mongol, China. The specimen consists of an almost complete skeleton preserved two-dimensionally on a slab. The short and deep skull proportions and unfused neurocentral sutures in most preserved vertebrae suggest that the ZMNH M8812 is a juvenile individual. Osteohistological study confirms a very early developmental stage. The study reveals the ontogenetic changes of Bolong for the first time. The specimen revealed one additional autapomorphy for Bolong yixianensis: the lingual face of the maxillary crown is bounded by thickened mesial and distal margins and bisected by a prominent median principal ridge. The study revealed the following ontogenetic trends of Bolong: increased tooth rows in both maxilla and dentary, increased robustness of the jugal and scapula, the radius and ulna become more robust and shorter relative to the hindlimb and the metatarsals become proportionally shorter. ZMNH M8812 represents the first juvenile non-hadrosaurid iguanodontian specimen described from the Lower Cretaceous of eastern Asia.     

Postcanine microstructure in Cricodon metabolus,a Middle Triassic gomphodont cynodont from south‐eastern Africa

Cricodon metabolus is a trirachodontid cynodont from the Anisian (Middle Triassic) of eastern and southern Africa. It has labiolingually expanded (gomphodont) postcanines but also a sectorial tooth in the last postcanine locus. In this paper, we examine the crown microstructure of isolated sectorial and gomphodont postcanines belonging to the holotype specimen of this taxon using scanning electron microscopy. The enamel of both teeth is prismless and composed of discontinuous columnar divergence units, supporting the consistent presence of synapsid columnar enamel in cynognathians. Abundant tubules and numerous irregularly spaced incremental lines are also visible in the enamel and dentine layers in each tooth. This study reveals that the enamel thickness varies along the tooth row in Cricodon as the enamel layer of the gomphodont postcanines is 11.5 times thicker than that of the sectorial crown. It is likely that this difference reflects occlusal stresses and fewer replacements in gomphodont postcanines relative to sectorial teeth. Approximately 100 incremental growth lines of von Ebner are present in the dentine layer, indicating that the deposition of the dentine by odontoblasts occurred for three months before the animal's death.     

Biostratigraphic significance of a new early sauropodomorph specimen from the Upper Triassic of southern Brazil

The Wachholz site (Caturrita Formation, Late Triassic), in Agudo, Rio Grande do Sul (RS), southern Brazil, has yielded several sauropodomorphs. This includes CAPPA/UFSM 0002, described here based on associated elements from the basalmost portion of the site. The specimen possesses a set of traits shared with typical ‘prosauropods’: a concave caudal margin of the trunk neural spines and a broadly convex proximal end of metacarpal V. However, it also retains some plesiomorphic features, for instance, the slender pedal digit I. Some bones closely resemble those of Unaysaurus tolentinoi, the other definitive sauropodomorph from the Caturrita Formation, an affinity corroborated by a new phylogenetic analysis. An updated biostratigraphic framework correlates the Wachholz, Água Negra (São Martinho da Serra/RS) and Botucaraí Hill (Candelária/RS) sites based on their sample of sauropodomorphs. In addition, the record of Jachaleria in the Botucaraí Hill site, a dicynodont also known from early Norian deposits of Argentina, indicates an equivalent age to deposits bearing U. tolentioni. Accordingly, a more constrained age is proposed for the Água Negra site. This is important as the early Norian marks the transition from an epoch of low sauropodomorphs representativeness to a period of extreme abundance of the group in Early-to-Middle Mesozoic ecosystems.     

Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs

Body masses of some South American dinosaurs are estimated. The sauropod Argentinosaurus huinculensis reached 73 tonnes, and therefore, is the largest of all land animals whose mass has been rigorously obtained. Another sauropod, Antarctosaurus giganteus, was the second largest, at nearly 69 tonnes, while Antarctosaurus wichmannianus reached 34 tonnes. A third sauropod, the bizarre-looking Amargasaurus cazaui, was much smaller, with a body mass of only 2.5 tonnes. Among theropods, the body mass of the strangely looking, horned Carnotaurus sastrei, was volumetrically estimated at 1.5 tonnes, while allometric equations on limb measurements yielded overestimations. Moreover, the holotype specimen of Giganotosaurus carolinii (MUCPv-CH-1) was about as large as the average-sized Tyrannosaurus rex, and only marginally smaller than “Sue”, the largest specimen. However, a new dentary of Giganotosaurus (MUCPv-95) is 8% longer than that of the holotype. Assuming geometric similarity, that individual must have had a body mass above 8 tonnes and hence must have been the largest theropod ever found.     

Common solutions to resolve different dietary challenges in the ruminant dentition: The functionality of bovid postcanine teeth as a masticatory unit

Plasticity of tooth shape in mammals is of great adaptive value for the efficient exploitation of specific feeding niches and is a crucial mechanism for ecological diversification. In this study, we aimed to infer chewing effectiveness from the functional shape of different postcanine teeth within bovids, the most diverse extant group of large herbivorous mammals. We consider the postcanine dentition as a masticatory unit and test for differences related to food biomechanical properties, dietary abrasiveness, and chewing dynamics. We compare functional properties of the postcanine tooth row among species with well‐known dietary strategies by integrating digitalization of high‐resolution occlusal surface 3D‐models of upper postcanine dentitions and quantification of the indentation index (D), a structural parameter representing enamel complexity. We test for differences in the occlusal shape among tooth positions in the postcanine dentition using robust, heteroscedastic tests in a one‐way analysis of variance. Our results show three distinct patterns of enamel complexity along the tooth row: (1) D is more homogeneously distributed among tooth positions; (2) D increases gradually in the mesiodistal axis along the tooth row; and (3) D increases abruptly only at the transition between premolars and molars. We interpreted these patterns as different adaptive configurations of the postcanine tooth row relating to diet. Grass‐ and fruit‐eating bovids show the same abrupt increase in enamel complexity at the transition from premolars to molars. Intermediate feeding and leaf‐browsing species show the same gradual, mesiodistal increase in complexity along the tooth row. The absolute physical dietary resistance (biomechanical properties plus abrasiveness) and its relation to mechanical constraints of the chewing stroke are the likely selective factors leading to convergence of enamel complexity patterns along the tooth row among taxa with different diets. J. Morphol. 275:328–341, 2014. © 2013 Wiley Periodicals, Inc.     

Reanalysis of the phylogenetic status of Nipponosaurus sachalinensis (Ornithopoda: Dinosauria) from the Late Cretaceous of Southern Sakhalin

Nipponosaurus sachalinensis is the only definitive lambeosaurine hadrosaurid from Sakhalin Island of Russia. Previous studies suggested it was a member of Lambeosaurini (derived lambeosaurines). However, its phylogenetic status within Lambeosaurini remains controversial. In addition, some studies argued the juvenile ontogenetic stage of the holotype and regarded Nipponosaurus as an invalid taxon. In order to solve these problems, its definite growth stage is determined through histological studies. Absence of a line of arrested growth, presence of osteons with large vascular spaces, and presence of primary bone remnants even in the highly modified regions of the femur confirm that the holotype was a juvenile. More than a hundred of the 350 characters used to determine the phylogenetic position of Nipponosaurus are ontogenetically variable characters based on the different ontogenetic stages of Hypacrosaurus stebingeri. Our phylogenetic analysis reveals that Nipponosaurus is a basal lambeosaurine hadrosaurid, much further down in the tree than previously suggested, and shows a polytomy with Blasisaurus and Arenyisaurus. This study also indicates that Nipponosaurus is a valid taxon because it possesses unique characters within the Lambeosaurinae (presence of massive surangular anterodorsal process, presence of lateral shelf of the dentary, and a relatively short ulna), which are independent of ontogeny.     

Structure, attachment, replacement and growth of teeth in bluefish, Pomatomus saltatrix (), a teleost with deeply socketed teeth

Tooth replacement poses many questions about development, pattern formation, tooth attachment mechanisms, functional morphology and the evolution of vertebrate dentitions. Although most vertebrate species have polyphyodont dentitions, detailed knowledge of tooth structure and replacement is poor for most groups, particularly actinopterygians. We examined the oral dentition of the bluefish, Pomatomus saltatrix, a pelagic and coastal marine predator, using a sample of 50 individuals. The oral teeth are located on the dentary and premaxillary bones, and we scored each tooth locus in the dentary and premaxillary bones using a four-part functional classification: absent (A), incoming (I), functional (F=fully ankylosed) or eroding (E). The homodont oral teeth of Pomatomus are sharp, deeply socketed and firmly ankylosed to the bone of attachment. Replacement is intraosseus and occurs in alternate tooth loci with long waves of replacement passing from rear to front. The much higher percentage of functional as opposed to eroding teeth suggests that replacement rates are low but that individual teeth are quickly lost once erosion begins. Tooth number increases ontogenetically, ranging from 15–31 dentary teeth and 15–39 premaxillary teeth in the sample studied. Teeth increase in size with every replacement cycle. Remodeling of the attachment bone occurs continuously to accommodate growth. New tooth germs originate from a discontinuous dental lamina and migrate from the lingual (dentary) or labial (premaxillary) epithelium through pores in the bone of attachment into the resorption spaces beneath the existing teeth. Pomatomus shares unique aspects of tooth replacement with barracudas and other scombroids and this supports the interpretation that Pomatomus is more closely related to scombroids than to carangoids.     

A NEW GENUS AND SPECIES OF SPHENODONTIAN FROM THE GHOST RANCH COELOPHYSIS QUARRY (UPPER TRIASSIC: APACHEAN), ROCK POINT FORMATION, NEW MEXICO, USA

Abstract: We document here a new taxon of sphenodontian, Whitakersaurus bermani gen. et sp. nov., that is also the most complete sphenodontian fossil from the Upper Triassic Chinle Group in the south‐western USA and the first Chinle sphenodontian represented by more than a single fragmentary dentulous element. The holotype was recovered during preparation of block C‐8‐82 from the famous Coelophysis (Whitaker) quarry at Ghost Ranch, New Mexico, and is the most complete small vertebrate recovered from the quarry. Detailed lithostratigraphy and geologic mapping demonstrate that the Whitaker quarry is in the Rock Point Formation of the Chinle Group, so Whitakersaurus is the first sphenodontian reported from this unit. Records of the phytosaur Redondasaurus at the quarry and elsewhere in the Chinle Group demonstrate that the quarry, and thus Whitakersaurus, is of Apachean (late Norian–Rhaetian) age. The sphenodontian specimen consists of incomplete left and right dentaries, a partial left? maxilla?, and impressions of a probable palatal element, all of which preserve multiple teeth. Whitakersaurus is distinct from other sphenodontians in possessing a unique combination of the following features: marginal dentition pleurodont anteriorly and posteriorly acrodont; pronounced heterodonty in dentary, with as many as 15 smaller, peg‐like teeth anteriorly and several larger, posterior teeth that are conical and striated; faint radial ornamentation of posterior tooth crowns; presence of c. 19 dentary teeth; and absence of a distinct flange on posterior teeth. Numerous other details distinguish it from both more primitive and more derived taxa. Whitakersaurus, therefore, helps to document further mosaic evolution and an extensive diversification event of sphenodontians during Triassic time. Although sphenodontian taxa are relatively easily recognized, widely distributed, and common small‐ or microvertebrate fossils, the long stratigraphic ranges of taxa known from multiple specimens hinders their utility as index fossils with which to correlate strata across Pangaea.     

Unique dentition of rhynchosaurs and their two-phase success as herbivores in the Triassic

Rhynchosaurs were key herbivores over much of the world in the Middle and Late Triassic, often dominating their faunas ecologically, and much of their success may relate to their dentition. They show the unique ankylothecodont mode of tooth implantation, with deep roots embedded in the bone of the jaw and low crowns that were rapidly worn down in use. During growth, the main area of oral food processing, located in the middle and posterior portions of the occlusal surfaces of the jaws, moved posteriorly relative to the anterior tips of the jaws, which curved up. As the maxilla and dentary grew by addition of new bone posteriorly, the dental lamina fed in new teeth at the back of the tooth rows. CT scanning of the holotype skull of Bentonyx sidensis from the Middle Triassic of England reveals previously concealed details of the dentition. Together with new dentary material from the same location, this has enabled us to examine the tooth replacement process and elucidate ontogenetic changes in dentition and jaw morphology as the animals aged. There were major changes in rhynchosaur anatomy and function through their evolutionary history, with the early forms of the Middle Triassic dying out before or during the Carnian Pluvial Episode (233–232 Ma), and the subclade Hyperodapedontinae, with broad skulls and adaptations to chop tough vegetation, subsequently diversifying worldwide in a successful ecological expansion until their global extinction 227–225 Ma.     

Omura's whale off West Africa: autochthonous population or inter-oceanic vagrant in the Atlantic Ocean?

The surveillance of marine mammal strandings within the framework of a biomonitoring scheme for the Mauritanian coast led to the discovery in 2013 of a 3.98?m long, juvenile rorqual Balaenoptera sp. in an advanced state of decomposition near Chott Boul (16°32.488′N, 016°27.0317′W). Photographs and skin samples were taken, but the specimen could not be collected. Based on limited morphological evidence, only Balaenoptera edeni and B. omurai were plausible. Sequences of three mtDNA regions, i.e. parts of the cox1 and the cytb genes as well as the D-loop, for a total of 2636?bp (> 16% of the mitogenome) identified the specimen as an Omura's whale, B. omurai, the first record in the Atlantic Ocean and at least 11,400?km away from its closest known range in the SW Indian Ocean (Madagascar). The question of whether the specimen is a vagrant or belongs to an unrecognized Atlantic population is discussed. Advection by currents or transport on a ship's bow bulb following collision are discarded. Circumstances (juvenile status, great distance from Indo-Pacific, necessary inter-oceanic passage through cold temperate waters) may slightly favour the hypothesis that B. omurai, if rare, could be autochthonous in the Atlantic. Beach surveys remain a useful tool to assess trends in cetacean species composition, to detect unusual mortality events and to help assess the impacts of anthropogenic activities. This is particularly applicable to remote areas where the marine mammal fauna is poorly known and where fisheries effort is high, such as the Mauritanian coast.     

Dental wear among cercopithecid monkeys of the Taï forest,Côte d'Ivoire

Studies of dental macrowear can be useful for understanding masticatory and ingestive behavior, life history, and for inferring dietary information from the skeletal material of extinct and extant primates. Such studies to date have tended to focus on one or two teeth, potentially missing information that can be garnered through examination of wear patterns across the tooth row. Our study measured macrowear in the postcanine teeth of three sympatric cercopithecid species from the Taï Forest, Côte d'Ivoire (Cercocebus atys, Procolobus badius, and Colobus polykomos), whose diets have been well‐described. Inter‐specific analyses suggest that different diets and ingestive behaviors are characterized by different patterns of wear across the molar row, with Cercocebus atys emphasizing tooth use near P₄‐M₁, P. badius emphasizing a large amount of tooth use near M₂‐M₃, and Colobus polykomos exhibiting wear more evenly across the postcanine teeth. Information regarding differential tooth use across the molar row may be more informative than macrowear analysis of isolated teeth for making inferences about primate feeding behavior. Am J Phys Anthropol 150:655–665, 2013. © 2013 Wiley Periodicals, Inc.     

A new galesaurid (Therapsida: Cynodontia) from the Lower Triassic of South Africa

A new galesaurid cynodont, Progalesaurus lootsbergensis gen. et sp. nov., is described on the basis of a well-preserved skull, lower jaw, right scapula and left atlantal neural arch. Autapomorphies of Progalesaurus include postcanine teeth bearing numerous mesial and distal accessory cusps that flank a recurved main cusp, a post-temporal fenestra bordered by the squamosal ventrally and a large external naris. Progalesaurus is similar to Galesaurus in possessing a poorly defined masseteric fossa on the dentary, a strongly recurved main cusp of the postcanine dentition, an incomplete secondary palate and a similar basisphenoid-parasphenoid morphology. A cladistic analysis of ten early cynodont genera resolves a monophyletic Galesauridae encompassing Cynosaurus , Progalesaurus and Galesaurus , although support for this clade is weak. Procynosuchus and Dvinia are placed at the base of Cynodontia whereas Thrinaxodon and Platycraniellus are positioned higher, but outside of Eucynodontia. The holotype and only known specimen of Progalesaurus was collected during systematic prospecting of Permo/Triassic boundary strata at New Lootsberg Pass, Graaff-Reinet District, South Africa. The discovery of Progalesaurus increases the number of valid Early Triassic cynodonts to four and sheds light on the tempo of early cynodont diversification after the end-Permian mass extinction.     

Evaluation of some medicinal plants and their mixtures for their bio-efficacy against crop and stored product pests

Plant based insecticides are gaining importance for their environmental safety. But their efficacy is greatly reduced in the field due to several factors. This study was undertaken to assess the insecticidal properties of medicinal plants viz., Cassia tora, Clerodendron enermi, Calotropis gigantea, Aloe vera, Vitex negundo and Andrographis paniculata, commonly found on farmlands and their mixtures. The extracts and mixtures were bio-assayed against a lepidopteran larva (Heliothis armigera) by modified leaf dip bioassay, and its effect on larval growth, development and survival; the oviposition deterrent effect against moths of H. armigera, and efficacy against the sucking pest Aphis gossypii and a stored product pest Callosobruchus chinensis were studied. The insecticidal activity in descending order was as follows: NSKE 10% > NSKE 5%, Botanical mixture II > A. paniculata > V. negundo > Botanical mixture I > C. gigantea > C. tora > C. enermi > A. vera. All botanicals showed greater ovipositional deterrence than insecticidal activity exhibiting 40–100% inhibition compared to untreated control. A. paniculata showed the highest activity against the store product pest C. chinensis. The complex of compounds in botanical mixtures could be synergistically used in eco-friendly pest management and botanical mixtures with neem as one of the ingredients, which could have a potential role as insect growth regulator.     

A new assemblage of freshwater sharks (Chondrichthyes: Elasmobranchii) from the Upper Triassic of India

This study reports the first occurrence of a varied xenacanth assemblage from the Upper Triassic Tiki Formation of India, based on multiple well-preserved isolated teeth. Based on distinct tooth morphology, two species of the genus Mooreodontus are described: M. indicus and a new species, M. jaini. The new species is diagnosed based on a tricuspid crown containing two stout, slightly diverging lateral cusps pointing in the same direction, a high median cusp, crown-base angle almost at 90°, large, rounded, apical button with several foramina and multiple, 8–9 coarse vertical cristae on all the cusps. Dental anomaly in the form of a partial quadri-cuspidate xenacanthid tooth is present in the collection. Another group of xenacanthid teeth have bicuspid crowns with two upright, asymmetric cusps, where the mesial cusp is thicker than the distal one, and consistently lack a median cusp. Such distinct bicuspid tooth morphology is usually present in Palaeozoic forms and is reported for the first time from the Late Triassic. It is considered to belong to a new taxon, Tikiodontus asymmetricus nov. gen., nov. sp., of indeterminate family. Distinctive tooth histology also differentiates the two Indian genera Mooreodontus and Tikiodontus nov. gen. from other xenacanthid taxa. In addition, the Tiki assemblage has yielded multiple chondrichthyan dermal denticles, which may be subdivided into two morphotypes based on their robustness and presence/absence of linear ridges on the fused cusps. India holds a unique position in terms of its Late Triassic freshwater shark fauna, as it exhibits distinct Laurasian affinities. These freshwater sharks had restricted occurrences in other parts of the Gondwanan landmass.     

Skeletal anatomy of the extinct shark Paraorthacodus jurensis (Chondrichthyes; Palaeospinacidae), with comments on synechodontiform and palaeospinacid monophyly

The skeletal morphology of Paraorthacodus jurensis, a Late Jurassic neoselachian from Nusplingen, is described based on the incomplete holotype and a newly discovered almost complete specimen. For the first time, the postcranial skeleton could be investigated. Paraorthacodus is characterized by a monognath dental heterodonty and tearing‐type dentition. The number of lateral cusplets in the lateral teeth differs between the holotype and the new specimen, possibly indicating sexual dimorphism. Clasper organs are not preserved in either of the two specimens. The notochord is sheathed by about 123 well‐calcified vertebral centra. The posterior‐most caudal vertebrae are lacking. The transition from monospondylous thoracic to diplospondylous abdominal vertebrae occurs at centra 48 and 49. The origin of the caudal fin is at the 80th centrum. Most conspicuous is the presence of a single spineless dorsal fin. In this respect, Paraorthacodus differs from most palaeospinacids, but resembles Macrourogaleus. Palidiplospinax possibly is sister to a group comprising Synechodus, Paraorthacodus, and Macrourogaleus (the Palaeospinacidae). A reinterpretation of dental and skeletal characters of synechodontiform taxa indicates that Synechodontiformes and Palaeospinacidae are monophyletic groupings of basal neoselachians. Synechodontiformes is probably sister to all living elasmobranchs.