A NEW BASAL BALAENOPTERID WHALE FROM THE PLIOCENE OF NORTHERN ITALY

Abstract:  A new basal balaenopterid genus and species, Archaebalaenoptera castriarquati , is described and compared with all the living and fossil members of the family Balaenopteridae and related fossil rorqual-like taxa. It was found in the Lower Pliocene of northern Italy, and is characterized by a supraoccipital with a transversely compressed anterior process, the zygomatic process of the squamosal diverging from the longitudinal axis of the skull, very long nasal bones, and subtle exposition of the parietal on the dorsal wall of the skull. It is primitive in having a maxilla with a long ascending process that is posteriorly unexpanded and round, and a dentary that is straight and not bowed outward, unlike that of living Balaenopteridae. In particular, the discovery of this new genus suggests that, among the early members of Balaenopteridae, the acquisition of the typical sutural pattern shown by maxilla, frontal, parietal and supraoccipital preceded the acquisition of the feeding-related traits that are characteristic of the family. The primitive morphology of the feeding-related structures of A. castriarquati (i.e. the straight dentary and the flat glenoid fossa of the squamosal) suggests that this whale was unable to undertake the intermittent ram feeding typical of Balaenopteridae as efficiently as living members of the family.     

New basal procolophonid reptile from the Katberg formation (Lower Triassic) of the South African Karoo

A new procolophonid reptile, Kitchingnathus untabeni n. gen. et n. sp., is described from the uppermost strata of the Lystrosaurus Assemblage Zone of the Karoo Basin, South Africa. The new taxon co-occurs with the well-known Procolophon trigoniceps. The most distinctive feature of the new taxon is the presence of numerous small bicuspid molariforms in both the maxilla and the dentary. A phylogenetic analysis indicates that Kitchingnathus occupies a basal position among procolophonids. Character optimisation suggests that bicuspid teeth were acquired independently by the new taxon, and originated twice in procolophonid evolution.     

Anatomical study of the skull of amphisbaenian Diplometopon zarudnyi (Squamata,Amphisbaenia)

This study investigates the amphisbaenian species skull which includes cranium, lower jaw and hyoid apparatus. The medial dorsal bones comprise the premaxilla, nasal, frontal and parietal. The premaxilla carries a large medial tooth and two lateral ones. The nasals are paired bones and separated by longitudinal suture. Bones of circumorbital series are frontal, orbitosphenoid and maxilla. The occipital ring consists of basioccipital, supraoccipital and exooccipital. Supraoccipital and basioccipital are single bones while the exo-occipitals are paired. The bones of the palate comprise premaxilla, maxilla, septomaxilla, palatine, pterygoid, ectopterygoid, basisphenoid, parasphenoid, orbitosphenoid and laterosphenoid. Prevomer and pterygoid teeth are absent. Palatine represent by two separate bones. The temporal bones are clearly visible. The lower jaw consists of the dentary, articular, coronoid, supra-angular, angular and splenial. The hyoid apparatus is represented by a Y-shaped structure. The mandible is long and is suspended from the braincase via relatively short quadrate. There is an extensive contact between the long angular and the large triangular coronoid. Thus inter-mandibular joint is bridged completely by the angular and consequently, the lower jaws are relatively rigid and kinetic. The maxillae are suspended from the braincase largely by ligaments and muscles rather than through bony articulation. In conclusion, the skull shape affects feeding strategy in Diplometopon zarudnyi. The prey is ingested and transported via a rapid maxillary raking mechanism.     

A revision of chamaeleonids from the Lower Miocene of the Czech Republic with description of a new species of Chamaeleo (Squamata, Chamaeleonidae)

A revision of Chamaeleo caroliquarti Moody and Ro?ek is presented. The comparisons of the holotypic left dentary with those of specimens subsequently assigned to C. caroliquarti and of the Recent species of Chamaeleo, Furcifer and Calumma is carried out. It is shown that the type dentaries of C. caroliquarti include two different morphotypes with the absence of unique features. Within the Recent chameleons, the exact determination of the individual species merely on the basis of the dentaries is impossible. The holotypic dentary of C. caroliquarti is basically identical with that of C. calyptratus. However, the same morphology of the dentary as present in C. caroliquarti is also present in other species of different genera such as Calumma globifer and Furcifer pardalis. The paratypic dentaries of C. caroliquarti have a different morphology to the holotype and are indistinguishable from that in the Recent C. chamaeleon. On the other hand, a new species of the genus Chamaeleo, C. andrusovi, is described on the basis of isolated cranial elements, which possess clear autapomorphic features. This material comes from the Lower Miocene (Ottnangian) zone MN 4 in the Dolnice locality of the Czech Republic, and it differs from Recent and fossil chameleons in the following combination of characters: (1) its typically developed strongly pustular ornamentation and its distribution on the external surfaces of the skull roofing bones; (2) the frontoparietal suture is digitiform with a well-developed, anteriorly directed mesial spine, and (3) the parietal bone narrows posteriorly at its midlength, it is not bowed dorsally and it does not contribute posteriorly to a dorsal sagittal crest. This new material expands our knowledge of the cranial anatomy of Lower Miocene chameleons.     

A New Taxon of Basal Ceratopsian from China and the Early Evolution of Ceratopsia

Ceratopsia is one of the best studied herbivorous ornithischian clades, but the early evolution of Ceratopsia, including the placement of Psittacosaurus, is still controversial and unclear. Here, we report a second basal ceratopsian, Hualianceratops wucaiwanensis gen. et sp. nov., from the Upper Jurassic (Oxfordian) Shishugou Formation of the Junggar Basin, northwestern China. This new taxon is characterized by a prominent caudodorsal process on the subtemporal ramus of the jugal, a robust quadrate with an expansive quadratojugal facet, a prominent notch near the ventral region of the quadrate, a deep and short dentary, and strongly rugose texturing on the lateral surface of the dentary. Hualianceratops shares several derived characters with both Psittacosaurus and the basal ceratopsians Yinlong, Chaoyangsaurus, and Xuanhuaceratops. A new comprehensive phylogeny of ceratopsians weakly supports both Yinlong and Hualianceratops as chaoyangsaurids (along with Chaoyangsaurus and Xuanhuaceratops), as well as the monophyly of Chaoyangosauridae + Psittacosaurus. This analysis also weakly supports the novel hypothesis that Chaoyangsauridae + Psittacosaurus is the sister group to the rest of Neoceratopsia, suggesting a basal split between these clades before the Late Jurassic. This phylogeny and the earliest Late Jurassic age of Yinlong and Hualianceratops imply that at least five ceratopsian lineages (Yinlong, Hualianceratops, Chaoyangsaurus + Xuanhuaceratops, Psittacosaurus, Neoceratopsia) were present at the beginning of the Late Jurassic.     

Cranial and appendicular ontogeny of Bactrosaurus johnsoni,a hadrosauroid dinosaur from the Late Cretaceous of northern China

Abstract: The juvenile anatomy of various cranial and appendicular elements of the hadrosauroid dinosaur Bactrosaurus johnsoni is described in detail. Growth changes are documented from juvenile to adult stages for each skeletal element available. In the studied skull, ontogenetic trends consist of: development of features on the ventral surface of the frontal; reduction in the slope of the posteromedial process of the premaxilla; a posterior shift of the dorsal process of the maxilla; development of concavities on the medial surface of the prefrontal; increased robustness and development of the ventral flange of the jugal; decreased curvature of the long axis of the quadrate; increased ventral deflection of the dentary; and changes in the length/width proportions and depth of the anterior surface of the predentary. In the appendicular skeleton, the majority of ontogenetic variation from juvenile to adult occurs in the limb bones, including increased robustness of the deltopectoral crest of the humerus; relative shortening of the ulna; increased development of the fourth trochanter and mediolateral widening of the distal end of the femur; increased expansion of the cnemial crest of the tibia; and the increased prominence of articular protuberances and flanges of the metatarsals. A survey of the phylogenetically informative characters present in B. johnsoni indicates that several characters concerning the frontal, maxilla, jugal, quadrate, predentary, dentary, scapula, humerus and ilium are affected by ontogeny. Nevertheless, the majority of phylogenetic characters are not ontogenetically variable, suggesting that a substantial amount of the information provided by juvenile and subadult specimens for phylogenetic inference is reliable in basal hadrosauroids.     

Early cretaceous mammals from the Khamryn-Us and Shalan-Ikher localities in Mongolia

New material of Early Cretaceous mammals from Mongolia, including dentary fragments of Gobiconodon borissiaki Trofimov, 1978 and G. hoburensis (Trofimov, 1978) from the well-known dinosaur locality Khamryn-Us (Dornogovi aimag) and a maxilla fragment of G. borissiaki from the new locality Shalan-Ikher (Övörkhangai aimag), is presented. The new data extend the knowledge on the morphology and intraspecific variability of Gobiconodon and the distribution of the Höovör Mammalian Assemblage in Mongolia.     

Osteological development of the lophiid anglerfish,lophius gastrophysus

The osteological development of the head skeleton and dorsal, pectoral, and anal fin supports, are described from cleared and stained specimens ofLophius gastrophysus larvae, ranging from 4.6 to 21.8 mm NL; the results are compared with those of juvenile (79.8 mm SL) and adult (398 mm SL) specimens. Tiny conical teeth are present on the premaxillary, dentary, palatine and vomer since early stage. The first three dorsal fin spines are initially positioned on the midline of body posterior to the supraoccipital, but they migrate forward with growth and become cephalic in juveniles. The forward movement of the dorsal spines is produced by the forward extension of the cartilaginous basal inside the subepidermal space. During the planktonic larval stage the pectoral fins are on the sides of body as in ordinary fishes, but they move ventrad and become leg-like in bottom living juveniles and adults. Ossification of the caudal complex ofL. gastrophysus larvae proceeds very slowly and only the 21.8 mm NL larva has an almost completely ossified caudal complex. Eight principal caudal rays are loosely attached on the posterior edge of the hypurals and no procurrent rays are present. Larvae have well developed parhypurapophysis at the mid-portion of the urostyle which transforms into keel-like structure in juveniles and adults.     

A new ichthyodectiform (Actinopterygii,Teleostei) from the Lower Cretaceous Marizal Formation,north‐east Brazil

Abstract: A new genus and species, Ogunichthys triangularis, from the Early Cretaceous Marizal Formation in the Tucano Basin, Bahia State, Brazil, can be assigned to the teleost order Ichthyodectiformes and to the suborder Ichthyodectoidei by the presence of ten synapomorphies of these clades. Ogunichthys gen. nov. cannot be placed into any of the currently recognized families within Ichthyodectoidei and differs from all other ichthyodectoid genera in the ratio between the depth of the dentary symphysis and the depth of the coronoid process, the relationships between the length of the coronoid process and the alveolar border of the dentary, and a supraoccipital crest with posterior border fringed. The new taxon occurs in Early Cretaceous (Aptian) strata of the Marizal Formation, which are related to periods during epicontinental seas extended from the Caribbean Tethys into the South American continent. Rather than representing a single continuous widespread seaway, these epicontinental seas reflect local tectonic events, sometimes including locally distinctive faunas.     

Redescription of Bonatitan reigi (Sauropoda: Titanosauria), from the Campanian–Maastrichtian of the Río Negro Province (Argentina)

The titanosaur sauropod Bonatitan reigi is redescribed. The material collected, originally interpreted as pertaining to two different individuals, is reorganised in five individuals, and the original type specimen is separated into three different individuals. One of the braincases is designated as a new type specimen. Some materials are described by the first time (sacral ribs, distal caudal, chevrons, metacarpals, astragalus and metatarsals), others reinterpreted as different bones (‘ulna’ and ‘radius’). The diagnosis of B. reigi is emended, removing some of the original characters (longitudinal groove located on the suture between the parietals that continues posteriorly over the supraoccipital to the foramen magnum) and adding some new (small paired pits on the frontals and posterior ridge of the metacarpal IV). The phylogenetic analysis does not support B. reigi as a member of the Saltasaurinae, but rather as a basal member of a broad clade of sauropods that in turn is recovered as the sister group of the Saltasauridae.     

A new basal sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), northwestern Argentina

Background

Argentinean basal sauropodomorphs are known by several specimens from different basins; Ischigualasto, El Tranquilo, and Mogna. The Argentinean record is diverse and includes some of the most primitive known sauropodomorphs such as Panphagia and Chromogisaurus, as well as more derived forms, including several massospondylids. Until now, the Massospondylidae were the group of basal sauropodomorphs most widely spread around Pangea with a record in almost all continents, mostly from the southern hemisphere, including the only record from Antarctica.

Methodology/Principal Finding

We describe here a new basal sauropodomorph, Leyesaurus marayensis gen. et sp. nov., from the Quebrada del Barro Formation, an Upper Triassic-Lower Jurassic unit that crops out in northwestern Argentina. The new taxon is represented by a partial articulated skeleton that includes the skull, vertebral column, scapular and pelvic girdles, and hindlimb. Leyesaurus is diagnosed by a set of unique features, such as a sharply acute angle (50 degrees) formed by the ascending process of the maxilla and the alveolar margin, a straight ascending process of the maxilla with a longitudinal ridge on its lateral surface, noticeably bulging labial side of the maxillary teeth, greatly elongated cervical vertebrae, and proximal articular surface of metatarsal III that is shelf-like and medially deflected. Phylogenetic analysis recovers Leyesaurus as a basal sauropodomorph, sister taxon of Adeopapposaurus within the Massospondylidae. Moreover, the results suggest that massospondylids achieved a higher diversity than previously thought.

Conclusions/Significance

Our phylogenetic results differ with respect to previous analyses by rejecting the massospondylid affinities of some taxa from the northern hemisphere (e.g., Seitaad, Sarahsaurus). As a result, the new taxon Leyesaurus, coupled with other recent discoveries, suggests that the diversity of massospondylids in the southern hemisphere was higher than in other regions of Pangea. Finally, the close affinities of Leyesaurus with the Lower Jurassic Massospondylus suggest a younger age for the Quebrada del Barro Formation than previously postulated.     

Mosasaurus beaugei Arambourg, 1952 (Squamata, Mosasauridae) from the Late Cretaceous phosphates of Morocco

Mosasaurus beaugei Arambourg, 1952 was based on isolated teeth from the Maastrichtian phosphatic deposits of Morocco. The recent discovery of new material, including skull and mandibular remains, improves our knowledge of this species. M. beaugei shares the following synapomorphies with the genus Mosasaurus: large teeth bearing two prominent carinae and with asymmetrical labial and lingual surfaces, the labial one being flattened and strongly facetted and the lingual one being convex; premaxillae with a small pointed rostrum and dentary without rostrum; palatal elements closely united; coronoid with very large ventromedial process overlying the prearticular. M. beaugei is characterised by the following autapomorphies: 12-13 maxillary teeth; marginal teeth bearing 3-5 prisms on the labial surface and 8-9 on the lingual one; palatine with posterior border concave and perpendicular to the long axis of the skull; splenial visible laterally on half of the dentary ventral surface; coronoid with anterior wing well developed and bearing two notches. M. beaugei is only known to date in the Maastrichtian phosphates of Morocco.     

Characteristics of dentition in gekkonid lizards of the genus <Emphasis Type="Italic">Teratoscincus</Emphasis> and other Gekkota (Sauria,Reptilia)

The dentition and tooth crown microstructure of gekkonids and eublepharids are examined. Scanning electron microscopy shows that the lingual surface of teeth in these lizards has one, two, or, occasionally, several cusps separated by grooves. The teeth of geckoes usually have two (lingual and labial) cusps in the apical region. With respect to the number of teeth, the majority of Gekkota fall into two groups. The first includes a few species with many teeth (50 or more) in the dentary and maxilla, the eublepharids Goniurosaurus and Aeluroscalabotes, and the gekkonid Cyrtopodion louisiadensis. The second group, comprising most of the species, is subdivided into two subgroups, species with 20–30 or 30–40 teeth in jaw bones. Teratoscincus belongs to the first subgroup of the second group.     

A Basal Sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic,Carnian) and the Early Evolution of Sauropodomorpha

Background

The earliest dinosaurs are from the early Late Triassic (Carnian) of South America. By the Carnian the main clades Saurischia and Ornithischia were already established, and the presence of the most primitive known sauropodomorph Saturnalia suggests also that Saurischia had already diverged into Theropoda and Sauropodomorpha. Knowledge of Carnian sauropodomorphs has been restricted to this single species.

Methodology/Principal Findings

We describe a new small sauropodomorph dinosaur from the Ischigualsto Formation (Carnian) in northwest Argentina, Panphagia protos gen. et sp. nov., on the basis of a partial skeleton. The genus and species are characterized by an anteroposteriorly elongated fossa on the base of the anteroventral process of the nasal; wide lateral flange on the quadrate with a large foramen; deep groove on the lateral surface of the lower jaw surrounded by prominent dorsal and ventral ridges; bifurcated posteroventral process of the dentary; long retroarticular process transversally wider than the articular area for the quadrate; oval scars on the lateral surface of the posterior border of the centra of cervical vertebrae; distinct prominences on the neural arc of the anterior cervical vertebra; distal end of the scapular blade nearly three times wider than the neck; scapular blade with an expanded posterodistal corner; and medial lamina of brevis fossa twice as wide as the iliac spine.

Conclusions/Significance

We regard Panphagia as the most basal sauropodomorph, which shares the following apomorphies with Saturnalia and more derived sauropodomorphs: basally constricted crowns; lanceolate crowns; teeth of the anterior quarter of the dentary higher than the others; and short posterolateral flange of distal tibia. The presence of Panphagia at the base of the early Carnian Ischigualasto Formation suggests an earlier origin of Sauropodomorpha during the Middle Triassic.     

A new specimen of Biseridens qilianicus indicates its phylogenetic position as the most basal anomodont

A new well-preserved basal therapsid skull from the Xidagou Formation, Middle Permian of China, is identified as Biseridens qilianicus. The following synapomorphies distinguish Biseridens as an anomodont and not an eotitanosuchian as previously described: short snout; dorsally elevated zygomatic arch and septomaxilla lacking elongated posterodorsal process between nasal and maxilla. The presence of a differentiated tooth row; denticles on vomer, palatine and pterygoid; contact between tabular and opisthotic; lateral process of transverse flange of pterygoid free of posterior ramus and absence of mandibular foramen exclude it from other anomodonts. Our cladistic analysis indicates Biseridens to be the most basal anomodont, highlights separate Laurasian and Gondwanan basal anomodont clades and suggests that dicynodonts had their origins in the Gondwanan clade. The co-occurrence of the most basal anomodont (Biseridens) together with the most basal therapsid (Raranimus), basal anteosaurid dinocephalians, bolosaurids and dissorophids suggests that the earliest therapsid faunas are from China.     

The oldest rhynchosaur from Argentina: a Middle Triassic rhynchosaurid from the Chañares Formation (Ischigualasto–Villa Unión Basin,La Rioja Province)

Rhynchosaurs first appear in the Early Triassic fossil record and flourished during the late Carnian as the dominant members of several assemblages worldwide. In Argentina, the rhynchosaur record is currently restricted to the Ischigualasto Formation of late Carnian–earliest Norian age. Recent fieldwork in the new locality of Brazo del Puma, in the lowermost levels of the Chañares Formation, yielded three rhynchosaur tooth-bearing bones, which were collected five metres above the contact with the underlying Tarjados Formation. The most complete specimen is the posterior end of the alveolar region of a left dentary. The dentary possesses densely packed tooth rows on the lingual surface and medial half of the occlusal surface, showing longitudinal Zahnreihen. The teeth of the occlusal surface are worn flat and those of the lingual surface are organized in multiple rows, supporting the referral of the specimen to Rhynchosauridae. In addition, the dentary teeth are conical to mesiodistally compressed, resembling the condition observed in hyperodapedontines. The rhynchosaur remains reported here are the oldest collected in Argentina and among the oldest in South America, together with an unnamed form from Brazil. The new rhynchosaur specimens come from levels in which dicynodonts are numerically dominant, whereas cynodonts are considerably less abundant. Accordingly, the specimens reported here bolster faunal differences within the Chañares Formation and add a new faunal component to this already diverse vertebrate assemblage.     

Freshwater crocodile,Crocodylus siamensis Schneider, 1801, from the Middle Pleistocene deposits in Chaloem Phrakiat District,Nakhon Ratchasima,Thailand

Two crocodilian anterior cranium parts from Takut Khon Village sand pit, Chaloem Phrakiat District, Nakhon Ratchasima Province, are presently described. Their morphology indicates that the specimens belong to a single species based on the presence of several similar characters such as a hole for the reception of the first dentary tooth at the anterior edge of the premaxillary bone; anterior tip of nasal elongate and projecting into the posterior margin of the external nares; wavy suture line between the posterior part of the nasal with the anterior margin of prefrontal and frontal processes. The cranium morphology is extremely close to Crocodylus siamensis Schneider, 1801 (Siamese crocodile) and conforming the existence of C. siamensis from the Middle Pleistocene in Thailand.