Ontogeny of the redlichiid trilobite Eoredlichia intermediata from the Chengjiang Lagerstätte,lower Cambrian,southwest China

A detailed investigation of the morphology and ontogeny of the redlichioid trilobite Eoredlichia intermediata (Bulletin of the Geological Society of China, 3–4, 1940, 333) from the lower Cambrian Yu'anshan Member of the Heilinpu Formation, in Kunming, Yunnan Province, southwest China, is presented. The new material comprises a relatively complete ontogenetic series ranging from the early meraspid to the holaspid period, which reveals more details on morphological variation such as the appearance of bacculae in some holaspid specimens, contraction and disappearance of fixigenal spines, and macropleural spines of the first and second thoracic segments, which are all documented for the first time and can also be used as developmental markers defining ontogenetic phases. Two distinct morphotypes, possibly an expression of intraspecific variation or sexual dimorphism, are distinguished by the morphology of pleural spines of the second thoracic segment in meraspid degree 14 and holaspides. The trunk segmentation schedule of E. intermediata is also discussed and conforms to the protarthrous developmental mode. The distinction of the thoracic region into two portions can be observed during late meraspid and early holaspid periods, which might be considered as a reference for a better understanding on the relationship of tagmosis and growth segmentation among the Cambrian redlichiid trilobites.     

Two species of Tsinania (Trilobita,Corynexochida) from upper Furongian (Cambrian) of northern Anhui,China and their intraspecific variation

Hundreds of specimens of the trilobite Tsinania were collected from the Cambrian (upper Jiangshanian through Stage 10) at Fenghuangshan in northern Anhui, China, and were identified as Tsinania canens (Walcott, 1905) and Tsinania dolichocephala (Kobayashi, 1933). Comparisons between these two species and others referred to Tsinania, allow the redefinition of the two species. Fourteen synonyms and thirteen synonyms have been incorporated into T. canens and T. dolichocephala respectively. The key diagnosis of T. canens includes: the preglabellar field is flat, relatively short (sag.), has a slightly to obviously angular anterior margin; pygidium is rounded triangular and strongly convex; pygidial border is absent or very narrow. The key diagnosis of Tsinania dolichocephala comprises: the glabella is moderately convex with flat anterior part and convex posterior part (sag.); anterior border is relatively long (sag.), rounded to sharply angulated; pygidium is rounded triangularly with a wide, concave border. Upon such diagnoses, the potential intraspecific variations (e.g., the angularity of the anterior margin, the triangularity of the pygidium, and the width of the pygidial border) of the two species are discussed and listed. The late ontogeny of both species is described to further support the intraspecific variations.     

A new species of Ocydromia Meigen from China,with a key to species from the Palaearctic and Oriental Regions (Diptera,Empidoidea, Ocydromiinae)

Previously only one species of the genus Ocydromia Meigen was recorded from China. Here a second species of the genus from China, Ocydromia shanxiensis sp. n., is reported. A key to the species of the genus from the Palaearctic and Oriental regions is presented.     

Skeletal Morphology of Palaeocastor peninsulatus (Rodentia,Castoridae) from the Fort Logan Formation of Montana (early Arikareean): Ontogenetic and Paleoecological Interpretations

Palaeocastorine beavers were diverse members of the burrowing fauna of the Oligocene of North America best known from the Great Plains and the Great Basin. Palaeocastorines are also found in the northern Rocky Mountains. Several specimens of Capacikala, Euhapsis, and Palaeocastor have been reported from Montana within the Cabbage Patch beds fauna. New occurrences of palaeocastorine beavers from the Fort Logan Formation of central Montana show that the fauna there included Palaeocastor fossor, Capacikala sp., Palaeocastor sp., and three specimens of a species previously known only from the John Day Formation of Oregon: Palaeocastor peninsulatus. The three specimens include crania and associated postcrania forming an ontogenetic series from a juvenile to a mature adult. Careful examination of these specimens shows that morphological changes throughout ontogeny are associated with increased burrowing ability in adults. Palaeocastor peninsulatus is a scratch-digger with few cranial adaptations to burrowing susceptible to change with maturity. Dental characters, however, are modified with wear and vary greatly across individuals of similar wear stage. Cranial morphology thus appears to be a reliable source of taxonomic information in palaeocastorines unlike dental material. These new specimens provide evidence for increased chisel-tooth digging in adults compared to juveniles as is observed throughout the evolution of palaeocastorines. This study demonstrates the need for future work focusing on intraspecific variation to help better define species boundaries among palaeocastorines and improve phylogenetic analyses.     

Moulting,ontogeny and sexual dimorphism in the Cambrian ptychopariid trilobite Strenuaeva inflata from the northern Swedish Caledonides

Abstract: Three thousand seven hundred disarticulated remains together with several articulated specimens of the Cambrian Series 2 ptychopariid trilobite Strenuaeva inflata Ahlberg and Bergström, 1978 have been collected from the Torneträsk area, northern Sweden. The material provides significant new data on the morphology, ontogeny, moulting and enrolment of the species. Two distinct morphotypes, possibly an expression of sexual dimorphism, are recognized. The morph with a pair of bulbs in the frontal area, interpreted as brood pouches, is considered to represent females. Statistical treatment of the length/width ratio in cranidia reveals isometric growth during ontogeny for both morphotypes. The transition from the meraspid to holaspid ontogenetic period has been established through recognition of the successive development of the number of thoracic segments in articulated late meraspides. Throughout its life cycle, S. inflata went through 11 meraspid degrees and at least 17 holaspid growth stages. Inferred moult ensembles and exuviae reveal the successive opening of cephalic sutures and the function of the rostral plate during exuviation. As in other ellipsocephalid trilobites in which enrolment is known, the pygidium and two or three thoracic segments of S. inflata are concealed beneath the cephalon (spiral enrolment) during complete enrolment.     

Smithian (Early Triassic) ammonoids from Tulong, South Tibet

Intensive sampling of the Tulong Formation in South Tibet has facilitated the construction of a highly-resolved middle and late Smithian ammonoid succession. The new biostratigraphical sequence comprises the middle Smithian Brayardites compressus beds, Nammalites pilatoides beds, and the Nyalamites angustecostatus beds followed by the late Smithian Wasatchites distractus beds and Glyptophiceras sinuatum beds. This faunal succession correlates very well with that of other Tethyan sequences such as the Salt Range (Pakistan), Spiti (India), Oman and South China. The Smithian faunal sequence from Tulong contains several taxa with broad geographic distribution (e.g., Owenites, Paranannites spathi, Shigetaceras, Wasatchites), thus enabling correlation with faunal successions from areas outside the Tethys (e.g., USA, British Columbia, Arctic Canada, South Primorye, Siberia). Early Smithian ammonoid faunas are almost absent in Tulong because of a preservation bias (absence of carbonate rocks). Five new ammonoid genera (Brayardites, Nammalites, Nyalamites, Shigetaceras, Tulongites) and six new species (Brayardites crassus, Brayardites compressus, Prionites involutus, ?Subflemingites compressus, Tulongites xiaoqiaoi, Urdyceras tulongensis) are described.     

Phylogenetic relationships among monogenean gill parasites (Dactylogyridea, Ancyrocephalidae) infesting tilapiine hosts (Cichlidae): systematic and evolutionary implications

We studied the systematics of 14 species of monogenean (Ancyrocephalidae) gill parasites from West African tilapiine hosts (Cichlidae) using both morphological and genetic data. With these tools, we were able to: (i) confirm the validity of the previously described morphological parasite species and of the genus Scutogyrus; (ii) propose that some stenoxenous species (i.e., parasite species with more than one host) may be composed of sister species (e.g., Cichlidogyrus tilapiae); (iii) state that the use of the morphology of the haptoral sclerites is more suitable to infer phylogenetic relationships than the morphology of the genitalia (which seems to be more useful to resolve species-level identifications, presumably because of its faster rate of change). These results imply that: (i) the specificity of these monogenean parasites is greater than initially supposed (what were thought to be stenoxenous species may be assemblages of oïoxenous sister species); (ii) related species groups (i.e., “tilapiae,” “halli,” and “tiberianus”) have to be, as genus Scutogyrus, validated within the 54 ancyrocephalid species described from 18 species of tilapiine hosts in West Africa, (iii) the group “tilapiae,” due to its morphology and host range, have to be considered as being the most primitive; (iv) the occurrence of lateral transfers and parallel speciation processes are necessary to describe the repartition of the newly described parasite groups on the three host genera studied (Tilapia, Oreochromis, and Sarotherodon).     

Basilotritus (Cetacea: Pelagiceti) from the Eocene of Nagornoye (Ukraine): New data on anatomy,ontogeny and feeding of early basilosaurids

A new specimen of early basilosaurid, now identified as Basilotritus sp., comes from the late Middle Eocene of Ukraine. It has basilosaurid-type cheek teeth with cinguli, similar to those of Zygorhiza, and roots resembling those of Georgiacetus vogtlensis and early Neoceti; an unusual feature of these teeth is the presence of accessory denticles of the second order located on the crown denticles. The postcranial anatomy shows a mixture of primitive and advanced basilosaurid traits. The phylogenetic position of the genus Basilotritus is confirmed to be near the base of Basilosauridae, between Supayacetus and Zygorhiza. The ontogeny of the specimen from Nagornoye is characterized by large body size, slow skeletal maturation and intensive pachyosteosclerosis that are interpreted as neotenic development. Rapid tooth wear with strong apical abrasion is the result of specialized diet, possibly feeding on sharks.     

Dinosaur census reveals abundant Tyrannosaurus and rare ontogenetic stages in the Upper Cretaceous Hell Creek Formation (Maastrichtian), Montana, USA

Background

A dinosaur census recorded during the Hell Creek Project (1999–2009) incorporates multiple lines of evidence from geography, taphohistory, stratigraphy, phylogeny and ontogeny to investigate the relative abundance of large dinosaurs preserved in the Upper Cretaceous Hell Creek Formation of northeastern Montana, USA. Overall, the dinosaur skeletal assemblages in the Hell Creek Formation (excluding lag-influenced records) consist primarily of subadult or small adult size individuals. Small juveniles and large adults are both extremely rare, whereas subadult individuals are relatively common. We propose that mature individuals of at least some dinosaur taxa either lived in a separate geographic locale analogous to younger individuals inhabiting an upland environment where sedimentation rates were relatively less, or these taxa experienced high mortality before reaching terminal size where late stage and often extreme cranial morphology is expressed.

Methodology/Principal Findings

Tyrannosaurus skeletons are as abundant as Edmontosaurus, an herbivore, in the upper Hell Creek Formation and nearly twice as common in the lower third of the formation. Smaller, predatory dinosaurs (e.g., Troodon and dromaeosaurids) are primarily represented by teeth found in microvertebrate localities and their skeletons or identifiable lag specimens were conspicuously absent. This relative abundance suggests Tyrannosaurus was not a typical predator and likely benefited from much wider food choice opportunities than exclusively live prey and/or specific taxa. Tyrannosaurus adults may not have competed with Tyrannosaurus juveniles if the potential for selecting carrion increased with size during ontogeny.

Conclusions/Significance

Triceratops is the most common dinosaur and isolated skulls contribute to a significant portion of this census. Associated specimens of Triceratops consisting of both cranial and postcranial elements remain relatively rare. This rarity may be explained by a historical collecting bias influenced by facies and taphonomic factors. The limited discovery of postcranial elements may also depend on how extensive a fossil quarry is expanded after a skull is collected.     

A Transitional Gundi (Rodentia: Ctenodactylidae) from the Miocene of Israel

We describe a new species of gundi (Rodentia: Ctenodactylidae: Ctenodactylinae), Sayimys negevensis, on the basis of cheek teeth from the Early Miocene of the Rotem Basin, southern Israel. The Rotem ctenodactylid differs from all known ctenodactylid species, including Sayimys intermedius, which was first described from the Middle Miocene of Saudi Arabia. Instead, it most resembles Sayimys baskini from the Early Miocene of Pakistan in characters of the m1-2 (e.g., the mesoflexid shorter than the metaflexid, the obliquely orientated hypolophid, and the presence of a strong posterolabial ledge) and the upper molars (e.g., the paraflexus that is longer than the metaflexus). However, morphological (e.g., presence of a well-developed paraflexus on unworn upper molars) and dimensional (regarding, in particular, the DP4 and M1 or M2) differences between the Rotem gundi and Sayimys baskini distinguish them and testify to the novelty and endemicity of the former. In its dental morphology, Sayimys negevensis sp. nov. shows a combination of both the ultimate apparition of key-characters and incipient features that would be maintained and strengthened in latter ctenodactylines. Thus, it is a pivotal species that bridges the gap between an array of primitive ctenodactylines and the most derived, Early Miocene and later, gundis.     

The morphology and post-hatching development of the skull of Bolitoglossa nicefori (Caudata: Plethodontidae): developmental implications of recapitulation and repatterning

The cranial morphology of the direct-developing salamander Bolitoglossa nicefori and its post-hatching development are described and compared with that of other urodeles. Four stages of cranial development are defined on the basis of conspicuous events that occur during post-hatching ontogeny. The adult skull morphology of B. nicefori is similar to that of other plethodontids; however, some regions show interspecific variation. The post-hatching ontogeny of the skull and the stage of ossification observed in the hatchlings of B. nicefori show two important ontogenetic features: (1) a mosaic of early larval, metamorphic and post-metamorphic skull features in hatchlings, and (2) absence of characteristic larval elements in skull and hyoid apparatus. The distinctive stage of ossification in the hatchlings of B. nicefori could be caused by heterochronic changes in the ossification sequence, compared to the ontogeny of metamorphic salamanders. The possible heterochronic changes and the absence of larval traits are perhaps due to ontogenetic repatterning, yet without an obvious impact on the adult skull morphology (absence of morphological novelties). This might indicate a compartmentalized development. Further studies should be performed in order to establish the possible occurrence of recapitulatory patterns or ontogenetic repatterning in the skull morphogenesis of B. nicefori during its embryonic development.     

Systematics,palaeoecology and palaeobiogeography of the Neogene fossil sharks from the Azores (Northeast Atlantic)

The Azores Archipelago is a group of isolated islands located in the North Atlantic Ocean. One of these oceanic islands – Santa Maria – exhibits marine fossiliferous sediments of late Miocene/early Pliocene and also of Pleistocene age. Recent research provided new selachian fossil material, with three new records (Carcharias acutissima, Megaselachus megalodon, and Carcharhinus cf. leucas) increasing the number of fossil sharks reported from the Azores (Santa Maria Island) to seven species (Notorynchus primigenius, C. acutissima, Cosmopolitodus hastalis, Paratodus benedenii, Isurus oxyrinchus, M. megalodon, and C. cf. leucas). So far, no teeth of batoids or small sharks have been found despite the screen-washing of several sediment samples from Santa Maria. The Azorean Mio-Pliocene selachian fauna clearly differs from those described from sediments deposited on continental shelves, in which batoids and small benthic sharks (e.g., scyliorhinids) are usually well represented. During the late Miocene/early Pliocene, subtropical to warm-temperate seas were prevalent in the area of the Azores, as deduced from palaeontological, geological and isotopic data, all indicating a warmer climate than in the present.     

New insights into the pollen morphology of the genus Mutisia (Asteraceae, Mutisieae)

The pollen morphology from 67 collections representing 52 species of Mutisia was analyzed by means of light, scanning electron and transmission electron microscopy. Pollen of Mutisia is comparable to that of the more widespread type found in Mutisiinae. The pollen grains of the genus are characterized by the spheroidal-subprolate to prolate shape, large size, tricolporate aperture, with mesoaperture, exine Mutisia type, with sculpturing microechinate to rugulate or microechinate-rugulate. This basic pollen type is very variable in size, endoaperture shape, and exine thickness of the pollen grains. A new type of arrangement of columellae was observed in pollen of Mutisia section Mutisia (e.g., M. stuebelli, M. microphylla, and M. sodiroi). It is suggested that it might have harmomegathic significance. The pollen morphology and polymorphism are discussed with regard to functional mechanisms and possible evolutionary significance.     

Percrocuta miocenica (Percrocutidae,Carnivora) from the middle Miocene of Brajkovac (Central Serbia)

This paper describes a well-preserved hemimandible of Percrocuta miocenica from Brajkovac (Lazarevac municipality, Central Serbia). Based on the faunal remains recovered so far, the site is attributed to Mammal Zone MN6 (Langhian, middle Miocene). Apart from Prebreza, this is only the second site where remains of P. miocenica have been found in Serbia, and the third one in the Balkans. The newly discovered fossil, along with other taxa (e.g., Bunolistriodon meidamon, Giraffokeryx punjabiensis, Alloptox sp.), underlines the similarities between the middle Miocene Balkan and Anatolian mammal faunas.     

Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany

A fragmentary cervico-pectoral lateral spine and partial humerus of an ankylosaur from the Early Cretaceous (early Valanginian) of Gronau in Westfalen, northwestern Germany, are described. The spine shows closest morphological similarities to the characteristic cervical and pectoral spines of Hylaeosaurus armatus from the late Valanginian of England. An extensive comparison of distal humeri among thyreophoran dinosaurs supports systematic differences in the morphology of the distal condyli between Ankylosauria and Stegosauria and a referral of the Gronau specimen to the former. The humerus fragment indicates a rather small individual, probably in the size range of H. armatus, and both specimens are determined herein as ?Hylaeosaurus sp.. A short overview of other purported ankylosaur material from the Berriasian-Valanginian of northwest Germany shows that, aside from the material described herein, only tracks can be attributed to this clade with confidence at present.     

Systematics and evolution of the genus Clathrobaculus Cossmann, 1912 (Gastropoda, Mathildidae)

The morphology and ontogeny of Jurassic gastropods those have been included in the genera Clathrobaculus Cossmann, 1912 and Gordenella Gründel, 1990 are discussed. Based on the ontogenetic research of their shells, several types of ontogeny are established in the species of these genera. The suggestion is made that the genus Gordenella should be considered as a junior synonym of Clathrobaculus within the family Mathildidae. The protoconchs of Clathrobaculus species are studied to reveal their morphological variability and a number of distinguishing characters in which they differ from the protoconchs of other mathildid genera. Four species of Clathrobaculus, of which two are new (C. medidilatatus and C. inconstantiplicatus), are described from the Jurassic deposits of the European part of Russia. The composition of C. fahrenkohli (Rouillier, 1846) and C. krantzi (Rouillier, 1849) is emended, and the protoconchs of these species and of the species C. inconstantiplicatus are described for the first time.     

An electrophoretic and morphological analysis of Labiostrongylus (Labiomultiplex) uncinatus (Nematoda: Cloacinidae), with the description of a new species, L. contiguus, from Macropus parryi (Marsupialia: Macropodidae)

An electrophoretic study was conducted on Labiostrongylus (Labiomultiplex) uncinatus, nematodes that occur in the stomachs of two species of Australian macropodid, Macropus dorsalis and M. parryi. The allelic profiles of these nematodes were compared to those of a morphologically distinct species, L. (Lm.) billardierii, which infests Thylogale billardierii. Nematodes were genetically characterized at 17 enzymes encoding a presumptive 18 loci. The results revealed the existence of two species, one in M. dorsalis and the other in M. parryi, that had fixed genetic differences at 72% of loci. This level of fixed difference between these species is equivalent to that when each is compared to L. billardierii (87–89%). The new species in M. parryi, Labiostrongylus contiguus n. sp., is described herein. A morphological comparison with L. uncinatus revealed slight but consistent differences in the morphology of their anterior end; namely, rectangular rather than conical shaped lateral lips, small inconspicuous, not larger hook-shaped cephalic papillae, and convex rather than flat floor of the buccal capsule for L. (Lm.) contiguus as compared with L. (Lm.) uncinatus. Differentiation of L. contiguus from L. uncinatus is more clearly demonstrated by biochemical characters than morphological ones.     

Morphology, development and homologies of the perianth and floral nectaries in Croton and Astraea (Euphorbiaceae-Malpighiales)

New observations are presented on the ontogeny, vasculature and morphology of both staminate and pistillate flowers of Croton and Astraea. These data support earlier hypotheses that the filamentous structures in pistillate flowers represent reduced and transformed petals. Staminate flowers of both genera possess five free nectaries, which are vascularised by divergences of the sepal traces in Croton and unvascularised in Astraea. In pistillate flowers, there are five separate non-vascularised nectaries in Astraea, but in Croton there is a single nectariferous disk that is vascularised by divergences of the sepal traces. The nectaries are initiated late in floral development, but their location indicates that they could represent the outer stamen whorl transformed into secretory staminodes. Other glandular structures occur in pistillate flowers of most Croton species, resulting in flowers with two secretory organ whorls. In these cases, the inner whorl is formed by modified staminodes. Our observations support the recent segregation of Astraea species from the larger genus Croton. Despite strong similarities between the two genera, there are clear structural differences, including the presence of colleters in Astraea (absent in Croton), moniliform trichomes on petals (rather than simple trichomes in Croton), non-vascularised nectaries (vascularised in Croton) and reduced, non-secretory filamentous structures (well developed and secretory in Croton).