A new trirachodontid cynodont from the lower levels of the Burgersdorp Formation (Lower Triassic) of the Beaufort Group, South Africa and the cladistic relationships of Gondwanan gomphodonts

We describe a new trirachodontid cynodont from the base of the Burgersdorp Formation (Subzone A fauna of the Cynognathus Assemblage Zone), of the South African Karoo Basin. Langbergia modisei gen. et sp. nov. is characterized by circular to ovoid in outline upper postcanines and the absence of a maxillary platform lateral to the postcanine series. Apart from the new taxon, we recognize two other species of this family in the Cynognathus Assemblage Zone: Trirachodon berryi and Cricodon metabolus , the latter also represented in the Tanzanian Manda Formation. A phylogenetic analysis of gomphodont cynodonts was conducted using a data matrix of 43 craniodental characters and 18 terminals. Trirachodontidae appears as a monophyletic assemblage, with Langbergia appearing as the sister taxon of Cricodon . The monophyly of trirachodontids is weakly supported, however, with one extra step breaking it. Traversodontid cynodont relationships were also inspected and compared with a recent phylogeny proposed for this group. Considering the resulting phylogeny and the sudden appearance and diversification of Cynognathia representatives, the origin of basal Cynognathia (i.e. Cynognathus , Diademodon , and trirachodontids) is suggested to predate their first appearance in the fossil record.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 147 , 383–413.     

Postcanine dental form in the mustelidae and viverridae (Carnivora: Mammalia)

This study investigates whether the gross morphology of mustelid and viverrid postcanine dentitions corresponds with differences in diet. For each species, the predominant foods ingested are used to form predictions of dental form and measurements of the carnassial and molar teeth determine the extent of shearing and crushing surfaces on the postcanine teeth. Principal components analysis distinguishes species according to morphological differences in the dentition and these differences are compared with predictions of dental form based on diet. Dietarily specialized species are more likely to be correspondingly specialized in the dentition and species with varied food sources are more likely to possess dental characteristics that are generalized in function. Consumers of foods with high fracture resistance, such as vertebrate tissue and hard-surfaced invertebrates, possess specialized shearing or crushing postcanine teeth. On the other hand, species that consume foods of lesser fracture resistance, such as fruit and soft invertebrates, differ greatly in dental form and are more generalized in dental function. A few species possess postcanine dentitions that do not correspond with diet; the absence of dental-dietary correlation in these species suggests that other factors, such as phylogeny, are important in determining dental form.     

Revision of the foraminiferal biozonation scheme in Upper Cretaceous carbonates of the Dezful Embayment,Zagros, Iran: Integrated palaeontological,sedimentological and geochemical investigation

Cretaceous carbonate successions of the Bangestan Group, such as the Sarvak and Ilam formations, are among the most prolific hydrocarbon reserves of the Middle East. However, relatively little is known about their detailed palaeontology and biostratigraphy. Moreover, due to lithological similarity of these carbonate formations recognition of their boundaries in subsurface studies is problematic. To investigate these units, biostratigraphic analyses were carried out on nearly 1100 m of cores, including core plug samples and thin sections prepared from five giant and supergiant oilfields in the northern and southern Dezful Embayment, SW Iran. Accordingly, 59 species of foraminifera (assigned to 43 genera) as well as 11 species of non-foraminifera (10 genera) were recognized. As a result, three biozones were identified, which in stratigraphic order are: Nezzazata-Alveolinids Assemblage Zone; Moncharmontia apenninica-Nezzazatinella-Dicyclina Assemblage Zone; and Rotalia skourensis-algae Assemblage Zone. These are compared with the Wynd's (1965) biozonation scheme, previously introduced in the Zagros area, and a revised scheme is presented. Accordingly, a Cenomanian–Turonian age and a Coniacian–Campanian age are envisaged for the Upper Sarvak and Ilam formations, respectively. In our new biostratigraphic scheme, the Sarvak–Ilam formations boundary is considered to be located above the Moncharmontia apenninica-Nezzazatinella-Dicyclina Assemblage Zone (equivalent of Valvulammina-Dicyclina Assemblage Zone of Wynd, 1965), that is Turonian in age. This zone is bounded by two palaeoexposure surfaces, which correspond approximately to the C–T boundary transitional interval and a post-Turonian, which can be possibly assigned to the Coniacian. Significant sedimentological features of these disconformities include bauxitic–lateritic horizons, karstified profiles and solution-collapsed breccias. Geochemical signatures of these meteorically altered surfaces are also considered to calibrate biofacies and biozones. Finally, we compared our new biozonation scheme with other studies in neighboring areas of SW Iran and the Middle East.     

Paleobiogeographic implications of the Middle Eocene ostracods from Cairo–Suez district,Egypt

The main targets of this paper are to examine the Middle Eocene ostracod assemblages collected from a succession exposed in the Cairo–Suez district, Egypt and to detect their paleobiogeographical implications. The studied succession is subdivided into two rock units: the Observatory and Qurn formations, in ascending order. The analysis of the ostracod assemblages led to the identification of 18 species, none of which is new. Three local biozones are established, Digmocythere ismaili - Xestoleberis kenawyi Assemblage Zone, Grinioneis moosi - Loxoconcha pseudopunctatella Assemblage Zone and Cativella qurnenis - Soudanella triangulata Assemblage Zone. The multivariate analyses indicate that there are three distinct bioprovinces, one of them represents the North Africa bioprovince, including Egypt, Libya, and Tunisia. The second bioprovince represents the Middle East, including Jordan and Israel. The third represents the West Africa bioprovince, including Senegal, Togo, Ivory Coast and Nigeria. Therefore, this deduction supports a migration of Eocene ostracods along the southern Tethys.     

Endothiodont dicynodonts from the Late Permian Kundaram Formation,India

The Kundaram Formation, a Lower Gondwana unit of the Pranhita-Godavari valley, contains the only known Permian dicynodonts in India. This dicynodont assemblage is dominated by Endothiodon. Two species (Endothiodon mahalanobisi sp. nov and Endothiodon uniseries Owen 1879) are described here. This is the first detailed study of Endothiodon from outside Africa. The study shows that Endothiodon jaw articulation permitted propalinal action when the opposing serrations in the upper and the lower jaw teeth occluded with the horn covered areas and helped in shearing and mastication. The presence of oblique wear facets on the upper and lower jaw teeth and a masseter-like muscle suggest a slightly lateral movement of the lower jaw which enhanced slicing of plant matter. A robust stapes with posterolateral notch constitutes the middle ear region though Endothiodon depended mainly on ground vibrations for hearing. Other features included a reduced olfactory sense and large eyes for vigilance and ease of detecting predators. Based on its vertebrate fauna, this fossiliferous Gondwana horizon of the Pranhita-Godavari valley is broadly correlated with the Tropidostoma and/or Cistecephalus Assemblage Zones of the Beaufort Group, Karoo Supergroup, South Africa. It indicates a probable Tatarian age for the Kundaram Formation.     

Dental Morphology of the Jurassic Holotherian Mammal Amphitherium, with a Discussion of the Evolution of Mammalian Post-Canine Dental Formulae

Four fragmentary mandibles from the Stonesfield Slate facies, Taynton Limestone Formation, Middle Bathonian (Middle Jurassic), England, represent two species of Amphitherium A. prevostii A. rixoni sp. nov. Both species had five lower premolariform teeth. The composite formula for the lower dentition of Amphitherium appears to have been I/4, C/1, P/5, M/6–7. The seventh molar is not present in the presumably oldest individual, and its presence is regarded as probably an individual variation.   The mosaic evolution of patterns of differentiation of the postcanine dentition from nonmammalian cynodonts to modern therian mammals is reviewed. It is concluded that Amphitherium probably had reached the grade of modern therians in the division between diphyodont premolars and monophyodont molars. The common ancestor of Amphitherium and zatheres probably had lost the primitive pattern of posterior shift of the postcanine dentition, which appears to have consisted of five premolars and four or possibly five molars. In Amphitherium the number of molars probably was secondarily increased.     

Dental morphometric variation between African and Asian colobines, with special reference to the other Old World monkeys

In order to reveal differences between Asian and African colobines (nonhuman primates) in terms of dietary adaptation and evolutionary development, a large number of the species of the cercopithecoids (Old World monkeys) was analyzed with morphometric methods. In addition to the raw data and ratios, deviations of the colobines, predicted from allometric baselines derived from the cercopithecines, were analyzed by univariate and multivariate analyses. Some results indicated that there exists significant differentiation between colobines and cercopithecines; the latter exhibit a larger dental scale relative to body size, and the less developed front teeth of the colobines may be related to their fewer frequent incisal use, compared with those of the cercopithecines. With regard to variations between the two subtribes of the colobines, which are found in African (Colobina) and Asia (Presbytina), the Asian subtribe displays a larger scale of postcanine teeth, referring to the results of the raw data. This may correspond to their larger body size. While ratios were considered, the variation between Presbytina and Colobina was diminished greatly. This implies that, unlike the scenario postulated to reflect the relationships between colobines and cercopithecines--which supposes that their differentiation is in both size and shape--the variation between the two subtribes is principally size associated: relative to body size Colobina exhibits more emphasized incisors, but less developed postcanine teeth--with the exception of width of M3s. In other words, the relationships between teeth and body size of the African colobines are more similar to those of the cercopithecines. This implies, compared to their Asian partners, that African colobines share more similarities with cercopithecines. This may be related to the episodes in which African species underwent a longer period of sharing environmental and climatic patterns with the cercopithecines that moved to Asia about 5 or 8 million years ago. Canines were found to be important in distinguishing colobines from cercopithecines and in separating one subtribe from the other.     

Metric variability of the postcanine dentition in colobus monkeys

The postcanine dentition of three species of colobus monkeys (Colobus polykomos polykomos, Procolobus badius badius and Procolobus verus) is compared metrically for three characters: interdental relations, sexual dimorphism and interspecific relations. Interdental relations reveal that the postcanine teeth represent a single morphogenetic field, which supports Butler's concept on the nature of the differentiation and variability of mammalian dentition. However, comparisons of the coefficients of variation show that interdental differences are not significant, except in a few cases. Also, sex differences in variability are not significant. However, comparisons of the means reveal highly significant sex differences, particularly in the dimensions of the first lower premolar in all three species. The analysis of interspecific relations of the postcanine dentition supports the current idea about the systematics of colobus monkeys. The findings are discussed with comparative data from other cercopithecoids and hominoids.     

Cenomanian Cephalopods of Bellezma-Aures mountains,NE Algeria: Taxonomy and biostratigraphy

The Cenomanian Smail Marl Formation in the Bellezma and Aures mountains of northeastern Algeria is well exposed and rich in macroinvertebrates, including cephalopods. Twenty-five ammonite species and two nautiloid species from the Thénièt El Manchar, Djebel Metrassi and Djebel Bouarif sections are described and seven assemblage zones proposed as provisional working units: Mantelliceras mantelli–Sharpeiceras laticlavium Assemblage Zone (lower Cenomanian), Mantelliceras dixoni Assemblage Zone (uppermost lower Cenomanian), Cunningtoniceras inerme Assemblage Zone (lower middle Cenomanian), Acanthoceras rhotomagense and Acanthoceras cf. rhotomagense Assemblage Zone (middle middle Cenomanian), Acanthoceras amphibolum Assemblage Zone (upper middle Cenomanian), Acanthoceras jukesbrownei Assemblage Zone (uppermost middle Cenomanian), and Neolobites vibrayeanus Assemblage Zone (lower upper Cenomanian). The lower Cenomanian Mantelliceras mantelli–Sharpeiceras laticlavium Zone is subdivided into the Submantelliceras aumalense, Sharpeiceras schlueteri and Mantelliceras saxbii subzones. The base of the middle Cenomanian is marked by the disappearance of species of Mantelliceras and the appearance of the scleractinian coral Aspidiscus cristatus (Lamarck, 1801), associated with Cunningtoniceras inerme (Pervinquière, 1907). The middle Cenomanian contains abundant A. cristatus and species of Acanthoceras, i.e., A. cf. rhotomagense (Defrance in Brongniart, 1822), A. jukesbrownei (Spath, 1926) and A. amphibolum Morrow, 1935. An ammonite zonal scheme is then applied to the Cenomanian exposed in the Bellezma-Aures mountains located on the southern Tethys margin in Algeria.     

A New Species of Garjainia Ochev, 1958 (Diapsida: Archosauriformes: Erythrosuchidae) from the Early Triassic of South Africa

A new species of the erythrosuchid archosauriform reptile Garjainia Ochev, 1958 is described on the basis of disarticulated but abundant and well-preserved cranial and postcranial material from the late Early Triassic (late Olenekian) Subzone A of the Cynognathus Assemblage Zone of the Burgersdorp Formation (Beaufort Group) of the Karoo Basin of South Africa. The new species, G. madiba, differs from its unique congener, G. prima from the late Olenekian of European Russia, most notably in having large bony bosses on the lateral surfaces of the jugals and postorbitals. The new species also has more teeth and a proportionately longer postacetabular process of the ilium than G. prima. Analysis of G. madiba bone histology reveals thick compact cortices comprised of highly vascularized, rapidly forming fibro-lamellar bone tissue, similar to Erythrosuchus africanus from Subzone B of the Cynognathus Assemblage Zone. The most notable differences between the two taxa are the predominance of a radiating vascular network and presence of annuli in the limb bones of G. madiba. These features indicate rapid growth rates, consistent with data for many other Triassic archosauriforms, but also a high degree of developmental plasticity as growth remained flexible. The diagnoses of Garjainia and of Erythrosuchidae are addressed and revised. Garjainia madiba is the geologically oldest erythrosuchid known from the Southern Hemisphere, and demonstrates that erythrosuchids achieved a cosmopolitan biogeographical distribution by the end of the Early Triassic, within five million years of the end-Permian mass extinction event. It provides new insights into the diversity of the Subzone A vertebrate assemblage, which partially fills a major gap between classic ‘faunal’ assemblages from the older Lystrosaurus Assemblage Zone (earliest Triassic) and the younger Subzone B of the Cynognathus Assemblage Zone (early Middle Triassic).     

POSTCANINE ROOT SYSTEM IN TRITYLODONTS

<正> Inspired by Dr. Tom Rich's letter inquiring the structure of the roots of tritylodont cheekteeth, we initiated this study. At first, only several isolated teeth were exposed. Later on, jaws and partial skull carrying the dentition have been included.The generic identification of the materials is based mainly on the morphology of the upper postcanine crowns. Among the four genera dealt with in this work, Yunnanodon is unique in having a cusp formula of 2-3-2:2 buccal, 3 median and 2 lingual cusps. From the smaller and a little medially situated posterior cusp of the lingual row, Lufengia could be separated from the other two genera.Bienotheroides is supposed to be distinguished by a cusp formula of 2-2-2, as those in the later tritylodonts: Stereognathus, Bocatherium, etc. However, in fact, this cusp pattern exists only in the type species, B. wanhsienensis. Another species, B. zigongensis from a lower horizon, namely, Lower Shaximiao Formation of Sichuan and Wucaiwan Formation of Xinjiang, possesses a cusp formula of 2-3-3, much similar to that of Bienotherium. Consequently, the localities and horizons are taken as a measure of discriminating those specimens with similar crown pattern, especially the lower postcanine teeth.     

Festuca inops and Festuca gracilior (Poaceae): are they two different species?

According to current systematics, Festuca inops and F. gracilior are two distinct species. However, they are hardly distinguishable from each other on the basis of their morphological characters. Festuca inops is considered a diploid species endemic to Italy, while F. gracilior has a discontinuous distribution area, apparently related to chromosomal levels: diploid populations in Italy and south-east France, tetraploid populations in north-east Spain. The diploid populations of both taxa from Italy and south-east France are investigated in the present study. Nearly 1000 exsiccata were examined and morphometric analysis was carried out on macro- and micromorphological features of 119 specimens (including type-specimens) and on 20 natural populations (including loci classici ). All these data showed that the two species should be referred to a single taxon, for which the rank of species seems to be appropriate. This result is supported by karyological, ecological and chorological data and was confirmed by the results of ISSR analysis. According to nomenclatural rules, the legitimate name for the species is Festuca inops De Not.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 239–258.     

Geographic variation in the long-nosed snake, Rhinocheilus lecontei (Colubridae): beyond the subspecies debate

Scalation, colour pattern, linear and geometric morphometrics were used to quantify geographical differentiation in the long-nosed snake, Rhinocheilus lecontei, and to test the hypothesis that all four subspecies are morphologically distinct. Also investigated were potential associations between morphological (scalation, colour pattern, linear measurements) and environmental variables (climate, vegetation, soil). Sexual dimorphism was weakest for geometric and strongest for linear morphometric variables. Morphological variables differed widely in their ability to differentiate subspecies. Linear morphometric variables achieved the most statistically significant pairwise Mahalanobis distances between subspecies, while geometric morphometrics largely failed to differentiate them. Colour pattern showed the strongest and linear morphometrics the weakest correlation with environment. Several characters varied continuously along latitudinal or longitudinal gradients, such that, in some cases, the clines for closely related traits were discordant. No one subspecies was consistently divergent in all analyses, leading to the conclusion that the three mainland subspecies are not sufficiently distinct to warrant separate subspecies status. The island subspecies, though not always statistically distinct, is geographically separate from other populations and differs in characters related to size. Given the small number of specimens available, a decision regarding its taxonomic status (i.e. elevation to species level) is best deferred until additional specimens can be examined and data on molecular variation can be analysed.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 65–85.     

Phylogenetic position and description of a new species of subgenus Mus (Rodentia, Mammalia) from Thailand

Molecular, chromosomal and morphometric analyses of wild-caught mice of subgenus Mus from the central plain of Thailand are presented. These specimens are distinct from all species previously described in the literature. This has led to the characterization of Mus fragilicauda sp. n., a new member of the set of closely related species encompassed by the subgenus . While this species may be considered as a sibling and sympatric species of the Asian M. cervicolor , M. fragilicauda sp. n. is phylogenetically closer to the M. musculus complex of species and to the other European species of Mus .     

Prozostrodon brasiliensis,a probainognathian cynodont from the Late Triassic of Brazil: second record and improvements on its dental anatomy

Probainognathian cynodonts are conspicuous elements of the Assemblage Zones of the Triassic Santa Maria Supersequence in southern Brazil. Within this group, the derived clade Prozostrodontia, in which the crown group Mammalia is included, is taxonomic diverse in the Hyperodapedon and Riograndia AZs. We describe here the second known specimen (CAPPA/UFSM 0123) of Prozostrodon brasiliensis, until now only represented by its holotype. CAPPA/UFSM 0123 includes a right dentary with dentition. As in the holotype of P. brasiliensis, it has four lower incisors, pc4 with conspicuous cusp a, and small cusps b, c, and d, pc5-pc6 of ‘triconodont’ type with cusps a > c > b > d, with continuous lingual cingulum bearing up to six small discrete cusps, length of the lower tooth row more than half the length of the dentary, and relatively deep horizontal ramus of the dentary. The new specimen is about 25% smaller than the holotype and there is not a diastema between the canine and postcanine teeth, indicating its juvenile condition. Based on both known specimens of P. brasiliensis, a discussion on tooth replacement is presented, showing that the adult individual has more postcanine tooth morphotypes than the juvenile one.     

美国北卡罗来纳州上三叠统北方阔齿兽(犬齿兽类:横齿兽科)的齿系和牙齿替换(英文)

描述了产自美国北卡罗来纳州上三叠统横齿兽类北方阔齿兽新材料的牙齿。基于牙齿的特征,尤其是犬后齿的形态,这些标本被暂归入杰斐逊北方阔齿兽Boreogomphodon jeffersoni;不过它们的下阔齿型犬后齿前横脊一般有两个而不是3个齿尖。根据牙齿大小、直接替换情况,推测阔齿型齿从后部萌发,从前部脱落。这个类群仅有一代阔齿型犬后齿;至少有一代,可能是两代裂齿型犬后齿。     

Metric variation in the postcanine teeth from Paşalar, Turkey

The coefficient of variation (CV) has frequently been used to evaluate variation in a morphologically homogeneous fossil assemblage and to make inferences about its species composition. Comparisons of coefficients of variation in single- and mixed-species assemblages have typically involved mixed-species assemblages made up of an equal number of data points from two or more different species, but in reality, a fossil assemblage may be biased in favor of one or more of the component species. In this paper, we evaluate the effects of unequal species composition in mixed-species assemblages on CV distributions by carrying out an extensive series of resampling experiments. The experiments were designed to replicate a paleontological situation in which the species affiliation of particular specimens is not known. We use this technique to explore the pattern of metric variation in the postcanine dental assemblage from the middle Miocene site of Pa?alar in a comparative context. The distributions of CVs from mixed assemblages that are heavily biased toward one species may be characterized by a greater range of CVs, increased skewing, and a tail of low values, but only heavily biased assemblages comprising species that differ markedly in size could be reliably identified on this basis. Evidence from the simulated CV distributions supports nonmetric evidence in indicating that the Pa?alar assemblage represents a heavily biased assemblage of two species that are similar in size but not entirely overlapping in the size distributions of their postcanine teeth.     

Folivory, frugivory, and postcanine size in the cercopithecoidea revisited

At a given body mass, folivorous colobines have smaller postcanine teeth than frugivorous cercopithecines. This distinction is a notable exception to the general tendency for folivorous primates to have relatively larger postcanine tooth rows than closely related frugivores. The reason for this anomalous pattern is unclear, but one potential explanation is that the difference in facial size between these two subfamilies confounds the comparison-i.e., it may be that the large postcanine teeth of cercopithecines are a consequence of their large faces. The goal of this study was to test this hypothesis. Phylogenetic comparative methods were used to examine the relationships among postcanine area, facial size, and body mass in 29 anthropoid primates, including eight colobines and eight cercopithecines. Results indicate that there is a strong and highly significant partial correlation between postcanine area and facial size when body mass is held constant, which supports the hypothesis that facial size has an important influence on postcanine size. Moreover, colobines have larger postcanine teeth relative to facial size than cercopithecines. Surprisingly, when facial size is held constant, the partial correlation between postcanine area and body mass is weak and nonsignificant. These results suggest that facial size may be more appropriate than body mass for size-adjusting postcanine measurements in some contexts. A phylogenetic comparative test of the association between diet and relative postcanine size (scaled using facial size) confirms that folivorous anthropoids are characterized by relatively large postcanine teeth in comparison to closely related nonfolivores.