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Page 8 of 19, showing 20 record(s) out of 366 total

Reflections on some Russian eotheriodonts (Reptilia, Synapsida, Therapsida)
Denise Sigogneau-Russell and P. K. Tchudinov
Published online: 28/02/1972

Keywords: Reptilia; Russia; Synapsida; Therapsida

https://doi.org/10.18563/pv.5.3.79-109

  Abstract

    As a result of the enrichment of eotheriodont material by one of us (P.K.T.), these specimens (essentially Biarmosuchur and Eotitanosuchur) are reexamined and refigured. A reevaluation of their particularities supports the distinction of two families, for which new diagnoses are proposed. This leads us to discuss the affinities of these families, with respect to the sphenacodonts on one hand, and to the South African primitive theriodonts on the other (gorgonopsids and ictidorhinids). This study contains inherent paleogeographic consequences which are considered in conclusion. 


  PV article infos

Published in Vol. 05, Fasc. 3 (1972)

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Les pantolestidés (Mammalia, Pantolesta) de l'Eocène inférieur de Prémontré (Aisne, France).
Richard Smith
Published online: 30/07/2001

Keywords: France; Mammals; Pantolestids; Ypresian

https://doi.org/10.18563/pv.30.1-2.11-35

  Abstract

    Study of pantolestid mammals from the late Ypresian locality of Prémontré (reference level MP 10) allows the recognition of three genera: Palaeosinopa. Pantolestes and Premontrelestes n. gen. Pantolestes, up to now only recorded from North America, is represented by P. sabatieri n. sp. Premontrelestes n. gen., represented by the type species P. duchaussoisi n. sp., is compared with Pantolestes and Buxolestes. The latter, known from middle Eocene sites in Europe, has not been recognized at Prémontré. Two other taxa, the first of which is close to Pantolestes and the second of Premontrelestes n. gen. are left in open nomenclature.    


  PV article infos

Published in Vol. 30, Fasc. 1-2 (2001)

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Eléments nouveaux sur l'évolution des genres Eucricetodon et Pseudocricetodon (Eucricetodontinae, Rodentia,Mammalia, de l'Oligocène d'Europe Occidentale.
Bernard Comte
Published online: 01/07/1985

Keywords: evolution; Occidental Europe; Oligocene; Rodentia; Systematics

https://doi.org/10.18563/pv.15.1.1-68

  Abstract

    The review of material recently collected in the new localities from the “Phosphorites du Quercy", and different localities from the South of France, bring new informations on the genus Eucricetodon THALER. 1966, and Pseudocricetodon  THALER,  I969 (Middle and Upper Oligocene. Western Europe). Thanks to Eucricetodon huerzeleri VIANEY-LIAUD, 1972, which were unsufficiently known until now, is proposed. During the middle Oligocene Eucricetodon atavus  MISONNE, 1957 seems to give rise to two lineages. One of them led to Eucricetodon huberi,which however exhibits a larger size and a development of progressive characters on the teeth. The other would be Eucricetodon huerzeleri well differentiated at the “Mas de Pauffié" standard level (beginning of the upper Oligocene). The ornementation of lower incisors is described, when possible. Though the fossils are not abundant, it seems that the ancestral lineage, Eucriretodon atavus, remains in  the upper Oligocene (Boningen standard level). evolving into Eucricetodon praecursor SCHAUB, 1925 (Rickenbach standard level). The characters of Eucricetodon dubius  (SCHAUB. 1925), represented by a numerous population in Pech Desse and Pech du Fraysse (Quercy). confirm that this species and Eucricetodon praecursor  belong to two different lineages. As Eucricetodon dubius shows more primitive features, this species could not originale from Eucricetodon atavus -Eucricetodon huberi. The appearance of this species at the level of Mas de Pauffié could be the result of an immigration. A new definition of Pseudocricetodon incertus (SCHLOSSER. 1884) is given. This species has been found in several localities, where it had not been identified until now. lts comparison with Pseudocricetodon moguntiacus  (BAHLO. l975), found at several localities from the standard level of Antoingt (end of middle Oligocene). shows a parallel evolution to that of Pseudocetodon incertus, which is  of larger size and with a less complicated pattern of teeth. 


  PV article infos

Published in Vol. 15, Fasc. 1 (1985)

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Rongeurs du Miocène inférieur et moyen en Languedoc. Leur apport pour les correlations Marin-Continental et la Stratigraphie.
Jean-Pierre Aguilar
Published online: 31/03/1980

Keywords: Languedoc; Miocene; Rodents; Southern France

https://doi.org/10.18563/pv.9.6.155-203

  Abstract

    The rodents (Cricetidae, Gliridae, Sciuridae) found in lacustrine, brackish marine and karstic sediments of Miocene age in Languedoc, assign the position of the different localities in the scale of "niveaux repères" used by mammalogists. Some detailed stratigraphical studies bring several correlations between this continental biochronological scale and the marine scale ; the most important results are the Aquitanian age of the "niveaux repères" of Coderet and Paulhiac, the Burdigalian age of Laugnac, Estrepouy, Vieux-Collonges, La Romieu and Sansan and the Langhian or Lower Serravallian age of La Grive M. The correlations between the Tethys and the Central Paratethys for the Lower Neogene profit also of these results, since the locality of Neudorf Spalte 1, 2 (Czechoslovakia) is shown to be younger than Sansan (France). The paleontological study has also several geological inferences for the Miocene of Languedoc ; with the calibration of this Miocene, we know quite precisely that the Lower Miocene is chiefly a time lacustrine sedimentation, and also that the marine Miocene sedimentation ends early in the Miocene Period, in Langhian or lower Serravallian times. 


  PV article infos

Published in Vol. 09, Fasc. 6 (1980)

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Additions to the elasmobranch fauna from the upper Cretaceous of New Jersey (middle Maastrichtian, Navesink Formation)
Gerard R. Case and Henri Cappetta Logo
Published online: 15/12/2004

Keywords: Elasmobranchs; New Jersey; new species; Upper Cretaceous; USA

https://doi.org/10.18563/pv.33.1-4.1-16

  Abstract

    A recently discovered, almost complete specimen of a hybodont tooth, allows us to describe as a new species, fairly common, but usually fragmentary teeth in the Navesink Formation of New Jersey: Hybodus novojerseyensis nov. sp.
    Three additional taxa are also described : Heterodontus creamridgensis, Squalicorax sp. and Pseudocorax affinis which is noted for the first time in North America.
    The whole elasmobranch fauna of the Early Maastrichtian localities of New Jersey is reevaluated and several generic assignments are changed in comparison to the list previously published in 1975 (Cappetta
    & Case). 


  PV article infos

Published in Vol. 33, Fasc. 1-4 (2004)

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Rongeurs nouveaux de l'Oligocène Moyen d'Espagne.
Louis Thaler
Published online: 15/09/1969

Keywords: Cricetidae; Oligocene; Pseudocricetodon; Rodents; Theridomys

https://doi.org/10.18563/pv.2.5.191-207

  Abstract

    Description of four new rodents from a recently discovered locality at Montalban. Theridomys crusafonti nov. sp. is considered as the ancestry of T. Iembronicus. Theridomys varian: nov. sp. includes «Theridomys» morphotypes and «Blainvilllimys» morphotypes; it could be ancestral to B. blainvillei. Pseudoltinomys nanus nov. sp. represents a new lineage paralleling in evolution that of P. gaillardi (which is equally found at Montalban). Pseudocricetodon montalbanensis nov. gen., nov. sp. designates a lineage of very small Cricetidae accompanying Eucricetodon. With these well defined new species and six others present in the locality, Montalban appears as the best faunal reference point within the biochronologic zone of La Sauvetat.
    As an annex, discussion of two rodent specimens from the classic localíty of Tárrega, close in age to that of Montalban. 


  PV article infos

Published in Vol. 02, Fasc. 5 (1969)

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On the genus Dikkomys (Geomyoidea, Mammalia)
Morton Green and Philip R. Bjork
Published online: 01/10/1980

Keywords: Dikkomys; Geomyoidae; North America

https://doi.org/10.18563/pv.9.ext.343-353

  Abstract

    The geomyoid genus Dikkomys is well represented in a sample from the Black Bear Quarry Il local fauna of Early Hemingfordian age in Bennett County, South Dakota. Isolated unworn P/4's of Dikkomys matthewi WOOD have a prominent median cristid (sagicristid) with a connection to the metaconid and the hypolophid. With wear, P/4 does not become as molariform as P/4 because of this cristid.
    A large sample of the Whitneyan beteromyid Proheteromys nebraskensis WOOD contains variants of the P/4 with on incipient sagicristid in approximately 18 percent of the population. The upper dentition and lower molars of Proheteromys nebraskensis are sufficiently generalized to indicate probable ancestry to Dikkomys


  PV article infos

Published in Vol. 9, Ext (1980)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 7 - Les proboscidiens Deinotheriidae
Heinz Tobien
Published online: 15/11/1988

Keywords: allometry; Astaracian; Deinotherium; Montredon; Systematics; taphonomy; Vallesian

https://doi.org/10.18563/pv.18.ext.135-175

  Abstract

    Some complete tooth rows and about one hundred isolated teeth enabled the identification of the deinothere of the Vallesian site Montredon (Hérault) as Deinotherium giganteum KAUP 1829, mainly by comparisons with the likewise Vallesian sample of the type locality Eppelsheim (Rheinhessen, F.R.G.).
    Scatterdiagrams of the teeth show the importance of allometry during the phyletic size increase of the European deinotheres.
    Some taphonomic problems of the Montredon deinothere are briefly mentioned. 


  PV article infos

Published in Vol. 18, Ext (1988)

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The Late Cretaceous nesting site of Auca Mahuevo (Patagonia, Argentina): eggs, nests, and embryos of titanosaurian sauropods.
Luis M. Chiappe Logo, Rodolpho. . Coria, Frankie D. Jackson and Lowell Dingus
Published online: 15/12/2003

Keywords: Argentina; Eggs; embryos; Late Cretaceous; nests; Patagonia; titanosaurian sauropods

https://doi.org/10.18563/pv.32.2-4.97-108

  Abstract

    The late Cretaceous Auca Mahuevo nesting site (Neuquén Province, Argentina) has produced a large number of sauropod eggs, many of them containing the remains of embryos. Research at this site has generated important information about the development of the embryos, the morphology and eggshell microstructure of the eggs, and the reproductive behavior of sauropod dinosaurs. Cranial features present in the embryos have allowed their identification as those of titanosaurian sauropods. Differences in the texture of the sediments that contain some of the egg-clutches have illuminated their nest architecture. Microstructural studies of eggshells have expanded our knowledge of their variability and the incidence of pathologies within a reproductive titanosaurian population. Maps showing the spatial distribution of eggs and clutches. the stratigraphic distribution of the egg-beds, and the sedimentological context in which they are contained, have provided the basis for several inferences about the nesting behavior of these dinosaurs. 


  PV article infos

Published in Vol. 32, Fasc. 2-4 (2003)

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Contributions à l'étude des micromammifères du gisement Miocène supérieur de Montredon (Hérault). 4 - Les chiroptères
Bernard Sigé
Published online: 30/06/1982

Keywords: Chiroptera; Hérault; Late Miocene; Micromammals; Montredon

https://doi.org/10.18563/pv.12.3.133-140

  Abstract

    The Montredon local fauna yielded very rare bats, represented by damaged isolated teeth. Only a few documents are available for this period of the European Neogene. ln this poor state of knowledge, the material represents three undetermined species, a supposed molossid and two vespertilionids. 


  PV article infos

Published in Vol. 12, Fasc. 3 (1982)

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Difficulties with the origin of dinosaurs: a comment on the current debate
Matthew G. Baron Logo
Published online: 01/07/2020

Keywords: dinosaur anatomy; dinosaur evolution; Ornithoscelida; palaeobiogeography; Triassic Period

https://doi.org/10.18563/pv.43.1.e3

  Abstract

    The origin and early evolutionary history of the dinosaurs is a topic that has recently gone through a period of renewed interest and academic debate. For 130 years, one way of classifying the various dinosaur subgroups persisted as the accepted model, with increasing levels of research in the past quarter-century also providing evidence for the hypothesis that dinosaur origination occurred in the Southern Hemisphere, particularly in South America. It is, after all, from within the Late Triassic strata of countries like Argentina and Brazil that we get some of the very best early dinosaur specimens; many of these specimens are the earliest known representatives of some of the major dinosaur subgroups, such as the theropods and sauropodomorphs. However, some recent analyses have brought about a shift in terms of what is currently accepted and what is now disputed regarding the origin of dinosaurs – the Southern Hemisphere origination hypothesis was questioned (although this was based upon observations and not with quantitative analysis techniques), as has the shape of the dinosaur tree. Responses to the new hypothesis were numerous; many further supported a Southern Hemisphere point of origin. Whilst the interrelationships between the major dinosaur clades remains to be resolved, the current data does seem to comprehensively answer the question of where the dinosaurs first originated. However, it is arguable whether the current data that is being used in such palaeobiogeographical analyses is sufficient to provide an answer to the question of where specifically the dinosaur clade first appeared. This short communication urges a degree of caution about the current consensus and what steps may need to be taken to ensure that more meaningful results are produced in the future. 


  PV article infos

Published in Vol 43-1 (2020)

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First early Eocene tapiroid from India and its implication for the paleobiogeographic origin of perissodactyls
Thierry Smith Logo, Floréal Solé Logo, Pieter Missiaen, Rajendra S. Rana Logo, Kishor Kumar Logo, Ashok Sahni Logo and Kenneth D. Rose
Published online: 08/09/2015

Keywords: Ceratomorpha; Helaletidae; Paléogène; Tapiromorpha; Vastan

https://doi.org/10.18563/pv.39.2.e5

  Abstract

    The presence of cambaytheres, the sister group of perissodactyls, in western India near or before the time of collision with Asia suggests that Perissodactyla may have originated on the Indian Plate during its final drift towards Asia. Herein we reinforce this hypothesis by reporting two teeth of the first early Eocene tapiromorph Perissodactyla from the Cambay Shale Formation of Vastan Lignite Mine (c. 54.5 Ma), Gujarat, western India, which we allocate to a new genus and species, Vastanolophus holbrooki. It presents plesiomorphic characters typical of the paraphyletic “Isectolophidae,” such as small size and weak lophodonty. However, the weaker hypoconulid and low paralophid, higher cusps, lower cristid obliqua, and the lingual opening of the talonid are found in Helaletidae, the most primitive tapiroid family. V. holbrooki, gen. et sp. nov., may be the oldest and the most primitive tapiroid, suggesting that at least tapiroid perissodactyls originated on India. 


  PV article infos

Published in Vol.39-2 (2015)

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Les nouvelles faunes de rongeurs proches de la limite mio-pliocène en Roussillon. Implications biostratigraphiques et biogéographiques
Jean-Pierre Aguilar, Jacques Michaux, Bernadette Bachelet, Marc Calvet Logo and Jean-Pierre Faillat Logo
Published online: 29/04/1991

Keywords: Arvicolidae; Cricetidae; Gliridae; Miocene; Muridae; Pliocene; Rodents; Southern France

https://doi.org/10.18563/pv.20.4.147-174

  Abstract

    Three new fossiliferous localities, two of karstic origin, Castelnou 3 and Font Estramar, respectively Late Upper Miocene and Lower Pliocene, and one of lacustrine origin, Thuir, Lower Pliocene, add data about the transition between Miocene and Pliocene faunas of rodents in southern France. An unexpected association of taxa was present in the late Upper Miocene, including between others, Myocricetodon, Hispanomys, Ruscinomys, Cricetus barrierei, Promimomys and a new species of Stephanomys, S. dubari nov. sp. Myocricetodon is still known in the Lower Pliocene. It is shown that the large field-mice known since the Late Upper Miocene belong to two different lineages, on one side, A. jeanteti, on the other side, A. gudrunae followed by A. gorafensis. Biochronological and biogeographical implications are discussed. 


  PV article infos

Published in Vol. 20, Fasc. 4 (1991)

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Un crane de Chalicothere (Mammalia, Perissodactyla) du Miocène supérieur de Macédoine (Grèce) : remarque sur la phylogénie des Chalicotheiinae
Louis de Bonis Logo, Geneviève Bouvrain, George D. Koufos and Pascal Tassy Logo
Published online: 14/06/1995

Keywords: Chalicotheriidae; Cladistics; Greece; Miocene; Perissodactyla; PHYLOGENY

https://doi.org/10.18563/pv.24.1-2.135-176

  Abstract

    The discovery in the Turolian (Late Miocene) of Dytiko 3 (Macedonia, Greece) of a complete skull with mandibles and cervical vertebrae, atlas and epistropheus, is a very important contribution to the knowledge of the subfarnily Chalicotheríinae. After the description, the comparison with other specimens of Miocene chalicotheres permits the revival of the generic name Macrotherium with a new species M. macedonicum. This genus is mainly characterized by a short snout and an inflated cerebral skull. It coexists during the Miocene with Chalicotherium. A cladistic analysis leads to conclusion that the species which has been described from the Early Middle Miocene of Rusinga must be identified as the type-species of a new genus: Butleria.





      


  PV article infos

Published in Vol. 24, Fasc. 1-2 (1995)

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Nouveaux Mammifères Eocènes du Sahara Occidental
Jean Sudre
Published online: 01/11/1979

Keywords: Eocene; Mammals; Occidental Sahara

https://doi.org/10.18563/pv.9.3.83-115

  Abstract

    The fossil mammals collected from the Eocene of Hammada du Dra (northwest Sahara. Algeria) and two fragmentary teeth from the Lutetian of M'Bodione Dadere (Senegal) are described.
    The fossils from the northwest Sahara come from a lacustrian deposit dated by charophytes (Raskyella aff. pecki, Raskyella n. sp.. Maedleriella lavocati, Maedleriella sp. et ? Peckichara sp.) as Middle Eocene or perhaps Lower Eocene (Gevin, Feist and Mongereau, 1974). Several hyracoids (3 or 4) identified from this formation extends the age of the family Pliohyracidae Osborn in Africa. Three forms appear to belong in the genera Megalohyrax, Titanohyrax and perhaps Bunohyrax which have been know until now only from the lower Oligocene of the Fayum (M. gevini n. sp. ; T. mongereaui n. sp.. ? Bunohyrax or Megalohyrax indet.). Another hyracoidof small size is referred to a new genus, Microhyrax (M. lavocati n. sp.).
    Helioseus insolitus n. g. n. sp. is described without ordinal assignment. Azibius (Sudre, 1975) which has been the subject of questions and interpretations is reviewed.
    Only one tooth from the Lutetian of M'Bodione Dadere is complete enough to interpret. lt probably belongs to a condylarth and demonstrates for the first time, the presence of the order in Africa. The second tooth is too fragmentary for comment.
    In conclusion., the paleobiogeographic role of Africa at the end of the cretaceous and the beginning of the Cenozoic is discussed. 


  PV article infos

Published in Vol. 09, Fasc. 3 (1979)

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Evolution des Aplodontidae Oligocènes Européens
Norbert Schmidt-Kittler and Monique Vianey-Liaud Logo
Published online: 01/10/1979

Keywords: Aplodontidae; Europe; Oligocene

https://doi.org/10.18563/pv.9.2.33-82

  Abstract

    Until now Aplodontidae of the European Oligocene have been documented by four species only. The phylogenetic relations remained obscure. as the distribution of only one species has been known in some detail. New material made it possible to define the stratigraphic range of two of the already existing species (Plesispermophilus angustidens, Sciurodon cadurcense) and to follow their development during the Oligocene beginning with the event of the « Grande Coupure ››. Sciurodon remained nearly without change until the end of the Middle Oligocene. Plesispermophilus angustidens split into two distinct phyletic lines, one of which (P. macrodon n. sp.) reaching considerable size, is represented till the beginning of the Upper Oligocene (Pech de Fraysse, Gaimersheim). The other line leads to Plesispermophilus ernii (basal Upper Oligocene of Burgmagerbein 1. terminal Upper Oligocene of Coderet). Besides the already known forms a new small-sized species (P. atavus n. sp.) is described, which by its primitive features closely resembles the genus Plesispermophilus. Two other small-sized species already known from the Upper Oligocene (? P. argoviensis) and Lower Miocene (? P. descedens) seem to be closely related to the new species. It cannot be decided whether they are descendents of this line or have developed independently, because of their poor fossil record.
    Comparison of the evolutionary modalities in the different phylogenetic lines reveals general trends. the most striking of which is the complication of the tooth pattern by the development of additional crests. In the lower molars the cusps diminuate in size and are more and more transformed into ridges. ln addition new connection between the crests appear. in the upper molars, the « selenodont » shape of the teeth becomes more and more dominant, and in the two main evolutionary lines of Plesispermophilus the metaconulus becomes duplicated. A further evolutionary trend is the size increase of the premolars compared to the molars, which is even more pronounced in the Miocene Aplodontidae.
    Phylogenetic relations between the primitive Plesispermophilus and certain « prociurines ›› of Northern America as well as between Plesispermophilus (P. angustidens) and more progressive forms of the Upper Oligocene (P. ernii, P. macrodon n. sp.) can be documented. In this light, the taxonomic distinction between Prosciurinae (bunodont) and Allomyinae (selenodont) sensu Rensberger 1976 can be shown to be artificial, because it separates forms from each other, which are evidently closely related. Consequently the separation into two subfamilies has been abolished. 


  PV article infos

Published in Vol. 09, Fasc. 2 (1979)

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Eggshell microstructure and porosity of the Nicobar scrubfowl (Megapodius Nicobariensis, great Nicobar island, India)
Géraldine Garcia Logo, Ashu Khosla Logo, Ashok Sahni Logo and Monique Vianey-Liaud Logo
Published online: 16/12/2008

Keywords: conductance porosity; eggshell microstructure; incubation conditions; Megapodes

https://doi.org/10.18563/pv.36.1-4.75-88

  Abstract

    The eggshell of Nicobar scrubfowl (Megapodius nicobariensis) is described for the first time. Its egg porosity is calculated and discussed with data from several taxa (another megapode, some extant and fossil reptiles including a titanosaur group) in order to compare incubation types with eggshell structure. Eggshell microstructure reflects first phylogenetic traits and does not seem to have developed major adaptative features due to the incubation conditions, except for the pore canals. 


  PV article infos

Published in Vol. 36, Fasc. 1-4 (2008)

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Enamel hypoplasia on rhinocerotoid teeth: Does CT-scan imaging detect the defects better than the naked eye?
Manon Hullot Logo and Pierre-Olivier Antoine Logo
Published online: 03/01/2022

Keywords: fossil teeth; method; micro-CT imaging; Rhinocerotoidea

https://doi.org/10.18563/pv.45.1.e2

  Abstract

    Micro-CT imaging is an increasingly popular method in paleontology giving access to internal structures with a high resolution and without destroying precious specimens. However, its potential for the study of hypoplasia defects has only recently been investigated. Here, we propose a preliminary study to test whether hypoplastic defects can be detected with micro-CT (μCT) scan and we assess the costs and benefits of using this method instead of naked eye. To do so, we studied 13 fossil rhinocerotid teeth bearing hypoplasia from Béon 1 (late early Miocene, Southwestern France) as positive control and 11 teeth of the amynodontid Cadurcotherium (Oligocene, Phosphorites du Quercy, Southwestern France), for which enamel was partly or totally obscured by cement. We showed that all macroscopically-spotted defects were retrieved on 3D reconstructions and selected virtual slices. We also detected additional defects using μCT scan compared to naked eye identification. The number of defects detected using μCT was greater in the Cadurcotherium dataset (paired-sample Wilcoxon test, p-value = 0.02724) but not for our control sample (paired-sample Wilcoxon test, p-value = 0.1171). Moreover, it allowed for measuring width and depth of the defects on virtual slices (sometimes linked to stress duration and severity, respectively), which we could not do macroscopically. As μCT imaging is both expensive and time consuming while not drastically improving the results, we recommend a moderate and thoughtful use of this method for hypoplasia investigations, restricted for instance to teeth for which enamel surface is obscured (presence of cement, uncomplete preparation, or unerupted germs). 


  PV article infos

Published in 45-1 (2022)

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S.I. Data
Designating a lectotype for Mesacanthus pusillus (Gnathostomata: Acanthodii)
Matthew G. Baron Logo and Kevin Seymour
Published online: 03/03/2021

Keywords: acanthodians; Chordata; Devonian; Midland Valley; Orcadian Basin

https://doi.org/10.18563/pv.44.1.e2

  Abstract

    The early gnathostome genus Mesacanthus is well represented in both Lower Old Red Sandstone and Middle Old Red Sandstone assemblages of northern and central Scotland. This ‘acanthodian’ taxon is currently thought to comprise two valid species: M. mitchelli and M. pusillus. Although the whereabouts of the holotype of M. mitchelli (NHMUK PV P560) is known, the syntype material for M. pusillus has long been thought lost. Here we identify at least one specimen that formed part of the original syntype material for M. pusillus, albeit in a slightly different condition than when it was originally figured. This specimen is ROM 25872, which is here designated as the lectotype. A second specimen – ELGNM 1978.191.1 – could represent another of the syntype specimens, but poor preservation quality makes it impossible to be certain. 


  PV article infos

Published in 44-1 (2021)

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S.I. Data
Functional aspects of the evolution of rodent molars
Percy M. Butler
Published online: 01/10/1980

Keywords: Chewing; Muridae; Rodents; Wear facets

https://doi.org/10.18563/pv.9.ext.249-262

  Abstract

    The wear facets of primitive rodents can be homologized with those of primitive primates and ungulates. As in primates, the jaw movement was ectental, with an increased anterior component in the lingual phase (phase ll). The buccal phase (phase I) in rodents approaches the horizontal and it tends to be reduced in importance in comparison with the lingual phase. ln more advanced rodents the efficiency of grinding is increased by the development of additional cutting edges of enamel (e.g. enlargement of hypocone, development of mesoloph and lingual sinus). The buccal phase movement becomes lined up with the lingual phase movement to form a single oblique chewing stroke,resulting in planation of the crown. As the stroke becomes more longitudinal (propalinal) the enamel edges become more transverse. In Muridae propalinal chewing evolved before the loss of cusps, facets were reorientated and additional cusps developed. 


  PV article infos

Published in Vol. 9, Ext (1980)

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Page 8 of 19, showing 20 record(s) out of 366 total