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Discovery of the most ancient Notidanodon tooth (Neoselachii: Hexanchiformes) in the Late Jurassic of New Zealand. New considerations on the systematics and range of the genus
Published online: 21/09/2018
Keywords:
Chondrichthyes; Hexanchiformes; new genus; New Zealand; Tithonian
https://doi.org/10.18563/pv.42.1.e1
Abstract
This paper describes the first hexanchid tooth from the Tithonian (Late Jurassic) of New Zealand. For the moment, this tooth represents the earliest representative of the fossil genus Notidanodon in the world and one of the most ancient neoselachians in the Southern Hemisphere. Despite the perfect state of preservation of the unique tooth, the species is left in open nomenclature, pending the discovery of additional specimens. Few nominal species have been assigned to the genus Notidanodon. Four from Cretaceous deposits: N. antarcti Grande & Chatterjee, 1987, Notidanodon dentatus (Woodward, 1886), Notidanodon lanceolatus (Woodward, 1886), Notidanodon pectinatus (Agassiz, 1843) and only two from Paleocene: Notidanodon brotzeni Siverson, 1995, and Notidanodon loozi (Vincent, 1876). Considering the important morphological variations observed between some of these species, it seems obvious that the genus Notidanodon is not monophyletic and will need a revision in the future.
PV article infos
Published in Vol 42-1 (2019)
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Les mammifères Montiens de Hainin (Paléocène moyen de Belgique) Part III : Marsupiaux
Published online: 30/09/1983
Keywords:
Belgium; Marsupials; Paleobiogeography; Paleocene
https://doi.org/10.18563/pv.13.3.51-64
Abstract
The oldest european marsupials are described from some specimens (isolated upper molars) recently found from the Hainin sediment (Middle Paleocene of Belgium). These fossils document a new species of the Peradectes genus. They give evidence of a much older occurrence of the marsupials in Europe than it was assumed. They allow us to postulate a didelphid dispersal from South America towards the western-holarctic area operating in two phases : the first one of the Peradectes genus at the end of the Cretaceous; the second one of the Didelphíni tribe at the end of the Paleocene. A central american crossing is likely for the first one, whereas a transafrican way is tentatively argued for the second one.
PV article infos
Published in Vol. 13, Fasc. 3 (1983)
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Agriotherium intermedium (Stach 1957) from a Pliocene fissure filling of Xiaoxian County (Anhuei Province, China) and the phylogenetic position of the genus.
Published online: 30/09/1983
Keywords:
Carnivora; China; PHYLOGENY; Pliocene; skull anatomy; Ursidae
https://doi.org/10.18563/pv.13.3.65-81
Abstract
A fragmentary mandible and maxilla of a small sized Agriotherium of a young individual discovered from a Pliocene fissure filling in Xiaoxian county (Anhuei Province, China) are described. Judging from the morphology of the dentition and its dimensions the new material can be identified as Agriotherium inlermedium (STACH l957). Hendey's proposition (1980) that the Agriotherium species are derived from Indarctos is reconsídered on the basis of the new documents. As a result of a more general phylogenetic discussion it can be stated, that: 1. the supposed size increase as well as other trends, leading from Indarctos to Agriotherium are untenable ; 2. there are no positive indications to assume a phylogenetic transition of these two genera. 3. there are no real arguments in favor of an adaptational reversal in the evolution of Agriotherium. Hence, many features of that genus supposed by Hendey to be derived are plesiomorphic ; 4. regardless of the previous points it is methodologícally impossible to establish direct ancestor - descendant relationships between Indarctos and Agriotherium species, as Hendey did. Based on the data available and especially on the characters of the new material from China it is more likely that Agriotherium and Indarctos are two genera which developed independently. While advanced Agriotherium species, e.g. A. africanum, resemble in some respects Indarctos by adaptational analogies, more primitive species, e.g. Agriotherium intermedium, are quite dissimilar to lndarctos. While Indarctos might be derived from an Ursavus like forerunner, Agriotherium has its roots more likely somewhere in between Ursavus and the Hemicyon-group.
PV article infos
Published in Vol. 13, Fasc. 3 (1983)
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Fallen in a dead ear: intralabyrinthine preservation of stapes in fossil artiodactyls
Published online: 09/03/2016
Keywords:
allometry; bony labyrinth; inner ear; middle ear ossicles
https://doi.org/10.18563/pv.40.1.e3
Abstract
The stapes is the last of the middle ear ossicle chain and the smallest bone of the mammalian skeleton. Because it rests on the membrane of the fenestra vestibuli during life, the stapes may often fall within the bony labyrinth cavity when soft structures decay after death. In this work, we highlight the unexpected role that the bony labyrinth plays in the preservation of the stapes. Systematic investigation of the bony labyrinth of 50 petrosal bones of extinct and extant artiodactyls led to the discovery of eight cases of “intralabyrinthine” stapes. Three dimensional reconstructions of these stapes allow documenting stapes morphology of four extinct artiodactyl taxa: Microstonyx erymanthius (Suidae), Elomeryx borbonicus (Hippopotamoidea), ?Helohyus plicodon (Helohyidae), and an undetermined Cainotheriidae; and four extant ones Choeropsis and Hippopotamus (Hippopotamidae), and Tayassu and Phacochoerus (Suoidea). ?Helohyus plicodon from the Middle Eocene documents the oldest stapes known for the order Artiodactyla. Morphological study and metric analyses of our sample of artiodactylan stapes show that stapes are likely to carry relevant phylogenetic characters/signal within artiodactyls, and a potential Euungulata signature.
PV article infos
Published in Vol.40-1 (2016)
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The Quaternary avifauna of Crete, Greece.
Published online: 01/09/1988
Keywords:
Avifauna; Crete; Quaternary; Systematics
https://doi.org/10.18563/pv.18.1.1-94
Abstract
Pleistocene bird fossils have been studied from nine localities on Crete. Part of this material was described earlier by the author (Weesie, 1982) and will not be treated here in extenso, the results will be incorporated. More than one third of the over 10,000 fossil bird bones available could be identified ; they were found to represent at least 65 bird species. The following species of the Pleistocene Cretan avifauna are new to the fauna of Crete : Branta ruficollis, Haliaeetus albicilla, Gyps melitensis, Aquila chrysaetos simurgh n. ssp., Ketupa zeylomensis, Aegolius funereus, Dendrocopos leucotos, Zoothera dauma, Turdus iliacus and Pyrrhula pyrrhula. The Pleistocene Cretan avifauna differs less from comparable mainland avifaunas than (fossil) avifaunas from oceanic islands do. Still, the Pleistocene Cretan avifauna has two qualities that are characteristic of island avifaunas : the almost complete absence of a group of birds (the Galliformes) and the presence of two endemic (sub)species : the giant eagle Aquila chrysaetos simurgh n. ssp. and the long-legged owl Athene cretensis (Weesie, 1982). The new subspecies is described in the present study.
These endemic birds of prey were found in association with their supposedly principal prey species (now extinct as well) : endemic mice for the owl and endemic deer for the eagle. Endemic mammals have been found in association with endemic birds of prey on many islands, not only in the Mediterranean. There is evidence that the size of endemic birds of prey becomes optimally adapted to their feeding on certain endemic mammals, especially rodents. Another characteristic of the Pleistocene Cretan avifauna is the great number of species of birds of prey. This appears to be a common characteristic of fossil avifaunas from caves on Mediterranean islands as well as from caves on the European mainland. However, we think that ecological conditions on Pleistocene Crete (especially the abundant presence of mice) helped to account for the high representation of birds of prey. Furthemore, the fossil avifauna enables us to draw some conclusions about the climate and vegetation on Pleistocene Crete : it is concluded that the climate was cooler than today and that Crete was largely covered with forests. Finally, the reasons for the extinction or disappearance from Crete of some bird species of the Pleistocene Cretan avifauna are discussed.
PV article infos
Published in Vol. 18, Fasc. 1 (1988)
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Deux nouveaux primates dans l'Oligocène inférieur de Taqah (Sultanat d'Oman): premiers Adapiformes (?Anchomomyini) de la péninsule arabique?
Published online: 15/11/1993
Keywords:
Adapids; Afro-Arabian plate; Early Oligocene; New taxa; Primates; Trans-Tethyan dispersals
https://doi.org/10.18563/pv.22.4.141-196
Abstract
Two new species, Omanodon minor n. g., n. sp. and Shizarodon dhofarensis n. g., n. sp., known from fifteen isolated teeth, are described here as the first adapiform primates (?Anchomomyini) recognizable to date in the Taqah material (early Oligocene of Sultanate of Oman).
Omanodon minor n. g., n. sp. displays special morphological similarity to the adapid tribe Anchomomyini from the Eocene of Europe, and especially to the Anchomomys lineage. Resemblances with the extant lemurifonn Microcebus are also noticeable and could be regarded as supporting Schwartz & Tattersall (1983) hypothesis of special relationships between the anchomomyine adapids and the cheirogaleid lemuriformes. However, these morphological affmities can be interpreted, altematively, as the results of parallelisms: important differences in upper molars indicate that the resemblances of cheirogaleids and Omanodon minor n. g., n. sp. are indeed probably due to parallelisms. Phyletic relationship of O. minor n. g., n. sp. to Anchomomyini is finally the most likely hypothesis.
Shizarodon dhofarensis n. g., n. sp., although much more poorly known, is closely related to Omanodon minor n. g., n. sp., at least at a familial level. The general morphology of this species suggests
also a close link with adapid Anchomomyini, although precise relationships within this tribe remain obscure. Interesting resemblances of Shizarodon dhofarensis n. g., n. sp. to Djebelemur martinezi lower molars (early Eocene of Tunisia) are also noticeable. These resemblances are even stronger than those betwen Omanodon minor and Djebelemur martinezi. However the very bunodont upper molars referred to D. martinezi are unusual for adapids, and there are moreover some notable differences in their lower molars. Thus resemblances in Djebelemur and Shizarodon are probably due to paralellisms.
Because of the fragmentary nature of the material and of possible parallelisms, the systematic position of Omanodon and Shizarodon within adapiformes cannot however yet be established definitively.
PV article infos
Published in Vol. 22, Fasc. 4 (1993)
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A femur of the Late Cretaceous giant bird Gargantuavis from Cruzy (southern France) and its systematic implications
Published online: 27/06/2019
Keywords:
Aves; femur; France; Gargantuavis; Late Cretaceous
https://doi.org/10.18563/pv.42.1.e3
Abstract
A large avian femur recently discovered at the Late Cretaceous Montplo-Nord locality at Cruzy (Hérault, southern France) is referred to the giant bird Gargantuavis philoinos. The estimated mass of the bird is 57 kg, within the range of living cassowaries. The specimen provides new evidence about the anatomy of G. philoinos, notably showing that the distal end of the femur was similar to that of modern birds in having a condylus lateralis subdivided into two semicondyles. A new diagnosis of Gargantuavis philoinos is provided and the taxon is placed in a new family of basal ornithurines.
PV article infos
Published in Vol 42-1 (2019)
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Observations sur des remaniements structuraux post-mortem dans des dents de mammifères fossiles provenant des phosphorites du Quercy
Published online: 01/12/1974
Keywords:
Quercy Phosphorites; rearrangements; Teeth
https://doi.org/10.18563/pv.6.3-4.163-176
Abstract
Deux types de remaniements post mortem me paraissent caractéristiques de l'état de conservation des dents de mammifères fossiles dans les Phosphorites du Quercy :
1) Des destructions localisées d'origine biologique, sous forme de galeries de morphologie très variable creusées dans la dentine et le cément, et impliquant sans doute la participation de différents types de micro-organismes. Ces altérations se sont développées peu de temps après la mort, avant la fossilísation proprement dite et se sont rapidement arrêtées après l'enfouissement dans le sédiment phosphaté.
2) Des perturbations dans les structures de la dentine liées aux variations locales de minéralisation, provoquées par une imprégnation diffuse des zones les moins calcifiées par divers minéraux et probablement surtout de l`apatite.
PV article infos
Published in Vol. 06, Fasc. 3-4 (1975)
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Pantolestidae nouveaux (Mammalia, Insectivora) de l'Eocène moyen de Bouxwiller (Alsace).
Published online: 31/03/1970
Keywords:
Bouxwiller; Insectivora; Mammalia; Middle Eocene; Pantolestidae
https://doi.org/10.18563/pv.3.3.63-82
Abstract
The Pantolestidae from the middle eocene of Bouxwiller are the subject of a detailed study. Buxolestes hammeli (n. g., n. sp.) is not closely related to any other European or North American form described until now; it presents, however, some characters in common with Pantolestes, a form of the same age from North America. A parallel evolution from a common ancestral form could explain this ressemblance.
Another form (gen. and sp. indet.) accompanies Buxolertes hammeli in the Bouxwiller fauna.
PV article infos
Published in Vol. 03, Fasc. 3 (1970)
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New datation of the Tafna Basin (Algeria): A combination between biochronological and magnetostratigraphical data
Published online: 11/03/2015
Keywords:
correlations; Late Miocene; North Africa; Rodentia
https://doi.org/10.18563/pv.39.1.e1
Abstract
The Tafna Basin corresponds to the lowlands, which are located in front of Tessala and Traras ranges, below the Tlemcen mountains, Algeria. This basin displays a complete sedimentary cycle dominated by lagoonal-fluvial and marine deposits. The continental formations located at the base of these deposits are mainly composed of alternating sandstones and clays. An early late Miocene age has been previously attributed to them, based on direct correlations with marine deposits. Search for micromammal fossils led to the discovery of three different rodent species from a single level of the Djebel Guetaf section, located at the bottom of these deposits. The rodent assemblage indicates a late Miocene age. Combined magnetostratigraphical and biostratigraphical investigations were carried out to provide a more accurate age control of these continental deposits. Sixty-four oriented rock samples were collected for a magnetostratigraphic study along a 92 meters thick section including the fossiliferous layer. Rock magnetic investigations indicate the presence of both high and low coercivity minerals. Specimens subjected to progressive thermal demagnetization procedures show that the samples exhibit a high temperature magnetization component and display a normal polarity. Based on biostratigraphic constraints, the Guetaf section is correlated with Chron C4An, indicating an age ranging from
9.1 to 8.7 Myr.
PV article infos
Published in Vol.39-1 (2015)
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A mandible of the hyracoid mammal Titanohyrax andrewsi in the collections of the Muséum National d'Histoire Naturelle, Paris (France) with a reassessment of the species
Published online: 18/04/2016
Keywords:
Afro-Arabia; Fayum; Oligocene; Titanohyracidae
https://doi.org/10.18563/pv.40.1.e4
Abstract
An unpublished mandible of the large hyracoid Titanohyrax andrewsi from the early Oligocene Jebel Qatrani Formation, Fayum Depression, Egypt is described. This specimen has a twofold importance. Firstly, it opens an unexpected window on early paleontological research in the Fayum because it was discovered as early as 1904 by the French paleontologist René Fourtau during an expedition to the Fayum organized by the Muséum National d’Histoire Naturelle, Paris (MNHN). This expedition has remarkably never been mentioned in the literature. Secondly, the mandible documents the best-preserved specimen of T. andrewsi, permitting a revision of one of the very rare Paleogene hyracoids. Interestingly, the new mandible was discovered two years before the first report of the species by Charles W. Andrews. The hypodigm of T. andrewsi is reviewed and the dentition as a whole is compared in detail, notably with other Titanohyrax species from the Fayum. The validity of the large Titanohyrax “schlosseri” species is discussed, but a pronounced sexual size dimorphism for T. andrewsi is favoured.
PV article infos
Published in Vol.40-1 (2016)
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L'occlusion dentaire chez Peradectes, Amphiperatherium et Peratherium, Marsupiaux du tertiaire d'Europe.
Published online: 01/10/1980
Keywords:
Didelphidae; Eocene; Mastication; Oligocene; Wear facets
https://doi.org/10.18563/pv.9.ext.79-89
Abstract
The general principles guiding the study of wear facets which develop during mastication in mammals possessing tribosphenic molars are named. The application of this method of study to the molars of European Tertiary Didelphidae shows that the lineage of this family as represented by the species Peratherium cuvieri (Upper Eocene), P. elegans (Lower-middle Oligocene) and P. antiquum (Upper Oligocene) has propessively evolved toward a more carnivorous diet.
PV article infos
Published in Vol. 9, Ext (1980)
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Artiodactyla aus den Eozänen Braunkohlen des Geiseltales bei Halle (DDR)
Published online: 04/12/1989
Keywords:
Artiodactyles; Eocene; Europe; Paleoecology; Stratigraphy; taxonomy
https://doi.org/10.18563/pv.19.3.131-160
Abstract
The present study of Artiodactyla from the Middle Eocene of the Geiseltal lignite beds concems systematics, biostratigraphy, and palaeoecology on the basis of 174 specimens: isolated remains to more complete skeletons. Instead of the formerly known five species of two families are now recognized 14 species of the Diacodexeidae, Dichobunidae, Cebochoeridae, and Haplobunodontidae. New species are Aumelasia maniai, Anthracobunodon neumarkensis, Masillabune franzeni. Four species of the Geiseltalfauna are definitely known from elswere, and five species are closely related to those from other European localities. Evidently the faunal situation of artiodactyls during the Middle Eocene of Europe was largely uniform. The distribution of artiodactyls within the sequence of the Geiseltal strata corroborates the biostratigraphical concept of the land mammal age Geiseltalian (Franzen & Haubold l986b) as well as the mammalian reference levels MP 11-13 (Franzen 1987). Reconstructions of the skulls and skeletons allow conclusions on the functional morphology and palaeoecology of the artiodactyls of the European Middle Eocene
PV article infos
Published in Vol. 19, Fasc. 3 (1989)
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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 4 - Les artiodactyles Suidae.
Published online: 15/11/1988
Keywords:
Artiodactyla; France; Mammalia; Montredon; Upper Miocene
https://doi.org/10.18563/pv.18.ext.57-64
Abstract
There is only one suid known in the Upper Miocene of Montredon (Hérault): Microstonyx (Limnostonyx nov. subgen.) antiquus (KAUP). It is differenciated from Microstonyx major by the presence of upper and lower canines which are considerably longer and biger. Its presence at Montredon corroborates the palustrine habitat for the species.
PV article infos
Published in Vol. 18, Ext (1988)
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Neolicaphrium recens Frenguelli,1921,the only surviving proterotheriidae (Litopterna, Mammalia) into the south american Pleistocene.
Published online: 30/07/2001
Keywords:
Litopterna; Neolicaphrium recens; Pleistocene; Proterotheriidae; South America
Abstract
The litoptem Proterotheriidae are extinct endemic South American ungulates frequently used as an example of evolutionary convergence with the horses. They were considered to be exclusively Tertiary representatives with the youngest record being in the late Pliocene, before the appearence of the equids and cervids during the Great American Interchange. Two undoubted Pleistocene records in Argentina and the specimen here described from Uruguay, confirm the persistence of the proterotherids into that period. In the Quaternary, these ungulates are found outside the typical pampean region and probably were confined to a few northern and warmer more forested relictual microhabitats.
PV article infos
Published in Vol. 30, Fasc. 1-2 (2001)
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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 2 - les carnivores
Published online: 15/11/1988
Keywords:
anatomy; Carnivora; France; Montredon; Systematics; Upper Miocene
https://doi.org/10.18563/pv.18.ext.15-42
Abstract
The locality of Montredon has provided 8 species of camivores, often little documented, that are discribed and depicted. All the remains are fragmentary and generally badly preserved which lowers very much the possible precision of the taxonomic study; this one has however allowed the creation of a new subspecies. The most richlypdocumented forms are an ursid (Indarctos) and a felid (Machairodus). Issuing often from a westem Europe evolution, the carnivores are well inserted between those of the better known faunas of the "Classical Pontian" and of the lower Vallesian and this situation fits also well with their stratigraphic level, that cannot however be more accurately defined with them alone.
PV article infos
Published in Vol. 18, Ext (1988)
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Mammals and stratigraphy of the continental mammal-bearing Quarternary of South America
Published online: 16/12/1984
Keywords:
Geochronology; Mammalia; Quaternary; South America; Stratigraphy
https://doi.org/10.18563/pv.14.ext
Abstract
Previous chronological arrangements of South American Quaternary land mammal faunas are appraised on the basis of current geological and paleontological data. Three South American late Pliocene-Pleistocene land mammal ages are conventionally recognized, from oldest to youngest, the Uquian, Ensenadan, and Lujanian ; all are defined on Argentine faunas.
The Uquian is based fundamentally and historically on the fauna from the Uquía Formation in Jujuy Province, northwestern Argentina. Important known formations in Argentina yielding Uquian Age faunas include the sub-surface Puelche Formation (or Puelchense) near the city of Buenos Aires, and the Barranca de Los Lobos and Vorohué Formations between Mar del Plata and Miramar, Buenos Aires Province. A tentative subdivision is propos-ed for the Uquian into three subages based on knowledge of the Mar del Plata-Miramar sequence, from oldest to youngest, the Barrancalobian, Vorohuean, and Sanandresian. In Argentina the Uquian is presently marked by the first known record of Scelidodon, Hydrochoeropsis, Ctenomys, Canidae, Ursidae, Gomphotheriidae, Equidae, Tapiridae, Camelidae, Cervidae, and the last known record of Thylatheridium, Thylophorops, Dankomys, Eumysops, Pithanotomys, Eucoelophorus, Hegetotheriidae, Sparassocynidae, and Microtragulidae.
The Ensenadan Age is based on the fauna from the Ensenada Formation near the city of Ensenada, Buenos Aires Province. In Argentina the Ensenadan is marked by the first known record of Lomaphorus, Neothoracophorus, Plaxhaplous, Cavia, Lyncodon, Lutra, Galera, Smilodon, Dicotyles, Lama, Vicugna, the last known record of Orthomyctera, and the only known record of Brachynasua.
Typícal beds of late Lujanian Age in Argentina consist of fluvial deposits occupying stream channels, and shallow basins, often incised into beds of early Lujanian (i.e. Bonaerian of early workers) and Ensenadan Age. The Lujanian Age is based on a fauna from beds along the Rio Luján, about 65 km west of the city of Buenos Aires, Buenos Aires Province. The Lujanian in Argentina is marked by the first record of Equus, Chlamyphorus, and Holochilus, and the last record of Megatherioidea, Glyptodontoidea, Arctodus (=Arctotherium), Smilodon, Litopterna, Notoungulata, Proboscidea, Equidae, Morenelaphus, and Palaeolama.
These land mammal ages are often difficult to recognize in other South American countries. The compositions of South American Pleistocene faunas vary with the environment. Some taxa were widely distributed in fossil deposits throughout the continent, but their occurrences need not reflect synchroneity. This is a result of changing climates and habitats in time. Consequently, proposed intracontinental correlations need confirmation based on magnetostratigraphy and a radioisotope time scale. Paleontologic characterizations of these land mammal ages (i.e. first and last record, and guide fossils) are useful for much of Argentina, but extensions to most of the other parts of South America are at best tenuous.
The majority of known non-Argentine Pleistocene faunas are believed to be Lujanian in age. Possible non Argentine early Pleistocene (Uquian) faunas include Ayo Ayo and Anzaldo in Bolivia, and Cocha Verde in southern Columbia. A possible middle Pleistocene (Ensenadan or early Lujanian) fauna is the Chichense of Ecuador. Paleomagnetic and radioisotopic date (MacFadden et al., 1983) clearly indicate that the greater part of the Tarija fauna (Bolivia) is Ensenadan in age.
The end of the Pleistocene and beginning of the Holocene in South America is marked by extinction of nearly all large mammalian herbivores and their specialized large predators. Radiocarbon age determinations suggest that large scale extinctions of megafauna occurred between 15,000 and 8,000 yrs. B.P. (years before present).
PV article infos
Published in Vol. 14, Ext (1984)
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An Australian Miocene Brachipposideros (Mammalia, Chiroptera) related to Miocene representatives from France
Published online: 15/12/1982
Keywords:
Australia; bats; Chiroptera; Miocene
https://doi.org/10.18563/pv.12.5.149-172
Abstract
A new middle Miocene hipposiderid bat is described from a limestone deposit on Riversleigh Station in north-western Queensland. Hipposideros (Brachipposideros) nooraleebus n. sp. is the first record of this subgenus from anywhere in the world outside of France. The palaeoecological setting of the fossil bats appears to have been a relatively quiet, sunny lime-enriched tropical pool that contained tortoises, crocodiles and fish. It is possible that the bats were washed into the pool from an adjacent cave.
The Riversleigh bat most closely resembles the French Burdigalian (early middle Miocene) bat H. (B.) aguilari. It is also possible that it may have been closely related to the original Australian hipposiderid stock that ultimately gave rise to the endemic monotÿpic Rhinonycteris aurantius. The disjunct distribution of species of H. (Brachipposideros) suggests that representatives of this subgenus will be found in at least tropical southern Asia.
PV article infos
Published in Vol. 12, Fasc. 5 (1982)
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Le genre Plagiolophus (Palaeotheriidae, Perissodactyla, Mammalia): révision systématique, morphologie et histologie dentaires, anatomie crânienne, essai d'interprétation fonctionnelle
Published online: 15/12/2004
Keywords:
New taxa; Paléogène; perissodactyls; skull anatomy; tooth histology
Abstract
The genus Plagiolophus is documented, almost solely in Western Europe, from the middle Eocene up to the mid Oligocene (MP 12 to MP 25), i.e. more than for 15 MY. Seventeen species are now recorded whose two of them are new, P. ringeadei nov. sp. and P. mamertensis nov. sp. Some anatomical variations and the deflection of certain evolutionary trends justify the distinction of three subgenera, Paloplotherium, Fraasiolophus nov. and Plagiolophus s.s. The genus displays a wide range in size and weight (between 10 and 150 kg). The detailed description of the skull of several species is here given for the first time. Despite important evolutionary drifts during this long time span, the dentition shows a great structural homogeneity, which renders difficult the determination of fragmentary specimens or isolated teeth. It is characterized by a great heterodonty; premolars are little molarized and present a certain regression through time with paradoxically some progress in the molarization. The hypsodonty increases: the first Plagiolophus are hardly less brachyodont than Propalaeotherium, and the last ones are nearly as hypsodont as Merychippus from the early Miocene. The upper molars change from a wide crown pattern, with an open occlusal surface, lightly oblique transverse lophs and rounded internal cusps, to a narrower pattern, with a frontally constricted occlusal surface and internal lophs aligned parallel to the ectoloph. The M3/3 become always longer.
The dental enamel displays horizontal Schreger-bands with imprecise limits occupying only the middle part of the enamel layer. The dentine is remarkable by its high rate of pericanalicular dentine. The crown cementum, lacking in earlier forms, increases to the point where it fills the occlusal valleys of the teeth.
The masticatory musculature shows a increasing prominence of the temporal, with probably an important role devoted to the pterygoid muscles in lateral movements related to a two-phase type of chewing.
The evolution of the dentition, of the masticatory musculature and of the repartition of masticatory forces indicate that the Plagiolophus have known different diets through their long evolutionary history; at first browsers they became mixed feeders and finally grazers. Their relatively long neck allowed these animals to reach different vegetal layers. The strength of the nuchal crests also suggests that they were able to have strong backwards movements of the head to pull up their food.
This evolution of diet seems related to the slow degradation of environmental conditions attested during this period in western Europe, with the generalization of more open landscapes, increasing aridity and more marked seasons.
Besides, a remodeling of the face is ontogenetically and along time observed, in relation with the evolution of the masticatory apparatus and especially with that of the mandibular lever arm. The postcanine diastemata become longer in the course of evolution; the free extremities of the nasals are always relatively long which contradicts the hypothesis according to which Paloplotherium may have had a trunk. At last the lineage Fraasiolophus can be distinguished by the presence of a deep malar fossa, probably related to a strong development of the maxillo-labialis superior muscle.
The orbit is always large and tends to increase in size, which indicates a good development of the vision and its increasing role in the life relations. A peculiar type of epitympanic sinus could have been used as a resonance chamber insuring a certain amplification of sounds before their transmission to the eardrum. The endocranial cast reveals a relatively large brain with an advanced degree of gyrencephaly. Beside the role eventually played in food research and social relations, these neurophysiological abilities, also related to an advance in cursorial fitness, could have contributed to the survival of these animals facing the predation pressure of the first fissipede carnivores and the competition with new immigrant herbivores after the "Grande Coupure". On the basis of some shared apomorphies with the Pachynolophinae, which prevent from considering the latter as Equidae (molarization of the premolars, reduction of the premaxilla dorsal apophysis, peculiar epitympanic sinus, splitting of the jugular process), the hypothesis of an autochthonous origin of Plagiolophus issued from a form near Propalaeotherium, is once again proposed and discussed. Finally, intra-generic relationships are taken into consideration.
PV article infos
Published in Vol. 33, Fasc. 1-4 (2004)
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Nouvelles données sur les Ichnites de dinosaures d'El Bayadh (Crétacé Inférieur, Algérie)
Published online: 16/12/2008
Keywords:
Algeria; Brezina; El Bayadh; Ichnites; Lower Cretaceous; Sauropoids; Theropoids
https://doi.org/10.18563/pv.36.1-4.7-35
Abstract
Evidence of 350 Lower Cretaceous Dinosaur footprints is pointed out in El Bayadh area. Their preliminary study allow to distinguish four trackway assemblages which reveal vertebrate bipedal presence forms of tri-and tetradactylous Dinosauroïds (Assemblages 1-3) and quadrupidal Sauropoïd (Assemblage 4).
The analysis of their footprint biometric features will attribute the quadrupidal Sauropoïd form to Brontopodus ichnogenus which is weIl known in the Jurassic and Cretaceous periods. In retum and despite their age, the dinosauroïd forms were approached, temporarily, to Grallator and Eubrontes types.
The occurrence of the dinosaur traces (Theropoïd and Sauropoïd) constitutes, in the Lower Cretaceous, an important first step of the knowlege of the marshy Reptilian fauna which takes over, from the begining of the Secondary Era, a wide paleogeographie area on the Southem Tethyan margin.
PV article infos
Published in Vol. 36, Fasc. 1-4 (2008)
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