Le Lias et le Dogger du sud du Bassin parisien (France) : rôle de la tectonique syn-sédimentaire et reconstitutions paléogéographiques à l'échelle de la biozone d'ammonite

The Lias and Dogger series in the southern Paris Basin outcrops are precisely dated following the ammonite biozonation scale. In these series, the depositional environment context is accurately identified and thus various isopic zones can bee recognized. From the outcrop study, the depositional sequence and the tectonics events are also distinguished. The poorly dated subsurface data should be not anymore interpreted as diagraphic signatures, with the traditional peak to peak correlation. They now need to be analysed according to the geodynamic evolution of each isopic zone. The Liassic transgressive series (in the Armorican continent) and the Dogger platforms numerous carbonate bodies are correlated at biostratigraphic scale, throughout the whole southern Paris Basin. Subsequently, paleogeographic maps are established and based on depositional sequences. The basin evolution image changes radically. This shows clearly that the complexes carbonate bodies layout prohibits any depositional environment interpretation and any isopach mapping at geological stage level. If not, the carbonate platforms of different age would be amalgamated, without any connection with the reality. Over the time, paleogeographic maps show syn-sedimentary short wavelength deformations, more or less well expressed according to the local sedimentary context. During the Lias and the Dogger, three steps can be distinguished in the southern Paris Basin. Hettangian to Lower Aalenian, the progressive increase in accommodation drives to total immersion of the continental areas; the maximum of accommodation during the Middle Toarcian entails uniform sedimentary conditions. However, short wavelength deformations persist. The major accidents defining the isopic zones are mainly North-South oriented. Middle Aalenian to Middle Bathonian, isopic zones are contrasted, controlled by the North-South accidents but also the North West-South East ones ; the variable accommodation allowed the development of regional sedimentary gaps and shallow limestone progradations on a marly area (so called “Sillon marneux”) ; tectonics events correspond to the Tethyan and the North Sea riftings influences. Upper Bathonian to Upper Oxfordian, the North West-South East tectonics accidents are particularly active; this tectonic phase could be associated to the thermal event, described in the Paris Basin and announcing the Malm depositional environment.     

Oxygen Transport System in Children Living in the Russian Far North

We studied 654 healthy ten- to twelve-year-old children living in the Russian Far North (Taimyr peninsula) and in Siberia (town of Krasnoyarsk). The state of the body oxygenation and the systems responsible for oxygen delivery were studied according to the length of time living in the Russian Far North and season of the year. An examination of newcomer children revealed the following changes during the first year of living in the Russian Far North: an increased respiration rate and changes in its circadian rhythm; an increase in the heart rate, cardiac output, and cardiac index; an increase in the mean corpuscular volume in the red blood system; the activation of lipid peroxidation, and the changes in electrolyte balance of cells. The control mechanisms of oxygen transport system gradually stabilized during the ages of two to five years. In children living more than five years in the Russian Far North, the increased oxygen demand was met by the activation of cardiovascular and red blood systems aimed at more effective and adequate oxygen delivery to tissues.     

Évolution de la préhension chez les primates humains et non humains : la précision et l'utilisation d'outils revisitées

The term “precision”, involving the contact between the tips of thumb and the index is generally attributed to humans, tool use and associated with morphological criteria. Identified in fossils, those criteria are used to assert that they manipulated tools. Observations of 69 individuals belonging to Catarrhines and Platyrrhines allowed us to quantify surfaces of fingers used during simple tasks of grasping both small and large objects, as well as during complex tasks of proto-tool and tool use. We concluded that precision grasping is not peculiar to humans and that it is not systematically linked to tool use. These results allowed us to discuss morphological traits used till now to deduce precision and tool use from the fossils. Besides, our analyses let appear a recurrent proximity between the capuchins and the humans, species distant in a phylogenetic point of view, suggesting the possible existence of functions and close behaviours in spite of great genetic distinctions.     

Paléogéographie des chasseurs de l’Europe du Paléolithique supérieur : répartition et spécialisation des sites

During the Upper Paleolithic, Europe was occupied by human populations mainly living from hunting of big terrestrial mammals. A repartition of fauna and of archeological sites was done with a database: a repartition of Upper Paleolithic sites in central and western Europe. This study shows that the european space was structured following several factors; climate, environment, cynegetic behaviours… We observe a partition of Europe with a mediterranean area with mainly deer, and ibex and an atlantic area with reindeer. Equally, most of the occupations are localized in the “aquitano-cantabric horn” around the Gulf of Gascony. The occupation of Europe undergone a pulsation with a retreat of occupations toward the west and the south during the glacial maximum, then a colonization of North Europe during the Tardiglacial climatic amelioration.     

Comparaison de l'expression de certains caractères crâniens sur les hominidés chinois du Pléistocène récent et de l'Holocène (grotte supérieure de Zhoukoudian, sites de Longxian et de Yanqing)

The human remains recovered from “Grotte supérieure de Zhoukoudian” are the best-preserved Late Pleistocene human fossils in East Asia. For decades, as the representative of the Late Pleistocene human in East Asia, the Upper Cave skulls have been playing important role in the research of origins of modern Mongoloids and American Indians. With the advance of the origin and evolution of modern humans, more attention has been paid to the details and the mechanisms for the late Pleistocene human evolution and the formation of modern human populations. Both the origin and diversification of modern humans have been stressed. Some studies further trigger the debaters on the Upper Cave Man concerning its evolutionary level and its role in the formation of modern human populations in East Asia. To further explore these problems, we examined and compared 12 non-metric features on the 3 Late Pleistocene Upper Cave skulls and 162 Holocene individuals earthed from two archaeological sites of North China (Longxian and Yanqing). Our results indicate that 8 on the 12 features have different expression patterns between Upper Cave Man and recent Chinese leading the authors to believe that more primitive expressions appeared on the Upper Cave Man than on recent Chinese populations. Based on these findings, some problems on the intragroup variation in Late Pleistocene and Holocene populations are discussed.     

Corrélation des successions de l'Albien par les ammonites entre la Province Nord-Pacifique et les Provinces européenne et arctique du Domaine boréal : zonation, eustatisme et paléobiogéographie

The vertical distribution of Albian ammonites of the North Pacific Province is described on the basis of several sections located in Northern California. Nine Albian ammonite assemblages are identified, compared to the 4 previously described by Murphy in 1956. Owing to several gaps of observation possibly more assemblages could exist. In the North California Albian history, the first results show a succession of confinement periods - with numerous endemic faunas - followed by periods of open communications with other faunal provinces. As an example, the base of the Middle Albian is marked by exotic ammonites coming from the Tethyan realm (Oxytropidoceras, Lyelliceras) and from the Arctic Province of the Boreal realm (Gastroplites, Pseudopulchellia). These ammonites - except Oxytropidoceras - were not known in that area and are described relatively to their palaeobiogeographical interest. Although rare these migrant faunas give valuable elements to correlate these various provinces. Planktonic foraminifera confirm the existence of open sea communications during the uppermost Albian.With such faunal links, a comparison is proposed between the Albian ammonite zonation of Northern California and the standard and phyletic ones of Europe. This attempt suggests that the major connections between the three faunal provinces are established at second order peak transgressions in the Early and Middle Albian, and during the sea-level high of the Late Albian transgressive period. So, it seems that the vertical distribution of Albian non-endemic ammonites of North California and Europe is largely controlled by global eustatic events. Two palaeobiogeographic maps for Early and Middle Albian and one map for the late Late Albian show the migration outer of these exotic ammonites.     

Le « nucléus Donggutuo » et sa signification dans l’industrie du paléolithique inférieur de Donggutuo, bassin de Nihewan, Chine du Nord

As one of the most important Lower Pleistocene sites of the Nihewan basin in North China, Donggutuo (DGT) site is well known for its fine retouched small tools and characters of flake industry. However, new excavations still reveal some new discoveries and educe some new issues to us. For example, the “DGT core” introduced in this article is a new discovered typotechnology and indicates new economic strategy of the local people, which was never known before in this area at the time of 1.1 Ma B.P. The paper provides general background and statistic analysis of DGT industry including special method applied to the “DGT core” and discusses possible influence of environmental change for the emerging of the “DGT core”. The “DGT core” shows a germinated microlithic tradition and reflects a cultural diversity of early humans in the Lower Paleolithic in North China.     

Histoire plio-pléistocène des écosystèmes végétaux de Méditerranée sud-occidentale : apport de l’analyse pollinique de deux sondages en mer d’Alboran

The pollen analysis of sediments of two boreholes located in the northeastern Morocco (Nador 1) and in the southeastern Spain (Andalucia G1) has allowed shedding a new light on the vegetation and climate of the North African littoral plains, the Rif Massif and the Betic Range during the Pliocene. The vegetation around the Alboran Sea was open and xeric during the Zanclean, dominated by herbs including subdesertic elements as Calligonum, Lygeum, Nitraria and Neurada. This type of vegetation indicates a dry and hot climate. The southwestern Mediterranean steppes have therefore a climatic character; they existed before the presence and the heavy pressure of Man on the environment. From the Piacenzian, the development, at Andalucia as well as at Nador, of Artemisia and the appearance of some altitude trees such as Cedrus and Cathaya indicate a vegetation change linked to a climatic change. Modifications in the vegetation observed during the same period in northwestern Mediterranean seem to indicate that the vegetation changes observed at Andalucia and Nador are controlled by the appearance of the first arctic glacial-interglacial cycles. The cedar tree appears at Nador only at the end of the Piacenzian, at time of the first cooling, while it has been found punctually in Messinian and early Pliocene sediments of Habibas in Algeria and in Messinian sediments of the Bou Regreg section at Salé in Morocco. The regular presence of Cedar at Bou Regreg during the Messinian, allows supposing that it was present in the Middle Atlas Mountains and that its development was favoured by colder conditions.     

Ostracodes du Dévonien moyen et supérieur du Tafilalt (Maroc)

Forty-four ostracod species are recognised from the upper part of the Eifelian to the base of the Famennian of the Djebel Mech Irdane, Bou Tchrafine and El Atrous sections, in the Tafilalt. The majority are in open nomenclature, and one is new: Tubulibairdia tafilaltensis nov. sp. Ostracods belong principally to the Eifelian Mega-Assemblage and they are generally indicative of poorly oxygenated relatively deep marine environments below storm wave base. However, in the base of the Famennian of the Bou Tchrafine section, ostracods belong to the Myodocopid Mega-Assemblage indicative of strong hypoxic water conditions. They confirm that the hypoxic water conditions linked to the “Upper Kellwasser Horizon”, subsisted in North Africa, in the extreme base of the Famennian. Twenty-four ostracod species are recognized in the Djebel Mech Irdane Eifelian/Givetian stratotype, where the most important change in the ostracod fauna is related to the 40 cm-thick level of grey silty-marl located 10 cm below the boundary. However, this change is not indicative of an extinction event at this level. Three zones established on ostracods are recognized in the Frasnian and in the base of the Famennian of the Tafilalt.     

Des steppes aux déserts, à l’Aurignacien. Les hommes modernes venus d’Asie

From east to west, Aurignacian populations and civilizations moved into Europe during dry and cold climatic conditions. The zones of origin in the Middle East at that time had a steppic environment with large fauna that were rich caloric resources. Alongside many other examples, this new cultural unit has strict parallels that are clearly evidenced at Jabrud (Syria) and Yafteh (Iran). Now a desert region, during the Aurignacian this vast geographic and ethnic region extended on both sides of the Central Zagros Mountains, towards Central Asia where immense steppes seem having formed the epicenter.     

Spatial,Temporal and Genetic Dynamics Characteristics of Influenza B Viruses in China, 1973–2018

Annual influenza B virus epidemics and outbreaks cause severe influenza diseases in humans and pose a threat to public health. China is an important epidemic area of influenza B viruses. However, the spatial, temporal transmission pathways and the demography history of influenza B viruses in China remain unknown. We collected the haemagglutinin gene sequences sampled of influenza B virus in China between 1973 and 2018. A Bayesian Markov chain Monte Carlo phylogeographic discrete approach was used to infer the spatial and temporal phylodynamics of influenza B virus. The Bayesian phylogeographic analysis of influenza B viruses showed that the North subtropical and South subtropical zones are the origins of the Victoria and Yamagata lineage viruses, respectively. Furthermore, the South temperate and North subtropical zones acted as transition nodes in the Victoria lineage virus dispersion network and that the North subtropical and Mid subtropical zones acted as transition nodes in the Yamagata lineage virus dispersion network. Our findings contribute to the knowledge regarding the spatial and temporal patterns of influenza B virus outbreaks in China.     

Insect taxonomic diversity in the Russian Far East

The insect fauna of the Russian Far East comprises 634 families from 31 orders. The estimated species number is 31500. The largest orders are Hymenoptera (76 families, 9000 estimated species), Diptera (120 families, 8000 estimated species), Coleoptera (114 families, 5500 estimated species), and Lepidoptera (81 families, 5000 estimated species). The fractions of the main insect orders in the fauna of the Russian Far East correspond to those in the Holarctic temperate zone. The high biodiversity of insects in the Russian Far East results from the position of this region extending across several climatic zones. There are four levels of diversity both for the families and for the species, corresponding to the tundra, taiga, the transitional area between taiga and broadleaved forests, and the broadleaved forest zone. The number of insect families increases by 3 times while that of species increases by 20 times from the tundra to the broadleaved forests. Differentiation of the insect fauna of the Russian Far East results from the recent climatic situation (the influence of the Pacific monsoon) and the geologic history (broadleaved forest refugia resulting from the absence of complete ice cover during Pleistocenic glaciation in the south of the Russian Far East); it reflects deep faunistic connections of the eastern Palaearctic with the Nearctic and Oriental Regions. The mountain areas in the North Pacific are the refugia of the Mesozoic and Tertiary insect faunas. The Pacific may have substantially reduced the Cenozoic aridization in the northern hemisphere, which was one of the important factors of formation of the recent biota in the Palaearctic and Nearctic regions.     

Photo‐identification matches of humpback whales (Megaptera novaeangliae) from feeding areas in Russian Far East seas and breeding grounds in the North Pacific

Humpback whales migrate seasonally from high latitude feeding areas to lower latitude breeding areas for mating and calving. In 2004–2006, a North Pacific basin‐wide study called SPLASH was conducted as an international collaboration among various groups of researchers. The Russian Far East consists of multiple high latitude feeding areas and during SPLASH, 102 whales were identified and compared to catalogs from breeding areas. Our goal in this study was to further investigate the migratory destinations of whales from the Russian Far East using a total of 1,459 photographs of whales identified from 2004 to 2014. We compared the latest Russian catalog with the SPLASH catalog from wintering areas (2004–2006) and with two additional regional catalogs from Okinawa (1989–2006) and the northern Philippines (2000–2006). We found a total of 152 matches: 106 with Asian, 35 with Hawaiian, and 11 with Mexican breeding grounds. The match rate was higher in mainland Kamchatka and consisted mostly of whales from the Asian breeding ground. In the Commander Islands, the proportion of whales from Asia was twice that of Hawaii and six times higher than Mexico. The total match rate was low, supporting the hypothesis of some undiscovered humpback whale breeding location in the North Pacific.     

Stress physiologique et état de santé des plus anciens Hommes anatomiquement modernes du sud-est de l’Europe (données dentaires,couche 6-1, Buran-Kaya III,Crimée)

Buran-Kaya III site, in Crimea, provides an exceptional stratigraphic sequence, extending from Middle Paleolithic to Neolithic. Among the archaeological layers allocated to the Gravettian (sensu lato), more than 170 anthropological remains have been discovered in the layer 6-1. They represent the oldest Upper Paleolithic modern humans from Eastern Europe in a well-documented archaeological context. The aim of this article, based on dental remains and enamel dental hypoplasias in particular, is to evaluate the health of the modern humans, which lived more than 32,000 years BP ago in Crimea. This study puts into the light the low frequency of hypoplasias (occurring in the two youngest individuals). This article complete the rare studies concerning the presence of this physiological stress during the Early Upper Paleolithic and confirm the scarcity of enamel dental hypoplasias and dental pathologies, such as caries, at this period.     

Lithostratigraphie et biostratigraphie des formations paléocènes et éocènes entre Bayonne et Pau (SW France)

The lithostratigraphy and biostratigraphy of the Paleocene and Eocene formations have been reconsidered on the basis of 18 dated boreholes that intersect the Basque Country, Peyrehorade, Sainte-Suzanne and Sauvelade allochthonous tectonic units, as well as the autochthonous units of the Pey-Saint-Lon anticline, the Arzacq Basin and the North Pyrenean Trough. Correlation of the formations identified in the boreholes and at outcrop has made it possible to outline the sedimentary evolution of this region during the Early Paleogene and to date the various stages of Pyrenean compression on the basis of sedimentary gaps and syntectonic detrital input. The Lasseube Formation is present over the entire study area. Sedimentation becomes differentiated during the Late Selandian-Early Ypresian period. In the North Pyrenean Trough and in the Peyrehorade, Sainte-Suzanne and Sauvelade units, the detrital-clayey Pont-Labau Formation is well developed and all its members are represented (Guillempau, Latapy, Néez, Libaros and Artigueloutan; zones upper P 3b-P 6b; upper NP 5-NP 11). A sedimentary gap showing erosion, and involving zones upper P 3b-upper P 4a and upper NP 5-NP 7, characterises the Basque units, the Pey-Saint-Lon anticline and the western part of the Arzacq Basin. Sedimentation recommences in zone P 8 with middle-bathyal deposits of the Cassoua Member and then continues with the Artigueloutan Member (transition facies towards the Louts Formation) or limestone resembling that of the Meilhan Formation. The Gan Formation shows an east-west polarity. In the east, between the Sainte-Suzanne Unit and the North Pyrenean Trough, the formation is argillaceous with a dominant neritic character, apart from a circalittoral to epibathyal passage in its lower part (zone P 7) containing numerous planktonic foraminifera. The formation is of a detrital and carbonate nature in the west (Sainte-Marie-de-Gosse 1). The bathyal Donzacq Formation appears to transgress a previously deformed surface. Two domains existed during the Lutetian: a continental to neritic domain in the south and a bathyal domain in the north (the Saint-Geours-d'Auribat and Miretrain formations) separated by a variably thick transition zone that is affected by thrust fronts. Two new formations - the Orthez and Sorde-l'Abbaye formations - are proposed, and the Marly limestone formation of Saint-Barthélémy (Douvillé, 1905) is redefined. The Orthez Formation (Sauvelade Unit) is composed of marl and continental conglomerate with neritic carbonate interbedding and belongs to the sub-zones NP 15a and b. The Sorde-l'Abbaye Formation (Peyrehorade Unit and the Basque units p. p.) is composed of neritic carbonate sediments (Lutetian-Priabonian). The Saint-Barthélémy Formation is made up of syntectonic conglomerate, turbiditic limestone and pelagic marl in the central part of the Basque units (NP 15a-NP 16). The Bartonian and Priabonian stages are characterised by carbonate sediments in the Arzacq Basin (Siest Formation). Its base is diachronous: Upper Lutetian (zone SB 16) in the east and Late Bartonian grading to Priabonian in the west (zones SB 17/18 and SB 19). The sediments are argillaceous (Côte des Basques Formation) along the Atlantic coast, in the central part of the Basque units and in the Bayonne-Cauneille syncline. Major thickness variations reflect tectonic phases at the top of the Lasseube Formation in the north (erosion pre NP 8), the Néez Member (NP 7/NP 8 boundary), the Artigueloutan Member (NP 11/NP 12 boundary), and the Gan Formation (P 8/P 9 boundary). The syntectonic conglomerate and breccia indicate the development of thrust fronts in the Libaros Member (NP 8), at the base of the Pillardou and Artigueloutan members (NP 9b, c-NP 10), in the Saint-Geours-d'Auribat Formation (NP 14b) and in the Orthez and Saint-Barthélémy formations (between zones NP 15a and NP 16).     

Les associations des calpionelles du Berriasien et du Valanginien inférieur de la Tunisie septentrionale. Comparaison avec les associations du Rif externe (Maroc)

The study of ten thin sections from outcrops from Lower Cretaceous deposits and several thin sections obtained from three petroleum wells, allow us to better characterize the associations of calpionellid zones and subzones of the Berriasian and Lower Valanginian in northern Tunisia. The B and C zones, respectively, show three and two levels with calpionellid associations corresponding to B1, B2, B3 and C1, C2 subzones. In the D zone, associations of the D1 and D2 subzones were identified. The E zone has been characterized for the first time in Tunisia and in southern-Tethyan margin of North Africa, on the basis of its index specie and associated species.     

L’étude des conditions d’habitabilité des établissements préhistoriques : à propos des amas coquilliers mésolithiques de la région cantabrique occidentale (Nord de l’Espagne)

We show the methodology we followed in order to reliably estimate a factor that, to our judgement, is fundamental for the assessment of the characteristics of a prehistoric settlement: the conditions of exposure to the sun. This methodology is applied to the study of Mesolithic shell middens in the North of Spain, with the aim to introduce a new kind of information in the debate about the meaning of shell middens. Throughout this century, different ways to understand the behaviour these remains conceal have been proposed. Our thesis with regard to it, presented in this paper, is based on the observation of a series of variables, among which we can find the exposure to the sun the settlements undergo. We therefore show in the last part of the paper, how to join the information from the proposed analysis with the other data subsequent from the study of other variables such as the environmental conditions prevailing during the period of formation of the sites; the situation of the settlements; the location of the remains in the caves; the entity of the occupations; and the energy spent on the transportation of the aquatic resources from the coast towards the places where their rests are found nowadays. In short, we propound a methodology for the study of one of the variables that falls upon the habitability of a prehistoric settlement and we point out the contribution that the incorporation of an analysis of this kind means for the research of Mesolithic shell middens in the North of Spain.     

L’évolution de l’homme en Eurasie : nouveaux fossiles, nouveaux outils d’analyse

Due to the numerous discoveries of fossils and the technical and analytical improvements in paleoanthropology that occurred recently, a new investigation on the first inhabitants in Eurasia was necessary. The research deals with the facial pattern of the fossil hominids from Europe and Asia and focussed on the ones discovered in the Atapuerca-Gran Dolina site in Spain, which are oldest than 850,000 years and in the Yunxian site in China, which are dated by 936,000 years. Methods used combined 2D and 3D morphometrics providing with the possibility to consider not only the overall conformation but also the more localized measurements. The Procrustes analysis, which put apart the individual size parameter, were used to investigate the morphological alteration of the face during growth in order to interpret the facial conformation juvenile fossils such as those from Atapuerca-Gran Dolina. Moreover, a specific protocol using tomography and 3D imaging techniques was carried out to reconstruct the Yunxian specimens which have been badly crushed during fossilization process. The results of this research put in light two facial patterns: (1) a facial pattern in extension expressed in Neandertals which european lineage could have been older than previously thought including the Atapuerca-Gran Dolina specimens and (2) a facial pattern in contraction shared between modern humans and the oldest fossil hominids from continental Asia (i.e. Yunxian specimens) which suggests that this conformation corresponds to a primitive condition.     

Composition des faunes de mammifères quaternaires en Chine selon un gradient Nord-Sud

During Pleistocene Epoch, quite a number of meridionale mammals inhabited north China, such as Stegodon, Macaca, Hystrix, Dicerorhinus, Bubalus and several kinds of other probscideans. On the contrary, some boreal mammals once appeared in south China, such as Megaloceros and Ursus arctos etc. The frequent appearance of warm-adapted mammals in North China can be explained by two alternative assumptions: one is that those mammals were of palearctic origin; the other is the climate-driven northward dispersal. According to the fossil evidences, it seems that the northward dispersal events were much more frequent than the southward ones during Pleistocene in China. It maybe means that during Pleistocene, the temperature fluctuated very frequently and the boundary between the Paleartic and Oriental Regions were always keeping on shifting. But it's still not clear how many episodes or phases of such dispersal events had occurred. The Qinling Mountains weren't responsible for the faunal differentiation between the North and the South, neither was the Yangtze River; because the former is not big enough, and the latter cannot be regarded as an efficient barrier for those animals, which are capable of flying and swimming. Maybe the climate zonation is the root cause of zoogeographical changes.     

Anthropurgic foci of pseudotuberculosis and the mechanisms of their formation in groups of servicemen

At the period of 1982 - 2003, morbidity rate in pseudotuberculosis and the Yersinia pseudotuberculosis culture rates in groups of servicemen (from different abiotic objects, from humans and small rodents) in different geographic zones were studied. The cases of the isolation of Y. pseudotuberculosis were most frequently registered in groups of servicemen in the Far East and the Kola Peninsula. In these regions the highest morbidity rate in pseudotuberculosis was registered among servicemen. The contamination rate of vegetables during the year was always greater than in other objects under study, including small rodents. The study demonstrated that in the Armed Forces could appear, temporary and relatively constant anthropurgic foci of pseudotuberculosis even in non endemic regions. They were formed in the objects of the food supply service due to the supply of contaminated vegetables. Synanthropic rodents played a secondary role, though they too facilitated the formation of new anthropurgic foci. Under definite conditions anthropurgic foci could exist autonomously, independently of natural foci.