New insights on Cricetodontini (Rodentia,Mammalia) from the Duero Basin,Spain

Abstract

The tribe Cricetodontini is a common cricetid group found in several European basins from the Miocene. Here we present a study of the fossils of this group found in the Duero Basin. We updated the biostratigraphical assignation of some of the localities in which several species of Cricetodontini have been found. Cricetodontini remains from eight localities from the central sector of the Duero Basin have been described, measured and assigned to a species. The presence in these localities of Hispanomys aguirrei, H. lavocati, H. nombrevillae and H. aragonensis has allowed correlating them to the biostratigraphic scale built for the Miocene in Calatayud-Daroca Basin, identifying biozones G3, H and I (MN7/8 – MN10, Late Aragonian – Early Vallesian, Middle – Late Miocene). Furthermore, this study constitutes the first citation of this species in this basin, except H. aguirrei, previously described in the Duero Basin. After this work, the biostratigraphical assignation of the studied sites is now well known. We evidenced the resemblance of Duero and Calatayud-Daroca basins.     

Sciuridae (Rodentia,Mammalia) from the Late Miocene of Venta del Moro (Cabriel Basin,Spain): biostratigraphical,phylogenetic and palaeoecological inferences

Abstract

Fossil squirrels are relatively abundant in Aragonian and Ramblian assemblages, but very scarce in the Late Turolian and Ruscinian of the Iberian Peninsula. Until now, the locality of Venta del Moro has yielded over 4500 micromammal dental remains, but just nine of them are sciurids. In this assemblage, we have identified the taxa Pliopetaurista pliocaenica, Heteroxerus cf. mariatheresae and Atlantoxerus cf. margaritae. This is the first co-occurrence of the genera Pliopetaurista, Heteroxerus and Atlantoxerus in the same locality, being also one of the oldest records of P. pliocaenica, the oldest record of a form that could be related to A. margaritae, and the youngest record of the genus Heteroxerus. In addition, we hypothesize about the phylogeny of Pliopetaurista in the light of recent discoveries. Finally, the presence of the genera Heteroxerus and Atlantoxerus suggests an open environment and relatively dry environmental conditions, while Pliopetaurista is purportedly a flying squirrel, dweller of forested habitats and wet climates. Based on this, we infer an open environment of grassland type, bordered by forested habitats, agreeing with the conditions supposed for Venta del Moro according to its macromammal and floral assemblages.     

New Late Miocene murids from China (Mammalia, Rodentia)

New murids of Late Miocene (medial Baodean Chinese Mammal Unit) age from Inner Mongolia, northern China, and from Yunnan Province, southern China, are described. Hansdebruijnia perpusilla nov. sp. represents the earliest known and morphologically most primitive species of the genus, which is known from the latest Miocene of Europe and western Asia. The new species suggests an eastern Palaearctic origin of Hansdebruijnia. “Progonomys” yunnanensisQIU and STORCH, 1990 from Lufeng, Yunnan Province, is referred to Linomys nov. gen. New samples from Leilao, Yuanmou County, Yunnan Province, are included in this species, although this population is somewhat more primitive than that from Lufeng. Leilaomys zhudingi nov. gen. and sp. from Leilao shows a unique combination of apomorphic and plesiomorphic characters, which suggest an early divergence from the murid stem. The new findings indicate that our knowledge of the early radiation of murids in southeast Asia is still in its infancy.     

An analysis of the mole rats (Mammalia: Rodentia) from Langebaanweg (Mio-Pliocene, South Africa)

A study of the taphonomy and age profiles of the mole rat population from Langebaanweg ‘E’ Quarry was undertaken in order to see if these subterranean rodents had been accumulated by predation (coprocoenosis hypothesis) or as a result of drowning in their burrows during a flood event (catastrophocenosis hypothesis). Previous research has cited the bathyergids as being the most common rodent at Langebaanweg, however, a comprehensive study of new micromammal material indicates that murids, rather than mole rats, dominate most of the assemblages. The concentration of mole rat remains in many of the fossil-bearing levels at Langebaanweg is, nevertheless, still extremely high compared to other fossil sites or predation assemblages in the area. A taphonomic examination of mole rat incisor surfaces indicates that digestion occurs on between 44% and 54% of incisors in the different assemblages, and this, together with the degree of digestion suggests that category 1 and category 2 predators had been responsible for the accumulation of the fossil mole rat assemblages. The absence of rounding, polishing or weathering on the fossils indicates that there has been little or no transport by water, and that burial of the bones was rapid. Breakage and damage to the anterior portion of many of the mandibles made it impossible to accurately assess the age of the older mole rats, and the majority of mandibles could provide only a minimum age of the animal at the time of death. The age profile indicates that very young individuals are missing from the assemblages. This allows for refutation of the previously made suggestion that flooding was responsible for the death of the majority of Langebaanweg mole rats and also introduces the possibility that Bathyergus hendeyi may have been a social animal, unlike extant bathyergids which are solitary.     

New data on the origin of Nesiotites (Soricidae,Mammalia) in Menorca (Balearic Islands,Spain)

The presence of the shrew Nesiotites in Menorca is not yet adequately explained. Some authors consider that its ancestor arrived during the Messinian Salinity Crisis, as happened in Mallorca. Other authors consider that fossil populations in Menorca are the result of a later migration from Mallorca. In this work, several biometrical and morphological characters of abundant fossil populations from both islands have been studied. The results indicate that Early Pleistocene populations in Mallorca and Menorca are rather indistinguishable. Therefore, an early post-Messinian (Pliocene) isolation of Nesiotites in both islands is quite unlikely.     

Eomyops noeliae sp. nov., a new Eomyidae (Mammalia,Rodentia) from the Aragonian of Spain

A new species of Eomyops, Eomyops noeliae, is described. from the locality MT-20A (Morteral section, Magro basin, eastern Spain). It is intermediate in size between the large eomiid, E. hebeiseni, and the small species of the group E. catalaunicus, E. bodvanus and E. oppligeri. The age range is Lower Aragonian. MT-20A is located between deposits that contain Megacricetodon primitivus and M. collongensis. Morphologically, E. noeliae sp. nov. is clearly different from the rest of species of the genus, due to an important reduction of the lingual anteroloph of M^1,2,3 and the labial anterolophid of M₃. The lower incisor shows two parallel ridges along the enamel like the type species of the genus, E. catalaunicus. This character is basic for the distinction between Eomyops and the North American genus Leptodontomys.     

Evolutionary trends in Mio-Pliocene Leporinae, based onTrischizolagus (Mammalia, Lagomorpha)

New material ofTrischizolagus dumitrescuae from Moldova and Ukraine is described. The variation of p3 inTrischizolagus shows the gradual shift of morphotype frequencies from the ‘Hypolagus’ pattern in Turolian through the mixture of three patterns (including ‘Nekrolagus’ morphotype) in Early Ruscinian to the dominant ‘Alilepus’ pattern in the Late Ruscinian samples. These transformations took place parallel to that of the North AmericanNekrolagus. Probably North AmericanSylvilagus, Brachylagus, andRomerolagus had an North American origin fromNekrolagus, whereas Eurasiatic and AfricanOryctolagus, Caprolagus, Nesolagus, andPoelagus could have originated in the Old World fromTrischizolagus.     

Foraging behaviour of the Brazilian squirrelSciurus aestuans (Rodentia, Sciuridae)

We describe the foraging behaviour of the Brazilian squirrelSciurus aestuans Linnaeus, 1776 in a natural free-living population, in an area with a high concentration of palm fruitsSyagrus romanzoffiana (Chamisso) Glassman. Our objective was to investigate if the abundance ofS. romanzoffiana fruits, an important food item for squirrels, temporally influenced the foraging behaviour of this population. The observations were carried out over an eight-month (April–November 2001) period. Fruiting phenology ofS. romanzoffiana was also monitored. The most consumed food item for this period was the fruit ofS. romanzoffiana (70%), followed by foods of human origin (14%). The percentage of time spent feeding increased in September, and the time spent travelling declined in September, October and November, when females were observed showing evidence of reproductive activity. At the same timeS. romanzoffiana fruits become available. The consumption of human items illustrates the opportunistic feeding habit of these squirrels, but variations in foraging behaviour detected probably were more strongly related to availability ofS. romanzoffiana fruits.     

Comparative study of the phylogenetic structure in six Apodemus species (Mammalia,Rodentia) inferred from ISSR-PCR data

The utility of the Inter Simple Sequence Repeat-Polymerase Chain Reaction (ISSR-PCR) was explored in order to determine genetic variation in six species of the genus Apodemus (A. flavicollis, A. sylvaticus, A. uralensis, A. agrarius, A. mystacinus and A. epimelas) at the individual level, population level, in separate geographic samples and in the species as a whole. Six optimized primers produced highly reproducible and polymorphic DNA markers with 98.3% polymorphic bands on a total sample of 91 individuals from 32 localities in Europe and Asia. Moreover, each primer allowed for an exact diagnosis of each of the six Apodemus species and thus provides a simple and reliable tool for the hitherto problematic discrimination of species from the subgenus Sylvaemus. Genetic distances between species ranged from 0.079, among the closely related A. flavicollis and A. sylvaticus, to 0.203 between A. mystacinus and A. agrarius. A. flavicollis, A. uralensis and A. sylvaticus display a strong population substructure. The range of genetic distances among geographic samples within last two species reaches the values obtained for closely related species. ISSR markers proved to be a simple and reliable tool for species diagnosis, as well as for estimating genetic diversity below the species level and for closely related species, but they showed questionable reliability for larger genetic distances.     

New species of Hispanomys (Rodentia,Cricetodontinae) from the Upper Miocene of Batallones (Madrid,Spain)

Material of Hispanomys (Rodentia, Cricetodontinae) is described from various localities at Batallones (MN10) (Madrid, Spain). All of it belongs to a single species, which differs from the other known species of the genus and a new taxon, Hispanomys moralesi sp. nov. , is created for it. The samples from the various localities show differences interpreted as being the result of slight age disparities amongst the different sites. Although they were previously thought to be coeval, Batallones 10 is probably older than Batallones 1, which is possibly older than Batallones 3. Hispanomys moralesi sp. nov. is characterized by several morphological features such as the lack of cingula and mesolophs, the presence of well‐developed ectolophs, four‐ or five‐rooted M1, short or absent mesolophids, and reduced and simplified M3. Hispanomys moralesi sp. nov. is a relatively derived species, the evolutionary stage of which is comparable to those of other members of the genus from the Upper Vallesian. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 725–747.     

Impact of radio-collars on Yellow-necked Mice, Apodemus flavicollis (Mammalia, Rodentia)

The impact of wearing a radio-collar was investigated for 124 Yellow-necked Mice Apodemus flavicollis, in mixed deciduous woodlands. Collared mice neither lost more weight nor lost weight more frequently than control individuals. The cost of wearing a collar was not greater for small individuals than for larger ones. The impact of wearing a radio-collar was mostly due to the shape and size of the radio-collar and the external antenna rather than the package weight. This aspect was particularly acute in the presence of ticks. One solution to this problem may be to build and use radio-transmitter packages as compact (but nevertheless resistant to gnawing) and symmetrical as possible and to use collars impregnated with tick repellent.     

A New Genus of Aplodontid Rodent (Mammalia,Rodentia) from the Late Oligocene of Northern Junggar Basin,China

A new genus and species of aplodontid rodent, Proansomys dureensis, from the late Oligocene of the northern Junggar Basin of China is described. The new genus is referred to as Ansomyinae because the ectoloph on the upper cheek teeth, although not fully crested, has attained the same characteristic bucket-handle-shaped configuration as other members of the subfamily. It represents the earliest record of the subfamily yet discovered in Asia and is more plesiomorphic than species of the genus Ansomys in having a partly crested ectoloph, a lower degree of lophodonty, and less complex tooth basins (lacking accessory lophules). Proansomys has transitional features between Prosciurus and Ansomys, suggesting that the Ansomyinae derived from a group of aplodontids related to Prosciurus, as did other advanced aplodontid rodents. This provides new light on the paleobiogeography of the Ansomyinae.     

A new species of Orycteropodidae (Mammalia, Tubulidentata) in the Mio-Pliocene of northern Chad

A new species of fossil Tubulidentata has been found by the Mission Paléoanthropologique Franco-Tchadienne in Northern Chad. It is the first fossil Orycteropodidae (aardvark) from the Mio-Pliocene of Central Africa. The new taxon, Orycteropus abundulafus sp. nov. , is considered in the framework of the available Orycteropodidae fossil record. The Chadian specimen is characterized by the highest dental robustness index among all Tubulidentata, the presence of crests on the pterygoid, the triangular-shaped olecranon fossa and the reduction of the deltoid crest. All of these characters are linked to a less fossorial animal that had a tougher diet. This new African species is closer to the Eurasian O. gaudryi than to any other Tubulidentata. Together they form a clade distinct from that which includes O. afer . This is the first evidence of a relationship for aardvarks between Africa and Eurasia. An initial step is made towards revision of the phylogeny of the order.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 143 , 109–131.     

中国四种鼯鼠的头骨形态学(英文)

针对长期以来有关鼯鼠分类地位的争议,该研究基于查看、测取60号鼯鼠成体头骨(每号头骨测取26个可量性状)共计1560个数据,运用多变量、单变量分析方法,对鼯鼠属(Petaurista)中的P.yunanensis,P.philippensis,P.hainana以及P.petaurista头骨可测量数据进行了统计学分析,以探讨上述4种鼯鼠的头骨形态差异以及P.yunanensis和P.hainana的分类地位。结果显示:(1)上述可测量头骨性状在该4种鼯鼠中不存在性二型现象;(2)上述4种鼯鼠在所测量的头骨性状上两两间均存在显著差异;(3)P.philippensis与P.hainana之间的头骨形态差异程度远大于P.yunanensis与P.philippensis之间的差异。该结果在宏观统计分析水平上为上述4种鼯鼠的种地位有效性提供了佐证,与前人基于分子水平(mtDNA)的种地位有效性研究结果相似。     

Genetic connections and differentiation of ground squirrels Marmotinae Pocock, 1923 (Rodentia, Sciuridae) from Palearctics]

Genetic distances between eight species of sousliks (Spermophilus) and five species of marmots (Marmota) were estimated on the basis of 39 biochemical loci. All taxa were shown to be genetically discrete. The genetic differentiation was minimal (Pfd = 11.3) between parapatric species of Palearctic sousliks of the suslicus pigmaeus group and Marmota species, intermediate (Pfd = 34.7) between allopatric sousliks species, and maximal (Pfd = 56.7) between representatives of different genera. The following trends were revealed in the geographic differentiation of the genus Spermophilus: (1) genetic similarity was associated with the geographic distance; (2) the eastern and western Palearctic phyla were markedly different genetically; (3) the eastern Palearctic forms exhibited higher differentiation than the western ones. The revealed speciation pattern is consistent with the general trend of temporal differentiation in Palearctic phyla and confirms the periodic speciation mode in the Palearctics.     

Mandible of Golunda (Rodentia,Mammalia) from the Upper Siwalik Subgroup of Jammu,India

A left mandibular fragment bearing M₁–M₃ recovered from the mudstones underlying an Upper Siwalik bentonitised tuff exposed 0.375 km NW of Barakhetar village, Jammu district, Jammu and Kashmir (state), India, is described here. The new specimen represents the first mandibular fragment of fossil Golunda with all three molars in situ. Based on crown morphology of the molars, it is tentatively referred to Golunda kelleri Jacobs, 1978, possibly representing a lineage distinct from G. ellioti ancestry.     

New data on the Cainotheriidae (Mammalia, Artiodactyla) from the early Oligocene of south-western France

The Cainotheriidae are small artiodactyls that suddenly appeared in the late Eocene of western Europe. A revision of early Oligocene cainotheriid lineages is proposed on the basis of newly dated material from the Quercy Phosphorites (south-western France). A significant diversification of the group occurred at the end of the Eocene. Few species seem to have persisted through the Eocene/Oligocene boundary, but the Cainotheriidae subsequently diversified rapidly during the early Oligocene.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 144 , 145−166.