Francisco Javier Ruiz-Sánchez

Evidence for an African-Iberian mammal dispersal during the pre-evaporitic Messinian

The accurate timing of biogeographic dispersal can be determined by examining the age of fossiliferous strata on either side of a physical barrier. Here we show that African mammals migrated to Iberia and European mammals migrated to North Africa at the same time before isolation of the Mediterranean Sea during the Messinian. The fossil site of Venta del Moro (Spain) exhibits western Europe’s most complete vertebrate fauna for the latest Miocene. Its uniquely cosmopolitan assemblage is evidence of faunal dispersals from Africa and Asia to Europe during the latest Miocene glaciation. A preliminary paleomagnetic study suggested an age of 5.8 Ma for this site, but our expanded magnetostratigraphy dates the site at 6.23 Ma. In addition, we recalibrated the paleomagnetic age of the Librilla site (Spain) and the North Africa site of Afoud-1 (Morocco) using the Astronomical Tuned Neogene Time Scale. Our results show a two-way African-Iberian mammal dispersal just before 6.2 Ma. These new ages indicate that an ephemeral land corridor existed between the two continents 250 k.y. before the onset of the Messinian Salinity Crisis, reflecting a tentative initial isolation of the Mediterranean Sea. This corridor developed after tectonics closed the Betic Seaway at 6.3 Ma and during the intensification of the latest Miocene glaciation at 6.26 Ma, when water circulation in the Mediterranean became very restricted.

Mio-Pliocene rodent assemblages from Alcoi Forn (Alcoy Basin, Eastern Spain). Biostratigraphical and palaeoclimatical inferences

Abstract In this work, we describe four new micromammal sites in the northern side of the Gormaget ravine, in the Alcoy Basin (Spain): AF-1’06, AF-1’07, AF-1A and AF-2. Based on the study of the faunal remains from these localities, we infer a latest Turolian-earliest Ruscinian age for AF-1’06 and AF-1A, and an earliest Ruscinian age for AF-1’07 and AF-2. The species assemblage of the locality AF-1’06, the only one which have yielded a sufficient number of remains to perform a palaecological analysis, shows warm and dry conditions near the Mio-Pliocene boundary in the Alcoy Basin. These data show a reduction of dry and warm indicators from older to younger localities in the Alcoy Basin, suggesting a change to colder and more humid conditions during the Early Pliocene.

Apocricetus barrierei (Rodentia, Mammalia) from La Bullana 2B and La Bullana 3 (Cabriel Basin, Valencia, Spain). Revision of the Late Miocene–Early Pliocene forms of the genus Apocricetus

Apocricetus Freudenthal et al. (Treballs del Museu de Geologia de Barcelona 7: 11–93, 1998) is a medium to large Cricetinae, practically without mesolophids in the m1 and m2, with long third molars; anterior and posterior protolophule are present and the posterior metalophule is reduced or absent. Apocricetusbarrierei (Mein and Michaux Comptes Rendus Academie de Sciences de Paris D 270: 2780–2783, 1970) was defined on the basis of three specimens from the French locality Chabrier. Apart from this site, several French and Spanish localities of Early Pliocene age contain remains of this species. Despite this extra material, the species is poorly characterized, and none of the localities contains material of all six dental elements. In this paper, two new assemblages from La Bullana 2B and La Bullana 3 (Cabriel Basin, Spain) are described. The rich assemblage from La Bullana 2B provides a better insight in the metrical and morphological variability of this species.KurzfassungApocricetus Freudenthal et al. (Treballs del Museu de Geologia de Barcelona 7: 11–93, 1998) ist eine mittelgrosze bis grosze Cricetine, fast ohne Mesolophid in m1 und m2, lange dritte Molaren; vorderer und hinterer Protolophulus und hinterer Metalophulus reduziert oder fehlend. Apocricetusbarrierei (Mein and Michaux Comptes Rendus Academie de Sciences de Paris D 270: 2780–2783, 1970) gründet sich auf drei Zähnen aus der Französischen Lokalität Chabrier. Daneben ist sie dokumentiert in verschiedenen Französischen and Spanischen frühpliozänen Fundstellen. Die Art ist mangelhaft charakterisiert und keine seiner Fundstellen enthält Material von allen sechs Zahnpositionen. In dieser Arbeit beschreiben wir zwei neue Populationen aus La Bullana 2B und La Bullana 3 (Cabriel Becken, Spanien). Die reiche Aufsammlung aus La Bullana 2B erlaubt eine bessere Einsicht in die metrische and morphologische Variabilität dieser Art.

A New Species of Glirid Rodent Vasseuromys from the Aragonian (Miocene) of the Ebro Basin (North-Eastern Spain)

We describe a new species of Vasseuromys from the locality of Pico del Fraile 2 (PF2) in the Ebro Basin of northeastern Spain, which has yielded a fauna comprising several rodents and insectivores (Eumyarion cf. weinfurteri, Megacricetodon cf. primitivus, Democricetodon aff. hispanicus, Spermophilinus cf. besana, Microdyromys cf. legidensis, Galerix sp., and Lagomorpha indet.) indicative of Aragonian zones C or D. Vasseuromys cristinae sp. nov. differs from other Vasseuromys species in the constant presence of four extra ridges on the lower molars, one of them being connected to the posterolophid in the posterior valley, as well as three extra ridges on the upper molars, with none of them located outside the trigone. Morphological comparisons of this new taxon to other Vasseuromys species from the western Mediterranean area allow the reconstruction of their phylogenetic interrelationships during the Early and Middle Miocene of Europe, suggesting that V. cristinae sp. nov. is a descendant of V. autolensis.

Sierra del Colmenar 1A, a new late Messinian (Late Miocene) locality in the Bajo Segura Basin (SE Spain): biostratigraphic and palaeoenvironmental implications

Abstract In this paper, we have studied a new micromammal site from the Sierra del Colmenar section (Elche, SE Spain), named Sierra del Colmenar 1A (SCO-1A), representing the uppermost levels of Messinian age of the Bajo Segura Basin. The sedimentary context of this locality corresponds to a costal lagoon with marine influence. The fossil site has yielded remains of Apodemus aff. gorafensis, Paraethomys meini, Apocricetus alberti, Occitanomys alcalai, Ruscinomys sp., Eliomys cf. truci, Muscardinus sp., Parasorex ibericus, Prolagus michauxi and Soricidae indet. Based on this assemblage, we propose a Late Miocene age (MN13) for the locality SCO-1A, matching the previously inferred age for the stratigraphic unit in which the fossil site is situated. According to its faunal composition, we infer warm and humid climate conditions in the moment of formation of this locality, agreeing with the environmental conditions of the Messinian age in a parallic sedimentary context.

Muridae from the late Miocene site of Venta del Moro (Eastern Spain)

Abstract Murids are usually the dominant faunas of the late Miocene and early Pliocene micromammal assemblages. The present work deals with the murid faunas of the well-known late Miocene locality of Venta del Moro, comprising over 2700 molars ascribed to the taxa Apodemus gorafensis, Occitanomys alcalai, Paraethomys meini and Stephanomys dubari. This list differs from those of previous studies by the presence of A. gorafensis instead of A. gudrunae. The presence of A. gudrunae in younger localities than Venta del Moro implies that both species, considered ancestor and descendant, coexisted for some time. In addition, the analysis of such an extensive collection has allowed us to check the variability of the studied species in great detail, such as the development of the longitudinal connections of O. alcalai, to a greater extent than previously described. Finally, we discuss the biometrical changes of the lineages of Paraethomys in Southern Europe from MN13 to MN15, and hypothesize about the mechanisms behind these variations in size.

A new species of Vasseuromys (Gliridae, Mammalia) from the Upper Oligocene of the Ebro Basin (Spain)

In this paper, a new species of Vasseuromys, V. bergasensis sp. nov., from the locality of Bergasa (Ebro Basin, Spain), is described. Bergasa contains a fauna belonging to the Late Oligocene (zone MP30), composed—among other species—of Issiodoromys pseudanaema and Rhodanomys transiens. The main diagnostic features of V. bergasensis sp. nov. are the presence of a long centrolophid (fused or not to the mesoconid) in the lower molars, a large reduction in the number and length of extra ridges in the upper and lower molars, the absence of extra ridges between metalophid and centrolophid and between centrolophid and mesolophid, and the absence of the metatrope in more than half the specimens of the upper teeth M1 and M2. V. bergasensis sp. nov. is similar in size to V. elegans and smaller than the other members of the genus. The age and simple dental pattern of the new species of Vasseuromys allow us to hypothesize about relationships within the genus.KurzfassungIn dieser Arbeit wird eine neue Art von Vasseuromys, V. bergasensis sp. nov., aus der Lokalität Bergasa (Ebro Becken, Spanien) beschrieben. Bergasa enthält eine Fauna des späten Oligozän (Zone MP30) mit, unter anderen Arten Issiodoromys pseudanaema und Rhodanomys transiens. Die wichtigste diagnostische Merkmale von V. bergasensis sp. nov. sind: ein langes Centrolophid, verbunden oder nicht mit dem Mesoconid, in den unteren Backenzähnen, die starke Reduzierung der Anzahl und der Länge der zusätzlichen Rippen in den oberen und unteren Molaren, die Abwesenheit von zusätzlichen Graten zwischen metalophid und centrolophid und zwischen Centrolophid und Mesolophid und die Abwesenheit des Metatropes in mehr als die Hälfte der M1,2. Die Größe des V. bergasensis sp. nov. ist V. elegans ähnlich, und kleiner als die anderen Arten der Gattung. Das Alter und das einfache Zahnmuster der neuen Art erlauben Hypothesen auf die Beziehungen innerhalb der Gattung.

A new species of Plesiodimylus (Dimylidae, Eulipotyphla, Mammalia) from the Early Miocene of Spain

Abstract We report a new dimylid species, Plesiodimylus ilercavonicus sp. nov., from the Early Miocene locality of Mas d’Antolino B-5 (Ribesalbes-Alcora, Castelló, Spain). This new species of Plesiodimylus is an amblyodont form of the genus and exhibits some primitive characters. The phylogenetic and palaeoenvironmental implications of this southern occurrence of Plesiodimylus in Lower Miocene sediments are discussed. http://zoobank.org/lsid:zoobank.org:pub:E78DB979-6552-4BE2-BEC9-FA2EA05B7B39

Vasseuromys rambliensis sp. nov. (Gliridae, Mammalia) from the Ramblian (Lower Miocene) of the Tudela Formation (Ebro basin, Spain)

In this paper, a new species of Vasseuromys, V. rambliensis sp. nov., from the locality Pico del Fraile 1 (PF1, Ebro basin, North-eastern Spain) is described. The association of Ligerimys, Peridyromys murinus and Simplomys simplicidens, and the absence of Eucricetodon and Democricetodon, allows dating of the PF1 locality as Late Ramblian (Early Miocene, MN3, local zone A). Main diagnostic features of V. rambliensis sp. nov. are the presence of four extra ridges in the lower molars, a very reduced anterotropid and a metaloph connected to the posteroloph and not to the protocone. The size and morphology of V. rambliensis sp. nov. are very close to V. bacchius from the upper part of unit MN2, from which it may have been derived. The new data allow a better understanding of the relationships within this genus and its biostratigraphy.

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.