First evidence of faunal succession in terrestrial vertebrates of the Plio-Pleistocene of the Balearic Islands,western Mediterranean

Terrestrial vertebrates from the karst filling in Cap d’Artrutx, situated in the extreme Southwest of Menorca (Balearic Islands, western Mediterranean) have yielded interesting information on the migration and extinction dynamics in the terrestrial island vertebrate faunas in Mallorca and Menorca between the late Pliocene and early Pleistocene. In this site, remains of the Menorcan giant tortoise (“Testudo” gymnesica Bate, 1914) and two mammals (Nesiotites sp. and Hypnomys sp.) have been found. The remains of the Menorcan giant tortoise represent the youngest record of this species and of the so-called second faunistic group of the island. The morphology and size of Nesiotites sp. are comparable to those of Nesiotites aff. ponsi Reumer, 1979 from the Plio-Pleistocene of Pedrera de S’Ònix (Mallorca) and Nesiotites meloussae Pons and Moyà, 1980 (= Nesiotites aff. ponsi sensu Pons-Monjo et al., 2012) from the lower Pleistocene of Binigaus (Menorca). Hypnomys sp. can belong to an archaic species not yet described. They represent the first evidence of the entrance of the third faunistic group, which originally evolved on the neighbouring island of Mallorca. This association is interpreted, therefore, as the first evidence of a faunal succession in the Plio-Pleistocene in the Balearic Islands.     

Ancient DNA from an extinct Mediterranean micromammal—Hypnomys morpheus (Rodentia: Gliridae)—Provides insight into the biogeographic history of insular dormice

The dormice (Gliridae) are a family of rodents represented by relatively few extant species, though the family was much more species-rich during the Early Miocene. Intergeneric phylogenetic relationships among glirids in some cases remain unresolved, despite extensive molecular and morphological analyses. Uncertainty is greatest with respect to the relationships among fossil taxa and how extinct lineages are related to modern species. The fossil genus Hypnomys from the Balearic Islands (western Mediterranean Sea) includes the Late Pleistocene–Holocene species Hypnomys morpheus, which has variously been considered a close relative or subgenus of the extant Eliomys. In the present study, we sequenced ancient mitochondrial DNA from H. morpheus, which suggests a sister relationship with the extant members of Eliomys. In addition, the pairwise sequence variation between Hypnomys and Eliomys is higher than that observed between congeneric glirid species (e.g., many Graphiurus spp.), which allows us to reject the hypothesis that Hypnomys is a subgenus of Eliomys. Our molecular dating analyses suggest that Hypnomys and Eliomys diverged 13.67 million years ago (95% highest posterior density [HPD] = 7.39–20.07). The relatively early split between these genera together with the molar morphology of early representatives of Hypnomys points to a Middle-Late Miocene origin from a continental glirid with a complex molar pattern, such as Vasseuromys or a closely related genus.     

Extinction of the autochthonous small mammals of Mallorca (Gymnesic Islands, Western Mediterranean) and its ecological consequences

Aim To investigate the chronology, causes and consequences of the extinction of the autochthonous Pleistocene small mammals of Mallorca. Location Mallorca (Gymnesic Islands, Balearics, Western Mediterranean). Methods We have obtained the first direct ¹⁴C ages from the bone collagen of selected samples of two extinct endemic small mammals from Mallorca: the Balearic dormouse, Eliomys morpheus (Rodentia: Myoxidae) and the Balearic shrew, Asoriculus hidalgoi (Soricomorpha: Soricidae). We also present evidence for the absence of both endemics from the earliest Mallorcan archaeological sites and for the introduction of the garden dormouse, Eliomys quercinus, and the wood mouse, Apodemus sylvaticus. Combined information from direct dating of bone collagen of E. quercinus and A. sylvaticus and from cultural associations provides an adequate framework to establish the chronology of the faunal change and to compare it with the chronological information available on climatic change and the first arrival of humans on the islands. Results The chronological record includes the latest evidence available for the survival of endemic species and the earliest introduction of small mammals into Mallorca. We present ‘uncertainty periods for extinction’ (UPEs) of both endemic mammals based on the chronology of their last occurrence and on the inferred timing of their extinction (restricted UPEs). Main conclusions Possible causes for the extinction of autochthonous small mammals on Mallorca are discussed. Once we have discarded climatic causes, predation by invasive species, competition with newcomers and habitat deterioration, the introduction of diseases emerges as the most reasonable explanation for these extinctions. Based on the identification of changes in keystone species in Mallorcan ecosystems, we propose a tentative schedule of key ecological changes that have taken place over the past 5 millennia.     

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.     

Une nouvelle forme insulaire d'Effraie geanteTyto balearica N. sp., (Aves,Strigiformes), du Plio-Pleistocene des Baleares

Tyto balearica is a barn owl whose size is about one and half larger than the size of modern barn owls, Tyto alba. It was found in Mallorca and Menorca, in sites dating back from the end of Pliocene and the beginning of Pleistocene. Numerous insular forms of giant barn owls are known in Mediterranean islands and in West Indies.     

Une espèce géante de MuscardinusKaup, 1829(Gliridae,Rodentia, Mammalia) dans le gisement karstique de Cala Es Pou (Miocène supérieur de Minorque,Baléares)

In this paper, Muscardinus cyclopeus nov. sp., from the locality of Cala Es Pou, in Menorca (Balearic Islands)), is described. M. cyclopeus is close to M. viretiHugueney & Mein, but shows a greater size. This species belongs to a new phase of insularity in the Balearic Islands, different from the classical Myotragus-Hypnomys-Nesiotites faunas. This phase may be due to variations in the sea level within the Messinian. Other elements belonging to this phase are: Geochelone gymnesicaBate, cf. Alilepus nov. sp. and Rhinolophus cf. grivensis (Deperet).     

Early evidence of Prunus and Prunus cf. amygdalus from Palaeolithic sites in the Khorramabad Valley,western Iran

Along with the early age obtained for the cultural remains attributed to anatomically modern humans from Kaldar Cave, the archaeological assemblages recovered from both Kaldar and Gilvaran Cave located in the Khorramabad Valley (Iran), have yielded charcoal remains that allow the identification of Prunus spp. These remains correspond to the Middle and Upper Palaeolithic, which are the earliest finds attesting to the presence of this taxa in the area. Our anatomical observation of the samples revealed the presence of Prunus spp. (plums) and Prunus cf. amygdalus (cf. almond). This also reflects specific plant communities in the area, characteristic of open forest growing in cool, dry conditions. These results provide new insights into the arboreal cover in this area during an Upper Pleistocene period. Furthermore, anthracological evidence together with other contextual materials provides new clues to assess how Neanderthals and early modern humans adapted to their surrounding landscape, and their relationship with their environment in this region and beyond.     

Radiocarbon evidence for a prehistoric deliberate translocation: the weasel (Mustela nivalis) of Mallorca

We present radiocarbon evidence for the presence of the weasel (Mustela nivalis) on Mallorca prior to the Roman colonization of the Balearics. Bone collagen from a single specimen recovered at Cova del Ninot, Mallorca rendered two radiocarbon ages, independently obtained at two laboratories (2σ interval: 386–206 cal BC). These dates indicate that the translocation of the weasel to Mallorca occurred in Late Prehistory. The inhabitants of Mallorca at that time were the Talaiotic people (Iron Age settlers of the Balearics). The weasel appears to have been introduced by Talaiotic mercenaries returning to the island on Carthaginian ships. This is the first documented case of the translocation of a wild carnivorous mammal to the Gymnesic Islands (i.e., Mallorca and Menorca) in prehistoric times. Some ecological consequences of this invasion are outlined.     

A new whale barnacle from the early Pleistocene of Italy suggests an ancient right whale breeding ground in the Mediterranean

The fragmentary fossil history of whale barnacles (Cirripedia: Coronulidae) is mainly constituted by remains of Coronula spp. in Plio-Pleistocene deposits found along extant humpback whale migration routes, and especially in occurrence of breeding areas. Here we report the presence of a single compartment of Cetopirus along with remains of Coronula bifida in Lower Pleistocene open shelf deposits of Salento (South Italy). This is the first occurrence of the genus Cetopirus prior to the Late Glacial period (ca. 15–10 ky before Present), and the specimen here studied is designated as the holotype of the new fossil species Cetopirus fragilis. Since Cetopirus is currently found exclusively inhabiting the skin of the right whales (Eubalaena spp.), the fossil material here studied suggests the persistence of Balaenidae in the Mediterranean Basin during the Early Pleistocene and supports the existence of a baleen whale migratory route active between the central Mediterranean and the North Atlantic during the Plio-Pleistocene.     

Morphological divergence in giant fossil dormice

Insular gigantism—evolutionary increases in body size from small-bodied mainland ancestors—is a conceptually significant, but poorly studied, evolutionary phenomenon. Gigantism is widespread on Mediterranean islands, particularly among fossil and extant dormice. These include an extant giant population of Eliomys quercinus on Formentera, the giant Balearic genus †Hypnomys and the exceptionally large †Leithia melitensis of Pleistocene Sicily. We quantified patterns of cranial and mandibular shape and their relationships to head size (allometry) among mainland and insular dormouse populations, asking to what extent the morphology of island giants is explained by allometry. We find that gigantism in dormice is not simply an extrapolation of the allometric trajectory of their mainland relatives. Instead, a large portion of their distinctive cranial and mandibular morphology resulted from the population- or species-specific evolutionary shape changes. Our findings suggest that body size increases in insular giant dormice were accompanied by the evolutionary divergence of feeding adaptations. This complements other evidence of ecological divergence in these taxa, which span predominantly faunivorous to herbivorous diets. Our findings suggest that insular gigantism involves context-dependent phenotypic modifications, underscoring the highly distinctive nature of island faunas.     

Understanding Late Quaternary extinctions: the case of Myotragus balearicus (Bate, 1909)

Aim In this study we present a new view on the extinction of Myotragus balearicus, an extinct highly modified dwarf caprine from the Gymnesic Islands (or eastern Balearic Islands), as a methodological case study for interpretation of Late Quaternary extinctions (LQEs). Methods We analyse all available ¹⁴C ages obtained from M. balearicus bones from the uppermost part of the Pleistocene and the Holocene, together with the available chronological data of the putative causes of Myotragus extinction. Results It has been possible to define two critical dates that allow us to establish an ‘uncertainty period for the Myotragus extinction’ (UPME) in each analysed island (Mallorca, Menorca and Cabrera). For Mallorca, the UPME corresponds to the interval c. 3700 to 2030 calbc (i.e. c. 1670 years of uncertainty). In the case of Menorca, the UPME spans from 10,000 to 1930 calbc (8070 years of uncertainity). In Cabrera the UPME is placed between 3650 and 300 calbc (3350 years of uncertainty). These periods, together with a review of the available information on the chronology of human arrival and the chronology of Holocene climatic change, shed light on the possible causes of the extinction of this species. Main conclusions Extinction of Myotragus because of climatic change can be definitively rejected. The Myotragus extinction must be attributed to the rapid effects of the first human occupation. The use of uncertainity periods for the disappearance of species represents a useful tool for the analysis of LQEs.     

Arboreal gaits in three sympatric rodents Apodemus agrarius,Apodemus flavicollis (Rodentia,Muridae) and Myodes glareolus (Rodentia,Cricetidae)

Vertical stratification of the arboreal habitat allows the coexistence of several species in a given area, because the complex arboreal strata can be used in different ways by arboreal and scansorial mammals. The present report experimentally investigated the gait metrics on different arboreal substrates, of three sympatric rodents living in a deciduous forest in Poznań, Poland. Arboreal locomotion was compared between the burrowing striped field mouse, Apodemus agrarius, the scansorial bank vole, Myodes glareolus, and the more arboreal yellow-necked mouse, Apodemus flavicollis. We filmed two wild-caught individuals from each species walking on four different substrate diameters (2 mm, 5 mm, 10 mm, 25 mm) and three different inclinations (45° descending, horizontal, 45° ascending) at 240 fps and collected a set of gait parameters from a total of 273 complete cycles. Our results did not demonstrate clear relationships between arboreal locomotion and the ecology of the three species. Only A. flavicollis exhibited locomotor features partly associated with arboreal competence, including lower velocity and diagonality on narrow substrates and asymmetrical gaits on wider ones. On the other hand, the two Apodemus species, despite their different ecologies, shared a few locomotor similarities, such as velocity regulation primarily by stride frequency, and similar effects of substrate size and inclination on diagonality, duty factor, and duty factor index indicating the possibility of a phylogenetic signal. Because the selected gait parameters provided limited insight into the ability of small mammals to move competently through an arboreal habitat, these findings indicate that the relationship between behaviour and ecology is complex.     

Jumping and the aerial behavior of aquatic mayfly larvae (Myobaetis ellenae,Baetidae)

Mayfly larvae generally are aquatic, but some madicolous taxa (i.e., living in thin water films) crawl over rocks within streams and waterfalls. When startled, these larvae can break the water film, jump, and enter an aerial phase of locomotion. Because mayfly larvae have been suggested as potential exemplars for the origin of insect wings as tracheal gills, and furthermore represent the most basal extant lineage of pterygotes, we analyzed jumping behavior and free-fall trajectories for one such species of mayfly (Myobaetis ellenae, Baetidae) in Costa Rica. Jumping was commonplace in this taxon, but was undirected and was characterized by body spinning at high angular velocities. No aerodynamic role for the tracheal gills was evident. By contrast, jumping by a sympatric species of bristletail (Meinertellus sp., Archaeognatha) consistently resulted in head-first and stable body postures during aerial translation. Although capable of intermittently jumping into the air, the mayfly larvae could neither control nor target their aerial behavior. By contrast, a stable body posture during jumps in adult bristletails, together with the demonstrated capacity for directed aerial descent in arboreal representatives of this order, support ancestrally terrestrial origins for insect flight within the behavioral context of either jumping or falling from heights.     

Influence of phenological barriers and habitat differentiation on the population genetic structure of the balearic endemic Rhamnus ludovici-salvatoris Chodat and R. alaternus L.

Rhamnus ludovici-salvatoris, endemic to the Gymnesian Islands, coexists with the related and widespread R. alaternus in Mallorca and Menorca. In both species, the population genetic structure using RAPD, and flowering during a 3-year period to check for possible phenological barriers, were analyzed. Rhamnus ludovici-salvatoris showed lower genetic diversity and stronger population structure than R. alaternus, the Cabrera population being less diverse and the most differentiated. Rhamnus ludovici-salvatoris flowered one month later, although flowering of both species coincided sporadically. These congeners seem to have diverged through isolation by time and differentiation in habitat. The population genetic structure of R. ludovici-salvatoris could mainly be due to the existence of small populations on the one hand, and a gene flow caused by rare hybridization events on the other, which may also explain the presence of morphologically intermediate individuals in Menorca. The conservation of R. ludovici-salvatoris populations may include population reinforcements and other in situ interventions.     

Vue d'ensemble de la végétation des Îles Baléares

Résumé La végétation des îles Baléares est nettement méditerranéenne. Les climax forestiers appartiennent à l'alliance méditerranéenne septentrionale du Quercion ilicis (parties pluvieuses de Majorque et de Minorque) et à l'alliance méditerranéenne méridionale de l'Oleo-Ceratonion (Querco-Lentiscetum d'affinité ibérique à Ivice; groupement àCeratonia siliqua etCneorum tricoccum dans la partie sèche de Majorque, groupement àOlea europaea etPrasium majus dans la partie la plus sèche de Minorque). Des groupements riches en endémiques caractérisent le karst des hauts sommets de Majorque et les rochers littoraux des côtes venteuses de Majorque et de Minorque. L'influence tyrrhénienne, importante dans les Gymnésies (Majorque et Minorque) est bien plus faible dans le groupe des Pithyuses (Ivice et Formentera), plus rapproché de la Péninsule Ibérique.

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Summary The vegetation of the Balearic Islands is pure mediterranean. The climax forests belong to the northern mediterranean alliance of the Quercion ilicis (rainy regions in Majorca and Menorca) and to the southern mediterranean community of the Oleo-Ceratonion (Querco-Lentiscetum with Iberic affinity in Ibiza; community withCeratonia siliqua andCneorum tricoccum in the dry region in Majorca, community withOlea europaea andPrasium majus in the driest region in Menorca). Communities rich in endemic plants characterize the karst of the high summits in Majorca, and coastrocks of the windy shores in Majorca and Menorca. The tyrrhenic influence, important in the Gymnesies (Majorca and Menorca), is more feeble in the group of the Pithyuses (Ibiza and Formentera), nearer to the Iberic Peninsula.

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Zusammenfassung Die Vegetation der Balearischen Inseln ist rein mediterran. Die Klimaxwälder gehören zu dem nördlichen Mittelmeerverband des Quercion ilicis (regnerische Gegenden von Mallorca und Menorca) und dem südlichen Mittelmeerverband des Oleo-Ceratonion (Querco-Lentiscetum mit iberischer Verwandtschaft auf Ibiza; Gesellschaft mitCeratonia siliqua undCneorum tricoccum in der trockenen Gegend von Mallorca, Gesellschaft mitOlea europaea undPrasium majus in der trockensten Gegend von Menorca). Endemitenreiche Pflanzengesellschaften charakterisieren den Karst der hohen Gipfel von Mallorca, und die Küstenfelsen der windreichen Küsten Mallorcas und Menorcas. Der tyrrhenische Einfluß, bedeutend in den Gymnesien (Mallorca und Menorca), ist entschieden schwächer in der Gruppe der Pithyusen (Ibiza und Formentera), die der Iberischen Halbinsel näher liegt.

     

Distal Humeral Morphology Indicates Locomotory Divergence in Extinct Giant Kangaroos

Previous studies of the morphology of the humerus in kangaroos showed that the shape of the proximal humerus could distinguish between arboreal and terrestrial taxa among living mammals, and that the extinct “giant” kangaroos (members of the extinct subfamily Sthenurinae and the extinct macropodine genus Protemnodon) had divergent humeral anatomies from extant kangaroos. Here, we use 2D geometric morphometrics to capture the shape of the distal humerus in a range of extant and extinct marsupials and obtain similar results: sthenurines have humeral morphologies more similar to arboreal mammals, while large Protemnodon species (P. brehus and P. anak) have humeral morphologies more similar to terrestrial quadrupedal mammals. Our results provide further evidence for prior hypotheses: that sthenurines did not employ a locomotor mode that involved loading the forelimbs (likely employing bipedal striding as an alternative to quadrupedal or pentapedal locomotion at slow gaits), and that large Protemnodon species were more reliant on quadrupedal locomotion than their extant relatives. This greater diversity of locomotor modes among large Pleistocene kangaroos echoes studies that show a greater diversity in other aspects of ecology, such as diet and habitat occupancy.

     

Micromammals (rodents and insectivores) from the early Late Pleistocene cave site of Bois Roche (Charente, France): Systematics and paleoclimatology

We present the study of rodents and insectivores from the 1995 season of excavation at the early Late Pleistocene site of Bois Roche (Charente, France). The site is a small cave with a low ceiling, used as a den by hyenas. It contains a large herbivore assemblage (mainly bovids and equids) with a smaller representation of medium-size taxa (cervids), many microvertebrates, abundant coprolites and deciduous hyena teeth, and a few lithic artifacts (Middle Paleolithic) introduced into the cave by gravity and slope wash. The rodent fauna consists of Eliomys quercinus cf. quercinus, Apodemus sp., Microtus gregalis, Microtus oeconomus, Arvicola terrestris and Dicrostonyx torquatus. Insectivores are represented by Neomys cf. fodiens. The most common species is M. gregalis which forms 93.7% of the total MNI. The micromammal fauna suggests an open landscape, with some vegetation mainly of the steppe or tundra type, with areas of water and more wet vegetation and some areas with trees. The micromammal association of Bois Roche is characteristic of a cold or very cold dry climate.     

Bony labyrinth morphometry indicates locomotor adaptations in the squirrel-related clade (Rodentia,Mammalia)

The semicircular canals (SCs) of the inner ear detect angular acceleration and are located in the bony labyrinth of the petrosal bone. Based on high-resolution computed tomography, we created a size-independent database of the bony labyrinth of 50 mammalian species especially rodents of the squirrel-related clade comprising taxa with fossorial, arboreal and gliding adaptations. Our sampling also includes gliding marsupials, actively flying bats, the arboreal tree shrew and subterranean species. The morphometric anatomy of the SCs was correlated to the locomotion mode. Even if the phylogenetic signal cannot entirely be excluded, the main significance for functional morphological studies has been found in the diameter of the SCs, whereas the radius of curvature is of minor interest. Additionally, we found clear differences in the bias angle of the canals between subterranean and gliding taxa, but also between sciurids and glirids. The sensitivity of the inner ear correlates with the locomotion mode, with a higher sensitivity of the SCs in fossorial species than in flying taxa. We conclude that the inner ear of flying and gliding mammals is less sensitive due to the large information flow into this sense organ during locomotion.     

Locomotor Behavior and Body Mass of Paramys delicatus (Ischyromyidae,Rodentia) and Commentary on Other Early North American Paramyines

Paramyine ischyromyids are one of the first ancestral rodent groups to appear in North America. Studying ecological indicators of these extinct animals enables us to better understand how they integrated into North American mammalian communities. In this study we reassess the locomotor behavior of a nearly complete skeleton of a paramyine, Paramys delicatus (AMNH FM 12506), using functional limb indices and living squirrels as extant analogues. We then used the results of the functional limb index study to select an appropriate locomotor group for body mass estimations of Paramys delicatus and other early North American (Wasatchian-Bridgerian) paramyines. This was done because body mass is strongly tied to locomotor patterns and more reliable body mass estimates can be generated from an extant sample that functionally resembles the fossils being studied. Functional limb indices were calculated for three locomotor groups (arboreal, semifossorial, and gliding) of living sciurids. Comparisons among arboreal, semifossorial, and gliding sciurids show that the functional indices related to mechanical advantage of muscles and limb robusticity enable distinction among locomotor groups; however, there is considerable overlap between arboreal and semifossorial taxa. Paramys delicatus was found to have generally greater mechanical advantages and limb robusticity than most living squirrels, including semifossorial taxa. As these traits are associated with semifossorial squirrels that frequently use scratch-digging, this suggests that Paramys delicatus and perhaps other early paramyines were likely proficient scratch-diggers. However, indices reflecting limb proportions of paramyines suggest that these early rodents may have used more hind limb dominated locomotion than do living squirrels. Body mass estimations for early paramyines were therefore derived from a semifossorial squirrel sample. Statistical comparisons suggest that many of the most reliable estimators for body mass in Paramys delicatus and other paramyines are those derived from humeral dimensions, with the most reliable estimate being humeral head superoinferior breadth. Using these estimators, individual body mass estimates of early paramyines range from 3391 to 4005 g for Paramys delicatus, 1137–1329 g for Paramys copei, 1291 g for Paramys taurus, and 3357 g for Notoparamys costilloi. All body mass estimations derived from postcranial elements are substantially larger than previously published estimates derived from the dentition, which may be because postcranial elements play a larger role in supporting body weight.

     

Water loss, cutaneous resistance, and effects of dehydration on locomotion of Eleutherodactylus frogs

Water loss, cutaneous resistance, and the effects of dehydration on jumping ability were measured in two neotropical frogs, the common coquí (Eleutherodactylus coqui) and the cave coquí (Eleutherodactylus cooki). In both species jumping performance declined with an increase in water loss and a greater duration of exposure to dehydrating conditions. The arboreal species, E. coqui, had a slightly higher rate of water loss and lower cutaneous resistance than the non-arboreal species, E. cooki. However, differences in cutaneous resistance and water loss were too small to explain differences in geographic distributions of these species. In both species, a decline in boundary layer resistance contributed to an increased rate of water loss at higher temperature. Accepted: 4 January 1999