Skills and Expertise
Jan 2004 - Dec 2011
Museo Nacional de Ciencias Naturales
- Madrid, Spain
The National Museum of Natural Sciences
- Madrid, Spain
- Research Professor
Research Items (428)
Monitor lizards (genus Varanus) inhabited Europe at least from the early Miocene to the Pleistocene. Their fossil record is limited to about 40 localities that have provided mostly isolated vertebrae. Due to the poor diagnostic value of these fossils, it was recently claimed that all the European species described prior to the 21st century are not taxonomically valid and a new species, Varanus amnhophilis, was erected on the basis of fragmentary material including cranial elements, from the late Miocene of Samos (Greece). We re-examined the type material of Varanus marathonensis Weithofer, 1888, based on material from the late Miocene of Pikermi (Greece), and concluded that it is a valid, diagnosable species. Previously unpublished Iberian material from the Aragonian (middle Miocene) of Abocador de Can Mata (Vallès-Penedès Basin, Barcelona) and the Vallesian (late Miocene) of Batallones (Madrid Basin) is clearly referable to the same species on a morphological basis, further enabling to provide an emended diagnosis for this species. Varanus amnhophilis appears to be a junior subjective synonym of V. marathonensis. On the basis of the most complete fossil Varanus skeleton ever described, it has been possible to further resolve the internal phylogeny of this genus by cladistically analyzing 80 taxa coded for 495 morphological and 5729 molecular characters. Varanus marathonensis was a large-sized species distributed at relatively low latitudes in both southwestern and southeastern Europe from at least MN7+8 to MN12. Our cladistic analysis nests V. marathonensis into an eastern clade of Varanus instead of the African clade comprising Varanus griseus, to which it had been related in the past. At least two different Varanus lineages were present in Europe during the Neogene, represented by Varanus mokrensis (early Miocene) and V. marathonensis (middle to late Miocene), respectively.
The sequence of cheek teeth mineralization, eruption, and replacement of an extinct horse species is here documented with radiological techniques for the first time thanks to the exceptional preservation of Hipparion sp. mandibles from Cerro de los Batallones (Madrid Basin, Spain). The sequence of dental ontogeny in mammals provides valuable insights about life history traits, such as the pace of growth, and about the mode of formation of fossiliferous assemblages. We have determined that the order of permanent cheek teeth mineralization and eruption of hipparionine horses is m1, m2, (p2, p3), p4, m3. Cheek teeth mineralization timing of hipparionine horses coincides with the one observed in modern equids. In turn, there are differences in the eruption timing of the p4 and m3 between horses belonging to the Anchitheriinae and Hipparionini compared to equids of the Equus genus that might be related to the shorter durability of the deciduous tooth dp4 in anchitheriine and hipparionine horses and, more broadly, to an increased durability of equid teeth through their evolutionary history. Based on the dental eruption sequence, hipparionine horses are slow-growing, long-living mammals. The Hipparion sp. assemblage from Batallones-10 conforms to an attritional model, as individuals more vulnerable to natural mortality predominate.
The Early Pliocene site of Layna (MN15, ca 3.9 Ma) is renowned for its record of several mammalian taxa, among which the raccoon-dog Nyctereutes donnezani. Since the early description of this sample, new fossils of raccoon-dogs have been discovered, including a nearly complete cranium. The analysis and revision here proposed, with new diagnoses for the identified taxa, confirm the attribution of the majority of the material to the primitive taxon N. donnezani, enriching and clarifying our knowledge of the cranial and postcranial morphological variability of this species. Nevertheless, the analysis also reveals the presence in Layna of some specimens with strong morphological affinity to the derived N. megamastoides. The occurrence of such a derived taxon in a rather old site, has critical implications for the evolutionary history and dispersal pattern of these small canids. For instance, it reconciles the Western European and Asian records. Formerly, it was commonly thought that the evolutionary pattern of Early Plio-cene raccoon-dogs in Europe was substantially different from the Asian one, where the advanced N. sinensis and the primitive N. tingi apparently coexisted in the same sites ; conversely, Europe was characterized by the occurrence of the single species N. donnezani. Our recognition of a derived taxon in the MN15 zone suggests the existence of similar ecological dynamics at the two extremes of the paleobiogeographic range of the genus (i.e., across the entire Eurasia).
- Aug 2018
Macaques dispersed out of Africa into Eurasia in the framework of a broader intercontinental faunal exchange that coincided in time with the sea level drop associated with the Messinian Salinity Crisis. They are first recorded in Europe (Italy and Spain) by the latest Miocene, being subsequently recorded all over Europe, albeit sparsely, throughout the Pliocene and Pleistocene. These fossil European macaques are attributed to several (sub)species of the extant Barbary macaque (Macaca sylvanus). In Iberia, fossil macaques are best documented by Macaca sylvanus florentina from various Early Pleistocene sites, whereas their published Pliocene record is very scarce. Here we report the oldest post-Messinian occurrence of macaques in the Iberian Peninsula, based on the description and metrical comparisons of two upper teeth (a male canine and a third molar of two different individuals) from the early Pliocene (MN14, 5.0-4.9 Ma) site of Puerto de la Cadena (Murcia, SE Spain). The male C1 is fully comparable in morphology with those of extant and fossil M. sylvanus, and larger than those of Mesopithecus. The M3, in turn, displays the typical papionin morphology that characterizes the dentally-conservative genus Macaca-thereby discounting an alternate assignment to either the extinct colobine monkey Mesopithecus or the more dentally-derived papionin Theropithecus. Dental size and proportions of the M3 further support an attribution to an extinct subspecies of M. sylvanus instead of the larger papionin Paradolichopithecus. Mostly on biochronologic grounds, the two macaque teeth from Puerto de la Cadena are here assigned to Macaca sylvanus cf. prisca, albeit tentatively, given the lack of clear-cut criteria to distinguish this subspecies from the younger Macaca sylvanus florentina. The described material represents the oldest well-dated Pliocene record of macaques in Iberia, predating the record of Paradolichopithecus by almost 1.5 million years.
We describe new dental remains of the genus Iberictis (Carnivora: Mustelidae) from the late early Miocene of the Iberian Peninsula. The new fossils of Iberictis azanzae from Artesilla (16.5–16.3 Ma, MN4; Calatayud-Teruel Basin, Zaragoza, Spain) add important morphological information about this species. Material from another species, Iberictis buloti, is described from els Casots (16.5–16.3 Ma, MN4; Vallès-Penedès Basin, Barcelona, Spain). This material constitutes the most complete sample of Iberictis and the first record of I. buloti in the Iberian Peninsula. Our analyses confirm the taxonomic validity of both species, and confirm the more plesiomorphic status of I. buloti compared to I. azanzae. Reexamination of large mustelid Miocene genera (Dehmictis, Ekorus, Eomellivora, Hoplictis, Iberictis, Ischyrictis, and Plesiogulo) and their inclusion for the first time in a cladistic analysis indicate that Iberictis is the sister taxon of Plesiogulo, and that these genera constitute the sister group of the extant wolverine (Gulo gulo). Our analysis thus confirms a close relationship between the early Miocene Iberictis, the late Miocene Plesiogulo, and the Plio-Pleistocene Gulo. Iberictis is the oldest member of Gulonini, the total clade of wolverines, thereby tracking the fossil record of this clade back to the early Miocene. We further propose a new systematic arrangement for the aforementioned large Miocene mustelids into the subfamilies Guloninae, Mellivorinae, and Mustelinae.
The end of the Miocene was an eventful period of changes in climate and geography, and a restructuring of terrestrial plant and mammals. The tendency towards global aridification has attracted much recent interest, making the late Miocene a striking case‐study for testing current and near‐future scenarios involving global warming. Little is known about the consequences of global changes in temperature and precipitation at regional or local scales. Given its geographical position and extraordinary fossil record, the Iberian Peninsula offers many insights into short‐ and long‐term shifts in climate, and the local response. Here, we explore the diet and ecology of large‐mammals through tooth‐wear patterns, and examine changes in local climate and habitat conditions in central Spain in a period (9.1–6.3 Ma) for which there exists a dearth of palaeoenvironmental information. Relatively dry climates and open‐woodland landscapes evolved locally during the late Vallesian and early Turolian (9.0–7.7 Ma). Unexpectedly, we detect a period of high precipitation and a peak of humidity at the end of the Turolian (7.0 Ma) that prompted the development of wetter, more forested habitats, suggesting that the traditional view of the late Miocene as a steppe landscape is a misconception. We also find a period of relatively drier and warmer conditions from the early Ventian onwards. Overall, our finding that a local episode of increased humidity in central Spain was synchronous with a global warming trend in Europe provides evidence that the greatest climatic changes may have an opposite impact at regional and local scales.
Batallones-3 is one of the nine late Miocene mammalian sites found in the Batallones butte (Madrid basin, central Spain). Although the paleoartistic reconstructions of the site are detailed, a three-dimensional reconstruction of cave geomorphology would be very useful for future works. At Batallones-3, a total of 19,187 large-mammal remains have been retrieved, belonging to at least 15 different species. 99.58% of the determinated fossils can be classified as carnivoran. Remains are found as part of a fossiliferous breccia in marl, deposited inside a domically-shaped pseudokarstic cave. As a result of this geology, spatial distribution of the remains delimitates the geomorphology of the cave. Using this spatial information, a three-dimensional reconstruction of the Batallones-3 pseudokarstic cave has been produced.
- Mar 2018
Corral de Lobato, a karstic site in the area of Molina de Aragón has been studied in a preliminary way. Even though there are not many Neogene karstic sites in the Iberian Chain, they occur in four clusters, with ages ranging from latest middle Miocene (MN7/8) to early Pleistocene (MN17). Correlations between these clusters and the reference stratigraphical units of the Tagus Basin, as well as with local and global events, are proposed. These karstic sites provide a complementary source of fossil vertebrate remains to that of the stratified sites formed lowland. The Heritage significance of such sites arises from the enhanced preservation of rare taxa or associations, and the operation of biotic concentrative processes.
Preliminary taphonomic study of Batallones-3 remains.
Giraffids include the only living giraffomorph ruminants and are diagnosed by the presence of bi-lobed canines and a special type of epiphyseal cranial appendages called ossicones. The family Giraffidae ranges from the latest early Miocene until today. However they are currently extant relics with only two living representatives, the African genera Okapia and Giraffa. Giraffids were much more diverse and widespread in the past, with more than 30 fossil species described. For the past decades a number of studies intended to resolve the phylogenetic relationships of the family, but due to the lack of really good cranial material no clear consensus was reached regarding the phylogenetic relationships amongst the different members of the group. The exceptionally complete remains of a new large giraffid from the late Miocene of Spain, Decennatherium rex sp. nov., allows us to improve and reassess giraffid systematics, offering a lot of new data, both anatomic and phylogenetic, on the large late Miocene giraffids of Eurasia. The results of our cladistic analysis show Decennatherium as a basal offshoot of a clade containing the gigantic samotheres and sivatheres, characterized by the presence of a Sivatherium-like ossicone-plan among other features. Decennatherium thus offers the most ancient evidence of this Sivatherium-plan and firmly establishes the early morphological patterns of evolution of a sivathere / samothere-clade that is defined as the less inclusive clade that contains Decennatherium and Sivatherium. Finally, this large group of four-ossiconed giraffids evolutionarily links Miocene Europe and Africa indicating vicariance / migration processes among the giraffid genetic pools separated by the Mediterranean Sea.
- Nov 2017
The Spanish late Miocene locality of Batallones-1 yielded a rich sample of large carnivorans, including saber-toothed felids, amphicyonids, and ailurids, but also of smaller species, with the small cats being especially interesting. Two species are known from Batallones-1, one of them the size of a wildcat, Felis silvestris, the other one the size of a caracal, Caracal caracal. The former is represented by skulls, mandibles, and postcranial bones, whereas the latter is known from a collection of long bones. Both species are less abundant than their larger relatives, the saber-toothed felids Promegantereon ogygia and Machairodus aphanistus, but the available sample allows us to assess body proportions and adaptations of the smallest species, and to propose a new genus for this feline, Leptofelis vallesiensis. Its limb bones are remarkably gracile compared to fossils of the earlier genera Pseudaelurus, Miopanthera, and Styriofelis, and comparable in cursorial adaptations to the wildcat, very different from extant arboreal cats. While middle Miocene felids were likely semi-arboreal forest dwellers, L. vallesiensis would be mostly terrestrial, climbing essentially for protection. This indicates an adaptation to a mosaic of habitats, including relatively open terrain, and may be related to the climatic changes detected in Eurasia during the late Miocene.
Measurements (cranial, dental) of Decennatherium rex sp. nov. from BAT10. Excel sheets in order: skull, ossicones, maxillae, mandibles, canines, incisors, upper deciduous dentition, lower deciduous dentition, upper molars, lower molars, upper premolars, lower premolars. (XLS)
Descriptive parameters of the measurements of the Giraffidae analyzed (cranial, dental, postcranial). Excel sheets in order: skull, ossicones, juvenile mandible, adult mandible, p3, p4, m3, atlas, axis, radius metacarpal III-IV, tibia, phalanges, measurements references. (XLSX)
Description of the measurements (cranial, dental, postcranial). Fig 1, Skull measurements; Fig 2. Ossicone measurements; Fig 3, Atlas measurements; Fig 4, Axis measurements; Fig 5, Cervical measurements; Fig 6, Thoracic and lumbar measurements; Fig 7, Rib measurements; Fig 8, Pelvis measurements; Fig 9, Patella measurements; Fig 10. Sesamoid measurements. (PDF)
Measurements (postcranial) of Decennatherium rex sp. nov. from BAT10. Excel sheets in order: vertebrae, ribs, scapulae, humerus, radius-ulna, carpals, metacarpal III-IV, pelvis, femur, tibia, tarsals and patella, metatarsal III-IV, lateral metatarsals, phalanges, sesamoids. (XLS)
- Aug 2017
- 15th European Association of Vertebrate Palaeontologists Annual Meeting (EAVP-2017)
- Meeting of the European Association of Vertebrate Palaeontologists
Mustelids represent the most diverse living family of Carnivora, displaying a broad range of locomotor behaviors, including terrestrial, semi-fossorial, scansorial, arboreal and semi-aquatic. Moreover, mustelid body mass (BM) ranges between the 0.025 kg (Mustela nivalis) and 45 kg (Enhydra lutris), spanning three orders of magnitude. We analyzed 14 linear measurements from humerus, radius, ulna, femur and tibia of a living sample of 192 specimens of carnivorans to evaluate the locomotion and BM of a sample of extinct Neogene and Quaternary large mustelids, procyonids and ailurids. The predictive equations generated based on postcranial remains indicate that the largest extinct mustelid could weigh more than 200 kg, which means four orders of magnitude in BM for the whole family. These predictive equations allow us to propose an updated definition for giant musteloids, including giant mustelids, ailurids and procyonids. Gigantism in mustelids appears early in their evolutionary history, as observed in several independent radiations in North America, Eurasia and Africa throughout the Neogene and Quaternary. This gigantism is also present in other musteloids as ailurids and procyonids. Our research shows that several unique ecomorphotypes of giant musteloids evolved in the Neogene that are different from any living carnivorans, such as a Puma-sized oligobunine with terrestrial and semifossorial traits, Megalictis ferox, wolf to leopard-sized mellivorines with hypercarnivorous dentitions and terrestrial and cursorial traits (Ekorus ekakeran and Eomellivora piveteaui) or black bear-sized otters (Enhydriodontini), that were somewhat more terrestrial than living otters.
We investigate resource and habitat use by apex predators through stable isotope analysis at two Spanish Late Miocene localities: Los Valles de Fuentidueña (~9.6 Ma, LVF) and Cerro de los Batallones (~9.1 Ma, BAT). The temporal window represented by LVF and BAT was crucial in the shaping of the current Iberian mammalian structure because it corresponds to the initial stages of a faunal turnover episode and regional environmental change at ~9.5–8.5 Ma (Vallesian–Turolian transition), associated with an increase in the seasonality of precipitation. Herbivore and carnivore δ13C and δ18O values do not point to significant changes in either the vegetation cover (a woodland to mesic C3 grassland) or the hydrological regime during the time lapse represented between LVF and BAT. This suggests that the environmental shift recorded around the Vallesian–Turolian boundary may have occurred later in time, since LVF and BAT ages are synchronic with the onset of the turnover event. From the standpoint of predator–prey evaluation by means of stable isotope analysis, statistical post hoc tests, mixing model output, and the assessment of niche occupation by LVF and BAT carnivores point to high levels of interspecific competition among large active carnivores, albeit some genera, such as the amphicyonid Magericyon and specially the hyaenid Lycyaena, seemed to avoid competition by taking prey from a more open habitat. Despite the drop in diversity and change in faunal components observed between the LVF and BAT assemblages, a high degree of resource and habitat competition is evident from stable isotope data.
We describe the skull and neck morphology of the late Miocene amphicyonid Magericyon anceps, focusing on aspects related to functional anatomy. This species, recorded only from the Vallesian sites of Batallones-1 and Batallones-3 (Madrid, Spain), is the last known amphicyonid in the fossil record of Western Europe, with the Batallones populations being one of the best-known of the family. The morphology of its skull and cervical vertebrae allows us to infer aspects of its associated musculature, such as muscle strength and range of movement. Magericyon anceps had well-developed neck muscles, suited for providing the head with a high capacity for lateral and rotatory movements, as well as for playing an important role in the extension and stabilization of the head and neck, improving its efficiency in killing and consuming prey. Magericyon anceps shared its habitat with other large carnivorans, which would have strongly influenced its behaviour. Rapid killing and processing of prey would have been an advantage for avoiding kleptoparasitism by other large predators, as well as reducing consumption time, during which M. anceps would have been more vulnerable to attack from competitors.
In this paper, we synthesize sedimentological, magnetostratigraphic and paleontological data from the continental vertebrate site of Puerto de la Cadena (Murcia, SE Spain), in order to clarify its age. The study site is located on the northern edge of the Carrascoy mountain range, in the upper part of the Cigarrón Unit. The end-Messinian discontinuity has been detected at the base of this unit, which indicates it has an early Pliocene age. Abundant remains of small and large vertebrates, including rodents, lagomorphs, primates, carnivorans, perissodactyls, artiodactyls, proboscideans, testudines, squamats, and crocodiles, have been found in this area. Some of these elements are of African origin, such as Debruijnimys sp., Macaca sp., and Sivatherium cf. hendeyi, and their presence is related to the Messinian Salinity Crisis. In addition, remains found at this site verify the persistence of Crocodylia in the European record beyond the late Miocene. The association includes typical elements of the early Ruscinian terrestrial record (MN14), like Apocricetus cf. barrierei, Sivatherium, Gazella aff. baturra, and Hipparion fissurae. The Puerto de la Cadena site is located in a reversed geomagnetic chron that has been correlated with C3n.3r (from 4.997 to 4.896 Ma). According to this correlation, the MN13/MN14 boundary has a minimum age of 4.9 Ma.
We re-evaluated the Austrian material for Hadrictis fricki Pia, 1939, from the localities Wien XII-Altmannsdorf and Gaiselberg (MN9, Vallesian, Late Miocene), concluding that Hadrictis can be considered as a synonymy of Eomellivora Zdansky, 1924; we therefore named it as Eomellivora fricki. This species is one of the earliest representatives of the genus, together with E. piveteaui Ozansoy, 1965. Our phylogenetic analyses indicate that Eomellivora forms a monophyletic group, establishing the sister clade of the large and derived Late Miocene Ekorus ekakeran. Eomellivora fricki shows a primitive dental morphology and is the largest species of the genus. This species shows the complexity of the genus Eomellivora, in which large and small species coexisted since the beginning of the Late Miocene
The subfamily Guloninae Gray, 1825 is composed of generalist and hypercarnivorous mustelids, distributed over much of North America and Eurasia, with only one genus in South America. This clade includes three extant groups: (1) a heterogeneous group of small to medium-sized species, including the fisher (Pekania) and martens (Martes and Charronia); (2) the medium-sized South American tayra (Eira); and (3) the large sized wolverine (Gulo). This study is focused on the lineage of the wolverine, which is the largest terrestrial extant mustelid and one of the most iconic members of this family. The origin of the wolverine lineage remains obscure, but according to recent molecular data, it diverged from other gulonines around 7.6–5.5 Ma (Li et al., 2014). This time interval coincides with the expansion of the wolverine-like extinct mustelid Plesiogulo Zdansky, 1924, characterized by a large to giant body size. The relationship of this genus with Gulo is controversial, being considered as a direct ancestor by some researchers, and a representative of a distinct lineage without living descendants by others (e.g., Zdansky, 1924; Kurtén, 1970; Sotnikova, 1995). Iberictis Ginsburg & Morales, 1992 is a medium-size mustelid known from scarce remains from the early Miocene (MN4) of Europe, which shows strong affinities with Plesiogulo, despite of the important temporal gap existing between them. Herein, we present new material of Iberictis buloti Ginsburg & Morales, 1992 from the early Miocene (16.5–16.3 Ma, MN4) of els Casots (Vallès-Penedès Basin, Catalonia, Spain). Els Casots has yielded abundant micro- and macrovertebrate remains, including fishes, amphibians, reptiles, birds and macromammals (Moyà-Solà & Rius Font, 1993; Casanovas-Vilar et al., 2011; Alba et al., 2014; Díaz Aráez et al., 2016). However, except for crocodylians, some rodent species, and several groups of Artiodactyla, most of the fauna from this site remains unpublished. The dentognathic sample of I. buloti from els Casots (minimal number of individuals of 7) includes more abundant material than that from the type locality (Pellecahus, France, MN4). Therefore, it significantly increases the previous knowledge of this genus. An advance of our phylogenetics results indicates that Iberictis is very close to the large late Miocene Plesiogulo, and both genera could be the ancestral group of Gulo.
Abstract.: The Cuesta del Rey mammal sites located on the NE border of the Duero Basin are of great importance with regard to understand the general biostratigraphy of the basin, because Miocene mammal sites are extremely scarce in this area in comparison with the central part of the basin. The mammals identifi ed in Cuesta del Rey-1 are: Eulipotyphla: cf. Miosorex sp.; Rodentia: Heteroxerus sp., Armantomys cf. tricristatus, Megacricetodon ibericus, Megacricetodon minor-Megacricetodon debruijni, Hispanomys sp. and Democricetodon sp. The Cuesta del Rey-1 rodent assemblage is characteristic of the end of the upper Aragonian (MN 7/8, end of the middle Miocene), equivalent to the local subzone G3 of the G zone. The presence of the genera Heteroxerus and Armantomys, and the predominance of Megacricetodon (with 80% of the total percentage of the minimum number of individuals of the micromammals) suggested an open savannah or steppe palaeoenvironment. The mammals identifi ed in Cuesta del Rey-3 are: Rodentia: Megacricetodon cf. ibericus; Artiodactyla: Dorcatherium sp. and Listriodon cf. splendens. Dorcatherium sp. represents the fi rst appearance of the Tragulidae family in the Duero Basin, suggesting the existence of permanent watercourses. Resumen: Los yacimientos con mamíferos de Cuesta del Rey, situados en el borde NE de la cuenca del Duero, tienen una gran importancia para el conocimiento general de la biostratigrafía de la cuenca debido a la extrema escasez de yacimientos miocenos con mamíferos en comparación con las partes centrales de la misma. Los mamíferos identifi cados en Cuesta del Rey-1 son: Eulipotyphla: cf. Miosorex sp.; Rodentia: Heteroxerus sp., Armantomys cf. tricristatus, Megacricetodon ibericus, Megacricetodon minor-Megacricetodon debruijni, Hispanomys sp. y Democricetodon sp. Esta asociación, principalmente por la composición de los roedores, es característica del fi nal del Aragoniense superior (fi nal del Mioceno medio), de la subzona G3 de la zona G, unidades MN 7/8. La presencia de los géneros Heteroxerus, Armantomys, y el predominio de Megacricetodon (que constituye el 80 % del porcentaje total del número mínimo de individuos de los micromamíferos), sugieren un ambiente abierto de tipo sabana o estepa. Los mamíferos identifi cados en Cuesta del Rey-3 son: Rodentia: Megacricetodon cf. ibericus; Artiodactyla: Listriodon cf. splendens and Dorcatherium sp. El tragúlido Dorcatherium sp. representa la primera aparición de la familia en la cuenca del Duero, y sugiere la existencia de cursos de agua permanentes. Palabras clave: Mamíferos, Mioceno medio, Aragoniense superior, Cuenca del Duero, Yacimientos de Cuesta del Rey. 64 SESÉ & MORALES Figure 1. a) Location map of the Duero Basin (DE), Ebro Basin (EB) and Madrid Basin (MB) in the Iberian Peninsula. b) Location map of Cuesta del Rey mammal localities (CR-1 and CR-3) in the Cenozoic Duero Basin. c) The geological scheme of Cuesta del Rey area is based on the MAGNA geological map of Burgos-Sheet 200-(Pineda, 1977). Resumen. Los yacimientos con mamíferos de Cuesta del Rey, situados en el borde NE de la cuenca del Duero, tienen una gran importancia para el conocimiento general de la biostratigrafía de la cuenca debido a la extrema escasez de yacimientos miocenos con mamíferos en comparación con las partes centrales de la misma. Los mamíferos identificados en Cuesta del Rey-1 son: Eulipotyphla: cf. Miosorex sp.; Rodentia: Heteroxerus sp., Armantomys cf. tricristatus, Megacricetodon ibericus, Megacricetodon minor-Megacricetodon debruijni, Hispanomys sp. y Democricetodon sp. Esta asociación, principalmente por la composición de los roedores, es característica del final del Aragoniense superior (final del Mioceno medio), de la subzona G3 de la zona G, unidades MN 7/8. La presencia de los géneros Heteroxerus, Armantomys, y el predominio de Megacricetodon (que constituye el 80 % del porcentaje total del número mínimo de individuos de los micromamíferos), sugieren un ambiente abierto de tipo sabana o estepa. Los mamíferos identificados en Cuesta del Rey-3 son: Rodentia: Megacricetodon cf. ibericus; Artiodactyla: Listriodon cf. splendens and Dorcatherium sp. El tragúlido Dorcatherium sp. representa la primera aparición de la familia en la cuenca del Duero, y sugiere la existencia de cursos de agua permanentes.
The Early Miocene Napak XV locality (ca 20.5 Ma), Uganda, has yielded an interesting assemblage of fossils, including the very well represented amphicyonid Hecubides euryodon. The remarkable find of a nearly complete mandible, unfortunately with poorly preserved dentition, together with new dental remains allow us to obtain a better idea about the morphology and variability of this species. Additionally, we describe a newly discovered mandible of Hecubides euryodon from the Grillental-VI locality (Sperrgebiet, Namibia), which is the most complete and diagnostic Amphicyonidae material found in this area. Comparisons with Cynelos lemanensis from Saint-Gérand-le-Puy (France), the type locality, and with an updated sample of the species of amphicyonids described in Africa leads us to validate the genus Hecubides. Hecubides would be phylogenetically related to the medium and large size species of Amphicyonidae from Africa, most of them now grouped into the genera Afrocyon and Myacyon, both endemic to this continent.
Decennatherium pachecoi Crusafont, 1952, is one of two giraffid species described from the Miocene of the Iberian Peninsula. This species is recovered exclusively from Vallesian faunas (MN9–10, late Miocene, 10–11 Ma). Despite being relatively well represented in the fossil record, except for the skull and ossicones, the complete vertebral column, and part of the upper dentition, its systematics and phylogenetic position among giraffids are the subject of debate. We update our knowledge of D. pachecoi, revising all Spanish material assigned to this species, as well as previously undescribed fossils. We reassess the systematics of Decennatherium, including its potential relationship with the second Iberian giraffid, the early Turolian Birgerbohlinia Crusafont, 1952, by means of the first cladistic analysis of the Giraffidae that includes Decennatherium together with the most relevant African and Eurasian taxa, both fossil and extant. Our results link Decennatherium with a ‘samothere’ clade, whereas Birgerbohlinia is nested within a ‘sivathere’ clade, thus refuting a previously assumed direct relationship between the two Spanish forms. Finally, we discuss some other possible finds of the genus Decennatherium in Greece, Turkey, and Iran. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Rios, M., I. M. Sánchez, and J. Morales. 2016. Comparative anatomy, phylogeny, and systematics of the Miocene giraffid Decennatherium pachecoi Crusafont, 1952 (Mammalia, Ruminantia, Pecora): State of the art. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1187624. 2016
Carnivore-rich fossil sites are uncommon in the fossil record and, accordingly, provide valuable opportunities to study predators from vantages that are rarely applied to ancient faunas. Through stable isotopes of carbon and a Bayesian mixing model, we analyze time-successive (nearly contemporaneous), late Miocene carnivoran populations from two fossil sites (Batallones-1 and Batallones-3) from central Spain. Stable isotopes of carbon in tooth enamel provide a reliable and direct methodology to track ancient diets. These two carnivoran-dominated fossil sites display differences in the composition and abundance of the carnivoran species, with some species present at both sites and some present only at one site. This disparity has been interpreted as the consequence of habitat differences between Batallones-1, the older site, and Batallones-3, the younger site. However, carbon isotope values of carnivore and herbivore tooth enamel suggest a common habitat of C 3 woodland originally present at both sites. The differences in the carnivoran faunas rather may be the consequence of the dynamics of species entrance and exit from the Madrid Basin during the time elapsed between Batallones-1 and Batallones-3 and changes in population densities due to biotic factors. We infer higher levels of interspecific competition in Batallones-3 than in Batallones-1 because of the larger number of similar-sized, sympatric predators; the clear overlap in their δ 13 C values (except for the amphicyonid Magericyon anceps ); and similarity of their preferred prey: the hipparionine horses. Finally, carbon stable isotopic composition of Indarctos arctoides teeth implies that this ursid was a carnivorous omnivore rather than a herbivorous omnivore. This work demonstrates the insights that stable isotopes can provide in characterizing the feeding ecology and trophic interactions of ancient carnivoran taxa.
We describe cranial and mandibular remains of three undescribed individuals of the giant mustelid Megalictis ferox Matthew, 1907 from the latest Arikareean (Ar4), Early Miocene mammal fauna of Nebraska, and Wyoming (USA) housed at the American Museum of Natural History (New York, USA). Our phylogenetic hypothesis indicates that Ar4 specimens assigned to M. ferox constitute a monophyletic group. We assign three additional species previously referred to Paroligobunis to Megalictis: M. simplicidens, M. frazieri, and “M.” petersoni. The node containing these four species of Megalictis and Oligobunis forms the Oligobuninae. We test the hypothesis that Oligobuninae (Megalictis and Oligobunis) is a stem mustelid taxon. Our results indicate that the Oligobuninae form the sister clade to the crown extant mustelids. Based on the cranium, M. ferox is a jaguar-size mustelid and the largest terrestrial mustelid known to have existed. This new material also sheds light on a new ecomorphological interpretation of M. ferox as a bone-crushing durophage (similar to hyenas), rather than a cat-like hypercarnivore, as had been previously described. The relative large size of M. ferox, together with a stout rostrum and mandible made it one of the more powerful predators of the Early Miocene of the Great Plains of North America.
Inferences of function and ecology in extinct taxa have long been a subject of interest because it is fundamental to understand the evolutionary history of species. In this study, we use a quantitative approach to investigate the locomotor behaviour of Simocyon batalleri, a key taxon related to the ailurid family. To do so, we use 3D surface geometric morphometric approaches on the three long bones of the forelimb of an extant reference sample. Next, we test the locomotor strategy of S. batalleri using a leave-one-out cross-validated linear discriminant analysis. Our results show that S. batalleri is included in the morphospace of the living species of musteloids. However, each bone of the forelimb appears to show a different functional signal suggesting that inferring the lifestyle or locomotor behaviour of fossils can be difficult and dependent on the bone investigated. This highlights the importance of studying, where possible, a maximum of skeletal elements to be able to make robust inferences on the lifestyle of extinct species. Finally, our results suggest that S. batalleri may be more arboreal than previously suggested
The panda’s false thumb is an iconic structure, described as one of the most shocking cases of anatomical convergence, and has been studied in many essays about evolution. However, in a recent paper in which we evaluated this feature within the Carnivora, we concluded that the developed radial sesamoid could be taken as a plesiomorphic character for at least the Arctoidea, rather than an anatomical convergence of the pandas (both red and giant). Following this argument, in this research we describe the action of a radial sesamoid as a real false thumb for the first time outside the mammalian carnivorans. The cricetid Sigmodon peruanus shows a very similar radial sesamoid compared to that of the giant panda (Ailuropoda melanoleuca) but somehow relatively even more developed, compared to the other bones of the manus than in the latter, showing that the use of this structure as a opposable pincer is much more expanded in mammals than thought previously.
Palaeomerycids were strange three-horned Eurasian Miocene ruminants known through fossils from Spain to China. We here study their systematics, offering the first cladistic phylogeny of the best-known species of the group, and also reassess their phylogenetic position among ruminants, which is currently disputed. The beautifully preserved remains of a new palaeomerycid from middle Miocene deposits of Spain, Xenokeryx amidalae gen. et sp. nov., helps us to better understand palaeomerycid anatomy, especially that of the nuchal region in the skull, significantly improving our current knowledge on these enigmatic ruminants. Our results show two main lineages of palaeomerycids, one containing the genus Ampelomeryx diagnosed by a characteristic type of cranium / cranial appendages and some dental derived traits, and another one that clusters those forms more closely related to Triceromeryx than to Ampelomeryx, characterized by a more derived dentition and a set of apomorphic cranial features. Xenokeryx branches as a basal offshoot of this clade. Also, we find that Eurasian palaeomerycids are not closely related to North American dromomerycids, thus rejecting the currently more accepted view of palaeomerycids as the Eurasian part of the dromomerycid lineage. Instead of this, palaeomerycids are nested with the African Miocene pecoran Propalaeoryx and with giraffoids. On the other hand, dromomerycids are closely related to cervids. We define a clade Giraffomorpha that includes palaeomerycids and giraffids, and propose an emended diagnosis of the Palaeomerycidae based on cranial and postcranial characters, including several features of the cranium not described so far. We also define the Palaeomerycidae as the least inclusive clade of pecorans containing Triceromeryx and Ampelomeryx. Finally, we reassess the taxonomy of several palaeomerycid taxa.
Computational methods for estimating diversification rates from extant species phylogenetic trees have become abundant in evolutionary research. However, little evidence exists about how their outcome compares to a complementary and direct source of information: the fossil record. Furthermore, there is virtually no direct test for the congruence of evolutionary rates based on these two sources. This task is only achievable in clades with both a well-known fossil record and a complete phylogenetic tree. Here, we compare the evolutionary rates of ruminant mammals as estimated from their vast paleontological record -over 1200 species spanning 50 myr- and their living-species phylogeny. Significantly, our results revealed that the ruminant's fossil record and phylogeny reflect congruent evolutionary processes. The concordance is especially strong for the last 25 myr, when living groups became a dominant part of ruminant diversity. We found empirical support for previous hypotheses based on simulations and neontological data: the pattern captured by the tree depends on how clade-specific the processes are and which clades are involved. Also, we report fossil-evidence for a post-radiation speciation slowdown coupled with constant, moderate extinction in the Miocene. The recent deceleration in phylogenetic rates is connected to rapid extinction triggered by recent climatic fluctuations. This article is protected by copyright. All rights reserved. More in http://onlinelibrary.wiley.com/doi/10.1111/evo.12787/abstract
The localities of La Bullana 3 and La Bullana 2B (Valencia, E Spain) have yielded remains of Apodemus gorafensis, Paraethomys aff. abaigari, Stephanomys dubari, Apocricetus barrierei, Sciuridae indet. and Asoriculus cf. gibberodon the former, and Apodemus gorafensis, Paraethomys aff. abaigari, Stephanomys dubari, Apocricetus barrierei, Sciuridae indet., Asoriculus cf. gibberodon, Castillomys gracilis, Occitanomys brailloni, Occitanomys sp., Paraethomys meini, Ruscinomys sp., Eliomys intermedius, Debruijnimys cf. julii and Atlantoxerus sp. the latter. Based on the study of these micromammal assemblages, we propose an Early Pliocene age (MN14) for both sites. The presence a gerbilid related to Debruijnimys julii in La Bullana 2B open new questions about the phylogenetic relationship between Debruijnimys species from the Miocene and Pliocene of the Iberian Peninsula. Furthermore, preliminary paleomagnetic data indicate an age between 4.997 Ma and 4.896 Ma for La Bullana 2B, and between 5.235 Ma and 4.997 Ma for La Bullana 3.
Carnivore mammals (Carnivora, Mammalia) constitute a significant component of the Spanish Neogene faunas, not so much due to their fossil abundance, which is generally low, but rather because of their high degree of taxonomic diversity. We assessed their evolutionary dynamics from the fossil record of Iberian carnivores using per-taxon rates of origination, extinctions and turnover combined with a recent approach for removing the sampling signal from diversity curves. Our analysis interval covers most of the Neogene and the early Pleistocene (MN 2 to MN 17), spanning from around 21.6 to 1.8 Ma. We identified six carnivore associations by applying factor analysis to our data. The diversification pattern shows four origination episodes: MN4, MN7/8, MN12 and MN14. We also identified four extinction episodes. The first two are coincident with the onset of the MN 4 and MN7/8 faunas. The last two extinction episodes take place during MN9, coinciding with the Mid Vallesian Crisis (MVC), and MN13, co-occurring with the Messinian Salinity Crisis (MSC). Two major turnover pulses are recognised during MN4 and MN14, the turnover rate remaining moderately high between MN6 and MN13. We suggest that the pattern observed might be primarily triggered by the biogeographic and climatic shifts that took place during the Neogene. © 2015, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg.
- Jul 2015
Mammals of numerous lineages have evolved high-crowned (hypsodont) teeth particularly during the last 20 million years. This major phenotypic change is one of the most widely studied evolutionary phenomena in a broad range of disciplines, though the mechanisms underlying its transformation remain unresolved. Here, we present the first Finite Element Analysis (FEA) to investigate the alternative hypothesis that there is a biomechanical link between increased hypsodonty and a more effective mastication in deer. Our FE experiments compared patterns of stress and strain within and between different fossil and living species under different loading conditions, and found that more hypsodont teeth are suited for restricting stresses to those areas where chewing loading occurs. This mechanical improvement is consequence of specific and pronounced variations in tooth geometry and morphology of the occlusal surface that are strongly related to crown growth in the vertical plane. We demonstrate that hypsodonty enables selenodont-teeth to adopt a mechanically improved design that increases the pressure whilst shearing foods. As ruminants are physiologically limited by both the quantity of food consumed and the time spent in the mastication and digestion, hypsodonty is highly advantageous when feeding on mechanically resistant, tough and fibrous foods. Consequently, it allows grass-eaters to spend less time chewing, thereby increasing the volume of food ingested and/or providing more time for digestion. This study provides a promising line of evidences in support of biomechanical effectiveness, in addition to or instead of increased wear resistance, as a factor in explaining the evolutionary origins of the hypsodont phenotype.
We investigate the relative development of the carnivoran radial sesamoids to untangle the evolution of this iconic structure. In the pandas (both giant and red), this ‘false thumb’ is known to perform a grasping role during bamboo feeding in both the red and giant pandas. An original locomotor role has been inferred for ailurids, but this remains to be ascertained for ursids. A large sample of radial sesamoids of Indarctos arctoides from the Miocene of Batallones-3 (Spain) indicates that this early ailuropodine bear displayed a relatively hypertrophied radial sesamoid, with a configuration more similar to that of the red panda and other carnivorans than to that of giant pandas. This false thumb is the first evidence of this feature in the Ursidae, which can be linked to a more herbivorous diet. Moreover, in the two extant pandas, the false thumb should not be interpreted as an anatomical convergence, but as an exaptive convergence regarding its use during the bamboo feeding, which changes the evolutionary view of this singular structure.
In this paper we review the collection of fossil carnivores from the late Early Pleistocene site of Cueva Victoria (south-eastern Iberian Peninsula) including the families Ursidae, Hyaenidae and Felidae. The studied material includes the species Ursus deningeri, Pachycrocuta brevirostris, Homotherium latidens, Megantereon sp., Panthera gombaszoegensis, Puma pardoides and Lynx pardinus. The former species are characteristic of the late Early Pleistocene assemblages of the Mediterranean Europe corresponding to the Epivillafranchian biochron with an approximate age of 1.1-0.78 Ma. Taking into account the known first and last appearances of the identified species the chronology of the site can be restricted to ca. 1.0 Ma.
We describe cranial, mandibular, and dental remains of five individuals of the giant mustelid Eomellivora piveteaui Ozansoy, 1965, from the late Miocene (MN10) site of Cerro de los Batallones (Madrid, Spain)—the first complete cranial remains recorded for this species and the most complete remains of the genus. This new sample enables a review of the systematic status of Eomellivora, leading us to accept as valid the species E. piveteaui Ozansoy, 1965, E. wimani Zdansky, 1924, E. ursogulo (Orlov, 1948), and E. hungarica Kretzoi, 1942. Our phylogenetic hypothesis indicates that Eomellivora is the sister taxon of the extant Mellivora capensis and E. piveteaui had a common ancestor within the crown group E. wimani–E. ursogulo. Eomellivora piveteaui was specialized for a more hypercarnivorous diet than the largest extant terrestrial mustelids, although it also had some derived bone-crushing adaptations. Eomellivora piveteaui had an active predatory role in the late Miocene carnivore faunas, exploiting both small and relatively large prey.
We investigate the relative development of the carnivoran radial sesamoids to untangle the evolution of this iconic structure. In the pandas (both giant and red), this 'false thumb' is known to perform a grasping role during bamboo feeding in both the red and giant pandas. An original locomo-tor role has been inferred for ailurids, but this remains to be ascertained for ursids. A large sample of radial sesamoids of Indarctos arctoides from the Miocene of Batallones-3 (Spain) indicates that this early ailuropodine bear displayed a relatively hypertrophied radial sesamoid, with a configuration more similar to that of the red panda and other carnivorans than to that of giant pandas. This false thumb is the first evidence of this feature in the Ursidae, which can be linked to a more herbivorous diet. Moreover, in the two extant pandas, the false thumb should not be interpreted as an anatomical convergence , but as an exaptive convergence regarding its use during the bamboo feeding, which changes the evolutionary view of this singular structure.
The effect of climate change on extant mammal faunas is a frequent topic in ecological research and the analysis of past mammalian communities and their correlated evolution with global climatic change can provide data relevant to this question. Late Pleistocene and Holocene carnivore mammal faunas from the Rancho La Brea Tar Pits (Los Angeles, CA) are highly diverse and well-preserved, and were used to analyze how past climatic shifts shaped the structure of mammalian communities from southwestern North America over the past 30,000 years. Using bibliographical data, we clustered all extant terrestrial carnivores in 11 Carnivore Functional Groups with similar ecological features (diet, locomotion, and body size), and subsequently defined the functional spectra of 26 modern localities from the Nearctic. By means of discriminant analysis, we explored how the ecological structure (functional spectrum) of these communities varies with environmental conditions (type of biome). Morphofunctional analyses of La Brea species allowed us to determine their ecological features and thereby define the functional spectra of communities at different stages (pits). The selected pits varied in age: Pit 91 (around 29 ka), Pit 3 (around 18.5 ka) and Pit 61/67 (around 11.5 ka). This allowed us to analyze how community structure changed in association with climatic shifts that occurred in North America during the Late Pleistocene and Holocene, and finally compare them with the fauna found in Los Angeles today. We successfully detected the climatic shifts associated with the Last Glacial Maximum together with the Holocene warming. While a sclerophyllous woodland-shrubland is detected for Pit 91 and in modern Los Angeles, a more humid, temperate forest (taiga type) is inferred for Pits 3 and 61/67. We also identified the ecological groups mainly affected by these climatic alterations. The main difference in our communities among different climatic stages is the absence of scansorial predators and several large omnivores in the arid periods (Pit 91 and modern Los Angeles). Finally, since all extinct giant, cursorial hypercarnivores were members of the same functional group, we were also able to detect a structural pattern in the Holocene megafaunal extinction. Founding source: Project CGL2011-25754, MINECO (Spanish Government) and The Research Group BSCH-UCM 910607. FPU predoctoral contract (Spanish Ministry of Education) granted to B.A.G.Y.
New remains of the small tragulid Dorcatherium songhorensis Whitworth, 1958 from the Early Miocene fossil site of Napak XXI (Uganda) include the first significant sample of postcranial bones from this species ever described. The limb bones of this tragulid are very similar to that described in the Miocene Asian long-legged tragulids of the genus Siamotragulus Thomas et al., 1990, a type previously unknown in the African Miocene. A cladistic analysis links D. songhorensis to a Siamotragulus clade as its basal offshoot, so we propose the name Siamotragulus songhorensis (Whitworth, 1958) for this species. Also, the Siamotragulus clade belongs to a monophyletic group that includes Afrotragulus Sánchez et al., 2010 and the extant Asian genera Moschiola and Tragulus. This inclusive clade is characterized by both a derived selenodont dentition and an advanced postcranial skeleton. Additionally Siamotragulus shows some cursorial refinements reflected in its postcranial skeleton including the pecoran-like metatarsals III-IV. Siamotragulus songhorensis shows that the genus Siamotragulus was not endemic to Asia as previously thought, and that a highly diverse guild of tragulids, including different members of the advanced selenodont clade, inhabited Africa as early as the Early Miocene (19-20 Ma).
We describe and discuss several aspects of the functional anatomy of the shoulder of the Miocene amphicyonid Magericyon anceps, focusing on the scapula and proximal half of the humerus. This species, only known from the late Miocene (Vallesian, MN 10) site of Batallones-1 (Madrid, Spain), is the last amphicyonid known in the fossil record of Western Europe. Magericyon anceps combines a more hypercarnivorous dentition than previous amphicyonids (including relatively more flattened ca- nines) with primitive features on its shoulder region: its scapulo-humeral region shows a reduced caudoventral projection of the acromion, the postscapular fossa, and the teres major process, suggest- ing some differentiation from the two morphotypes ex- hibited by other derived amphicyonids, and showing similarities with primitive, generalized, medium-sized species of this family. This unique combination of a derived dentition and a relatively generalized shoulder region points towards M. anceps being a different eco- logical morphotype from that showed by other amphicyonids such as the larger, bear-like amphicyonines from the European middle Miocene and the markedly cursorial North American temnocyonines and daphoenines.
In the present work we conduct a comparative study of the cranial and dental samples of the early machairodontine Machairodus aphanistus from the Vallesian (MN 10) sites of Batallones-1 and Batallones-3 (Torrejón de Velasco, Madrid, Spain). These sites, which have yielded the most abundant and complete samples of this felid, show interesting differences in faunal composition and age, thus providing a unique opportunity for both qualitative and quantitative comparisons between two populations of the same species. The study reveals differences in a number of cranial features, and statistically significant differences in teeth size and proportions. Although probably not enough to support a separation at the species level, these observations fit well with the morphological evolution of the lineage leading towards more derived forms such as the Turolian Amphimachairodus giganteus.
We compare two populations of the primitive saber-toothed felid Promegantereon ogygia from the late Miocene (Vallesian, MN 10) of Spain. These populations come from two fossil sites, Batallones-1 and Batallones-3, located very close to each other, within the Cerro de los Batallones complex. The sites show differences in age and in their faunal assemblages, with Batallones-1 being older than Batallones-3. We find that the population from this latter site shows slightly derived characters in both dentition and postcranial elements, which clearly indicate evolution within the Promegantereon lineage, but are not strong enough to support a separation at the species level.
In the present study we analyse the diversity of the Superfamily Ursoidea during the Neogene of the Iberian Peninsula to further compare it with that of the Neogene of Western Europe to find the different associations of this group. The results indicate that both the diversity and the taxonomy amongst these two regions show important variations, thus letting their interpretation in terms of climatic differentiation. We might relate variations in the abundance of the Ursoidea to the environmental fluctuations taking place during the Miocene and Pliocene. Therefore, they could enable us to reach the assessment of these biogeographical distributions in order to deduce the preferential niches of each different group of Ursoidea.
Global climate shifts and ecological flexibility are two major factors that may affect rates of speciation and extinction across clades. Here, we connect past climate to changes in diet and diversification dynamics of ruminant mammals. Using novel versions of Multi-State Speciation and Extinction models, we explore the most likely scenarios for evolutionary transitions among diets in this clade and ask whether ruminant lineages with different feeding styles (browsing, grazing and mixed feeding) underwent differential rates of diversification concomitant with global temperature change. The best model of trait change had transitions from browsers to grazers via mixed feeding, with appreciable rates of transition to and from grazing and mixed feeding. Diversification rates in mixed-feeder and grazer lineages tracked the palaeotemperature curve, exhibiting higher rates during the Miocene thermal maxima. The origination of facultative mixed diet and grazing states may have triggered two adaptive radiations-one during the Oligocene-Miocene transition and the other during Middle-to-Late Miocene. Our estimate of mixed diets for basal lineages of both bovids and cervids is congruent with fossil evidence, while the reconstruction of browser ancestors for some impoverished clades-Giraffidae and Tragulidae-is not. Our results offer model-based neontological support to previous palaeontological findings and fossil-based hypothesis highlighting the importance of dietary innovations-especially mixed feeding-in the success of ruminants during the Neogene.
- Feb 2014
De nouveaux restes dentaires d’un Tragulidé de la localité de la fin du Miocène inférieur (16,5 à 16,3 Ma, MN4) d’Els Casots (bassin de Vallès-Penedès, Catalogne, Espagne) sont décrits ici. Cet échantillon correspond bien, en termes de taille et de morphologie occlusale, au matériau de Dorcatherium crassum de la localité type (Sansan, France ; MN6). Nous attribuons donc le Tragulidé d’Els Casots à cette espèce, également d’après sa répartition chronostratigraphique connue dans toute l’Europe (MN4–MN6) et des enregistrements antérieurs de cette espèce dans d’autres localités du MN4 du bassin de Vallès-Penedès. Les restes décrits – qui comprennent la dentition postcanine inférieure de lait et permanente, ainsi que plusieurs dents jugales supérieures permanentes – constituent l’échantillon le plus complet de D. crassum de la péninsule Ibérique. La présence de cette espèce à Els Casots est compatible avec le milieu de dépôt lacustre déduit des caractéristiques sédimentologiques et de la faune associée ; elle confirme aussi la présence, à proximité, d’environnements à forêt dense, témoins d’un climat humide et d’une saisonnalité peu marquée.
- Jan 2014
Phylogenetic community structure may help us understand how macroecological and macroevolutionary processes shape assemblages at large geographical scales. In this paper, we test hypotheses linking the formation of large-scale assemblages, evolutionary processes and macroecology. To provide new insight into ruminant biogeography and evolution, phylogenetic community structure metrics were calculated for faunal assemblages at four hierarchical levels. Phylogenetic relatedness indices (net relatedness index and nearest taxon index) were determined for 59 ruminant assemblages at the landscape scale and scale of their respective climate domains (continuous biome stretches). Species pools at the global and biogeographic realm levels were used to construct null observation models. Significantly, assemblages were selected if they were distributed across biogeographic realms and represented all the world's biomes. Non-random patterns were also tested for biogeographic realms within the global ruminant species pool. By examining ruminant assemblages at different scales we were able to observe that ruminant faunas show a distribution mainly limited within the boundaries of their biogeographic realms. However, the diversification of some clades was found to be restricted to extremely arid domains in the Sahara and Arabia. The random patterns featured by other extreme climate domains could reflect phylogenetically heterogeneous filling by less biome-restricted lineages outside Africa.
In the present study we analyse the diversity of the Superfamily Ursoidea during the Neogene of the Iberian Peninsula to further compare it with that of the Neogene of Western Europe to find the different associations of this group. The results indicate that both the diversity and the taxonomy amongst these two regions show important variations, thus letting their interpretation in terms of climatic differentiation. We might relate variations in the abundance of the Ursoidea to the environmental fluctuations taking place during the Miocene and Pliocene. Therefore, they could enable us to reach the assessment of these biogeographical distributions in order to deduce the preferential niches of each different group of Ursoidea. Resumen En este trabajo se analiza la diversidad de la Superfamilia Ursoidea durante el Neógeno de la Península Ibérica, comparándola con la de Europa Occidental de la misma época, con el objetivo de localizar las diferentes asociaciones de los miembros de este grupo. Los resultados indican que tanto la diversidad como la taxonomía varían considerablemente entre las dos regiones estudiadas pudiendo interpretarse en tér-minos de diferenciación climática. Estas variaciones en la abundancia de Ursoidea se pueden relacionar con las fluctuaciones ambientales que tuvieron lugar durante el Mioceno y el Plioceno. Por tanto, nos ayudarán a evaluar las causas de estas distribuciones biogeográficas y a encontrar los nichos preferentes de cada uno de los diferentes grupos de Ursoidea.
- Dec 2013
Fossil mammal sites of late Miocene age (ca 9 Ma) occur in hourglass-shaped, non-interconnected cavities up to 15 m deep, hosted in mudstone (mostly sepiolite), chert and carbonate bedrock in Cerro de los Batallones. This paper provides a model for the sedimentary infilling of the cavities, which functioned as traps for vertebrate faunas and contain one of the richest and best preserved Neogene mammal assemblages of the Iberian Peninsula. Generation of the mammal-bearing cavities started with the solution of underlying evaporites, which resulted in fissures that were subsequently enlarged by subsurface piping, a process rarely preserved in the ancient sedimentary record. The system of subterranean cavities evolved into a pseudokarst landscape, resulting in doline-like shafts reaching the ancient land surface. The sedimentary infilling of the cavities comprises both clastic and carbonate lithofacies that were investigated by outcrop observation, standard and scanning electron microscope petrography, mineralogical analysis, and stable isotope geochemistry. Gravel and breccia talus deposits, clast and mud-supported gravel, pebbly sandstone and mudstone are common detrital infill deposits mostly derived by overflow erosion of bedrock. The deposits containing the mammal bones are marls, and occur both in subsurface cavities and doline-like depressions. In the underground cavities, marlstone was mainly of clastic origin and accumulated in ponds scattered over the floor of the cavity. In contrast, marlstone deposits in the surface dolines formed mostly as a result of biochemical carbonate deposition in small shallow lakes subjected to fluctuation of the water level. The δ18O and δ13C carbonate values indicate different origins for the two kinds of marls. During the final phases of pipe infill the doline marlstone sealed the mammal sites, usually off-lapping the adjacent bedrock.
The Ventian land mammal age includes most of the Spanish faunas assigned to the biochronologic unit MN 13. It is correlatable with the Messinian, although it may include, in its latest part, Early Pliocene faunas. We propose that the Ventian begins with the fi rst occurrence of the Muridae genus Stephanomys (7 Ma, paleomagnetic dating from El Bunker, Teruel basin), well recorded in Teruel basin, and ends with the appearance of Promimomys (ca. 5 Ma), also registered in the Teruel basin. We suggest a new reorganization of the Ventian. The first subdivision corresponds to the zone M (Dam et al., 2001). The second, zone N, is proposed here for the first time, being equivalent to the zone with Celadensia (Mein et al., 1990; Dam et al., 2006) plus the part of the zone with two Paraethomys (Dam et al., 2006) in which Celadensia has dissappeared and still does not register Promimomys. The Ventian is now accurately recognized with quite precise boundaries and divisions, so that it can be easily recognized in the Iberian continental basins with Mio-Pliocene sediments allowing refi ned intra- and inter-basin correlations.
Key innovations are newly acquired structures that permit the performance of a new function and open new adaptive zones, and are therefore of paramount significance for understanding the history of the Ruminantia -particularly its diversification through the Miocene. Here we review and discuss what is known about these evolutionary novelties, with special emphasis on the appearance and evolution of cranial appendages and high-crowned (or hypsodont) teeth. Cranial appendages probably favored the diversification of pecorans by being structures strongly related to sexual selection, whereas the acquisition of hypsodont teeth could have expanded potential dietary breadth and allowed species to extend diets into the grazing range without eliminating browsing as a potential diet. When analyzed in conjunction with patterns of faunal diversity and in the context of climatic changes, it seems that the overall view that ruminant cranial appendages and hypsodonty may have started responding to increased patterns of seasonality and the opening-up of ecosystems is roughly valid. Instead, they occurred through several distinct pulses and varied widely among continents. This review is, to our knowledge, the first to highlight that the evolution of these innovations has been far from constant and uniform through time. Further, we also identify that both a first attempt to increase hypsodonty starting in the early Miocene and a first evolution of antlers and pronghorns was interrupted as a consequence of wide climatic fluctuations in the early-middle Miocene transition.
A new genus and species of otter-like mustelid, Teruelictis riparius, is created on the basis of a partial skeleton from the Late Miocene (Vallesian age, MN 10) locality of La Roma 2 (Teruel, Spain), including several postcranial elements, the skull, and the mandible. The combination of a typically lutrine dentition, similar to that of other fossil otters such as Paralutra jaegeri, with a very slender postcranial skeleton, including a long back and gracile long bones and metacarpals, thus lacking any aquatic adaptations, was previously unknown in the fossil record. This mosaic of features strongly suggests the possibility that the aquatic lifestyle of otters could have appeared after the initial development of the distinctive dental morphology of this specialized group of mustelids.
The fossil bacula, or os penis, constitutes a rare subject of study due to its scarcity in the fossil record. In the present paper we describe five bacula attributed to the bear Indarctos arctoides Depéret, 1895 from the Batallones-3 site (Madrid Basin, Spain). Both the length and morphology of this fossil bacula enabled us to make interpretative approaches to a series of ecological and ethological characters of this bear. Thus, we suggest that I. arctoides could have had prolonged periods of intromission and/or maintenance of intromission during the post-ejaculatory intervals, a multi-male mating system and large home range sizes and/or lower population density. Its size might also have helped females to choose from among the available males.
The Tragulidae are the most basal of extant Ruminantia, and the only living remnant of an ancient radiation of ruminants that produced successive sister groups to the Pecora. They comprise the smallest living cetartiodactyls and survive today as Old World tropical relics: Moschiola in India and Sri Lanka, Tragulus in Southeast Asia and the Philippines, and Hyemoschus in Africa from Sierra Leona to Uganda. As the most primitive representatives of the extant Ruminantia, tragulids are less advanced than living pecorans in almost all of their morphological and physiological features. The origin and early evolution of tragulids are still a mistery because their fossil record during the Paleogene is extremely scarce. However, tragulids were the only non-pecoran ruminant group that surpassed the Paleogene, showing an amazing radiation that produced several genera that spread out all over the Old World by the end of the early Miocene: ‘Dorcatherium’ (Africa, Asia, and Europe), Dorcabune (Asia), Siamotragulus (Asia and Africa) and Afrotragulus (Africa). We present the first large-scale cladistic analysis of the Tragulidae. In our study we include a large number of fossil and extant species, integrating the study of cranial, dental and postcranial morphological features with near 50 characters. Our aim is to test several phylogenetic hypotheses on tragulid evolution: e.g. the extant disjunct distribution of the Tragulidae is related to phylogeny, that is, both an African and an Asian clade of tragulids do exist; Hyemoschus is closely related to Dorcatherium; Dorcatherium is a deeply paraphyletic taxon; and there was a still-unrecorded large-scale radiation event of tragulids previous to their first Miocene record. All of these hypotheses have been classically considered in the recent (and not so recent) works on the Tragulidae. Our results not only give answers to these questions but also incorporate some interesting paleo-biogeographical interrogants that have to be explored in future works.
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