Plesippus francescana (Frick) from the late Pliocene, Coso Mountains, California, with a review of the genus Plesippus

Two mammalian types, occurring in a late Pliocene fauna from the Coso Mountains, California, have already been described. Among the more abundant forms in this assemblage are the horses of the genus Plesippus. These are of particular interest not only for purposes of correlation of the geologic horizon in which they occur, but also because of their phylogenetic relationships. Opportunity is taken therefore to make a comparative study of characters of the species from the Coso Mountains with reference to nearly related forms found in beds of similar age and to define more clearly, than has been previously attempted, the position of Plesippus in the lineage of the horse group

CliqueStream: an efficient and fault-resilient live streaming network on a clustered peer-to-peer overlay

Several overlay-based live multimedia streaming platforms have been proposed in the recent peer-to-peer streaming literature. In most of the cases, the overlay neighbors are chosen randomly for robustness of the overlay. However, this causes nodes that are distant in terms of proximity in the underlying physical network to become neighbors, and thus data travels unnecessary distances before reaching the destination. For efficiency of bulk data transmission like multimedia streaming, the overlay neighborhood should resemble the proximity in the underlying network. In this paper, we exploit the proximity and redundancy properties of a recently proposed clique-based clustered overlay network, named eQuus, to build efficient as well as robust overlays for multimedia stream dissemination. To combine the efficiency of content pushing over tree structured overlays and the robustness of data-driven mesh overlays, higher capacity stable nodes are organized in tree structure to carry the long haul traffic and less stable nodes with intermittent presence are organized in localized meshes. The overlay construction and fault-recovery procedures are explained in details. Simulation study demonstrates the good locality properties of the platform. The outage time and control overhead induced by the failure recovery mechanism are minimal as demonstrated by the analysis.Comment: 10 page

El equus stenonis cocchi como indicador biostatigráfico del plio-pleistoceno en Italia y España

[Resumen] Se esquematiza la cronoestratigrafía de los principales yacimientos de Vertebrados italianos del Plio-pleistoceno, de el Villafranquiense medio al Galerino. Se estudia, desde un punto de vista evolutivo, la presencia de las distintas formas de Equus stenonis Cocchi hasta la llegada de Equus caballus Linn. La comparación de los distintos estadios evolutivos de E. stenonis y su fauna acompañante permiten la elaboración de un Cuadro sinóptico en el cual los yacimientos españoles con Equus se correlacionan con sus sincrónicos italianos sobre una base estratigráfica comparada (BONADONNA, 1982; ARIAS et all., 1982) con los principales eventos geológicos en Europa[Abstract] The chronostratigraphy of the Plio-pleistocene marnmals italian deposits from middle Villafranchian to Galerian is surnmarized. The presence of different forms of Equus stenonis Cocchi until the appearance of the first kinds of Equus caballus Linn. is studied by an evolutive point of view. The comparison among the different evolutive levels of Equus stenonis and the associated fauna allow us to build a synoptic Table in which the spanish deposits with Equus are correlate to analogous italian ones ln a stratigraphic scale yet compared (BONADONNA, 1982; ARIAS et all., 1982) to the most important geological event ln Europ

Large mammal remains from the early pleistocene site of Podere San Lorenzo (Perugia, Central Italy)

Most of the research on fossil mammals from Umbria (central Italy) has been carried out in the southwestern branch of the Tiber basin, due to its paleontological richness. This portion of the basin extends from Perugia to Terni and corresponds to a well-defined half-graben filled with fluvial-lacustrine deposits. The paleontological sample presented here was discovered in a sand and gravel quarry at Podere San Lorenzo, East of the town of Deruta. The stratigraphic succession exposed in the quarry is no longer visible, but we describe here a new outcrop (Palazzone), which is not far from Podere San Lorenzo and shows comparable facies associations. The two successions were deposited in a fluvial environment characterized by an average reduction of the hydrodynamic energy from the bottom upwards. They are referred to the Early Pleistocene Santa Maria di Ciciliano Subsyntheme (Madonna dei Bagni Lithofacies). Large mammal remains are attributed to Mammuthus cf. meridionalis (Nesti, 1825), Stephanorhinus etruscus (Falconer, 1859), Equus stenonis Cocchi, 1867, Leptobos cf. etruscus (Falconer, 1868), ‘Pseudodama’ nestii (Azzaroli, 1947), and Sus strozzii Forsyth Major, 1881. Some hyena coprolites are also reported. The assemblage is typical of the early Late Villafranchian Land Mammal Age and can be referred to the Olivola/Tasso Faunal Units (about 2.0–1.8 Ma). This is in agreement with the alleged age of some other assemblages found in the southwestern branch of the Tiber basin (e.g., Torre Picchio, Villa San Faustino, Colle Sant’Andrea, Pantalla)

Testing Equid Body Mass Estimate Equations on Modern Zebras-With Implications to Understanding the Relationship of Body Size, Diet, and Habitats of Equus in the Pleistocene of Europe

The monodactyl horses of the genus Equus originated in North America during the Pliocene, and from the beginning of the Pleistocene, they have been an essential part of the large ungulate communities of Europe, North America and Africa. Understanding how body size of Equus species evolved and varied in relation to changes in environments and diet thus forms an important part of understanding the dynamics of ungulate body size variation in relation to Pleistocene paleoenvironmental changes. Here we test previously published body mass estimation equations for the family Equidae by investigating how accurately different skeletal and dental measurements estimate the mean body mass (and body mass range) reported for extant Grevy's zebra (Equus grevyi) and Burchell's zebra (Equus quagga). Based on these tests and information on how frequently skeletal elements occur in the fossil record, we construct a hierarchy of best practices for the selection of body mass estimation equations in Equus. As a case study, we explore body size variation in Pleistocene European Equus paleopopulations in relation to diet and vegetation structure in their paleoenvironments. We show a relationship between diet and body size in Equus: very large-sized species tend to have more browse-dominated diets than small and medium-sized species, and paleovegetation proxies indicate on average more open and grass-rich paleoenvironments for small-sized, grazing species of Equus. When more than one species of Equus co-occur sympatrically, the larger species tend to be less abundant and have more browse-dominated diets than the smaller species. We suggest that body size variation in Pleistocene Equus was driven by a combined effect of resource quality and availability, partitioning of habitats and resources between species, and the effect of environmental openness and group size on the body size of individuals.Peer reviewe

Grotta Romanelli (Southern Italy, Apulia). Legacies and issues in excavating a key site for the Pleistocene of the Mediterranean

Grotta Romanelli, located on the Adriatic coast of southern Apulia (Italy), is considered a key site for the Mediterranean Pleistocene for its archaeological and palaeontological contents. The site, discovered in 1874, was re-evaluated only in 1900, when P. E. Stasi realised that it contained the first evidence of the Palaeolithic in Italy. Starting in 1914, G. A. Blanc led a pioneering excavation campaign, for the first-time using scientific methods applied to systematic palaeontological and stratigraphical studies. Blanc proposed a stratigraphic framework for the cave. Different dating methods (C-14 and U/Th) were used to temporally constrain the deposits. The extensive studies of the cave and its contents were mostly published in journals with limited distribution and access, until the end of the 1970s, when the site became forgotten. In 2015, with the permission of the authorities, a new excavation campaign began, led by a team from Sapienza University of Rome in collaboration with IGAG CNR and other research institutions. The research team had to deal with the consequences of more than 40 years of inactivity in the field and the combined effect of erosion and legal, as well as illegal, excavations. In this paper, we provide a database of all the information published during the first 70 years of excavations and highlight the outstanding problems and contradictions between the chronological and geomorphological evidence, the features of the faunal assemblages and the limestone artefacts

What does the “Elephant-Equus” event mean today? Reflections on mammal dispersal events around the Pliocene-Pleistocene boundary and the flexible ambiguity of biochronology

The dispersal of primitive elephantines and monodactyl equids in Eurasia has long been regarded as representative of a substantial turnover in mammal faunas, denoting the spread of open environments linked to the onset of cold and dry conditions in the Northern Hemisphere. During the 1980s, this event was named the “Elephant-Equus event” and it was correlated with the Gauss-Matuyama reversal, today corresponding to the Pliocene-Pleistocene transition and the beginning of the Quaternary, dated at ~2.6 Ma. Therefore, the Elephant-Equus event became a concept of prominent biochronological and paleoecological significance, especially in western Europe. Yet, uncertainties surrounding the taxonomy and chronology of early “elephant” and “Equus”, as well as conceptual differences in adopting (or understanding) the Elephant-Equus event as an intercontinental dispersal event or as a stratigraphic datum, engendered ambiguity and debate. Here, we provide a succinct review of the Elephant-Equus event, considering separately the available evidence on the “elephant” and the “Equus”. Elephantines dispersed out of Africa during the Pliocene (Piacenzian). Their earliest calibrated occurrences from eastern Europe date at ~3.2 Ma and they are usually referred to Mammuthus rumanus, although the allocation of several samples to this species is tentative. Available dating constraints for other localities do not resolve whether the dispersal of Mammuthus was synchronous across Eurasia, but this possibility cannot be ruled out. The spread of Mammuthus was part of an intercontinental faunal exchange between Africa and Eurasia that occurred during the Piacenzian, but in this scenario, Mammuthus is quite unique in being the only genus of African origin dispersing to western Eurasia. The arrival of monodactyl equids from North America coincides with the Pliocene-Pleistocene transition, with several occurrences dated or calibrated at ~2.6 Ma and no compelling evidence prior to this age. In Europe, early monodactyl equids are often aligned to Equus livenzovensis, but the material from the type locality of this species is chronologically time-averaged and taxonomically heterogeneous, and western European samples are seldom abundant or informative. Regardless, this does not diminish the biochronological significance of the “Equus event”. Indeed, while the term “Elephant-Equus event” should no longer be used, as the appearance of elephantines in the European fossil record markedly precedes that of monodactyl equids, we endorse the use of the “Equus event” as a valid alternative to refer to the intercontinental dispersal event that characterizes the middle Villafranchian faunal turnover, epitomized by but not limited to monodactyl equids

Social referencing in the domestic horse

Dogs and cats use human emotional information directed to an unfamiliar situation to guide their behavior, known as social referencing. It is not clear whether other domestic species show similar socio-cognitive abilities in interacting with humans. We investigated whether horses (n = 46) use human emotional information to adjust their behavior to a novel object and whether the behavior of horses differed depending on breed type. Horses were randomly assigned to one of two groups: an experimenter positioned in the middle of a test arena directed gaze and voice towards the novel object with either (a) a positive or (b) a negative emotional expression. The duration of subjects’ position to the experimenter and the object in the arena, frequency of gazing behavior, and physical interactions (with either object or experimenter) were analyzed. Horses in the positive condition spent more time between the experimenter and object compared to horses in the negative condition, indicating less avoidance behavior towards the object. Horses in the negative condition gazed more often towards the object than horses in the positive condition, indicating increased vigilance behavior. Breed types differed in their behavior: thoroughbreds showed less human-directed behavior than warmbloods and ponies. Our results provide evidence that horses use emotional cues from humans to guide their behavior towards novel objects

Prelude to the Anthropocene: Two new North American Land Mammal Ages (NALMAs)

Human impacts have left and are leaving distinctive imprints in the geological record. Here we show that in North America, the human-caused changes evident in the mammalian fossil record since c. 14,000 years ago are as pronounced as earlier faunal changes that subdivide Cenozoic epochs into the North American Land Mammal Ages (NALMAs). Accordingly, we define two new North American Land Mammal Ages, the Santarosean and the Saintagustinean, which subdivide Holocene time and complete a biochronologic system that has proven extremely useful in dating terrestrial deposits and in revealing major features of faunal change through the past 66 million years. The new NALMAs highlight human-induced changes to the Earth system, and inform the debate on whether or not defining an Anthropocene epoch is justified, and if so, when it began