A Late Occurring “Hipparion” from the middle Villafranchian of Monopoly, Italy (early Pleistocene; MN16b; ca. 2.5 Ma)

We report here for the first time the occurrence in the Montopoli large mammal fossil assemblage of a small equid taxon identified as “Hipparion” sp., associated to the monodactyl large horse Equus cf. livenzovensis. This occurrence has been recognised on a specimen that the late De Giuli (1938-1988) identified as Hipparion sp. in unpublished notes available in the archives of the Vertebrate Palaeontology Laboratory of the Dipartimento di Scienze della Terra at the Università degli Studi di Firenze. Although fragmentary, the specimen documents the occurrence of “Hipparion” at the middle Villafranchian (early Pleistocene, ca. 2.5 Ma) site of Montopoli, one of the latest occurrences of an hipparionine horse in western Europe. The western Eurasian “Hipparion” evolutionary history is summarised herein

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

Conformational Assignement, Absolute Configuration and Chiral Separation of all the Stereoisomers Created by the Combined Presence of Stereogenic Centers and Stereogenic Conformational Axes in a Highly Hindered 1,5-Naphthyl Sulfoxide.

The presence of two stereogenic centers and of two stereogenic conformational axes in 2,6-dimethyl-1,5-bis(2-methyl-2-propylsulfinyl)naphthalene (1) entails the existence of 10 stereoisomers. In particular, both the meso form (1a) and the racemic form (1b) are constituted by three atropisomers; in the case of the latter (1b) each of them entails a pair of enantiomers (total of six species), whereas owing to the symmetry only one of the three atropisomers of the meso form (1a) yields a pair of enantiomers (a total of four species). Despite the low conformational interconversion barrier (18.5 kcal/mol) all of them have been separated by low temperature (-45°C) chiral HPLC. Their configurational and conformational assignment has been achieved by a combined use of NMR (both in solution and solid state) and on-line CD-detected chiral HPLC. The single crystal X-ray diffraction yielded the absolute configuration of one of the stereoisomers ((ZR,ER)-1b) from which all the others could be obtained by CD relationship

Palynostratigraphy of the Triassic-Jurassic of the Silves Group, Lusitanian Basin, Portugal [Resumo]

ABSTRACT: We studied the miospore assemblage from an Upper Triassic to Lower Jurassic succession of the Silves Group near Coimbra, Portugal. The latter consists of, from base to top, the Conraria, Penela, Castelo Viegas, and the Pereiros formations. The palynological assemblages allowed establishing an informal palynozonation and providing new biostratigraphic that helped constrain the age attribution to the Silves Group formations.N/

SAHABI EURYGNATHOHIPPUS FEIBELI: ITS SYSTEMATIC, STRATIGRAPHIC, CHRONOLOGIC AND BIOGEOGRAPHIC CONTEXTS

Sahabi, Libya is an important latest Miocene locality having yielded an extensive paleobotanical and vertebrate fauna. Amongst the fossil mammals there occurs an extensive, species diverse record of hipparionine horses. We develop here a complete record of Sahabi Eurygnathohippus feibeli now based on dental and postcranial material, in comparison to other equids from late Miocene equids from Europe, West Asia and Africa. We find that E. feibeli is the earliest recognized species of the predominantly African clade Eurygnathohippus, that its biogeographic range was Kenya, Ethiopia, Libya and Morocco, it ranged between 7.0 and 5.7 Ma and that it had deep-time evolutionary roots extending back to first occurring Old World hipparions. We further find that Eurygnathohippus was restricted to Africa until a more advanced member of the clade extended its range into the Indian Subcontinent during the late Pliocene, ca. 3.6-2.6 Ma