Experimental examination of animal trampling effects on artifact movement in dry and water saturated substrates: a test case from South India

This paper presents the motivation, procedures, and results of an experiment that examines short episodes of animal trampling in dry and water saturated substrates in South India. While horizontal artifact displacement was similar to that modeled by other trampling experiments, vertical artifact displacement in water saturated substrates was greater than any reported experiment to date. The toolstone used in this experiment, a silicious limestone, exhibited minimal damage after trampling. Artifact inclination patterning appeared to be a potentially diagnostic middle-range marker of trampling in water saturated substrates. Given the abundant number of Paleolithic sites that are located on flat, open surfaces near water-bodies, or experience monsoonal climatic regimes, we propose that future excavations should measure artifact inclination on a regular basis.     

Changes in fluid pathways in a calcite vein mesh (Natih Formation,Oman Mountains): insights from stable isotopes

We present a structural, microstructural, and stable isotope study of a calcite vein mesh within the Cretaceous Natih Formation in the Oman Mountains to explore changes in fluid pathways during vein formation. Stage 1 veins form a mesh of steeply dipping crack‐seal extension veins confined to a 3.5‐m‐thick stratigraphic interval. Different strike orientations of Stage 1 veins show mutually crosscutting relationships. Stage 2 veins occur in the dilatant parts of a younger normal fault interpreted to penetrate the stratigraphy below. The δ¹⁸O composition of the host rock ranges from 21.8‰ to 23.7‰. The δ¹³C composition ranges from 1.5‰ to 2.3‰. This range is consistent with regionally developed diagenetic alteration at top of the Natih Formation. The δ¹⁸O composition of vein calcite varies from 22.5‰ to 26.2‰, whereas δ¹³C composition ranges from ?0.8‰ to 2.1‰. A first trend observed in Stage 1 veins involves a decrease of δ¹³C to compositions nearly 1.3‰ lower than the host rock, whereas δ¹⁸O remains constant. A second trend observed in Stage 2 calcite has δ¹⁸O values up to 3.3‰ higher than the host rock, whereas the δ¹³C composition is similar. Stable isotope data and microstructures indicate an episodic flow regime for both stages. During Stage 1, formation of a stratabound vein mesh involved bedding‐parallel flow, under near‐lithostatic fluid pressures. The ¹⁸O fluid composition was host rock‐buffered, whereas ¹³C composition was relatively depleted. This may reflect reaction of low ¹³C CO₂ derived by fluid interaction with organic matter in the limestones. Stage 2 vein formation is associated with fault‐controlled fluid flow accessing fluids in equilibrium with limestones about 50 m beneath. We highlight how evolution of effective stress states and the growth of faults influence the hydraulic connectivity in fracture networks and we demonstrate the value of stable isotopes in tracking changes in fluid pathways.     

Chronicles of vadose zone diagenesis: cone‐shaped iron oxide concretions,Triassic Trujillo Formation,Palo Duro Canyon,Texas

Unusual cone‐shaped iron oxide concretions occur in the Late Triassic, lower fluvial sandstone member of the Trujillo Formation at Palo Duro Canyon in the Texas panhandle. In situ concretions are significant because they record both historical information about past processes that occurred within the geologic unit and present‐day information about the ability of the unit to conduct fluids. The dominant orientation of the concretions is cone‐apex up, body radiating down and out, with long axis perpendicular to bedding. Concretion morphologies are associated with the sedimentary texture and primary bedding structure of the host rock and the corresponding hydrologic regime (i.e. advection versus dispersion for iron‐transport behavior). Three lithofacies in the lower Trujillo member exhibit different cone forms. Field observations of cone orientation and morphology suggest vadose conditions for diagenetic precipitation of iron oxide cements, with timing potentially represented by the major pre‐Miocene unconformity.     

State‐Community Relations in Yemen: Soqotra’s Historical Formation as a Sub‐National Polity

Soqotra Island, the remote border outpost of the Yemeni state in the Indian Ocean, is a community of mixed ethnic composition with a non‐Arabic mother tongue. It offers an ideal socio‐political context for the study of state–community relations in terms of polity formation as part of a political incorporation process. This focus provides a corrective to the still dominant segmentary society paradigm and its tribes‐driven state politics in the anthropological discourse on Yemen. Polity formation in Soqotra occurred through a series of acts of political incorporation by a succession of political regimes from the late nineteenth century to the present. The study of this process is pursued through a historical narrative of the state’s politics of administration. This narrative is aptly described as a mesography, as its analytical focus is on the meso‐level institutional web of four different political regimes with their distinctive modes of polity regimentation and their structuring effects on Soqotrans’ communal life.     

The formation process of a paleoindian open-air site in Central Brazil: integrating lithic analysis,radiocarbon and luminescence dating

Lithic analysis, radiocarbon dating and luminescence dating are applied to a stratified open-air Paleoindian site in Central Brazil, lending some balance to a published record dominated by rock shelter sites. Most lithics are found in two discrete occupation layers. Lithics found outside these layers are attributed to post-depositional movement of small flakes mainly upwards. Single-grain luminescence dating on quartz grains also suggest post-depositional movement. Both wind and bioturbation are suspected mechanisms. The luminescence analysis does not provide precise depositional dates in this situation but does support such dates suggested by radiocarbon.     

Modelling site formation dynamics: geoarchaeological,chronometric and statistical approaches to a stratified rockshelter sequence,Polynesia

Formation processes and chronology are central to many archaeological endeavours, and accuracy in the latter is dependent on control of the former. Here we consider how to integrate geoarchaeological and chronometric evidence to better understand the formational history, along with the timing and duration of cultural activities, at a regionally significant site in the southern Cook Islands (Polynesia) which dates from ∼12th century AD. Initially we model natural and cultural processes of deposition using geoarchaeological evidence. The results are integrated with 21 radiocarbon dates, including nine new AMS results on identified medium and short-lived materials. Sample outliers are identified manually and statistically and a Bayesian analysis helps to refine age estimates for the site's 12 stratigraphic zones. The timing and rate of sediment accumulation is further considered through an age–depth model. Finally, the chronology developed from these combined approaches is used to address three key processes: 1) initial site use, potentially relevant to human colonisation of this Polynesian island and archipelago; 2) on-site activities and patterns of resource use; and 3) major marine deposition events which disrupted cultural activities and may have palaeoclimatological significance. The approach developed here potentially has utility elsewhere, particularly where human activities are recurrent and of limited duration.     

An additional basal sauropodomorph specimen from the Upper Triassic Caturrita Formation,southern Brazil,with comments on the biogeography of plateosaurids

Bittencourt, J.S., Leal, L.A., Langer, M.C. & Azevedo, S.A.K., June 2012. An additional basal sauropodomorph specimen from theUpperTriassic Caturrita Formation, southern Brazil, with comments on the biogeography of plateosaurids. Alcheringa, 1–10. ISSN0311-5518.

We describe an additional saurischian specimen from the Caturrita Formation (Norian) of the Parana Basin, southern Brazil. This material was collected in the 1950s and remained unstudied due to its fragmentary condition. Detailed comparisons with other saurischians worldwide reveal that some characters of the ilium, including the low ventral projection of the medial wall of the acetabulum and its concave ventral margin, together with the short triangular shape of the pre-acetabular process and its mound-like dorsocaudal edge, resemble those of sauropodomorphs such as Plateosaurus and Riojasaurus. This set of traits suggests that MN 1326-V has affinities with basal Sauropodomorpha, probably closer to plateosaurians than to Saturnalia-like taxa. Previous records of this clade in the Caturrita Formation include Unaysaurus, which has been related to Plateosaurus within Plateosauridae. Alternative schemes suggest that plateosaurids include Plateosaurus plus the Argentinean ‘prosauropods’ Coloradisaurus and Riojasaurus. Both hypotheses raise biogeographic questions, as a close relationship between faunas from South America and Europe excluding Africa and North America is not supported by geological and biostratigraphical evidence. Additionally, the absence of plateosaurids in other continents suggests that the geographical distribution of thistaxon is inconsistent with the geological history of western Pangaea, and this demands further investigations of the phylogeny of sauropodomorphs or improved sampling.

J.S. Bittencourt* [sigmaorionis@yahoo.com.br] Laboratório de Paleontologia, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 1404901, Ribeirão Preto, SP, Brazil. Fellow FAPESP; L.A. Leal, Departamento de Ciências Biológicas, Universidade Estadual do Sudoeste da Bahia, Rua José Moreira Sobrinho, s/n, 45206-190, Jequié, BA, Brazil; M.C. Langer, Laboratório de Paleontologia, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 1404901, Ribeirão Preto, SP, Brazil; S.A.K. Azevedo, Laboratório de Processamento de Imagem Digital, Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s/n, 20940-040, Rio de Janeiro, RJ, Brazil. Received 29.7.2011; revised 10.10.2011; accepted 18.10.2011.     

Selachian scales from the Cenomanian (Late Cretaceous) of Bathurst Island,northern Australia

Seven selachian scale types are described from the middle Cenomanian Moonkinu Formation, outcropping on the southern shores of Bathurst Island in northern Australia. The scales are classified in accordance with previously published scale morphologies of Cretaceous and modern sharks, and are representative of the Orders Squatiniformes (Family Squatinidae), Carcharhiniformes (Family Scyliorhinidae), and Lamniformes (Family Odontaspididae). The presence of typically bottom-dwelling, shallow-water angelsharks (squatinids), catsharks (scyliorhinids), and sand tiger sharks (odontaspidids) within the Moonkinu Formation support an inner neritic depositional environment interpretation for the unit, previously determined from foraminiferal biofacies and lithology. The biostratigraphic potential of these scales can only be assessed after scales from more Cretaceous localities are described and documented.     

A new species of Scirrotherium Edmund & Theodor, 1997 (Xenarthra,Cingulata, Pampatheriidae) from the late Miocene of South America

Góis, F., Scillato-Yané, G.J., Carlini, A.A. & Guilherme, E. 2013. A new species of Scirrotherium Edmund & Theodor, 1997 (Xenarthra, Cingulata, Pampatheriidae) from the late Miocene of South America. Alcheringa 37, 175–186. ISSN 0311-5518.

A new species of Scirrotherium Edmund & Theodor (Pampatheriidae) is described: S. carinatum. This genus was previously represented by a single species, S. hondaensis Edmund & Theodor, 1997, recorded from the middle Miocene (Laventan) of Colombia. Pampathere remains are common in the ‘Conglomerado osífero’ (late Miocene) of the Ituzaingó Formation in the Paraná River cliffs of Entre Ríos, Chubut (Argentina) and Acre (Brazil). All of them were referred to Kraglievichia paranense, and they are mostly osteoderms. However, only a few of these specimens are strictly consistent with that species. The new species described herein differs from S. hondaensis in having very thin osteoderms with more elaborate ornamentation. The movable band (or imbricate) osteoderms have a sculptured exposed surface and a single transverse row of anterior foramina; the lateral margins are wider and also bear foramina, and the longitudinal central elevation is long and proximally wide, and forms a posteriorly raised crest. This elevation is delimited by a fairly broad and shallow depression on each side, separating the marginal elevation from the longitudinal central one. The exposed surfaces of fixed (or fused) osteoderms bear large and deep anterior foramina, the longitudinal central elevation and delimiting depressions are very pronounced. This new species increases the known diversity of the pampatheres from the ‘Conglomerado osífero’. Additionally, a new nomenclatural scheme for Pampatheriidae osteoderms is proposed.

Flávio Góis [goisf@fcnym]unlp.edu.ar], Gustavo Juan Scillato-Yané [scillato@fcnym.unlp.edu.ar], Alfredo Armando Carlini [acarlini@fcnym.unlp.edu.ar], Departamento Científico Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque, s/n, 1900, La Plata, Buenos Aires, Argentina and CONICET; Edson Guilherme [guilherme@ufac.br], Universidade Federal do Acre, Laboratório de Pesquisas Paleontológicas (LPP), BR 364, Km 04, 69.915-900. Rio Branco, AC, Brazil. Received 11.5.2012; revised 31.7.2012; accepted 4.9.2012 .