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From slots to tubes: the influence of dimensionality on fracture dissolution models

100%

Szymczak P.

Acta Geophysica

2013

tom Vol. 61, no. 6

1556--1572

We briefly review the models of fracture dissolution process, discussing the experimental and numerical evidence showing that this phenomenon is inherently two-dimensional and hence cannot be accurately described by one-dimensional models. The physical reason for this incompatibility is that a dissolution front in a single rock fracture is potentially unstable to small variations in local permeability, leading to spontaneous formation of dissolution channels in the rock. This leads to a dramatic increase of fissure opening rates, which must be taken into account not only in the estimation of karstification times but also in the assessment of ground subsidence, dam collapse or toxic seepage risks.

Bats of the Sangkulirang limestone karst formations, East Kalimantan — a priority region for Bornean bat conservation

51%

Suyanto A. , Struebig M. J.

Acta Chiropterologica

2007

tom 09

nr 1

Borneo has a significant role to play in the conservation of bat diversity in Southeast Asia, yet there is little taxonomic and distribution information available for the Indonesian states that represent over two thirds of the island. We report the results of a four week harp-trap and mistnet survey of four limestone karst formations on the Sangkulirang peninsula in East Kalimantan during August 2004. We recorded 36 taxa, including two (a Pipistrellus and Rhinolophus) that may represent new species, and three (Hipposideros bicolor, Myotis horsfieldii and M. montivagus) that are new records for Kalimantan. Several species, including the karst dependent and patchily distributed Hipposideros larvatus, Rhinolophus creaghi and R. pusillus, were highly abundant at the formations. In Borneo, many of the species were previously known from only a few, or scattered, localities including four Red-Listed species (R. creaghi, M. montivagus, Murina rozendaali and Kerivoula minuta). We review the Bornean distributions of individual species given recent surveys in Kalimantan and present taxonomic data from 135 specimens collected during this study. This represents the largest bat collection in Kalimantan so far undertaken and highlights the Sangkulirang peninsula as a key site for bat diversity and conservation in Borneo. Threats to this area include disturbance from bird nest collection in caves, but also mass disturbance from logging and forest fires. We advocate inclusion of the formations and associated forests into a protected area to safeguard this biological resource.

Diversity of diapsid fifth metatarsals from the Lower Triassic karst deposits of Czatkowice, southern Poland - functional and phylogenetic implications

51%

Borsuk-Bialynicka M.

Acta Palaeontologica Polonica

2018

tom 63

nr 3

Three morphotypes of the fifth metatarsal (MttV), one of the most informative bones of the postcranium, have been described herein from the Early Triassic karst deposits of the Czatkowice locality (Southern Poland). Two of them have been assigned to a basal archosauriform Osmolskina czatkowicensis and a basal lepidosauromorph, Sophineta cracoviensis, respectively, while one is undetermined saurian. Two morphological categories of the hooked fifth metatarsals recognized from this assemblage account for two different solutions to the problem of improvement of locomotion. A strongly inflected (sensu Robinson 1975) MttV shaft consists of two parts, a distal one lying on the ground in a plantigrade manner and a proximal one bent at an angle to get align with the ventral surface of the crus and proximal tarsus. In contrast, a straight shaft of the hooked MttV, suggests its subvertical life position and thus a digitigrade foot stance. The hooking of the fifth metatarsal, that is currently accepted saurian synapomorphy, appeared in phylogeny in a primitive state referred to herein as a neckless type: with neither a neck-shaped articular protrusion for the fourth distal tarsal nor a directly medial orientation of the articular facet. A derived long-necked type with protruding arricular part and more directly medial orientation of the articular facet appeared, at various stages of further phylogeny. A strong plantar–dorsal inflexion of the fifth metatarsal associated with a protrusion of lateral plantar tubercle, dates from a directly pre-lepidosaurian stage of evolution.