Entity

Time filter

Source Type

Leiden, Netherlands

M. indraneil spec. nov. is described from locations in Sarawak, Malaysian Borneo. Both sexes of M. arthuri Fraser are re-described based on recent material. Records of M. amoena Ris from Borneo in fact refer to M. indraneil; there is no evidence that M. amoena occurs on Borneo. Relationships between Argiocnemis, Agriocnemis and Mortonagrion are discussed. Copyright © 2011, Magnolia Press. Source


Donovan S.K.,NCB Naturalis
Lethaia | Year: 2011

Artistic licence is kept under firm control when restoring fossil tetrapods and their natural environments, but the same care is not always applied to reconstructions of ancient invertebrates. Selected renderings of fossil crinoids illustrate grossly inaccurate skeletal geometry and outmoded ideas of palaeoautecology. Together, these combine to give the public an incorrect impression of what a fossil crinoid looked like and how it lived, in some instances inferior to what was possible in the 19th century. The reason why crinoids receive such poor service from artists is, in part, probably due to their being exotic; humans and other tetrapods are a common part of our experience, whereas stalked crinoids, although extant, can only be seen in life with the aid of a research submersible in deep water (>100m). Crinoids also have a complex endoskeleton that requires care in illustration. They are unusual creatures in an alien environment even at the present day. But echinoderm palaeontologists need to be more energetic in promoting the correct depiction of ancient species. □Crinoidea, illustration, morphology, palaeoenvironments, reconstruction. © 2011 The Author, Lethaia © 2011 The Lethaia Foundation. Source


Donovan S.K.,NCB Naturalis
Proceedings of the Geologists' Association | Year: 2013

'Localism' occurs when geologists are most influenced by data with which they are familiar, applying it to new, but not necessarily appropriate, areas of study. Jamaica has been particularly prone to localist interpretations. Henry T. De la Beche (1796-1855) mapped eastern Jamaica in 1823-1824, and made lithostratigraphic comparisons between Jamaica and Europe that were the first attempt at intercontinental correlation. He correlated the Jamaican succession on the basis of lithological similarity to rocks in Europe. Charles A. Matley (1866-1947) is best remembered for his mapping in North Wales. He was geologist to the second geological survey of Jamaica in 1921 and developed the Basal Complex hypothesis which envisaged a geological structure analogous to that of North Wales, where the deformed Mona Complex underlies the Lower Palaeozoic succession. Matley thus provided a 'factual' basis for theories that the Antillean islands were the peaks of a foundered continent. Charles T. Trechmann (1885-1964) was the principal opponent of the Basal Complex hypothesis, not recognising evidence for old basement in Jamaica. His 'answer' was the Theory of Mountain Uplift, based on gravitational tectonics, but Trechmann's theory was comparable to the earlier fixist theories of tectonics that he learnt as a student. © 2012 The Geologists' Association. Source


Donovan S.K.,NCB Naturalis
Proceedings of the Yorkshire Geological Society | Year: 2012

Lower Devonian crinoids are poorly known from the British Isles. The British Geological Survey, Geological Survey Museum collection of Lower Devonian crinoids, mainly made by amateur collectors in the 19th century, is described for the first time. Taxa include Hexacrinites sp. A, Hexacrinites sp. B, Floricrinus (col.) priscus (Goldfuss) (probably Middle Devonian) and Bystrowicrinus (col.) sp. sensu lato; some nautiloids were misidentified as crinoids. Hexacrinites is moderately speciose in the Middle Devonian of SW England; columnals described herein extend this record into the Lower Devonian (Emsian). Pentacrinus priscus Goldfuss, erroneously included in a Mesozoic genus for over 180 years ago, is reclassified within the Devonian morphogenus Floricrinus (col.) Stukalina. Both F. (col.) priscus and Bystrowicrinus (col.) sp. represent columnal morphologies similar to some crinoids locally common in the Upper Ordovician, but unknown from the Silurian of the British Isles. Source


Donovan S.K.,NCB Naturalis
Proceedings of the Yorkshire Geological Society | Year: 2012

Fossil echinoderms derived from the Chalk occur rarely as clasts eroded from erratic rafts on the beaches of north Norfolk and are almost invariably represented by the holasteroid echinoid Echinocorys scutata (Leske). A small collection of other echinoderms from the Overstrand to Cromer coast includes the crinoid Austinocrinus bicoronatus (von Hagenow), and the echinoids Temnocidaris (Stereocidaris) sp., phymosomatid sp. and Galerites sp. Most preserve at least some evidence of corrasion and/or bioerosion. The echinoids are preserved either as steinkerns or are otherwise protected by flint; the crinoid columnal had lost much of its surface detail due to corrasion. The known stratigraphic ranges of these species suggest that they are derived from the local part of the Norfolk Chalk, spanning the upper Campanian to lower Maastrichtian interval. Source

Discover hidden collaborations