Central Wales (central + wale)

Distribution by Scientific Domains
Earth and Environmental Science100%

Selected Abstracts

Cyclopygid Trilobites from the Ordovician Builth-Llandrindod Inlier, Central Wales

PALAEONTOLOGY, Issue 3 2002
R. M. Owens
Cyclopygids are a minor element in the abundant trilobite fauna of the Ordovician Llanfawr Mudstones Formation (teretiusculus,gracilis biozones) of the Builth-Llandrindod inlier. The rarity of these trilobites may be due to the accumulation of these sediments close to the shoreward limit of their depth range, and if this is the case, their presence, together with sedimentological evidence, can be used to infer the bathymetric limits within which the Llanfawr Mudstones Formation might have been deposited. Species of Degamella, Microparia (Microparia), Microparia (Heterocyclopyge), Sagavia and Emmrichops are described; some are common to the Dobrotivá Formation in Bohemia, whilst others have affinities with species from approximately coeval strata in Kazakhstan and north-west China. [source]

Unravelling causal components of the Ordovician Radiation: the Builth Inlier (central Wales) as a case study

LETHAIA, Issue 2 2008
JOSEPH P. BOTTING
Hypotheses about the causes of biodiversification during the Ordovician have been focused in three main areas: tectonic activity and nutrient supply, palaeogeography, and ecological escalation. There is as yet no consensus on mechanisms, and it is unclear whether it is better to study the patterns at local or regional scales. By applying ecological knowledge to the available palaeontological information, it can be shown that neither tectonic nor palaeogeographic effects could account for the permanence of the diversity rise, in the absence of elements of ecological escalation. However, it may be possible to identify trigger mechanisms resulting in enhanced speciation or reduced extinction. Areas of local diversity increase should be distinguished from speciation centres. An ongoing study of the Middle Ordovician Builth-Llandrindod Inlier of central Wales, conducted over 10 years, has identified elements of all three of the above categories of causal mechanisms affecting local diversity. This implies that the patterns of causal relationship and diversification are complex even at very local scales, and at this stage we should not anticipate a clear correlation of global diversity with any single factor. More data are needed from small-scale but intensive studies before we can generalize about the causal mechanisms of the Ordovician Radiation. [source]

The Wenlock Cyrtograptus species of the Builth Wells District, central Wales

PALAEONTOLOGY, Issue 2 2004
Mark Williams
The Wenlock sequence of the Builth Wells district, central Wales is dominated by long-ranging Monograptus, Pristiograptus and Monoclimacis species. Cyrtograptus species, which underpin the graptolite biozonation, represent only about 10 per cent of recovered individuals. Ten Cyrtograptus species are present, most being zonal index species for the Builth district or other Wenlock sequences. Redescription of these Cyrtograptus species and comparison with all pertinent type material indicates that: the early Wenlock Cyrtograptus insectus, C. centrifugus and C. murchisoni are best distinguished by means of first whorl diameter, sicula length and differences of cladial development; mid Wenlock Cyrtograptus rigidus may bear a secondary cladium, but at Builth there are no stratigraphically discrete subspecies; Cyrtograptus linnarssoni is known only from its type locality; the long, gracile proximal part of the rhabdosome of C. ellesae facilitates its distinction from C. perneri, with which it has been confused, and indicates similarities to C. ramosus and C. lundgreni. Differences in the ranges of key Cyrtograptus species present problems for correlation between the lundgreni Biozone of the Builth district and the perneri-ramosus and lundgreni biozones of central Europe. The low diversity and abundance of the cyrtograptid fauna of the Builth district, compared to those of Arctic Canada and the Czech Republic, suggests relatively inhospitable conditions for graptolites. [source]