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tebrate fauna of ostracoderms, arthrodires,
acanthodians and chondrichthyans, first described
in 1881. Although a significant series
of pterygotid fossils was acquired by the Natural
History Museum, London, in 1892, it received
little attention. A few small specimens
from the Geological Survey of Canada collections
were named Pterygotus atlanticus by
Clarke and Ruedemann, considered here to be
an invalid taxon. They suggested that
P. atlanticus might turn out to be a small
specimen of P. anglicus. The new material
described here, including one relatively complete
individual, confirms their suspicions and
provides evidence of Pterygotus anglicus in
the Lower Devonian of North America.
2008010229
美 国 蒙 大 拿 州 Bear Gulch 灰 岩 中 一 石 炭 纪
Synziphosurine( 剑 尾 目 ) = A Carboniferous
Synziphosurine (Xiphosura) From The
Bear Gulch Limestone, Montana, USA. ( 英
文 ). Moore R A; McKenzie S C; Lieberman B
S. Palaeontology, 2007, 50(4): 1013-1019
A new synziphosurine, Anderella parva gen.
et sp. nov., extends the known range of this
group from the Silurian to the Carboniferous
and is the youngest known so far from the
fossil record. Previously the youngest synziphosurine,
Kasibelinurus, was from the Devonian
of North America. Anderella parva has
a semi-oval carapace with pointed genal regions,
nine freely articulating opisthosomal
segments and a long styliform tail spine. It is
the third xiphosuran genus to be described
from the Bear Gulch Limestone and its discovery
highlights this deposit as containing an
unusually diverse xiphosuran biota. It is also
the only known locality where synziphosurines
occur alongside the more derived xiphosurids.
Xiphosurans reached their greatest diversity
in the Carboniferous when the xiphosurids
began to occupy brackish and freshwater
habitats and became dominant over the
synziphosurines. The discovery of the only
known Carboniferous synziphosurine in marine
sediments may indicate their inability to
exploit these same environments.
2008010230
三 叶 虫 聚 合 眼 中 富 集 镁 元 素 的 透 镜 体 间 结
构 = Magnesium-Rich Intralensar Structures
in Schizochroal Trilobite Eyes. ( 英 文 ). Lee M
R; Torney C; Owen A W. Palaeontology,
2007, 50(5): 1031-1037
The interpretation of the lenses of
schizochroal trilobite eyes as aplanatic doublets
by Clarkson and Levi-Setti over 30 years
ago has been widely accepted. However, the
means of achieving a difference in refractive
index across the interface between the two
parts of each lens to overcome spherical aberration
has remained a matter of speculation
and lately it has been argued that the doublet
structure itself is no more than a diagenetic
artefact. Recent advances in technologies for
imaging, chemical analysis and crystallographic
characterization of minerals at high
spatial resolutions have enabled a reexamination
of the structure of calcite lenses
at an unprecedented level of detail. The lenses
in the eyes of the specimen of Dalmanites sp.
used in the original formulation of the
aplanatic doublet hypothesis are shown to
have undergone diagenetic alteration, but its
products reflect original differences in mineral
chemistry between the upper lens unit and
lower intralensar bowl. The turbidity of the
bowl and of the core within the upper part of
the lens are the result of their greater microporosity
and abundance of microdolomite inclusions,
both of which were products of
diagenetic replacement of original magnesian
calcite in these areas. Such a difference in
magnesium concentration in the original calcite
has long been postulated as one of the
ways by which the interface between these
lens units could have produced an aberrationfree
image and the present study provides the
first direct evidence of such a chemical contrast,
thus confirming the doublet hypothesis.
2008010231
西 藏 西 南 部 Gyanyima 剖 面 乐 平 阶 和 二 叠
纪 - 三 叠 纪 界 线 的 介 形 类 = Ostracods from
the Lopingian and Permian–Triassic boundary
beds at the Gyanyima section in southwestern
Tibet, China. ( 英 文 ). Crasquin-SoleauS; Shen
Shu-Zhong; Li Wen-Zhong ; Cao Chang-Qun.
palaeoworld, 2007, 16(1-3): 222-232
Ostracods are reported for the first time in
the Late Permian Lopingian to earliest Triassic
carbonate sequence in the Ngari region,
southwestern Tibet, China. Fifty-three species
are recognized, of which 19 are illustrated.
One new species (Carinaknightina tibetensis n.
sp.) is described and one species is renamed
(Bairdia wangi n. nom.). The ostracod fauna
as a whole is very similar to those in the Palaeo-Tethys
and characteristic of warm water
platform deposits. The Early Triassic ostracod
assemblages in the section show no substantial
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