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Scott), Radiodiscus riochicoensis Crawford
and Lilloiconcha gordurasensis (Thiele)), and
hence they would be their first fossil record.
The high diversity of the assemblage (7 species)
is unusual for a single bed, and it is comparable
to the more diverse recent South
American microgastropod faunas. The gastropod
assemblage of the Rosado paleosol is
similar to present-day northwestern Patagonia
association, and indicates a humid and coldtemperate
climate. Such conditions would
have change during the late pedogenesis stage
(Late Eocene) towards a dry climate. The
abundance of the specimens and the preservation
of their delicate sculptures reflect appropriate
conditions for preservation related to
soil carbonate cementation.
2008010189
头 足 类 爱 丽 斯 木 角 石 目 ( 鹦 鹉 螺 亚 纲 , 头
足 纲 ) 的 一 些 少 为 人 知 的 特 征 = Some
lesser known features of the ancient Cephalopod
Order Ellesmerocerida (Nautiloidea,
Cephalopoda). ( 英 文 ). Kröger B. Palaeontology,
2007, 50(3): 565-572
Three specimens of the small breviconic
ellesmeroceratid Paradakeoceras minor
Flower, 1964 from the Tremadocian of the
New York area preserve the annular elevation
and muscle scars in moulds of the body chamber.
The annular elevation is positioned at the
base of the body chamber and is wider on the
convex side of the shell than on the concave
side. Multiple paired muscle scars can be seen
within this annular elevation. A wellpreserved
body chamber of the breviconic
ellesmeroceratid Levisoceras cf. edwardsi
Ulrich, Foerste and Miller is described. Its
body chamber shows a strong anterior–
posterior asymmetry, which is common within
the Ellesmeroceratida. The shape of the body
chamber and of the soft body attachment
structures has led to a reconstruction of an
ellesmeroceratid soft body that is organized
like a primitive conchiferan mollusc. Based on
this reconstruction, a tryblidian cephalopod
ancestor is supported. An evolutionary scenario
is reconstructed from an ancestral nautiloid
that is stretched along the anterior–
posterior axis, and has serially arranged shell
muscles and a small mantle cavity, towards a
modern cephalopod with a dorsal–ventral
body orientation, reduced number of shell
muscles and a large mantle cavity.
2008010190
穿 越 二 叠 纪 / 三 叠 纪 界 线 的 菊 石 : 分 支 分 类
学 的 视 角 = Ammonoids across the Permian/Triassic
boundary: a cladistic perspective.
( 英 文 ). McGowan A J; Smith A B. Palaeontology,
2007, 50(3): 573-590
The rapid diversification of ceratitid ammonoids
during the earliest Mesozoic has
been taken at face value as an example of explosive
radiation following the Permian/Triassic
mass extinction. However, the
validity of this interpretation has never been
tested within a phylogenetic framework. A
total evidence cladistic analysis of Mid–Late
Permian and Induan (earliest Triassic) ammonoids
confirms the monophyly of the
Ceratitida. Partitioned phylogenetic analysis
of suture line characters vs. shell shape and
ornament characters confirms the importance
of suture-line characters for resolving the
higher taxonomy of ammonoids. When the
cladogram is compared with the observed fossil
record, the resultant tree implies that the
divergence of a number of early Triassic lineages
actually occurred during the latest Permian.
If these range extensions are taken into
account the ammonoid per-genus extinction
rate across the Permian/Triassic boundary
drops from c. 85 per cent to c. 60 per cent.
2008010191
藏 南 喜 马 拉 雅 山 菊 石 及 二 叠 / 三 叠 纪 界 线 =
Ammonoids and the Triassic/Jurassic Boundary
in the Himalayas of Southern Tibet. ( 英
文 ). Yin Jiarun; Smith P L; Pálfy J; Enay R.
Palaeontology, 2007, 50(3): 711–737
The sections of Germig in the Nyalam area,
southern Tibet, provide a continuous exposure
of ammonoid-bearing, uppermost Triassic and
basal Jurassic strata. Eighteen species (three of
them new) are described and illustrated: Choristoceras
marshi Hauer, C. aff. marshi, C. cf.
nobile Mojsisovics, C. nyalamense sp. nov.,
Eopsiloceras germigense sp. nov., Pleuroacanthites
aff. biformis (Sowerby), Rhacophyllites
sp., Nevadaphyllites cf. psilomorphus
(Neumayr), Neophyllites sp. indet., Neophyllites
cf. biptychus (Lange), Psiloceras tibeticum
sp. nov., P. calliphyllum (Neumayr),
Euphyllites cf. struckmanni (Neumayr), Discamphiceras
pleuronotum (Canavari), Alsatites
spp., Kammerkarites frigga, and K. sp.
The ammonoid fauna shows a strong affinity
to that of the Northern Calcareous Alps, although
diversity in the Calliphyllum Zone is
markedly lower. The ammonoid succession
across the Triassic/Jurassic boundary is subdivided
into four zones: the Rhaetian Marshi,
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