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pidiformes and Pteraspidiformes) is analyzed.
Cyathaspids appeared in the Silurian
and achieved the peak of diversity
in the first half of the Early Devonian
(Lochkovian Stage and its analogues), as
did pteraspids. Cyathaspids are absent
from later beds. Pteraspids persisted to
the end of the Early Devonian, although
they sharply decreased in number in the
second half of the Early Devonian
(Pragian Stage and its analogues in
Europe and America). Adaptive features
of cyathaspids and pteraspids are considered.
Some data on accompanying
groups are discussed. It is proposed that
these heterostracan orders became extinct
mostly because of archaic locomotor
adaptations and insufficient protection
from predators. The insufficient
protection primarily concerns juvenile
cyathaspids. Cyathaspid and pteraspid
genera included in the diagrams of
changes in taxonomic diversity are listed.
2010010422
俄 罗 斯 欧 洲 部 分 晚 二 叠 世
Discordichthyiformes = Late Permian
Discordichthyiformes (Osteichthyes)
from European Russia. ( 英 文 ). Minikh
A V. Paleontological Journal, 2006,
40(5): 564-571 3 图 版 .
New Late Permian fishes combining
features characteristic of several classes
are analyzed and redescribed. They were
assigned to the family Discordichthyidae
of the order Discordichthyiformes comprising
three genera and four species:
Mutovinia stella Minich, Geryonichthys
longus A. Minich, G. burchardi A.
Minich, and Discordichthys spinifer A.
Minich (Minikh, 1998). A new species,
Mutovinia sennikovi sp. nov., is described.
Due to rapid evolutionary replacement,
discordichthyids are rather
useful stratigraphically. The photographs
of the skeleton and membrane
bones of these fishes are published for
the first time.
2010010423
“ 泥 泞 ” 中 的 四 足 动 物 起 源 = Muddy
tetrapod origins. ( 英 文 ). Janvier P; Clément
G. Nature, 2009, 463(7277): 40-41
The tracks left by organisms are
among the most difficult of fossils to
interpret. But just such evidence puts
debate about the origins of four-limbed
vertebrates (which include ourselves) on
a changed footing
2010010424
Rhipidistians 的 舌 鳃 骨 骨 骼 和 下 鳃 肌
= Hyobranchial skeleton and hypobranchial
muscles of rhipidistians. ( 英 文 ).
Kanyukin A A. Paleontological Journal,
2006, 40(3): 297-311 9 图 版 .
The hyobranchial skeleton of the
porolepiform rhipidistian Laccognathus
panderi Gross is described. The double
composition of the ceratohyal in crossopterygians
is proposed. The urohyal of
porolepiforms, like that of Latimeria,
consists of cartilaginous axial and membranous
peripheral portions. The differences
between porolepiforms and osteolepiforms
in the structure of the hyobranchial
skeleton, particularly, in the
shape of the urohyal are attributable to
different arrangements of the hypobranchial
muscles. Porolepiforms and coelacanths
have retained the coracomandibularis
muscle inherited from early gnathostomes,
whereas the same muscle of
osteolepiforms was transformed into the
geniohyoideus muscle. This transformation
is accounted for by functional
changes in the hyobranchial apparatus.
2010010425
拉 脱 维 亚 泥 盆 纪 Laccognathus 一 新
种 = A new species of Laccognathus
(Porolepiform Crossopterygii) from the
Devonian of Latvia. ( 英 文 ). Vorobyeva
E I. Paleontological Journal, 2006,
40(3): 312-322 8 图 版 .
A new species of the genus Laccognathus,
L. grossi sp. nov., from the upper
strata of the Gauja Formation of the
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