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1
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Graptolodendrum mutabile n.gen., n.sp. - an aberrant dendroid graptolite

100%
Kozlowski R.
Acta Palaeontologica Polonica
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1966
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tom 11
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nr 1
A representative of the order Dendroidea, described as Graptolodendrum mutabile n.gen., n.sp., differs from other dendroid graptolites in its bithecae whose position is not stabilized. Mostly, they occur on one side of the stipe and, rarely, on both sides alternatively which is a rule in the Dendroidea. The fusellar structure of autothecae, mostly irregular in the distal part, is also unstabilized. The position of the pore which pierces the wall of metasicula, as in the Graptoloidea, and not of prosicula, is a fully exceptional character in the representative of the Dendroidea. The material in vestigated has been etched out from the Middle Ordovician erratic boulders of Poland.
2
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First report on the occurrence of Neseuretinus and Ovalocephalus trilobites in the Middle Ordovician of Iran

80%
Ghobadi P. M., Popov L. E.
Acta Palaeontologica Polonica
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2009
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tom 54
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nr 1
125-133
In the Derenjal Mountains of east Central Iran, the upper part of the Shirgesht Formation (uppermost Darriwilian) contains a distinct trilobite assemblage that includes Neseuretinus birmanicus and Ovalocephalus aff. obsoletus among others. Both genera were previously unknown in Iran. The occurrence of Ovalocephalus represents the earliest sign of westward taxon migration from China towards higher latitudes along the West Gondwanan margin, which may be related to global warming, after a short episode of cooler climate in the early to mid Darriwilian. Patterns of biogeographical distribution of Ovalocephalus and Neseuretinussuggest that Central Iran was part of an “overlap zone” where tropical and high latitude benthic taxa mingled.
3
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Revision of Middle Ordovician orthoceratacean nautiloids from Baltoscandia

80%
Kroger B.
Acta Palaeontologica Polonica
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2004
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tom 49
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nr 1
The fauna of the Baltoscandic Orthocerataceae is important because it fills a documentary gap between the Lower Ordovician fauna of North America and the upper Middle Ordovician fauna of China and North America. A revision of the Orthoceratidae, Geisonoceratidae, and Arionoceratidae is given on a material of more than 450 specimens. Intraspecific and ontogenetic variations were observed. The following new taxa are erected: Plagiostomoceras fragile sp. nov., Archigeisonoceras repplingense sp. nov., Archigeisonoceras picus sp. nov. Archigeisonoceras folkeslundense sp. nov., Nilssonoceras latisiphonatum gen. et sp. nov., Kinnekulloceras kinnekullense gen. et sp. nov., and Arionoceras lotskirkense sp. nov. The genus Archigeisonoceras is described for the first time in the Baltoscandic area and the oldest occurrence of the genus Arionoceras is documented from the Middle Ordovician of Baltoscandia. It is shown that the endosiphuncular deposits of the Middle Ordovician orthoceratacaceans are highly variable and widespread in the apical parts of the phragmocone.
4
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Enrolment in a Middle Ordovician agnostoid trilobite

80%
Bruton D. L., Nakrem H. A.
Acta Palaeontologica Polonica
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2005
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tom 50
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nr 3
Study of silicified material of Trinodus elspethi, from the Edinburg Formation, Virginia, USA, shows there is no gliding of distal parts of segments but an articulating furrow and opposing flange with prongs, acting as apodemes for muscle attachment, allowed cephalon and thorax to move as a single unit. Articulation between thorax and pygidium was more rigid with prongs from the thorax articulating in sockets on the pygidium. Support is given to the view that agnostoids lived partially enrolled with cephalon and pygidium gaping. They are unique in lacking an articulating half−ring between cephalon and thorax and the hinge joint is modified medially to provide an opening for what is interpreted as an exhalatory organ through which water passed during feeding and swimming. Peculiarities of the thorax are connected with the presence of only two thoracic segments articulating as a unit with distal tips directed anteriorly rather than posteriorly. Otherwise articulating half rings are present in the rest of the thorax and pygidium and lack of articulating facets is not unique. It is concluded that agnostoids can be shown to be trilobites.
5
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Brachiopods from the Middle Ordovician Shihtzupu Formation of Yunnan Province, China

80%
Zhan R., Jin J.
Acta Palaeontologica Polonica
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2005
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tom 50
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nr 2
The brachiopod fauna of the Middle Ordovician (upper Darriwilian) Shihtzupu Formation in the Weixin area, northeastern Yunnan Province, southwestern China, comprises 16 genera and 18 species, including one new genus (Halirhachis) and five new species (Glyptorthis sarcina, Protoskenidioides weixinensis, Halirhachis leonina, Leptellina spatiosa, and Leptestiina veturna). Cluster and principal component analyses of the latest Arenigian–mid−Caradocian faunas of the Upper Yangtze Platform with selected faunas of similar age from other palaeoplates or terranes indicate that the Weixin brachiopods have closest faunal affinities to those of the typical Shihtzupu Formation in Guizhou Province and the Naungkangyi Group of Burma (Myanmar). During latest Arenigian–mid−Caradocian times, the brachiopods of the Upper Yangtze Platform, Sibumasu, and Chu−Ili palaeogeographical regions constituted a distinct faunal province, characterized by a large number of endemic taxa as well as regionally widespread genera such as Saucrorthis, Martellia, and Yangtzeella. This brachiopod faunal province has very low similarity coefficients with the coeval brachiopod faunas of Laurentia and Avalonia.
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