ELEMENT ASSOCIATION AND MORPHOLOGY IN SOME MIDDLE ORDOVICIAN PLATFORM-EQUIPPED CONODONTS

2003 ◽  
Vol 77 (4) ◽  
pp. 721-737 ◽  
Author(s):  
ANITA LÖFGREN ◽  
ZHANG JIANHUA
2003 ◽  
Vol 77 (4) ◽  
pp. 721-737 ◽  
Author(s):  
Anita Löfgren ◽  
Zhang Jianhua

Conodont elements other than those with platform ledges along the processes have often been unrecognized or disregarded in reconstructions and phylogenetic discussions of Ordovician “platform conodont genera.” The platform elements are larger than the other element types and often exhibit more rapid evolutionary changes in morphology. Nevertheless, to understand the evolution of, and relationships between and among “platform genera,” it is necessary to also consider the associated ramiform and geniculate elements. Thus, on the basis of large collections, together comprising 10,800 elements from Sweden and southern China, all element types of Lenodus antivariabilis (An, 1981), L. variabilis (Sergeeva, 1963), Yangtzeplacognathus crassus (Chen and Zhang, 1993) and Eoplacognathus pseudoplanus (Viira, 1974) are described and discussed. All these species had seven morphologically distinct element types, and probably seventeen individual elements in each apparatus. Ancestors and descendants of these species are discussed more briefly and it is concluded that the ramiform and geniculate elements also are characteristic within each lineage.


2014 ◽  
Vol 64 (4) ◽  
pp. 367-392 ◽  
Author(s):  
Karolína Lajblová ◽  
Petr Kraft

Abstract The earliest ostracods from the Bohemian Massif (Central European Variscides) have been recorded from the Middle Ordovician of the Prague Basin (Barrandian area), in the upper Klabava Formation, and became an abundant component of fossil assemblages in the overlying Šarka Formation. Both early ostracod associations consist of eight species in total, representing mainly eridostracans, palaeocopids, and binodicopids. The revision, description, or redescription of all species and their distribution in the basin is provided. Their diversification patterns and palaeogeographical relationships to ostracod assemblages from other regions are discussed.


Geology ◽  
2000 ◽  
Vol 28 (8) ◽  
pp. 727-730 ◽  
Author(s):  
Michael P. Joy ◽  
Charles E. Mitchell ◽  
Soumava Adhya
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document