Cliarlejf B. anb iHarp ^aux Mahott 3^tieattff jfunb 



NEW LOWER CAMBRIAN TRILOBITE FAUNULE 



FROM THE TACONIC SEQUENCE OF 



NEW YORK 



By 



FRANCO RASETTI 



Johns Hopkins University, Baltimore, Md. 



Honorary Research Associate, Smithsonian Institution 



(With 12 Plates) 



INTRODUCTION AND ACKNOWLEDGMENTS 



The Lower Cambrian formations of the Taconic sequence in New 

 York are among the most thoroughly investigated deposits of this age 

 in eastern North America. After the classic faunal studies of Ford 

 and Walcott in the second half of the last century, no essentially 

 new faunules were discovered. Lochman (1956) described several 

 new species and gave a general review of the known Lower Cambrian 

 fossils of the sequence, occurring in what was formerly known as the 

 Schodack Formation, now subdivided (Zen, 1964) into several units. 

 All the species may be considered members of a single assemblage, 

 named from the characteristic olenellid trilobite Elliptocephala asa- 

 phoides. 



The discovery of an essentially new Lower Cambrian trilobite 

 faunule was therefore unexpected. In 1956 Mr. Thomas W. Tal- 

 madge noticed the presence of fossiliferous limestone outcrops on a 

 hill south of North Chatham, Columbia County. In 1963 Dr. John 

 M. Bird collected small samples from two of these outcrops and 

 submitted them to the U.S. Geological Survey for identification of 

 the fossils. Dr. A. R. Palmer prepared and examined the specimens 

 and recognized in one of the collections the presence of trilobites 

 unlike any of those previously known from the Lower Cambrian of 

 the Taconic sequence or any other region. He suggested to the 

 writer a study of the new faunule. Collections much larger than the 

 original ones were made by Dr. Bird and the writer, until most of the 

 accessible, fossiliferous portions of the limestone outcrop had been 

 recovered and examined. Hundreds of trilobite specimens, represent- 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 148, NO. 9 



