to be little more than poorly understood curiosities. A new per- 

 spective on early evolution emerged in 1952 when Stanley Tyler, 

 an economic geologist from the University of Wisconsin, con- 

 tacted Barghoorn concerning structures resembling microorgan- 

 isms that he had observed in petrographic thin sections of the 

 2000 million year old Gunflint Iron Formation, Ontario. (Tyler 

 and Barghoorn had already begun to collaborate on the investi- 

 gation of a 2000 million year old coal from the Michigamme 

 Formation of Michigan — surely one of the rarest items in the 

 Coal collections.) Barghoorn confirmed the structures as micro- 

 fossils, and in a subsequently published report (Tyler and 

 Barghoorn, 1954), the two scientists quadrupled the known 

 length of the fossil record and ushered in a new era of paleobio- 

 logical research on the earth's most ancient rocks. Barghoorn 

 and Tyler made several collecting trips to the Gunflint in the 

 1950's, and since that time further collections by Barghoorn and 

 his students have increased both the size and comprehensiveness 

 of Harvard's Gunflint collection. Upon the death of Stanley 

 Tyler in 1963, his entire collection of Gunflint thin sections was 

 given to the Paleobotanical Collections. The Harvard Gunflint 

 collections include carbonaceous shales, stromatolites, anthrax- 

 olites, and other associated sedimentary rocks, as well as fossilif- 

 erous cherts, and they continue to serve as source material for 



paleobiological and geochemical research. 

 The Gunflint provides the historical nucleus of the Precam- 



brian collections, but numerous additional research projects 

 involving Barghoorn and his students have increased the scope 

 of the collections tremendously during the past two decades. The 

 collections now include material ranging in age from the Isua 

 Supracrustal rocks, at 3800 million years old the oldest known 

 rocks on earth, to the base of the Cambrian Period. Some 70 

 formations from six continents are represented. In addition to 

 the Gunflint Formation, highlights include some of the oldest 

 fossiliferous material known, microfossiliferous cherts from the 

 3400 Ma old Swaziland Supergroup, South Africa, and the orig- 

 inal collections of the important Late Precambrian biota of the 

 Bitter Springs Formation, Australia. Collections made by A.H. 

 Knoll in the Late Precambrian sequences of Svalbard and East 



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