74 AN INTRODUCTION TO THE STUDY OF FOSSILS 



in Spitzbergen and Europe from Russia to Portugal ; it continued 

 in abundance and with wide distribution during the Cretaceous 

 and Tertiary, but disappeared during the cold climate of the 

 Pleistocene, except in the California-Oregon region. Sequoia 

 langsdorfij, the direct ancestor of the redwood, was very wide- 

 spread in the great circumpolar 

 conifer forests of Upper Cretaceous 

 time ; while S. magnijica, so abun- 



\^ # dant in the Tertiary of the Yellow- 



stone National Park, was almost 

 identical with the living redwood. 

 (3) The genus Taxodium (Fig. 26), 

 consisting of the bald cypress, char- 

 acteristic of hard or sandy bottom 

 swamps, and of a Mexican species, 

 is now confined solely to the 

 southern Atlantic and Gulf Coastal 

 plain; but in early Tertiary time 

 this genus was as figure 26, A shows, 

 universal north of the tropic of 

 Cancer. Such a map indicates the 

 tremendous changes in plant distri- 

 bution brought on by the advent of 

 glacial conditions in the north polar 

 area, while the recent description 

 of the fossil flora of Graham Land (Upper Jurassic) by Halle 

 shows like changes on a gigantic scale in Antarctica, 



{d) CupressecB. — Including the juniper, arbor vitae, etc. 

 Known doubtfully from the Jurassic. 



Fig. 26, B. — A twig of 

 Taxodium distichum tniocen- 

 icum Heer (X2), from 

 the Tertiary of Utah. 

 (From Lesquereux.) 



1 . Name three living conifers with which you are acquainted. 



2. What is the geologic range of this order? 



3. Into w^hat two families is it divided? 



4. What is jet ? 



5. Discuss Sequoia, noting its appearance, present habitat, 

 and former distribution. 



