158 TREE ANCESTORS 



of years. A still flourishing forest giant with a height of upwards 

 of 170 feet and a trunk diameter of 10 or 11 feet, which are the 

 dimensions of some individuals of our American sycamore {Platanus 

 occidentalis L.), has survived more changes in human history than 

 almost any royal or ducal line. Columbus might have seen a still 

 surviving one as a young tree had he penetrated inland along the 

 river bottoms of our southern states. The family history is sur- 

 passingly more majestic for it extends back to the days when even 

 the ape-man was a distant promise and the reptilian tribe of 

 animals were the lords of creation. The gigantic uncouth dino- 

 saurs of the late Cretaceous, so many of which have been unearthed 

 and are now mounted in our larger museums, carry us a long way 

 back and yet we know from the records, that when the breath of 

 life left their massive bulks some of the leaves that fell around them 

 were those of plane trees not very different from the leaves that 

 strew the ground in our parks in October. 



These trees have interests for the forester, the lumberman, the 

 votary of culture and the botanist. For the latter they have an 

 especial interest because of their affinity with the figs (another 

 group of great antiquity) and their disputed position in the current 

 schemes of classification. 



A brief consideration of the Cretaceous records of Platanus sheds 

 a significant Hght on the place of origin of the genus. Excluding 

 the Laramie formation, since its records are confused in the Htera- 

 ture with those of the basal Eocene, I have collected the following 

 references to the existence of Platanus during the Cretaceous: The 

 oldest occurrences are two species in the Raritan formation of the 

 New Jersey region and two different species from the lower beds 

 of the Tuscaloosa formation of the Alabama region. Very slightly 

 younger are the strata of the Dakota Group extending from Minne- 

 sota and Colorado to Texas from v/hich Lesquereux has described 

 ten species and varieties. About the same age as the latter is the 

 Magothy formation of our Northern Atlantic coastal plain with 

 one species and the Atane beds of West Greenland with another. 

 The somewhat younger Patoot beds of West Greenland furnish 

 one species, there is artiother in the Ripley formation of Eastern 



