5] EVOLUTIONARY DEVELOPMENT AND PAST HISTORY 143 



Thus the group as a whole appears to be retreating before the angio- 

 spermic onslaught , from which it has suffered since before the dawn 

 of the Cainozoic era. Much as in the case of the so-called Pterido- 

 phytes, it may be that the Gymnosperms represent several largely 

 separate stocks as far back as we have yet any knowledge of them. 

 The Angiosperms, as we saw in Chapter II, are the most highly 

 evolved and successful group of plants at the present time, affording 

 most of the dominant species on land. After an apparently slow 

 start at least as early as the Jurassic, they gave rise before the end of 



Fig. 36. — Fossil parts of Conifer and Angiosperm. A, branch of Lebachia 



{Wolchio) frondosa, one of the Palaeozoic Coniferales (after Renault) ( \ about \); 



B, leaves of a dicotyledonous Angiosperm ( ■ about |). 



the Cretaceous to a vast assemblage of forms that between them 

 rapidly came to cover practically the whole surface of the earth, 

 comprising most of the land-vegetation we know today, and a good 

 deal of that developed in water. A considerable proportion of the 

 genera and even species which are familiar to us nowadays as common 

 shrubs or trees, particularly, seem to have persisted throughout the 

 Cainozoic — often with little if any apparent change, and sometimes 

 doubtless as dominants. Of the two main groups of Angiosperms, 

 the Monocotyledons are much less numerous as fossils, and especially 



