Contributions to Pennsylvanian Paleobotany 

 MAZOCARPON OEDIPTERNUM, sp. nov. 



AND 



SIGILLARIAN RELATIONSHIPS 



James M. Schopf 



INTRODUCTION 



T^HE PURPOSE of this paper is to de- 

 -*- scribe a new species of plant which 

 is illustrated by a remarkable series of 

 cones from the Calhoun (Richland 

 County) coal-ball horizon in Illinois. 



Mazocarpon oedipternum, although 

 scientifically interesting in itself, is sig- 

 nificant chiefly because it helps to 

 clarify the relationship between grou.ps 

 of Carboniferous plants that have sigil- 

 larian alliance. 



The close relationship of Mazocarpon 

 and Sigillaria, previously suggested by 

 Benson (1918) and Hagene (1926), re- 

 ceives additional support in the evidence 

 presented in this report. Sigillariostro- 

 hus and Mazocarpon are shown to be 

 closely allied, and one of the most im- 

 portant results of this study is recogni- 

 tion of the relationship of spores classi- 

 fied under the section Aphanozonati of 

 Triletes and the sigillarian alliance. 



The conclusion that the Aphanozonati 

 represent a natural closely allied group 

 of plants was reached in an earlier study 

 ( Schopf, 1938, b, pp. 23-24) . At that time 

 it was not known what particular group 

 of lycopods was represented nor how 

 trustworthy spore resemblances were for 

 evaluating plant relationships. Spores 

 of the sigillarians (the Aphanozonati) 

 now appear to be identifiable through- 

 out the Pennsylvanian system. By an- 

 alogy, and in the absence of conflicting 

 evidence, resemblances among other 

 kinds of spores assume a greater im- 

 portance since we have the present ex- 



ample to indicate that botanical affinity 

 between species based on spores alone 

 can be established with reasonable pre- 

 cision. 



Recognition of the botanical affinity 

 of the Aphanozonati greatly increases 

 the usefulness of these spores in coal 

 studies and in stratigraphic paleobotany. 

 Well-preserved megaspores can gener- 

 ally be recovered even from thin coal 

 beds, carbonaceous shales, and carbon- 

 aceous sandstone laminae which do not 

 provide other identifiable fossils. The 

 possibility of identifying spores in terms 

 having definite botanical significance 

 increases their usefulness in strati- 

 graphic correlation and in plant popu- 

 lation studies. In the latter capacity 

 they may aid in explaining differences 

 in constitution among the various types 

 of coal. 



Although the affinity of the aphano- 

 zonate megaspores is probably of great- 

 est immediate interest, the related cones 

 provide a good deal of additional paleo- 

 botanical inforaiation. Heretofore the 

 anatomy of sigillarian fructifications, 

 and particularly of the microsporangi- 

 ate structures, has been inadequately 

 known. Microsporangiate cones are now 

 described from abundant material. Well- 

 preserved female gametophytes can also 

 be described more completely than was 

 possible before. Thus considerable new 

 information is available to illustrate the 

 reproductive phases of a sigillarian life 

 cycle. 



