, Volume 17, Issue 6, pp 431-469

American coal-ball floras

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Conclusion

Interest in American coal-ball floras has increased perceptibly in the past few years, and some attempts have been made in this brief review to point out current lines of research and what may be expected during the next decade or two. Two other topics might have been considered, namely, a detailed comparison with the European fossils, and a stratigraphic compilation of the American floras. Such considerations would, I believe, be premature at present. We have many genera and a considerable number of species in common with those found in the European coal balls; it is also evident that there were certain elements in the American scene that did not occur on the other side of the Atlantic. Such a comparative picture is, however, only beginning to crystallize. The tendency to date has been to describe those fossils that are new, especially conspicuous and well preserved, and we are still a long way from the end of this “cream-skimming” stage. With continuation of such studies, which are now in progress in four or five laboratories, and the integration of botanical and geological interests, we should ultimately be able to work out a very interesting picture of the sequence of Upper Carboniferous floras and contribute notably to an understanding of the evolution of certain pteridophytic groups and the early seed plants.