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In this period, also, we find the earliest representatives of the endogenous plants. It is true that some plants found in the coal-formation have been doubtfully referred to these, but the earliest certain examples would seem to be some bamboo-like and screw-pine-like plants occurring in the Jurassic rocks. Some of these are, it is true, doubtful forms, but of others there seems to be no question. The modern Pandanus or screw-pine of the tropical regions, which is not a pine, however, but a humble relation of the palms, is a stiffly branching tree, of a candelabra-like form, and with tufts of long leaves on its branches, and nuts or great hard berries for fruit, borne sometimes in large masses, and so protected as to admit of their drifting uninjured on the sea. The stems are supported by masses of aërial roots like those which strengthen the stems of tree-ferns. These structures and habits of growth fit the Pandanus for its especial habitat on the shores of tropical islands, to which its masses of nuts are drifted by the winds and currents, and on whose shores it can establish itself by the aid of its aërial roots.
Some plants referred to the cycads have proved veritable botanical puzzles. One of these, the Williamsonia gigas of the English oölite, originally discovered by my friend Dr. Williamson, and named by him Zamia gigas, a very tall and beautiful species, found in rocks of this age in various parts of Europe, has been claimed by Saporta for the Endogens, as a plant allied to Pandanus. Some other botanists have supposed the flowers and fruits to be parasites on other plants, like the modern Rafflesia of Sumatra, but it is possible that after all it may prove to have been an aberrant cycad.
The tree-palms are not found earlier than the Middle Cretaceous, where we shall notice them in the next chapter. In like manner, though a few Angiosperms occur in rocks believed to be Lower or Lower Middle Cretaceous in Greenland and the northwest territory of Canada, and in Virginia, these are merely precursors of those of the Upper Cretaceous, and are not sufficient to redeem the earlier Cretaceous from being a period of pines and cycads.
On the whole, this early Mesozoic flora, so far as known to us, has a monotonous and mean appearance. It no doubt formed vast forests of tall pines, perhaps resembling the giant Sequoias of California ; but they must for the most part have been dark and dismal woods, probably tenanted by few forms of life, for the great reptiles of this age must have preferred the open and sunny coasts, and many of them dwelt in the waters. Still we must not be too sure of this. The berries and nuts of the numerous yews and cycads were capable of affording much food. We know that in this age there were many great herbivorous reptiles, like Iguanodon and Hadrosaurus, some of them fitted by their structure to feed upon the leaves and fruits of trees. There were also several kinds of small herbivorous mammals, and much insect life, and it is likely that few of the inhabitants of the Mesozoic woods have been preserved as fossils. We may yet have much to learn of the inhabitants of these forests of ferns, cycads, and pines. We must not forget in this connection that in the present day there are large islands, like New Zealand, destitute of mammalia, and having a flora comparable with that of the Mesozoic in the northern hemisphere, though more varied. We have also the remarkable example of Australia, with a much richer flora than that of the early Mesozoic, yet inhabited only by non-placental mammals, like those of the Mesozoic.
The principal legacy that the Mesozoic woods have handed down to our time is in some beds of coal, locally important, but of far less extent than those of the Carboniferous period. Still, in America, the Richmond coalfield in Virginia is of this age, and so are the anthracite beds of the Queen Charlotte Islands, on the west coast of Canada, and the coal of Brora in Sutherlandshire. Valuable beds of coal, probably of this age, also exist in China, India, and South Africa ; and jet, which is so extensively used for ornament, is principally derived from the carbonised remains of the old Mesozoic pines.
In the next chapter we have to study a revolution in vegetable life most striking and unique, in the advent of the forest-trees of strictly modern types.
NOTE TO CHAPTER V.
I APPEND to this chapter a table showing the plant-bearing series of the Cretaceous and Laramie of North America, from a paper in “ Trans. R. S. C.,” 1885, which see for further details :
(IN DESCENDING ORDER.)
Floras and subfloras.
Upper Laramie or Porcu-
Platanus beds of Souris River and
Calgary. Report of Geol. Survey of Canada for 1879, and Memoir of 1885.
Middle Laramie or Willow
Fox Hill series
Lemna and Pistia beds of bad lands
of 49th parallel, Red Deer River,
Parallel and Memoir of 1885.
Saskatchewan, Belly River, &c., with lignites. Memoir of 1885. Memoir of 1883. Many dicotyle
dons, palms, &c.
Coal measures of Nanai
mo, B.C., probably here.
Middle Cretaceous (Turonian and Cenomanian).
Dunvegan series of Peace
River. Dakota group,
Memoir of 1883. Many dicotyle
dons, cycads, &c. Dicotyledonous leaves, similar to
Dakota group of the U. S. Memoir of 1885.
Suskwa River beds and
Queen Charlotte Island
series of Virginia.
Cycads, pines, a few dicotyledons. Report Geol. Survey. Memoir of 1885.
Cycads, pines, and ferns. Memoir
THE REIGN OF ANGIOSPERMS IN THE LATER CRETACEOUS
It is a remarkable fact in geological chronology that the culmination of the vegetable kingdom antedates that of the animal. The placental mammals, the highest group of the animal kingdom, are not known till the beginning of the Eocene Tertiary. The dicotyledonous Angiosperms, which correspond to them in the vegetable kingdom, occur far earlier-in the beginning of the Upper Cretaceous or close of the Lower Cretaceous. The reign of cycads and pines holds throughoat the Lower Cretaceous, but at the close of that age there is a sudden incoming of the higher plants, and a proportionate decrease, more especially of the cycads. I bave already referred to the
Fig. 68.—Populus primæva,
Heer. Cretaceous, of angiospermous wood supposed Greenland. One of the
oldest known Angioto be Devonian, but I fear to
sperms. rest any conclusion on this isolated fact. Beyond this, the earliest indications of plants of this class have been found in the Lower Cretaceous. Many years ago Heer described and figured the leaves of a poplar (Populus primæva) from the supposed Lower Cretaceous of Komé, in Greenland (Fig. 68). Two species, a Sterculia and a Laurus or Salix, occur among fossils described by me in the upper part of the Kootanie series of the Rocky Mountains, and Fontaine has recently found in the Potomac group of Virginia—believed to be of Neocomian age-several angiospermous species (Sassafras, Menispermites, Sapindus, Aralia, Populus, &c.) mixed with a rich flora of cycads and pines. These are the early forerunners of the modern angiospermous flora; but so far as known they do not occur below the Cretaceous, and in its lower portions only very rarely. When, however, we ascend into the Upper Cretaceous, whether of Europe or America, there is a remarkable incoming of the higher plants, under generic forms similar to those now existing. This is, in truth, the advent of the modern flora of the temperate regions of the earth. A very interesting tabular view of its early distribution is given by Ward, in the "American Journal of Science” for 1884, of which the following is a synopsis, with slight emendations. I may add that the new discoveries made since 1884 would probably tend to increase the proportionate number of dicotyledons in the newer groups.
DICOTYLEDONOUS TREES IN THE CRETACEOUS.
group of America ; coal-measures of Na
naimo ? Turonian...
Belly R. group.
and Dakota groups of America); Dun-