These details have been mentioned in order to show that Araucaria and Agathis are sufficiently distinct in many respects from other Conifers to render their identification in a fossil state comparatively easy, at least much easier than the recognition of the majority of the members of the Coniferae. It would be going too far to state definitely that Araucarieae, as defined by reference to existing species, existed during the Palaeozoic period; on the other hand it would seem in a high degree probable that the vegetation of the Coal age and of the succeeding Permian period included trees in which certain Araucarian characters were clearly foreshadowed. The name Araucarioxylon was formerly applied to petrified wood, obtained from Palaeozoic as well as from later formations, which agrees anatomically with that of Araucaria and Agathis. It has been shown in recent years that much of the Palaeozoic wood of this type of structure belongs to the extinct genus Cordaites, a tree which played a prominent part in the earlier floras. Cordaites affords a good example of a generalised type: in its wood-structure it resembles very closely the existing Araucarieae; its long strap-like leaves are not unlike those of some species of Agathis; its male flowers have often been compared with those of the Maiden Hair tree, Ginkgo biloba, and certain anatomical features form connecting links between this Palaeozoic genus and the Cycads.
It is noteworthy that in another Palaeozoic genus, Walchia, the leaf-bearing branches are identical in appearance with those of the Norfolk Island Pine ([Fig. 17]) and some other species of Araucaria. Unfortunately our knowledge of the reproductive organs of Walchia is insufficient to warrant any definite statement as to the degree of consanguinity between this Permian and Upper Carboniferous plant and the Araucarieae; it is probable that in Walchia we have a type not far removed from the line of evolution which led to Araucaria. Petrified wood, identified as that of Walchia, and exhibiting the Araucarian type of structure, has been recorded from Permian rocks of the Vosges. Other instances might be quoted in support of the view that the Palaeozoic floras included a few plants with which the surviving Araucarieae may fairly claim relationship. Professor Zeiller of Paris has recently described some fossil shoots from Palaeozoic rocks in India under the name Araucarites Oldhami on the ground of the similarity of the leaves to those of Araucaria imbricata. Similarly, from Triassic rocks several fossils have been described as closely allied to Araucaria, in some cases because of anatomical resemblances and in others on the less satisfactory evidence furnished by a similarity in the foliage shoots. Professor Jeffrey of Harvard has recently given an account of a new type of stem (Woodworthia) from the petrified Triassic forest of Arizona possessing some Araucarian characters, though differing from existing species of Araucaria in certain structural features, a combination of characters regarded by this Author as an indication of relationship with the family of Conifers, which includes the Pines, Firs, Larches and other well-known northern genera.
It is, however, from the records of Jurassic rocks that we obtain the most satisfactory information as to the great antiquity and the very wide geographical range of the ancestors of the recent genus. The plant-beds of the Yorkshire coast afford clear evidence of the occurrence of Araucarian trees in the woodlands of the Jurassic period. Petrified wood has been found at Whitby, associated with jet, showing the minute structural characteristics of the surviving species of Araucarieae, and it is not improbable that some at least of the Whitby jet has been formed from the wood of Araucarian plants. The carbonised remains of leafy shoots preserved in the Jurassic shales near Scarborough and on other parts of the Yorkshire coast include twigs hardly distinguishable from those of Araucaria excelsa, though the resemblance of external form alone, especially in the case of foliage shoots, does not amount to proof of generic identity. We have, however, the much more trustworthy evidence of cones and seed-bearing scales in which the characteristic features of living species are clearly shown. Seed-bearing scales almost identical with those of Araucaria excelsa and other recent species have long been known from the Jurassic rocks of Yorkshire.
From other parts of England where samples of Jurassic floras are preserved, as at Stonesfield in Oxfordshire, in Northamptonshire and elsewhere, equally striking examples of undoubted Araucarias have been found.
[Fig. 18] represents part of a large cone described in 1866 by Mr Carruthers from Jurassic rocks at Bruton in Somersetshire: this specimen, now in the British Museum, consists of one side of a spherical cone about 5 inches long and 5 inches broad; in size, as in the form of the seed-scales, it shows a striking likeness to the cones of the Australian species Araucaria Bidwillii, the Bunya Bunya of Queensland. Other equally convincing examples of Jurassic Araucarian cones and seeds may be seen in the museums of York and Northampton. On the north-east coast of Sutherland there is a narrow strip of Jurassic beds forming a low platform between the granitic and Old Red Sandstone hills and the sea. From these rocks Hugh Miller described several fossil plants in his Testimony of the Rocks, and an examination of a large collection obtained from this district by the late Dr Marcus Gunn shows that Miller was justified in speaking of Araucaria as a member of this northern flora.
Fig. 18. Araucarites sphaerocarpus Carr. From Jurassic rocks at Bruton, Somersetshire. (British Museum, 2/3 nat. size.)]
There is abundant evidence pointing to the existence in Britain during the Jurassic period, and in the early days of the Cretaceous epoch, of Araucarian trees which differed but slightly from the modern species confined to the southern hemisphere. In several localities in France, Germany, and other parts of the continent, Araucarian fossils have been recognised in Jurassic rocks. It is almost certain that some foliage shoots and imperfectly preserved cones described by Dr Nathorst from Upper Jurassic rocks in Spitzbergen were borne by a species of Araucaria. Cone-scales very similar to those from Yorkshire have been discovered in Wealden beds in Cape Colony, and Araucarian wood of Jurassic and Cretaceous age has been found in Madagascar. From Jurassic strata in India and Victoria (Australia), as well as from Upper Jurassic and Lower Cretaceous rocks in Virginia and elsewhere in the eastern United States, well preserved Araucarian fossils are recorded. In a collection of Jurassic plants, obtained a few years ago by the members of a Swedish Antarctic Expedition in Graham's Land, Dr Nathorst has recognised some cone-scales of Araucaria, which demonstrate a former extension of the family beyond the southern limits of South America.