CHAPTER XI. ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS.
3. ON THE FORMS OF LIFE CHANGING ALMOST SIMULTANEOUSLY THROUGHOUT THE WORLD.
Scarcely any palaeontological discovery is more striking than the fact that
the forms of life change almost simultaneously throughout the world. Thus
our European Chalk formation can be recognised in many distant regions,
under the most different climates, where not a fragment of the mineral
chalk itself can be found; namely, in North America, in equatorial South
America, in Tierra del Fuego, at the Cape of Good Hope, and in the
peninsula of India. For at these distant points, the organic remains in
certain beds present an unmistakable resemblance to those of the Chalk. It
is not that the same species are met with; for in some cases not one
species is identically the same, but they belong to the same families,
genera, and sections of genera, and sometimes are similarly characterised
in such trifling points as mere superficial sculpture. Moreover, other
forms, which are not found in the Chalk of Europe, but which occur in the
formations either above or below, occur in the same order at these distant
points of the world. In the several successive palaeozoic formations of
Russia, Western Europe and North America, a similar parallelism in the
forms of life has been observed by several authors; so it is, according to
Lyell, with the European and North American tertiary deposits. Even if the
few fossil species which are common to the Old and New Worlds were kept
wholly out of view, the general parallelism in the successive forms of
life, in the palaeozoic and tertiary stages, would still be manifest, and
the several formations could be easily correlated.
These observations, however, relate to the marine inhabitants of the world:
we have not sufficient data to judge whether the productions of the land
and of fresh water at distant points change in the same parallel manner.
We may doubt whether they have thus changed: if the Megatherium, Mylodon,
Macrauchenia, and Toxodon had been brought to Europe from La Plata, without
any information in regard to their geological position, no one would have
suspected that they had co-existed with sea-shells all still living; but as
these anomalous monsters co-existed with the Mastodon and Horse, it might
at least have been inferred that they had lived during one of the later