The Story of the Earth and ManDawson, John William, Sir
Science
The Story of the Earth and Man
Dawson, John William, Sir
Human beings -- Origin; Paleontology
In addition to this inferential evidence, however, one well-marked
animal fossil has at length been found in the Laurentian of Canada,
Eozoon Canadense, (fig. 7), a gigantic representative of one of the
lowest forms of animal life, which the writer had the honour of naming
and describing in 1865--its name of "Dawn-animal" having reference to
its great antiquity and possible connection with the dawn of life on
our planet. In the modern seas, among the multitude of low forms of
life with which they swarm, occur some in which the animal matter is a
mere jelly, almost without distinct parts or organs, yet
unquestionably endowed with life of an animal character. Some of these
creatures, the Foraminifera, have the power of secreting at the
surface of their bodies a calcareous shell, often divided into
numerous chambers, communicating with each other, and with the water
without, by pores or orifices through which, the animal can extend
soft and delicate prolongations of its gelatinous body, which, when
stretched out into the water, serve for arms and legs. In modern times
these creatures, though extremely abundant in the ocean, are usually
small, often microscopic; but in a fossil state there are others of
somewhat larger size, though few equaling the Eozoon, which seems to
been a sessile creature, resting on the bottom of the sea, and
covering its gelatinous body with a thin crust of carbonate of lime or
limestone, adding to this, as it grew in size, crust after crust,
attached to each other by numerous partitions, and perforated with
pores for the emission of gelatinous filaments. This continued growth
of gelatinous animal matter and carbonate of lime went on from age to
age, accumulating great beds of limestone, in some of which the entire
form and most minute structures of the creature are preserved, while
in other cases the organisms have been broken up, and the limestones
are a mere congeries of their fragments. It is a remarkable instance
of the permanence of fossils, that in these ancient organisms the
minutest pores through which the semi-fluid matter of these humble
animals passed, have been preserved in the most delicate perfection.
The existence of such creatures supposes that of other organisms,
probably microscopic plants, on which they could feed. No traces of
these have been observed, though the great quantity of carbon in the
beds probably implies the existence of larger sea-weeds. No other form
of animal has yet been distinctly recognized in the Laurentian
limestones, but there are fragments of calcareous matter which may
have belonged to organisms distinct from Eozoon. Of life on the
Laurentian land we know nothing, unless the great beds of iron ore
already referred to may be taken as a proof of land vegetation.[C]
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