Some Salient Points in the Science of the EarthDawson, John William, Sir
Science
Some Salient Points in the Science of the Earth
Dawson, John William, Sir
Geology; Paleontology
"Among the specimens which I carried from Horton Bluff, one is of very
high interest. It exhibits the footprints of some reptilian animal.
Owen has no doubt of the marks being genuine footprints. The rocks of
Horton Bluff are below the gypsum of that neighbourhood; so that the
specimen in question (if Lyell's views are correct[125]) comes from the
very bottom of the coal series, or at any rate very low down in it, and
demonstrates the existence of reptiles at an earlier epoch than has
hitherto been determined; none having been previously found below the
magnesian limestone, or, to give it Murchison's new name, the 'Permian
era.'"
[125] Sir Charles Lyell had then just read a paper announcing his
discovery that the gypsiferous system of Nova Scotia is Lower
Carboniferous, in which he mentions the footprints referred to, as
being reptilian.
This extract is of interest, not merely as an item of evidence in
relation to the matter now in hand, but as a mark in the progress of
geological investigation. For the reasons above stated, the important
discovery thus made in 1841, and published in 1842, was overlooked; and
the discovery of reptilian bones by Von Dechen, at Saarbruck, in 1844,
and that of footprints by Dr. King in the same year, in Pennsylvania,
have been uniformly referred to as the first observations of this
kind. Insects and Arachnidans, it may be observed, had previously been
discovered in the coal formation in Europe.
The original specimen of these footprints is still in the collection
of the Geological Survey of Canada, and a cast which Logan kindly
presented to me is exhibited in the Peter Redpath Museum of McGill
University. It is a slab of dark-coloured sandstone, glazed with fine
clay on the surface; and having a series of seven footprints in two
rows, distant about three inches; the distance of the impressions in
each row being three or four inches, and the individual impressions
about one inch in length. They seem to have been made by the points of
the toes, which must have been armed with strong and apparently blunt
claws, and appear as if either the surface had been somewhat firm,
or the body of the animal had been partly water-borne. In one place
only is there a distinct mark of the whole foot, as if the animal
had exerted an unusual pressure in turning or stopping suddenly. One
pair of feet--the fore feet, I presume--appear to have had four toes
touching the ground; the other pair show only three or four, and it
is to be observed that the outer toe, as in the larger footprints
discovered by Dr. King, projects in the manner of a thumb, as in the
cheirotherian tracks of the Trias. At a later date another series of
footprints, possibly of the same animal, was obtained at the same
place by Prof. Elder, and is now in the Peter Redpath Museum. Each
foot in this shows five toes, and it is remarkable that the animal was
digitigrade and took a long step for its size, indicating a somewhat
high grade of quadrupedal organization.
Public-domain text, read in full here on John Shaqi.
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