Some Salient Points in the Science of the Earth

by Sir John William Dawson

I have since observed several instances of such impressions at the Joggins, at Horton, and near Windsor, showing that they are by no means rare, and that reptilian animals existed in no inconsiderable numbers throughout the coal field of Nova Scotia, and from the beginning to the end of the Carboniferous period. Most of these, when well preserved, shew five toes both on the anterior and posterior limb. On comparing these earlier Carboniferous footprints with one another, it will be observed that they are of similar general character, and may have been made by one kind of animal, which must have had the fore and hind feet nearly of equal size, and a digitigrade mode of walking. Footprints of similar form are found in the coal formation, as well as others of much larger size. The latter are of two kinds. One of these shows short hind feet of digitigrade character and a long stride, in this resembling the smaller footprints of the Lower Carboniferous, which are remarkable for the length of limb which they indicate by the distance between the footprints. The other kind shows long hind feet, as if the whole heel were brought down to the ground in a plantigrade manner. These have also the outer toe separated from the others, and sometimes provided with a long claw. The fore foot is sometimes smaller than the hind foot, and differently formed.[126] In these respects they resemble the great Labyrinthodont Batrachians of the subsequent Trias. Their stride also is comparatively short, and the rows of impressions wide apart, as if the body of the animal had been broad, and its limbs short.

[126] Fine slabs of these footprints have been presented by Mr. Sandford Fleming to the Geological Survey of Canada.

We have thus two types of quadrupedal footprints, to the first of which I have given the name Hylopus, and have restricted the term Sauropus,[127] to the second. The first apparently belongs to the usually small reptiles of the group Microsauria, which had a well-marked lizard-like form, with well-developed limbs, and perhaps also to some of the smaller Labyrinthodonts, the second to the group of Labyrinthodontia, which were often of large size and with stout and short limbs and plantigrade hind feet. There are also some small and uncertain tracks, which may have been made by newt-like animals with short feet, and a singular trail of large size, and with a row of impressions at each side (Diplichnites),[128] which, if made by a vertebrate animal, would seem to indicate that serpentiform shape which we know belonged to some Carboniferous Batrachians.

[127] Given by King.

[128] Impressions and Footprints of Animals, Am. Jour. Sci., 1873.

The bones of these animals, however, hitherto found in Nova Scotia, may all have belonged to the two groups first named, the Labyrinthodontia and Microsauria, and I shall proceed to give some examples of each of these.

In leaving the footprints, I may merely mention that the animals which produced them may, in certain circumstances, have left distinct impressions only of three or four toes, when they actually possessed five, while in other circumstances all may have left marks; and that, when wading in deep mud, their footprints were altogether different from those made on hard sand or clay. In some instances the impressions may have been made by animals wading or swimming in water, while in others the rain marks and sun cracks afford evidence that the surface was a subaërial one. They are chiefly interesting as indicating the wide diffusion and abundance of the creatures producing them, and that they haunted tidal flats and muddy shores, perhaps emerging from the water that they might bask in the sun, or possibly searching for food among the rejectamenta of the sea, or of lagunes and estuaries.

The Labyrinthodonts of the Coal Period, Baphetes Planiceps and Dendrerpeton Acadianum.

In the summer of 1851 I had occasion to spend a day at the Albion Mines in the eastern part of Nova Scotia, and on arriving at the railway station in the afternoon, found myself somewhat too early for the train. By way of improving the time thus left on my hands, I betook myself to the examination of a large pile of rubbish, consisting of shale and ironstone from one of the pits, and in which I had previously found scales and teeth of fishes. In the blocks of hard carbonaceous shale and earthy coal, of which the pile chiefly consisted, scales, teeth and coprolites often appeared on the weathered ends and surfaces as whitish spots. In looking for these, I observed one of much greater size than usual on the edge of a block, and on splitting it open, found a large flattened skull, about six inches broad, the cranial bones of which remained entire on one side of the mass, while the palate and teeth, in several fragments, came away with the other half. Carefully trimming the larger specimen, and gathering all the smaller fragments, I packed them up as safely as possible, and returned from my little excursion much richer than I had hoped.

The specimen, on further examination, proved somewhat puzzling. I supposed it to be, most probably, the head of a large ganoid fish; but it seemed different from anything of this kind with which I could compare it; and at a distance from comparative anatomists, and without sufficient means of determination, I dared not refer it to anything higher in the animal scale. Hoping for further light, I packed it up with some other specimens, and sent it to the Secretary of the Geological Society of London, with an explanatory note as to its geological position, and requesting that it might be submitted to some one versed in such fossils. For a year or two, however, it remained as quietly in the Society's collection as if in its original bed in the coal mine, until attention having been attracted to such remains by the discoveries made by Sir Charles Lyell and myself in 1852, at the South Joggins, and published in 1853,[129] the Secretary or President of the Society re-discovered the specimen, and handed it to Sir Richard Owen, by whom it was described in December, 1853,[130] under the name of Baphetes planiceps, which may be interpreted the "flat-headed diving animal," in allusion to the flatness of the creature's skull, and the possibility that it may have been in the habit of diving.