Chapter XVII (3)

The Labyrinthodont reptiles have been regarded as characteristic of the Permian and Triassic epochs, their remains being found in Germany and England in rocks of that age. The commencement of the existence of this family of sauroid-batrachians, however, is of greater antiquity, since their relics also occur in the formations of the Carboniferous epoch. The _Archegosaurus_ (p. 745), a batrachian but slightly removed from the true Labyrinthodont type, has left its well-characterized remains in the Coal of Germany; the _Parabatrachus_, in that of Scotland; and the allied _Dendrerpeton_, in the Nova Scotian coal-field. This last-mentioned great carboniferous formation has, however, afforded fossil evidence of the existence of the true Labyrinthodonts in the Coal-period, for some cranial bones, imbedded in a mass of Pictou coal, lately sent to England by Mr. J. W. Dawson, and the subject of a Paper by Professor Owen, read before the Geological Society, were demonstrated by that distinguished palæontologist to have close affinity with the corresponding parts of the skull of the Triassic genera _Capitosaurus_ and _Metopias_.

[Sidenote: ICHNOLITES.]

Ichnolites (_Foot-prints on stone_). _Lign. 245._--The sandstones and mud-stones of many localities retain the track-prints of animals that have passed along on the surface of the beds when in a soft state. These foot-prints, or _ichnolites_, either occur as impressions on the surface originally marked lay the animal in the act of progression, or as the reverse of such impressions, being casts _in relief_ on the under side of the layer covering the surface originally impressed. Such indications of footsteps and trails have been noticed especially in the forest marble, a member of the Lower Oolite series, where Crustacea and Mollusks have left their markings, and in the New Red Sandstone, where the indications of reptilian quadrupeds and of bird-like bipeds[709] have been here and there preserved in great distinctness. Tracks referable to Crustaceans have been found by Mr. W. E. Logan, on the very ancient and rippled surfaces of the Potsdam Sandstone of North America (see p. 543, _note_); and very lately Mr. J. W. Salter has communicated to the Geological Society the discovery of markings, referred by him to the little entomostracous Hymenocaris (see p. 526), on the Lower Lingula Flags of North Wales,--deposits of as great an age, if not older. The most ancient reptilian ichnolites are those discovered by Capt. L. Brickenden[710] in the Old Red, at Cummingston, near Elgin, which have some resemblance to the track of a club-footed Chelonian (_Ly._ _fig._ 521); and those of the Devonian sandstone of Sharp Mountain, Pennsylvania, discovered by Mr. I. Lea,[711] which exhibit distinct toes, and are probably allied to the Cheirotherian ichnolites, about to be mentioned, as are also other ancient fossil foot-tracks in the Carboniferous deposits[712] of Pennsylvania, which are figured and described in _Ly._ pp. 337-340.

[709] See Ornithoidichnites, in chap, xviii.

[710] Quart. Geol. Journ. vol. viii. p. 97, pl. iii.

[711] Across the ridges of the ripples on this slab is a narrow groove, passing along between the two rows of foot-prints; this might have been made by the body or the tail of the animal. _Rep. Brit. Assoc._ 1849, Sect. pp. 56 and 134; and _Trans. Americ. Phil. Soc._ new series, vol. x. part ii. plates xxxi. and xxxii.

[712] With regard to the distribution of reptilian life during the carboniferous and succeeding epochs, see above, page 748.

The sandstones of the New Red or Triassic series frequently retain the track-prints of animals, and numerous notices of such occurrences have been published.[713] In addition to the account of these invaluable evidences of the existence of bygone creatures that is here given, the attention of students is especially directed to Dr. Buckland’s most interesting description and illustrations of such as were known when his Treatise was published (_Bd._ i. p. 259, &c.; and ii. p. 36, pl. xxvi. &c.).

[713] The following are the principal notices of ichnolites by English authors which are not referred to in the text:--Cunningham, Yates, and Egerton on Cheirotherian traces in Cheshire, _Geol. Proc._ vol. iii. pp. 12-15; Dr. Black on foot-prints at Runcorn, _Quart. Geol. Journ._ vol. ii. p. 65, pl. ii.; Mr. Cunningham. _Liverpool Lit. and Phil. Proc._ 1848, p. 129, plates iii.-v.; Mr. Hawkshaw on the New Red with foot-prints at Lymm, _Rep. Brit. Assoc._ 1842, Sect. p. 56; Mr. Rawlinson on the same, _Quart. Geol. Journ._ vol. ix. p. 37; Prof. Harkness on the track-bearing beds of Dumfriesshire, _Rep. Brit. Assoc._ 1850, Sect. p. 83; _Quart. Geol. Journ._ vol. vi. pp. 389 and 393; and _Annals Nat. Hist._ 1850, vol. vi. p. 203; Sir W. Jardine, _Annals Nat. Hist._ _loc. cit._ Foreign authorities may be found by reference to Pictet’s _Traité de Paléontologie_, a new and enlarged edition, vol. i. 1853, p. 567, _et seq._

The imprints of the feet of some large quadrupeds, having the fore-paws much smaller than the hinder, have been found in Saxony (see _Wond._ p. 555, _Bd._ p. xxvi.); and also in strata of the same age in Warwickshire and Cheshire. The quarries at Storeton Hill, near Liverpool, are celebrated for the abundance and variety of these imprints.[714] Some of the strata of sandstone in this locality are divided by thin beds of clay; a lithological structure which admits of the ready separation of the stone in the direction of the sedimentary planes.

[714] The Museums at Warwick, Warrington, and Liverpool are rich in impressed slabs from the Triassic districts. Numerous fine specimens may be also seen in the Museum of the Geological Society, Somerset House, the Museum of Practical Geology, in Jermyn Street, and in the British Museum (see _Petrif._ pp. 14 and 63).

[Sidenote: RAIN-PRINTS ON STONE.]

Imprints are found on the face of each successive stratum; and on some of the layers, not only the tracks of animals that have walked over the clay when soft are distinctly observable, but the surface is often traversed with casts of the cracks caused by the desiccation of one layer of clay previously to the deposition of the succeeding layer of sand or mud; and it often presents a blistered or warty appearance, being covered with either little hemispherical eminences or depressions, which an accurate investigation of the phenomenon has proved to have been produced by showers of rain (_Ly._ figs. 526-528). On the slabs of sandstone, the forms of the sun-cracks, rain-drops, and foot-prints appear in relief, being casts moulded in the soft clayey mud upon which the original impressions were made; while on the clay or shale, corresponding depressions are apparent.[715]

[715] The impressions of rain-drops on stone were first noticed, and their origin explained, by Mr. Cunningham. _Geol. Proc._ vol. iii. p. 99. See also an interesting Paper by Sir C. Lyell, _Quart. Geol. Journ._ vol. vii. p. 240.

The foot-prints on these strata are of several kinds; some appear to have been produced by small reptiles and crustaceans; but the principal imprints are identical with those which have been observed in Saxony, and are referable to some large quadruped, in which the fore-feet were of a much smaller size than the hind-feet (_Lign. 245_). From a supposed resemblance of the imprints to those of a human hand, Professor Kaup proposed the name of _Cheirotherium_, to designate the unknown animal which had left these "footsteps on the sands of Time." But since Professor Owen’s discovery, that the bones and teeth of reptiles found in similar strata in Warwickshire belong to gigantic Batrachians, and since the fore and hind-feet of the frog-tribe are often as dissimilar in size as the impressions of the _Cheirotherium_, it has been suggested, with much probability, that the foot-prints in question may be those of Labyrinthodonts; but until the form of the feet of these extinct Batrachians can be ascertained, this inference must be regarded as conjectural (_Ly._ _fig._ 331).

[Sidenote: CHEIROTHERIUM.]

Casts of the foot-marks of a gigantic extinct Batrachian, probably a Labyrinthodon; with casts also of the cracks of the opposed surface.

_Trias._ _Hessburg, near Hildburghausen, Saxony._]

Fig. 1.--Casts of the imprints of a hind and a fore-foot of the same animal.

2.--Similar tracks of another individual on the same stone.

Allusion has already been made to foot-prints, supposed to be those of tortoises (see p. 729), on slabs of Triassic sandstone in Scotland. Of these there are five species at Corncockle Muir, in Dumfriesshire: they are termed _Chelichnus_ by Sir W. Jardine, who has lately described them in his _Ichnology of Annandale_, a splendid folio work, illustrated with full-sized lithographs, coloured after nature. They are accompanied with three other forms of footstep (_Herpetichnus_, _Batrachnis_, and _Actibatis_), one of which Sir W. Jardine regards as indicative of an animal probably of a saurian form.

At Grinsill quarry, from which the remains of the _Rhynchosaurus_ (p. 712) were obtained, some small foot-prints have been observed, which, with some probability, have been referred to that animal (_Rep. Brit. Assoc._ 1841, p. 146).

A beautifully distinct series of foot-prints, with the mark of a trailing tail, on a rippled slab from the New Red of Shrewley Common, Warwickshire, are figured and described by Strickland and Murchison (_Geol. Trans._ 2d ser. vol. v. pl. xvviii.). This ichnolite has been provisionally assigned by Professor Owen to _Labyrinthodon leptognathus_.[716] Similar impressions occur in company with other Cheirotherian imprints at Storeton Hill and at Grinshill.

[716] Geol. Trans. 2d ser. vol. vi. p. 525. The probable relations of _Cheirotherium Hercules_ to _Labyrinthodon Jægeri_, and of _Ch. Kaupii_ to _L. pachygnathus_, are pointed out by the same high authority, _ibid._ pp. 537, 538.

[Sidenote: ON COLLECTING FOSSIL REPTILES.]

On Collecting the Fossil Remains of Reptiles.--The length to which this article has extended, compels me to omit a retrospect of the geological distribution of fossil reptiles; and I must refer the reader to the brief review of the Age of Reptiles in _Wond._ p. 568, _et seq._, and _Petrif._ p. 147, &c., and close this chapter with some directions for collecting reptilian remains, and a list of a few British localities.[717]

[717] An able Summary on British Fossil Reptiles is appended to Prof. Owen’s Report, _Rep. Brit. Assoc._ 1841, p. 191.

The fossil _Teeth of Reptiles_ are commonly found in as perfect a state of preservation as those of fishes; and require but the usual care for their preservation. But the collector should assiduously search for vestiges of the jaw and cranium; and it is desirable to place in the same drawer any undetermined bones found associated with the teeth; as they may ultimately afford some clue to the nature of the original animal. The microscopical examination of the teeth is to be conducted in the manner previously directed (p. 639); but for valuable specimens the lapidary should be employed, and transverse sections made from near the apex, the middle, and base of the tooth; if due care be taken, several slices may be obtained from one specimen. I have ten slices from one tooth of the Labyrinthodon. The bones imbedded in limestone generally partake of the chemical character of the rock, and are often permeated with calcareous spar; mere fragments, when polished, frequently display the internal structure.

The suggestions for repairing fossil bones (p. 46) render further instructions on that head unnecessary; and the description of the development of the specimen of Hylæosaurus (p. 689) affords a practical lesson to the young collector.

When a vertebra is found in an imperfect state, it should be closely examined on the spot, and, if it present proofs of recent fracture, the detached processes should be sought for; even if the body of a vertebra be imbedded in stone, and the processes appear to have been broken off before it was enveloped in the rock, the corresponding parts will often be found in the same mass of stone. There is in the British Museum a very fine Saurian vertebra imbedded in a large slab of Tilgate stone, in which the spinous process is seen lying in the same block, several inches distant from the centrum or body; when observed in the quarry the latter only was exposed, and I was about to detach it from the slab, for the convenience of carriage, when I perceived indications of the spinous process. The vertebra was therefore allowed to remain, and the stone chiselled away, so as to expose the spine; and the specimen then displayed its present interesting character.

It may frequently happen that a fragment of a large bone,--as, for example, the thigh-bone of the Iguanodon,--may be obtained from a quarry; and after an interval of some weeks the corresponding portions be discovered. This was remarkably exemplified in the first specimen which revealed to me the peculiar characters of the femur of the Iguanodon. The lower part, or condyloid extremity, of a gigantic bone, firmly impacted in a block of Tilgate-grit, was found in a quarry near Cuckfield; it was evidently but a fragment of the fossil, for the fracture was recent; I therefore requested the quarry-men to make diligent search for the corresponding portion, but without success. Several months afterwards, upon a fresh explosion in the quarry, the head of a large bone was found loose among the fallen mass; but there were no indications that it belonged to the specimen previously found; and it was regarded as another relic of some one of the colossal animals whose bones were distributed in the Wealden deposits. Teeth, fragments of bones, and other fossils were from time to time obtained from the same quarry; and among these a huge quadrangular fragment of bone, similar to the enormous mass that had so long been in my possession, and had defied all attempts to ascertain its character.[718] It was some time before it occurred to me, that the three portions of unknown colossal bone might belong to the same specimen; but eventually they were found to correspond, and upon cementing them together, the femur of the Iguanodon was, for the first time, developed.

[718] The fragment alluded to is figured, _Foss. Til. For._ pl. xviii.

The figures in _Lign. 206_ will assist the collector in recognising the different vertebral processes, even when occurring as detached fragments. When specimens are evidently rolled or water-worn, there is, of course, no probability that the corresponding portions will be met with. Every fragment of a bone the nature of which is not obvious should be carefully preserved; for sooner or later its characters may be ascertained. It is scarcely necessary again to remind the collector, that search should be made for indications of the soft parts around the bones; the specimen of the paddle of the Ichthyosaurus (_Lign. 215_, p. 669), with its integument, must have impressed this fact too strongly on the mind to be soon forgotten. If the impression of the extremities of a bone, of which a fragment only remains, be observed, the block of stone should be preserved, as a cast may be taken, and the entire form of the original be ascertained.

BRITISH LOCALITIES OF FOSSIL REPTILES.

Aust Cliff, near Bristol. _Lias._ Plesiosaurus.

Barrow-on-Soar. _Lias._ Ichthyosaurus, Plesiosaurus.

Bath. _Lias._ Plesiosaurus.

Battle, Sussex. _Wealden._ Iguanodon, Cetiosaurus, Goniopholis,
Chelonians.

Binstead, Isle of Wight. _Upper Eocene._ Fresh-water Tortoises.
Bognor. Lower Eocene. Chelone.

Bolney, Sussex. _Wealden._ Hylæosaurus, Iguanodon, Chelonia,
Goniopholis.

Bracklesham Bay. _Middle Eocene._ Crocodiles, Serpents, Chelonians.
Brighton. Chalk. Vertebra of Mosasaurus or Leiodon.

Bristol. _Lias._ Ichthyosaurus.

Brook-Point, Isle of Wight. _Wealden._ Iguanodon, Cetiosaurus, &c.

Burham, near Maidstone. _Chalk._ Chelone, Dolichosaurus,
Pterodactylus.

Bur wash, Sussex. _Wealden_; quarries in the neighbourhood.
Goniopholis, Turtles.

Cambridge. _Lower Chalk._ Raphiosaurus, Polyptychodon. Charmouth.
Lias. Ichthyosaurus.

Charmouth. _Lias._ Ichthyosaurus.

Cheltenham. _Lias._ Ichthyosaurus.

Chipping Norton. _Oolite._ Streptospondylus.

Clayton. _Chalk._ Coniosaurus.

Corncockle Muir, Dumfries. _New Red._ Imprints of feet of Reptiles.

Coton-End, Warwickshire. _New Red._ Labyrinthodon, &c.

Cubbington, Warwickshire. _New Red._ Labyrinthodon.

Cuckfield. _Wealden_; quarries in the vicinity. Iguanodon,
Pelorosaurus, Hylæosaurus, Trionyx, &c.

Culver Cliff, Isle of Wight. _Wealden._ Streptospondylus.

Dover. _Chalk._ Ichthyosaurus, Plesiosaurus.

Garsington, Oxfordshire. _Oolite._ Cetiosaurus.

Glastonbury. _Lias._ Ichthyosaurus.

Grinsill, Warwickshire. _New Red._ Rhynchosaurus.

Guy’s Cliff, Warwick. _New Red._ Labyrinthodon.

Harwich. _London Clay._ Chelonia.

Hastings. _Wealden._ Iguanodon, Pelorosaurus, Goniopholis, Turtles.

Heddington, Oxfordshire. _Kimmeridge Clay._ Pliosaurus.

Hordwell. _Middle Eocene._ Crocodiles, Chelonians, Serpents.

Horsham, Sussex. _Wealden_; quarries in the vicinity. Hylæosaurus,
Iguanodon, Goniopholis, Turtles, &c.

Ilminster. _Upper Lias._ Ichthyosaurus, Teleosaurus.

Kyson, Suffolk. _Eocene._ Serpent, Lizard.

Leamington. _New Red._ Labyrinthodon.

Lewes. _Chalk._ Vertebra; of Mosasaurus or Leiodon.

Lyme Regis. _Lias._ Pterodactyles, Ichthyosauri, and Plesiosauri in
abundance.

Maidstone. _Lower Green Sand_; quarries near the town; particularly
Mr. Bensted’s "_Iguanodon quarry_." Iguanodon, Plesiosaurus,
Polyptychodon, Fresh-water Tortoise.

Malton. _Oolite._ Megalosaurus.

Market Rasen. _Kimmeridge Clay._ Pliosaurus.

Norfolk? _Chalk._ Leiodon: very rare.

Portland, Isle of. _Oolite._ Turtles.

Purbeck, Isle of. _Purbeck._ Goniopholis, Chelonians. _Kim. Clay._
Pliosaurus.

Redland, near Bristol. _Magnesian Conglomerate._ Palæosaurus,
Thecodontosaurus.

Saltwick. _Lias._ Teleosaurus.

Sheppey, Isle of. _London Clay._ Turtles, Serpents, Crocodiles.

Shotover, near Oxford. _Kimmeridge Clay._ Pliosaurus, Teleosaurus.

Southerham. _Chalk._ Mosasaurus, Plesiosaurus.

Stonesfield. _Oolite._ Megalosaurus, Teleosaurus, Pterodactyles.

Stourton, Cheshire. _New Red._ Foot-prints of reptiles
(Cheirotherium), &c.

Street, Somersetshire. _Lias._ Ichthyosauri and Plesiosauri.

Swanage, Isle of Purbeck. Goniopholis, Chelonians.

Tilgate Forest. _Wealden_; quarries in various localities. Iguanodon,
Megalosaurus, Hylæosaurus, Suchosaurus, Turtles, and Tortoises.

Watchett, Somersetshire. _Lias._ Plesiosauri, Ichthyosauri.

Warwick, Guy’s Cliff, near. _New Red._ Labyrinthodon.

Westbrook, Wilts. _Kimmeridge Clay._ Ichthyosaurus.

Weston, near Bath. _Lias._ Plesiosaurus.

Whitby, Yorkshire. _Lias._ Ichthyosauri, Plesiosauri, Teleosaurus.

Wight, Isle of; along the southern shore, near Brook-Point.
_Wealden._ Iguanodon, Cetiosaurus, &c., washed up on the sea-shore.