The occasional discovery of bones and teeth of an unknown animal
in the limestone of St. Peter's Mountain, near Maestricht, and the
innumerable shells, corals, teeth of fishes, claws of crabs, echini,
and other organic remains, had long since attracted the attention
of naturalists, and rendered these quarries celebrated throughout
Europe. In 1770, M. Hoffman, the surgeon of the Fort, who had for
some years been assiduously collecting the fossils of this locality,
had the good fortune to discover a specimen which has conferred an
enduring celebrity on his name. Some workmen, on blasting the rock
in one of the caverns of the interior of the mountain, perceived to
their astonishment the jaws of a large animal attached to the roof of
the chasm. The discovery was immediately made known to M. Hoffman,
who repaired to the spot, and for weeks presided over the arduous
task of separating the mass of stone containing these remains from
the surrounding rock. His labours were rewarded by the successful
extrication of the specimen, which he conveyed in triumph to his
house. This extraordinary discovery soon became the subject of
general conversation, and upon reaching the ears of the Canon of the
cathedral which stands on the mountain, excited in that functionary
a determination to claim the fossil, in right of being lord of the
manor; and he unfortunately succeeded, after a long and harassing
lawsuit, in obtaining this precious relic. It remained for years in
his possession, and Hoffman died without regaining his treasure,
or receiving any compensation. At length the French revolution
broke out, and the armies of the republic advanced to the gates of
Maestricht. The town was bombarded; but at the suggestion of the
committee of savans who accompanied the French troops to select their
share of plunder, the artillery was not suffered to bombard that part
of the city in which the celebrated fossil was known to be preserved.
In the mean time, the Canon of St. Peter's, shrewdly suspecting the
reason why such peculiar favour was shown to his residence, removed
the specimen, and concealed it in a vault; but when the city was
taken, the French authorities compelled him to give up his ill-gotten
prize, which was immediately transmitted to the Jardin des Plantes,
at Paris, where it still forms one of the most striking objects in
that magnificent collection.[130]
[Footnote 130: Faujus St. Fond, in whose beautiful work on the
fossils of St. Peter's Mountain the above account is given, remarks
with much sang froid, "La _justice_, quoique tardive, arrive enfin
avec le tems!" The reader will probably think that although the Canon
was justly despoiled of his ill-gotten treasure, the French _savans_
were a very equivocal personification of _Justice_!]
The beautiful model of this most interesting fossil in the British
Museum, was presented to me by Baron Cuvier. It is four and a half
feet long, and two and a half wide; it consists of the jaws, with
teeth, palatal bones, and the tympanic bone, or _os quadratum_,
a bone possessed by reptiles, as well as birds, and in which the
auditory cells are contained. There are likewise some fine portions
of jaws, with teeth, in the British Museum, presented by Camper.
The original animal was probably a terrestrial reptile, holding an
intermediate place between the Monitors and Iguanas. It was about
twenty-five feet long.
I discovered, many years since (1820), some vertebræ in the chalk
near Lewes, which closely resemble the corresponding bones of the
Mosasaurus, and in all probability belong to another species. In the
cretaceous strata of New Jersey, Dr. Harlan found and described, and
my friend. Dr. Morton, of Philadelphia, sent me, in 1834, teeth which
cannot be distinguished from those of Maestricht. Vertebræ, and other
bones, have since been obtained from the same deposits by Professor
Rogers, and described by Professor Owen in the Geological Journal.
XVI. Fossil Reptiles. Although when Mr. Parkinson's work was
published many fossil bones and teeth of reptiles had been discovered
in various parts of England, yet the abundance and variety, and
the extraordinary modification of form and structure of this class
of vertebrated animals, which prevailed throughout the secondary
geological formations, were not for a moment suspected. The few
examples of the remains of fossil reptiles described by Mr.
Parkinson, serve to mark the degree of knowledge which then existed
respecting a department of palæontology that rapidly acquired an
importance and interest unsurpassed by any other branch of fossil
osteology.
The announcement of the founder of palæontology,[131] that there
was a period when the lakes and rivers of our planet were peopled
by reptiles, and cold-blooded oviparous quadrupeds of appalling
magnitude were the principal inhabitants of the dry land; when
the seas swarmed with saurians, exclusively adapted for a marine
existence, and the regions of the atmosphere were traversed by winged
lizards instead of birds; was an enunciation so novel and startling,
as to require all the prestige of the name of Cuvier, to obtain for
it any degree of attention and credence, even with those who were
sufficiently enlightened to admit, that a universal deluge would not
account for the physical mutations which the surface of the earth and
its inhabitants had, in the lapse of innumerable ages, undergone.
[Footnote 131: In the "Ossemens Fossiles;" tom. v. Reptiles Fossiles.]
Subsequent discoveries have established the truth of this proposition
to an extent beyond what even its promulgator could have surmised;
and the "_Age of Reptiles_" is now admitted into the category of
established facts.
During the incalculable ages which the formation of the various
systems of secondary strata must have comprised, we find no evidence
in the fossils hitherto observed, of the existence of birds and
mammalia, as the characteristic types of the faunas of the dry land.
On the contrary, throughout the immense accumulations of the spoils
of the ancient islands and continents, amidst innumerable relics of
reptiles of various orders and genera, a few jaws and bones of two or
three kinds of extremely small marsupials, and the bones of a species
of wader, are the sole indications of the presence of the two grand
classes of Aves and Mammalia, which now constitute the chief features
of the terrestrial zoology of almost all countries.
The earliest indications of air-breathing vertebrata in the ancient
secondary formations are those of small saurian reptiles in the
carboniferous strata; a few vestiges occur in the succeeding group,
the Permian. In the next epoch, the Triassic, colossal Batrachians
(_Labyrinthodonts_) appear; and on some of the strata of this
formation are the footmarks of numerous bipeds, presumed to be those
of birds; but at present the evidence of the bones of the animals
that made those imprints is required to establish the hypothesis.
In the succeeding eras, the Lias, Oolite, Wealden, and Cretaceous,
swarms of reptiles of numerous genera and species everywhere prevail;
reptiles fitted to fly through the air, to roam over the land, to
inhabit the lakes, rivers, and seas; and yet not one identical
with any existing forms! These beings gradually decline in numbers
and species as we approach the close of the secondary periods,
and are immediately succeeded in the eocene epoch, by as great a
preponderance of warm-blooded vertebrata--birds and mammalia--as
exists at the present time; and an equal decadence in the class of
reptiles. With the Cretaceous Formation the "Age of Reptiles" may be
said to terminate.
XVII.--Fossil Reptiles of the Wealden. _The Iguanodon._ The
fluviatile deposits (termed _Wealden_), which in the south-east
of England, and in the north of Germany, are intercalated between
the oolitic and cretaceous formations, abound in the bones of
terrestrial, fresh-water, and marine reptiles, comprising some of
the most colossal land-saurians which have hitherto been brought
to light. These remains belong to various genera of Chelonians,
Saurians, and Crocodilians; and with these are associated those of
flying lizards (_Pterodactyles_), Plesiosauri, gigantic whale-like
reptiles (_Cetiosauri_), and of other oviparous quadrupeds of unknown
species and genera.
The occurrence of fossils of this nature in the strata forming the
districts denominated the Wealds of Sussex and Kent, was first
brought under the notice of geologists in 1822, in my work on the
"Fossils of the South Downs," in which the remains of several
unknown reptiles were described; and among them the teeth and bones
of that extraordinary herbivorous lizard, the _Iguanodon_, on which
I am induced to offer a few observations in this place; the recent
discovery of some previously undetermined parts of the skeleton,
having materially elucidated the structure and economy of the
original.[132]
[Footnote 132: The following is the description of the specimens
first discovered, given in the "Fossils of the South Downs; or,
Illustrations of the Geology of Sussex," 1 vol. 4to. 1822: "Incisors
and molar teeth evidently belonging to the same species of animal:
they differ from any previously known; the masticating surface is
perfectly smooth and rather depressed in the centre; these teeth
consist of the crown only, and are quite solid. An incisor tooth
1.3 inch long Is slightly bowed and smooth on its inner surface;
but it has externally a ridge which extends longitudinally down the
front. Its sides are angular and the edges finely crenated." From
the resemblance of these teeth in their general form to those of
the Iguana, a common land lizard in the West Indies, I subsequently
proposed the name of _Iguanodon_ (implying an animal having teeth
like the Iguana) for the fossil reptile. The teeth of an Iguana
four or five feet long are not larger than those of a mouse; the
Iguanodon's teeth are as large as the incisors of the rhinoceros. The
Iguana's teeth, when used, are chipped off at the points, no existing
reptile being capable of performing mastication; the teeth of the
Iguanodon, on the contrary, are ground down like the worn molars of
herbivorous mammalia, as I pointed out in my first memoir in the
Philos. Trans. 1825.]
Since the first announcement of the discovery of the remains of the
Iguanodon, vast quantities of bones belonging to a great number of
individuals of all ages have been collected; but until a few years
since, not a vestige of the jaws had been observed, notwithstanding
the most diligent research. In the early part of the year 1848, I
was surprised and highly gratified by receiving from Capt. Lambart
Brickenden (at that time a personal stranger to me), who then resided
at Warminglid, near Cuckfield, in Sussex, the greater part of the
right side (or _ramus_) of the lower jaw, with several successional
teeth in their natural position, of an adult Iguanodon.[133] See p.
202.
[Footnote 133: This beautiful and most instructive specimen is now in
my possession; it is figured of the natural size in Philos. Trans.
Part ii. for 1848, Plate XVI., as well as the portion of upper jaw in
the British Museum, Plate XIX. The character of the upper and lower
teeth of the Iguanodon are well represented in Plate XVIII. of the
same memoir.
A specimen very similar to that discovered by Capt. Brickenden,
but of a young individual, was found soon afterwards in a quarry
near Horsham; but I was not allowed the privilege of figuring or
describing it!]
In the course of last summer I obtained a very instructive fragment
of the middle part of the right ramus of the lower jaw of a much
larger Iguanodon, found by Mr. Fowlestone, with some enormous bones
of the extremities, in the Wealden strata of the Isle of Wight. A
portion of the upper jaw (without teeth) was discovered some years
since in Tilgate Forest, and is deposited, with the whole of the
collection I formed at Brighton, in the gallery of organic remains
of the British Museum. These three specimens are the only parts of
the jaws of the Iguanodon, with the exception of a fragment of the
angular bone, that I have had the opportunity of examining. The other
portions of the skeleton hitherto discovered are the following: the
tympanic bone;[134] cervical, dorsal, lumbar, and caudal vertebræ,
and chevron bones; ribs; the iliac bones, and sacrum composed of
six anchylosed vertebræ;[135] the coracoid, scapula and clavicles;
humerus, radius? metacarpals; femur, tibia and fibula, metatarsals
and ungueals. The cranium, carpals, and tarsals, have not been
discovered.
[Footnote 134: This may or may not belong to the Iguanodon: no
tympanic bone has been found in such connexion with other parts of
the skeleton as to afford certain proof that this maxillary element
is referable to the Iguanodon.]
[Footnote 135: In the Megalosaurus, the sacrum consists of five
anchylosed vertebræ.]
With the exception of the assemblage of bones promiscuously grouped
together in a block of _Kentish rag_ (of the greensand formation),
found in a quarry near Maidstone, by Mr. Bensted,[136] a few
connected caudal vertebræ, and two or three instances in which
a femur, tibia, and fibula and some metatarsals, were found in
contiguity, all the bones were isolated. They have been obtained
from the quarries in St. Leonard's and Tilgate Forests, near
Loxwood, Rusper, Horsham, Cuckfield, and Battel; and from the cliffs
at Hastings, and in Sandown, and Brixton, and Brook Bays, on the
southern shore of the Isle of Wight.
[Footnote 136: This most instructive specimen is in a glass-case
on the floor near the window, in the middle room of the Gallery of
Organic Remains in the British Museum. All the Wealden reptilian
remains of a large size, collected by me when residing in Sussex, are
in the upright glass cases in the same apartment.]
So anomalous is the osteology of the Iguanodon compared with that of
existing saurians, that from my discovery of the first vestige of
this reptile--a fragment of a tooth--thirty years ago, to the recent
important acquisition of the jaws, I have had to contend with the
opposition of eminent naturalists, who have refused assent to the
physiological inferences suggested by the specimens which were from
time to time brought to light, because the modifications of structure
in a colossal herbivorous reptile, essentially differed from the
hypothetical archetype skeleton of the class to which it belonged.
When the first discovered teeth were shown to Baron Cuvier, he
pronounced them to be the incisors of a Rhinoceros; the metatarsals,
those of a Hippopotamus; the fragment of a femur, with a medullary
canal, that of some large mammalian. But the candour and liberality
of the founder of Palæontology were worthy of his transcendent
genius; upon receiving further evidence, he immediately acknowledged
the error, and expressed his conviction that the teeth and bones
belonged to an herbivorous reptile more extraordinary than any that
had previously been brought under his notice.[137]
[Footnote 137: See Cuvier's Ossemens Fossiles, tom. v. part. ii. It
is much to be wished that those who aspire to emulate this great
man in scientific fame, would also endeavour to imitate him in the
yet nobler attributes of his character. It is stated by Professor
Owen, in Brit. Assoc. Reports on Fossil Reptiles, that the bones
of the Iguanodon were interpreted by me with the aid of Cuvier and
Clift. This is a mistake. Baron Cuvier died before I had obtained any
considerable portion of the skeleton; and neither Mr. Clift nor Mr.
Owen at that time could afford me any assistance in determining the
nature of the isolated bones I occasionally brought to the Hunterian
Museum for comparison. Any aid I ever received in my investigations
is most fully acknowledged in my works.]
Even the lower jaw, which presents characters so peculiar as to
admit, as I conceive, of but one interpretation--that enunciated in
my memoir on the teeth and jaws of the Iguanodon,[138]--has been
adduced as affording a signal instance of the incorrectness of my
physiological deductions. And why? Because in the entire class of
living reptiles there is not a single species that has cheeks and
flexible lips, which, according to my view of the subject, the
Iguanodon must have possessed. But I do not hesitate to affirm
that the structure and arrangement of the teeth, and the mammalian
character of the bones of the extremities, are in perfect accordance
with my exposition of the probable structure and functions of the
maxillary organs of the original. The naturalists who advance these
objections, forget that among the existing mammalia there is one
genus, the _Ornithorhynchus_, or Duck-billed Platypus, that exhibits
as striking a deviation from the typical maxillary structure of its
class, as does the Iguanodon. If before the discovery of New Holland
the jaw-bones of the Ornithorhynchus had been found in a fossil state
in the strata of Tilgate Forest, and I had ventured to infer that the
original, though a true mammalian, and giving suck to its young, had
the extremities of the jaws covered with flat horny beaks, like those
of a duck, instead of with the fleshy lips and integuments which are
the peculiar attributes of its class, what censures would not my
temerity have called forth! We cannot too often be reminded of the
profound remark of William Penn: "Experience, which is continually
contradicting theory, is the only test of truth."
[Footnote 138: See Philosophical Transactions, Part II. 1848.]
The following are the physiological inferences relating to the
structure and habits of the Iguanodon, which Dr. Melville and myself
conceive our investigations have established: the discovery of the
cranium, and of perfect examples of the upper and lower jaws with
both successional and mature molars in their natural position, may
modify, but, we believe, will in no material respect invalidate these
conclusions.
In instituting a comparison between the maxillary organs of the
Iguanodon, and those of the existing herbivorous lizards, we are at
once struck with their remarkable deviation from all known types
in the class of reptiles. In the _Amblyrhynchi_ (of the Galapagos
Islands), the most exclusively vegetable feeders of the Saurian
order, the alveolar process beset with teeth is continued round the
front of the mouth: the junction of the two rami of the lower jaw at
the symphysis presenting no edentulous interval whatever, the lips
not being more produced than in other reptiles; but this creature
only bruises its food; it cannot grind or masticate it. In fact, the
edentulous, expanded, scoop-shaped, procumbent symphysis of the lower
jaw of the Iguanodon, has no parallel among either recent or fossil
reptiles; and we seek in vain for organs at all analogous, except
among the herbivorous mammalia. The nearest approach is to be found
in certain _Edentata_; as for example in the _Cholæpus didactylus_,
or Two-toed Sloth, in which the anterior part of the lower jaw is
destitute of teeth, and much prolonged. The correspondence is still
closer in the extinct gigantic _Mylodons_, in which the symphysis
resembles the blade of a turf-spade, and has no traces of incisor
sockets; and were not this part of the jaw elevated vertically
in front, and the two sides confluent, it would present the very
counterpart of that of the Iguanodon. The great number and size of
the vascular foramina distributed along the outer side of the dentary
bone in the Wealden reptile, and the magnitude of the anterior
outlets which gave exit to the vessels and nerves that supplied the
front of the mouth, indicate the great development of the integuments
and soft parts with which the lower jaw was invested.
The sharp ridge bordering the deep groove of the symphysis, in
which there are also several foramina, evidently gave attachment
to the muscles and integuments of the under lip; and there are
strong reasons for supposing that the latter was greatly produced,
and capable of being protruded and retracted so as to constitute,
in conjunction with a long extensile tongue, a suitable instrument
for seizing and cropping leaves and branches, which, from the
construction of the teeth, we may infer was the food of the Iguanodon.
Thus we find the mechanism of the maxillary organs of the Wealden
herbivorous saurian, as demonstrated by recent discoveries, in
perfect harmony with the remarkable dental characters which
rendered the first known teeth so enigmatical. In the Iguanodon we
have a solution of the problem, how the integrity of the type of
organization peculiar to the class of cold-blooded vertebrata was
maintained, and yet adapted by simple modifications to fulfil the
conditions required by the economy of a gigantic terrestrial reptile,
destined to obtain support exclusively from vegetable substances;
in like manner as the extinct colossal sloth-like Edentata of
South America. In fine, we have in the Iguanodon the type of the
terrestrial herbivora, which in that remote epoch of the earth's
physical history--the _Age of Reptiles_--occupied the same relative
station in the terrestrial fauna, and fulfilled the same general
purposes in the economy of nature, as the Mylodons, Mastodons, and
Mammoths, of the tertiary periods, and the large pachyderms of modern
times.
Although some important data are still required to complete our
knowledge of the structure of the Iguanodon, we are warranted in
concluding that this colossal herbivorous reptile was as bulky as the
elephant, and as massive in its proportions: for, living exclusively
on vegetable substances, the abdominal region must have been largely
developed. Its limbs must have been of proportionate size to support
and move so enormous a carcass. The hinder extremities probably
presented the unwieldly contour of those of the Hippopotamus, and
were based on strong short feet, protected by broad horny ungueal
phalanges, or nails. The fore-legs appear to have been less bulky,
and adapted for seizing and pulling down plants and branches: the
teeth and jaws demonstrate the nature of its food; and the fossil
remains of coniferous trees, arborescent, ferns, and cycadeous
plants, with which its relics are commonly associated, indicate the
character of the flora adapted for its sustenance.[139]
[Footnote 139: Philosophical Transactions, for 1848, pp. 196-198.]
XVIII. The Pelorosaurus.--The humerus of a terrestrial reptile of
enormous magnitude, has lately been discovered by Mr. Peter Fuller
of Lewes, in the quarry near Cuckfield, from which many remains of
the Iguanodon and Hylæosaurus were obtained in my early researches.
This bone more nearly resembles the humerus of the Crocodiles, than
that of the Lizards. It Is four and a half feet in length, and of
corresponding proportions; it has a large medullary canal. As to
the size of the animal to which it belonged, while disclaiming the
idea that any certain conclusion can be drawn from a single bone, I
may mention, with the view of conveying some general notion, that
in a Gangetic crocodile eighteen feet long, the humerus is one
foot: according to this scale the fossil animal would be eighty-one
feet in length. I have proposed the name of _Pelorosaurus_ (from
πἑλωρ--_pelòr_--monster), or Colossal-saurian, for this new genus of
reptiles which Inhabited the country of the Iguanodon.[140]
[Footnote 140: A memoir on this fossil was read before the Royal
Society, Feb. 14th, 1850; an abstract has been published in the
Proceedings of the Society. It is entitled, "On the Pelorosaurus;
an undescribed gigantic terrestrial reptile, whose remains are
associated with those of the Iguanodon and other saurians in the
strata of Tilgate Forest." It will appear in the Phil. Trans. Part
11. 1850.]