Observations on the osteology of the iguanodon and hylaeosaurus / by Gideon Algernon Mantell ; with notes on the vertebral column of the iguanodon, by A.G. Melville.

  • Mantell, Gideon Algernon, 1790-1852.
Date:
1849
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the osteology of the iguanodon and hylaeosaurus / by Gideon Algernon Mantell ; with notes on the vertebral column of the iguanodon, by A.G. Melville. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    7/52 (page 275)
    Sacral and caudal vertehrce, Plate XXX.—The most important and novel announce- ment in relation to the osteology of the Wealden reptiles in Professor Owen’s Reports, was the exposition of the structure of the sacrum in the three remarkable extinct genera of his order Dinosauria; namely, the Megalosaurus, Hylaeosaurus, and Iguanodon; a peculiarity of mechanism which had escaped the penetration of all previous ob- servers. No one appears to have suspected that in these reptiles the pelvic arch was composed of a greater number of anchylosed vertebrae than in the living Saurians; and that the position of the neural arches was transposed from its usual place over the middle of the body of the vertebra, to the ossified intervertebral spaces formed by the anchylosis of the contiguous vertebrae; the foramina for the transmission of the sacral nerves from the spinal chord being situated above and behind the middle of the body (see Plate XXX. figs. 15, 16)*. Fragments of the pelvic arch, consisting of the body of one sacral vertebra, with a portion of the contiguous bones anchylosed to each extremity, are not uncommon in the Wealden deposits; and so long since as 1826, Sir R. Murchison transmitted to Baron Cuvier a specimen of this kind (from Loxwood in Sussex-^-), with several lumbar and caudal vertebrae. Upon these relics the illustrious founder of palaeonto- logy only remarked, that the united bodies of the vertebrae “ seem to indicate that the animal to which they belonged made such feeble use of its tail that the caudal vertebrae were occasionally anchylosed together.” Neither did the magnificent spe- cimen of the sacrum of the Megalosaurus, consisting of a series of five united ver- tebrae, made known by the present Dean of Westminster in 1824, suggest the correct interpretation of this part of the skeleton of the Dinosaurians. The announcement of Professor Owen was therefore to me of especial interest, since it elucidated the na- ture of many fossils in my collection which had previously been undeterminable. The present investigation rendering it necessary to acquire an accurate idea of the characters of the vertebrae composing the pelvic arch of the Iguanodon, I obtained permission of Mr. Saull to have the fine specimen of a sacrum in his museum (de- scribed in Report of Brit. Assoc, p. 131), more completely developed at my own ex- pense, as its true characters were in some measure obscured by the coating of hard calcareous grit with which, as is generally the case with the Isle of Wight Wealden fossils, it was partially invested. This interesting and instructive relic is figured as it now appears in Plate XXVI.; half the natural size in linear dimension. This sacrum consists of six anchylosed vertebrae (not of Jive as described in the Reports on Brit. Foss. Reptiles, p. 130), with the right iliac bone attached. The re- lative size and proportions of the several bones composing the sacral arch are now well displayed. The body of the first or anterior vertebra (Plate XXVI. 1) is large, strong, and expanded, forming a powerful buttress in front; the bodies of the two posterior vertebrae (Plate XXVI. 5, 6) are likewise large and strong ; but the second, third, and fourth, are constricted laterally in the middle (Plate XXVI. 2, 3, 4), and * See Reports on Brit. Foss. Reptiles, 1842, p. 105. t Geological Transactions, vol. ii. (New Series), p. 105, Plate XV^. figs. 4, 6.