[Plate III.]
I. The Classification and Affinities of the Dinosauria.
Contents.
2. The establishment of the Order Omithoscelida to include the Dinosauria and the Compsognatha.
3. The affinities of the Ornithoscelida with other Reptiles.
4. The affinities of the Ornithoscelida with Birds.1. The History and Definition of the Group.
The recognition of what are now commonly termed the Dinosauria, as a peculiar group of the Reptilia, is due to that remarkable man whose recent death all who are interested in the progress of sound palæontology must deplore—Hermann von Meyer. In his 'Palæologica,' published so long ago as 1832[1], Von Meyer classifies fossil reptiles according to the nature of their locomotive organs; and his second division, defined as "Saurians, with limbs like those of the heavy terrestrial Mammalia," is established for Megalosaurus and Iguanodon. To this group Von Meyer subsequently applied the name of Pachypodes or Pachypoda.
Nine years afterwards Professor Owen, in his "Report on British Fossil Reptilia," conferred a new name upon the group, and attempted to give it a closer definition, in the following passages:—
"Dinosaurians.—This group, which includes at least three well-established genera of Saurians, is characterized by a large sacrum composed of five ankylosed vertebræ of unusual construction, by the height and breadth and outward sculpturing of the neural arches of the dorsal vertebræ, by the twofold articulation of the ribs to the vertebræ, viz. at the anterior part of the spine by a head and tubercle, and along the rest of the trunk by a tubercle attached to the transverse process only; by broad and sometimes complicated coracoids and long and slender clavicles, whereby Crocodilian characters of the vertebral column are combined with a Lacertian type of the pectoral arch; the dental organs also exhibit the same transitional or annectent characters in a greater or less degree. The bones of the extremities are of a large proportional size for Saurians; they are provided with large medullary cavities and with well-developed and unusual processes, and are terminated by meta- carpal, metatarsal, and phalangeal bones which, with the exception of the ungual phalanges, more or less resemble those of the heavy pachydermal mammals, and attest, with the hollow long bones, the terrestrial habits of the species.
"The combination of such characters, some, as the sacral ones, altogether peculiar among reptiles, others borrowed, as it were, from groups now distinct from each other, and also manifested by crea-
- ↑ Von Meyer refers to the 'Isis' for 1830, as containing the first sketch of his views. I have not verified the citation.
