. Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural history) ... By Richard Lydekker ... Reptiles, Fossil; Amphibians, Fossil. HASTODOXSAr/RlD^. 141 Some writers divide this group into the two suborders of Stereo- spondyli and Temnospondyli, according as to whether the vertebrae are fully or imperfectly ossified, but the presence of rhachitomous vertebras in the young of Mastodonsaurus seems to render such division inadvisable. Family MASTODONSAURID^E. Skull triangular, and more or less elongated, with the cranial bones very strongly sculptured, the occipital condyle
. Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural history) ... By Richard Lydekker ... Reptiles, Fossil; Amphibians, Fossil. HASTODOXSAr/RlD^. 141 Some writers divide this group into the two suborders of Stereo- spondyli and Temnospondyli, according as to whether the vertebrae are fully or imperfectly ossified, but the presence of rhachitomous vertebras in the young of Mastodonsaurus seems to render such division inadvisable. Family MASTODONSAURID^E. Skull triangular, and more or less elongated, with the cranial bones very strongly sculptured, the occipital condyles ossified, and large palatal vacuities (fig. 32); dentine of teeth with very complex plications; no bony ring in sclerotic; and no ventral scutes. Bodies of vertebrae fully ossified in the adult. There are large palato-vomerine tusks on the inner side of the maxillary teeth; and the palatines run parallel to the maxilla. The mandible has a large postarticular process; and there is a small inner series of mandibular teeth. In the type genus the pubes are separate from the ischia, and do not enter into the formation of the acetabulum ; and the sacral ribs form kidney-like disks. the wedge-bones of Sphenodon ; this type of structure being known as the embolo- merous. In the trunk-vertebra of other genera like Trimerorhachis (fig. 46) and Archegosaurus each vertebra (fig. 30) con- sists of four portions—viz., a basal inter- centrum (hypocentrurn), a pair of pleuro- centra, and a neural arch. In this rha- chitomous type Cope regards the pleuro- centra as representing the centrum of the embolonierous type, since they both carry the arch; and as he finds that the func- tional centra in other forms, like Chely- osaurus, apparently correspond to the intercentra of Archegosaurus, while the pleurocentra are small and apparently about to disappear, it is argued that in other Amphibia the real centra are totally wanting, and the vertebral bodies, which in the caudal region have the chevr
Size: 1519px × 1645px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlydekkerrichard184919, bookcentury1800, bookdecade1880
