The Development of the Monotremata.–Part III. The Development of the Skull of Ornithorhynchus.
Article first published online: 7 JUL 2010
1936 The Zoological Society of London
The Transactions of the Zoological Society of London
Volume 23, Issue 1, pages 1–42, December 1936
How to Cite
de Beer, G. R. and Fell, W. A. (1936), The Development of the Monotremata.–Part III. The Development of the Skull of Ornithorhynchus. The Transactions of the Zoological Society of London, 23: 1–42. doi: 10.1111/j.1096-3642.1936.tb00336.x
- Issue published online: 7 JUL 2010
- Article first published online: 7 JUL 2010
- Received February 25, 1936
- 1The chondrocranium and bony skull are described in five stages of development of Ornithorhynchus.
- 2It is shown (p. 17) that Ornithorhynchus provides an intermediate condition between reptiles and higher mammals, representing a mosaic of characters some of which are typically reptilian and others equally typically mammalian.
- 3Ornithorhynchus is definitely a mammal which has preserved a number of reptilian characters.
- 4The pleurocentrum of the proatlas verterba fuses with that of the atlas vertebra, and forms part of the odontoid peg, as in Lacertilia, Rhynchocephalia, and higher mammals.
- 5The cochlear capsule is not formed out of cartilage of the basal plate (contra Gaupp).
- 6The dumb-bell bone probably ossifies independently of the palatal processes of the premaxillæ, and represents the prevomers (supporting Wilson and Broom).
- 7The “mammalian pterygoid” of Ornithorhynchus is the detached lateral wing of the parasphenoid of reptiles and the dorsal plate of the pterygoid of higher mammals.
- 8The “Echidna-pterygoid” is the pterygoid of reptiles and the secondary pterygoid cartilage (and subsequent ossification therein) of higher mammals.
- 9The alisphenoid is present in Ornithorhynchus as a perichondral ossification in the ala temporalis.