*In an earlier communication (Harris, 1937 a), I have described a dorsal fin spine found in several large specimens of Cladoselache in the Cleveland Museum. At the time that paper was written, I was never happy about the fitting of the anterior border of the first dorsal fin on to the posterior border of this spine, though the position of the spine in the only complete shark studied seemed to support this view. Since that time, the fact that in all other specimens the spine has been found occurring with the head skeleton (neurocraniun and jaws, Harris 1937 b), and that an early figure of Newberry's (1889) of “Cladodus kepleri” (P1. LXIV) shows, without comment, a “fin spine” which is well a head of the anterior border of the pectoral fin, has led me to think that possibly this structure is a head spine-perhaps functioning as a copulatory clasper in a similar fashion to that postulated by Dean (1906) for Chimaera. The “sphenonchus” spines of hybodonts may well have been used in a similar manner.
Diademodus hydei, a new fossil shark from the Cleveland Shale.
Article first published online: 21 AUG 2009
1951 The Zoological Society of London
Proceedings of the Zoological Society of London
Volume 120, Issue 4, pages 683–697, February 1951
How to Cite
HARRIS, J. E. (1951), Diademodus hydei, a new fossil shark from the Cleveland Shale. Proceedings of the Zoological Society of London, 120: 683–697. doi: 10.1111/j.1096-3642.1951.tb00672.x
- Issue published online: 30 OCT 2009
- Article first published online: 21 AUG 2009
- Received April 3, 1950.
- 1Diademodus hydei, a new genus and species of shark from the Cleveland Shale, is described and figured from the holotype in the Cleveland Museum of Natural History.
- 2About 40 centimetres in length, the fish is an adult male with well-developed claspers; it shows a combination of hybodont and cladoselachian characteristics.
- 3The teeth are many-cusped and bilaterally symmetrical, with the outer cusps longer than the inner; they approach more closely to the sculpturing of the scale pattern than in orther primitive sharks.
- 4A comparison with the contemporaneous Cladoselache and Ctenacanthus clarki suggests that Diademdus is an early and not distant offshoot from the primitive chondrichthyan stock, the main line of which led through Ctenacanthus and the hybodonts to the modern elamobranchs; Cladoselache is a specialized side line of this main stock and is not an appropriate ancestral type for the Chondrichthyes.