ANATOMY OF THE MELANONIDAE 



so rial 



19 



exca 



boc 



Fig. 7. Melanonus zugmayeri posterior part of cranium in lateral oblique view of 130mm SL specimen showing in A, first neural arch and 

 vertebra attached and in B, removed to expose the posterior features of the basi- and exoccipitals. Note the supraoccipital does not 

 contribute to the border of the foramen magnum. 



forms and ophidiiforms appears to be the common condition. 

 It is assumed that this feature has been repetitively evolved in 

 these groups. 



Jaws (Fig. 8) 



The premaxilla (Fig. 8C) has tall, thin and widely separated 

 ascending and articular processes, and a tall, spine-like 

 postmaxillary process. The toothed surface is narrow, bearing 

 for most of its length two rows of sharp pointed teeth. The 

 outer row teeth are straight or extend slightly laterad, the 

 inner row teeth which are about twice the length of the outer 

 are inwardly curved; posteriorly there are three rows of teeth, 

 the ones of the centre row being the same size as those of the 

 inner (Figs 8D,E). In a 100mm SL specimen of M. zugmayeri 

 the posterior teeth are so arranged as to form distinct 

 transverse rows (Fig. 8F) but this is not evident in the 66mm 

 or 130mm SL specimens. The maxilla has a tall articular head 

 and a short medial articular process forming a rather acute 

 angle with the head (Figs 8A,B). The shaft of the bone is 

 slender and posteriorly bears shallow dorsal and ventral 

 processes. 



The dentary (Fig. 8G) is short and deep with a correspond- 

 ing shallow mentomeckelian cavity; it has a high steep 

 coronoid process. The sharp pointed teeth are set in an 



irregular single row, numbering 22 in 88mm and 100mm SL 

 specimens of M. zugmayeri, 2% in a 130mm and 34 in a 175mm 

 SL specimen. The anterior teeth are small followed by four or 

 five successively larger ones, then four or five relatively large 

 teeth separated by three or four smaller ones. Posteriorly the 

 teeth diminish in size. The anguloarticular (Fig. 8G) is tall 

 with a steep posterior slope and short, vertical anterior 

 margin; the articular condyle is long and narrow. The coro- 

 nomeckelian bone (Fig. 8G) is a well-developed, cylindrical 

 element with slight dorsal and ventral posterior flanges. The 

 retroarticular (Fig. 8G) is boot-shaped, the leg being curved 

 forward and the foot long and shallow. A strong labial 

 ligament is anchored to the rim of the dentary (Howes, 1988, 

 fig- 12). 



The overall jaw morphology of Melanonus is plesiomorphic 

 for gadiforms, the upper jaw bones, apart from having a 

 smaller postmaxillary process of the premaxilla, are little 

 different from those in bathygadids (Howes & Crimmen, 

 1990). Macrouroids are characterised by having a large 

 postmaxillary process of the premaxilla situated posteriorly 

 (Okamura, 1970; Howes & Crimmen, 1990). There is no 

 'gadoid notch' at the base of the postmaxillary process. The 

 lower jaw more closely resembles that of gadoids or ophidii- 

 forms than macrouroids in having a relatively shallow angu- 

 loarticular and boot-shaped or J-shaped retroarticular. 



