144 



100 



< 

 on 



O 



O 10 



UJ 



< 



CO 



1 - 



1 10 100 



BODY WEIGHT IN KILOGRAMS 



Figure 19 Detailed elasmobranch minimum convex polygon, illustrating positions of 

 various taxa. Interspecific coefficient of allometry is 0.76 with a coefficient of determi- 

 nation of 0.86. AI, Aprionodon isodon; CF, Carcharhinus falciformis; CL, Carcharhinus 

 leucas; DS, Dasyatis sabina; G, Galeocerdo cuvieri; GC, Ginglymostoma cirratum; HF, 

 Heterodontus francisci; MC, Mustelus canis; OT, Odontaspis taurus; PM, Potamotrygon 

 motoro; PT, Platyrhinoidis triseriata; RE, Raja eglanteria; RP, Rhinobatos productus; SA, 

 Squalus acanthias; SC, Scyliorhinus caniculus; SL, Sphyrna lewini. (After Northcutt 

 1977.) 



Sharks and batoids listed in Table 2 are ranked in descending order of 

 their EQ values. These data suggest that galeomorph sharks possess higher 

 EQs than squalomorph sharks and that myliobatiforms possess EQ values 

 3 to 10 times larger than those of rajiforms. The elasmobranch sample now 

 available is too small to establish meaningful confidence intervals for the 

 EQ value of a given species; thus the exact ranking of any species may be 

 relative. 



Further study will certainly alter the present boundaries of the 

 chondrichthian polygon. The samples to date are extremely small, and no 

 brain: body data exist for chimaeras or large squalomorph sharks. Data on 

 chimaeras should be particularly interesting, as this group represents a sister 

 radiation of the elasmobranchs, with its own neural specializations. Data on 

 the large squalomorph sharks should extend the lower boundary of the 

 present polygon if the low encephalization quotient for Squalus is typical of 



