ing the middle or late Triassic (Nelson 89). Various highly advanced features have been responsible for this group's adaptive success. For example, electrical stimulation of the teleost midbrain tegmentum elicits coordinated swimming movements. This suggests that they may have a mesencephalic locomotor region similar to certain mammals (Bone et al. 284-285). The teleost fish also have a cornea which is similar to that of mammalian species (Geroski et al. 133-141). Finally, teleost evolution has resulted in an increasingly complex jaw apparatus. For example, one important development has been the emergence and retention of protrusible jaws (Bone et al. 164). Such adaptations have made teleosts the most successful fish group since they began to radiate in the Cretaceous. Teleost species far exceed those of any other fish group--or any other kind of vertebrate for that matter. Indeed, the diverse division includes 96 percent of living fishes (Bone et al. 22-23).
The cottids evolved some time after the emergence of teleost fish. For instance, Berra (1981) has identified fossil cottids in Belgium. These date back to between 25 and 36 million years ago (Jenkins & Burkhead 625-627).
Although the largest sculpin may grow to about 78 centimeters (e.g., Scorpaenichthys marmoratus), the long-horned sculpin is much smaller. Adult M. octodecimspinosus are typically about 36 centimeters (Khan 63-69). Moreover, they may weigh between 450 to 700 grams (Kiceniuk et al. 435-438). Teleost skeletal elements are well calcified, but are "lightened by being built from a scaffolding of struts (Bone et al. 22-23)." Sculpins have an anteriorly rounded body that tapers to a somewhat compressed caudal peduncle. The sculpin body is never completely encased in heavy bony armor; rather it often appears naked with scales or prickles.
Cottids usually have a large broad head and a large terminal mouth. The fishes' eyes are mounted on to...