Intracranial movement in the coelacanth Latimeria chalumnae Smith (Osteichthyes, Crossopterygii)
The intracranial kinesis of the coelacanth fish Latimeria chalumnae Smith was studied from motion picture records of manipulation of the skull of a "fresh" dead specimen. Frame-by-frame analysis provided data on the relationships between change in angle of the gape and the angle at the intracranial joint. The length relationships of the subcephalic and geniocoracoid muscles during the mouth-opening sequence were noted. The data suggest that anterior movement of the shoulder girdle is an important feature of the intracranial mechanism and that such movement allows the geniocoracoid to contract essentially isometrically when the gape is opened. The possible function of cranial kinesis is discussed.