Latimeria chalumnae and its pedigree

Synopsis Latimeria is the product of a long coelacanth lineage, usually viewed as having changed very little. In this paper a classification of better known coelacanth genera is proposed based on a cladistic computer analysis of 56 morphological characters. Biometrical data are then matched with the classification to explore the possibility of identifying subtle change. It is concluded that throughout coelacanth history there have been changes in the structure of the vertebral column involving an overall increase in the number of vertebral elements, and a consequent crowding of these elements within the abdominal region. These changes may be associated with increasing lobation of the second dorsal and anal fins. In the skull, parameters involving the intracranial joint have also changed in such a way that the anterior part of the skull has lengthened in relation to the posterior part and this may be associated with an increase in length of the basicranial muscle.Abbreviations in text figures Ang angular - a.o.r anterior opening of th rostral organ - Art articular - ba.cr.m basicranial muscle - Basi basisphenoid - Boc basioccipital - bpt.pr basipterygoid process - c.p.l cheek pit line - De dentary - Esc extrascapular - eth.sp etmosphenoid - f.e frontoethmoid - Fr frontal - Fr.d descending process of frontal - intr. j intracranial joint - io.s interorbital septum - sc jugal sensory canal - L.e lateral ethmoid - m.Cor modified coronoid - Mm memtomeckelian - m.ot.sc medial branch of otic canal - Op operculum - o.p.l oral pit line - ot,occ otico-occipital - Pa parietal - Pa.d descending process of parietal - Par parasphenoid - pa.s parietal shield - p.Cor principal coronoid - Po postorbital - Pop preoperculum - p.o.r posterior openings of the rostral organ - Pmx premaxilla, Pre-preorbital - Pro prootic - Pro.p posterior process of prootic - Rart retroarticular - Sc.o sclerotic ossicle - So supraorbital - Soc supraoccipital - Sop suboperculum - Sp spiracular - spl splenial - Sq squamosal - Stt supratemporal - Stt.com supratemporal commissure - Stt.d descending process of supratemporal - Par.a.w ascending wing of parasphenoid - Te tectal - X level of vagus exit