title: Evolutionary relationships of a "primitive" shark (Heterodontus) assessed by micro-complement fixation of serum transferrin.
abstract: The evolutionary relationships of six sharks were investigated by comparing their transferrins using the micro-complement fixation method. The immunological distances observed were used to build a tree that confirms that the squaloid and galeoid species examined belong to two separate groups and that Heterodontus, a genus of hitherto uncertain position, belongs with the galeoids. The divergence time estimated from the transferrin comparisons is roughly 240 +/- 65 million years between Heterodontus and galeoids.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003168:Complement Fixation Tests; D007106:Immune Sera; D007122:Immunoelectrophoresis; D012754:Sharks / Q000097:blood / Q000235:genetics*; D013045:Species Specificity; D014168:Transferrin / Q000235:genetics*
chemical_list: D007106:Immune Sera; D014168:Transferrin