Homology problems in cephalopod morphology: deceptive (dis)similarities between different types of ‘caecum’
Journal: Swiss Journal of Palaeontology
Year: 2019

Homoplasy is a common phenomenon in the evolution of the Cephalopoda. Many homology problems accordingly light up phylogenetic debates. The initial segment of the siphuncle, the so-called ‘caecum’, is one of these characters difficult to be unambiguously evaluated. Although rarely discussed, the caecum of the endocochleate decabrachian Spirula is traditionally seen as a plesiomorphy directly inherited from its ectocochleate ancestors. However, the Spirula caecum must be—according to recent phylo