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Fig. 2 | Swiss Journal of Palaeontology

Fig. 2

From: High-level classification of the nautiloid cephalopods: a proposal for the revision of the Treatise Part K

Fig. 2

Provisional scheme for the phylogenetic relationships amongst nautiloid cephalopods utilising muscle attachment scar patterns as a high-level criterion. 1. Dorsomyarian muscle attachment scars. 2. Thickening of connecting rings. 3. Endosiphuncular deposits (endocones) templated on conchiolin crests. 4. Differentiation of ventral pair (or pairs) of oncoceratid attachment scars. 5. Densely spaced conical endosiphuncular diaphragms form endocones. 6. Loss of cicatrix and development of small hemispherical protoconch. 7. Calciosiphonate connecting ring. 8. Appearance of annulosiphonate, parietal and ‘rod-like’ endosiphuncular deposits. 9. Appearance of cameral deposits. 10. Loss of cicatrix and development of small hemispherical protoconch. 11. Radial division of annulosiphonate endosiphuncular deposits. 12. Reduction in number of radial divisions of annulosiphonate deposits. 13. Development of ectosiphuncular deposits. 14. Thickening of connecting rings and development of bullettes. 15. Reduction of muscle attachment scars to pair or pairs of ventrally placed scars. 16. Truncation of conch and development of sinusoidal septa. 17. Migration of major muscle attachment scars to lateral or dorso-lateral positions

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