Original paper
Papers on cephalopod paleobiology and phylogeny. Editorial Introduction.
Seilacher, Adolf.
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 165 Heft 3 (1983), p. 327 - 329
1 references
published: May 9, 1983
DOI: 10.1127/njgpa/165/1983/327
ArtNo. ESP155016503001, Price: 29.00 €
Abstract
A few years ago the discovery, by hobby paleontologists, of belemnites with preserved soft parts in the Toarcian Posidonia Shales of Holzmaden has received much attention. Later the presumably complete specimens, that had been sold to various museums, were unmasked as forged composits. Nevertheless these happenings have fostered the scientific interest in fossil dibranchiate cephalopods in various respects: A. Belemnoid taphonomy 1. In the large majority of soft part specimens the rostral part is missing. This fact, which led to the forgeries, indicates that the habit of some cephalopod-eating vertebrates to bite off the indigestible rostra was instrumental in soft part preservation, because the lesion allowed the air to escape from the phragmocone, so that some of the carcasses could sink right to the toxic bottom. This hypothesis is supported by the presence, in the same beds, (a) of belemnoid arm hooks, but not of rostra in the stomach contents of ichthyosaurs and (b) of rostra with alveolar bite fragments still adhering. 2. Alveolar bites are conspicuously absent in those belemnite specimens that preserve only the chambered phragmocone in addition to the rostrum. They probably represent cases of normal death, after which the carcass drifted long enough for the soft parts and the non-calcified proostracum to disintegrate before the shell sank to the bottom. 3. In contrast, coleoids without chambered phragmocone seem to have sunk to the bottom right after death, allowing the regular and undisturbed preservation of soft parts and of the non-calcified gladius. B. Belemnoid paleobiology 1. After the belemnite rostra had been recognized as artifical additions, then known soft-part specimens could be affiliated with non-belemnite families that had only small rostra. 2. Continued search in the most prospective horizon (“Koblenzer” led to the discovery of other interesting coleoid remains such as the slender and seemingly uncalcified rostra of Chitinobelus Fischer.
Keywords
cephalopod paleobiology • cephalolpod phylogeny