Dictyocaris, een enigmatisch fossiel uit het Siluur

Dictyocaris can be regarded as a real Unidentified Paleontological Object. Salter (1860) and Størmer (1935) thought of a carapace, belonging to a large crustacean, however without convincing evidence. Ritchie (1968) is not even convinced that Dictyocaris is to be interpreted as an animal. Partly or almost entirely, three dimensionally very well preserved specimens of "Dictyocaris" give the impression that the object could have been beaker shaped in life. However, an other orientation remains a valid option. It is likely that these 3d fossilized specimens were hollow during their sedimentary covering, because of the infill of silt between two layers of associated Dictyocaris material. Numerous specimens show that the characteristic perforations are situated in a shallow depression with a clear outstanding rim and the other way round on the counterpart. Also depressions are observed including a rim, but lacking a visible perforation. This could mean that the small hole still had to develop or that the tissue recovered from a perforation. Two specimens, one of which is shown in fig. 2a and 2b, demonstrate the presence of ostracods. Some of them are situated in depressions, which could mean that the ostracods fed on Dictyocaris. Perhaps some of the perforations, especially the irregular ones, can be interpreted as eating marks, caused by ostracods. In order to have this confirmed more Dictyocaris specimens in combination with ostracods should be found. Ostracods were also active on Slimonia (fig. 5). No indications were found that Dictyocaris could have been a sponge or a plant (with thanks to dr Van Kempen and dr Van der Burgh). There are also no traces found that Dictyoaris was hitched on other objects or that it could move in one way or another. In case the original tissue has also been very thin, its composing material must have been very strong in order to fossilize three dimensionally. Chitin as composing material is one of the possibilities, which reminds of arthropods again, but also confirms it is a true riddle.