A siphunclde found

Shown here is part of the siphuncle of the Late Paleozoic nautiloid cephalopod Domatoceras that was found in a specimen at the New Mexico Museum of Natural History and Science. This may be a one-of-a-kind find that adds to our understanding of this genus.


Descriptions of Domatoceras so far have been limited to the evolutely coiled shell with a subquadrate whorl section.
The siphuncle is only mentioned in passing as being subcentral and probably orthochoanitic. Subcentral it is but orthochoanitic, at least in this case, it is not.



The picture to the left shows the specimen in which the siphuncle was found, exposed in the second whorl near the bottom.