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Earlier this week I had 2 concretions pop open that I weren’t too sure of what they were. Number one has the calcite desiccation cracks that are consistent with Achistrum sp. I guess the shape is what is kind of throwing me off, and the body seems to segmented, which reminded me of a millipede. Number 2 I cant really see any discernible features in it at all but if I had to guess a type of a polychaete worm? Anyway I’m gonna leave this to the experts lol. Any help is appreciated!

This Mazon Creek nodule arrived for me today. Label said : Polychaete worm - Astreptoscolex anasilosus Had a look in my copy of Wittry and it doesn’t quite seem to match. Thoughts ?

I found it in an area where traces of worms and crustaceans abound, but there are no other remains (shells or corals). I asked on national forum (Spain) and they tell me that it is too big to be a polychaete. They suggested a burrow. Any other ideas or votes for burrow? Thanks, The coin has a diameter of 1.62cm

I found it in an area where traces of worms and crustaceans abound, but there are no other remains (shells or corals). I asked on national forum (Spain) and they tell me that it is too big to be a polychaete. They suggested a burrow. Any other ideas or votes for burrow? Thanks, The coin has a diameter of 1.62cm

Might anyone be able to put a genus (and species?) to this Mazon Creek specimen? The nodule itself is about 4" in length. It may be a polychaete—or not. Thanks! I appreciate your expertise. IMG_0178 copy.tiff

A giant undersea sand worm’s fossilized lair by Eleanor Imster, EARTH, EarthSkyOrg, January 28, 2021 In 20-million-year-old rock off the coast of Taiwan, researchers have discovered what they think is the fossilized burrow of a giant, predatory sand worm. https://earthsky.org/earth/scientists-find-evidence-of-giant-predatory-sand-worms the open access paper is; Pan, YY., Nara, M., Löwemark, L. et al. The 20-million-year old lair of an ambush predatory worm preserved in northeast Taiwan. Sci Rep 11, 1174 (2021). https:// doi.org/10.1038/s41598-020-79311-0 https://www.nature.com/articles/s41598-020-79311-0 Yours, Paul H.

Hi all, this is one of the polychaete worms from the batch of Pit 11 concretions I'm working on. From what I can see of the conical jaws it most closely resembles Didontogaster corydylina but the jaws blend a bit together and aren't as distinct as some other specimens I've found. The body profile seems a little off (no swollen front section for one) so I wanted to ask for second opinions. Am I getting too hung up on the profile of a body that could just be more outstretched? I appreciate everyone's thoughts.

Didontogaster is a polychaete worm (sometimes referred to as bristleworms). The first formal descriptions of Mazon Creek polychaetes did not occur until 1979. At the time they were described, they were the earliest known polychaetes in the fossil record. Since this time, polychaete fossils have been found reaching back as early as possibly the Ediacaran. It is the most common worm found in the Essex portion of the Mazon Creek deposit. It has been classified as belonging to the family Nephtyidae. Members of this family still exist today and are sometimes referred to as cat worms. Didontogaster has a fairly basic body plan. It’s most defining characteristic is a pair of conical shaped jaws that are usually well preserved. Due to the position of the jaws within the body, early collectors nicknamed Didontogaster as a Tummy Tooth Worm. Didontogaster was able to extend it’s jaws outward to feed (see below). It was likely a burrower as they are occasionally found on multiple bedding planes within the concretion. Preserved gut contents show they fed on ostracodes along with plant material. If outstretched, this first specimen would measure around 8 centimeters which is about as big as they get. Most specimens range between 4-5 centimeters.