Hello, I was researching plectronocerids, and came across a few mentions (copied mentions) of some specimens from New Mexico and Texas, but I can't find any in the literature. Most seem to be Chinese. Does anyone know which plectronocerid(s) might be in North America and which formation? Thanks!
Also, I went looking for ascocerids lately, and found a few. They're the ones with the deciduous juvenile stage. Nothing really perfectly complete, but a few with the juvenile stage still attached in the matrix. One of which confirms that at least for Billingsites, they only lost one stage. Some had proposed that the juveniles lost pieces as they went, and so had a rounded adapical tip. But the specimen I have seems to go to a point. The problem, I think, is that most people don't get them in the matrix, and steinkerns can break at the septa.
I can post pictures soon. Gotta clean up and photograph first.