The Trilobite Paper website has pdfs of the "Trilobite Papers 20" newsletters from August 2018 to February 2020. The newsletter is Fred Sundberg's "reboot" of Rolf Ludvingsen's international journal for and by trilobite paleontologists. The issues are published about every six months and are filled with everything trilobite.
Rolf Ludvingsen was an paleontologist and author, that wrote many, many books on the subject.
Check them out!
One of the ongoing problems with lower and middle Cambrian trilobites (and most likely any aged trilobites) are the type species of genera are poorly known or represented by poorly preserved specimens. I have already pointed out (Sundberg, 2007), the specimen of Antagmus typicalis Resser, 1937, which is the type species of Antagmus, a commonly reported lower Cambrian genus. The type specimen is a nearly complete, internal mold of a cranidium preserved in a medium grained friable, limonite-cemented specimen. I suggested (Sundberg and McCollum, 2000; Sundberg, 2007) that the genus be considered nomen dubium, accepting this causes a chain reaction. Antagmus is the genotype of the subfamily Antagminae, which includes Austinvillia, Bicella, Crassifimbra, Eoptychoparia, Luxella, Onchocephalus, Onchocephalites, Periomma, Piaziella, Poulsenia, Proliostracus, Sombrerella, and Syspacephalus.
To complicate this even more, Rasetti (1955) tried to make sense of the taxonomy using better preserved specimens from limestone boulders from the Silly Formation. However, almost all of the type species were known from only cranidia (a couple have librigena). Furthermore, Rasetti commented that the different forms appear to grade from one to another. Authors have used Rasetti’s work to assign their specimens to the genera, but with the gradational nature of the different genera and the lack of other sclerites makes these assignments questionable.
