I think it is one.This article:
Links to an open paper:
Cambrian comb jellies from Utah illuminate the early evolution of nervous and sensory systems in ctenophores
Could that be the one being referred to?
we describe two ctenophore species from the Cambrian of Utah [fossils], which
illuminate the early evolution of nervous and sensory features in the phylum.
Thalassostaphylos elegans has 16 comb rows, an oral skirt, and an apical organ
with polar fields. Ctenorhabdotus campanelliformis has 24 comb rows, an oral
skirt, an apical organ enclosed by a capsule and neurological tissues preserved
as carbonaceous films. These are concentrated around the apical organ and
ciliated furrows, which connect to a circumoral nerve ring via longitudinal
axons. C. campanelliformis deviates from the neuroanatomy of living ctenophores
and demonstrates a substantial complexity in the nervous system of