Organic-walled dinoflagellate cysts have a long geological record with lowest occurrences during the mid Triassic, whilst geochemical markers suggest a presence to the Early Cambrian. Some of the Paleozoic acritarchs possibly are related to dinoflagellate cysts. "Arpylorus", from the Silurian of North Africa, was at one time considered to be a dinoflagellate cyst, but this palynomorph is now considered probably an arthropod remain. Another enigmatic form with possible early dinoflagellate affinity is "Palaeodinophysis altaica", which was found in the Devonian of Kazakhstan, however Fensome "et al." (1999) consider its dinoflagellate affinity (and also supposed age) unlikely.