Early Molluscs
The first bona fide radula dates to the Early Cambrian, although trace fossils from the earlier Ediacaran have been suggested to have been made by the radula of the organism Kimberella.
Another so-called radula has been reported from the early Cambrian in 1974, this one preserved with fragments of the mineral ilmenite suspended in a quartz matrix, and showing similarities to the radula of the modern cephalopod Sepia. However, this was since re-interpreted as Salterella .
Based on the bipartite nature of the radular dentition pattern in solenogasters, larval gastropods and larval polyplacophora, it has been postulated that the ancestral mollusc bore a bipartite radula (although the radular membrane may not have been bipartite).
Read more about this topic: Radula
Famous quotes containing the word early:
“Progress would not have been the rarity it is if the early food had not been the late poison.”
—Walter Bagehot (1826–1877)