Chitons have a relatively good fossil record, stretching back to the Cambrian,<ref name=Runnegar1974 /><ref name="LesleyCherns2007">{{cite journal |last1=Cherns |first1=Lesley |date=2 January 2007 |title=Early Palaeozoic diversification of chitons (Polyplacophora, Mollusca) based on new data from the Silurian of Gotland, Sweden |url=https://onlinelibrary.wiley.com/doi/10.1080/00241160410002180 |journal=[[Lethaia]] |volume=37 |issue=4 |pages=445-456445–456 |doi=10.1080/00241160410002180 |access-date=25 November 2022}}</ref> with the genus ''Preacanthochiton'', known from fossils found in Late Cambrian deposits in [[Missouri]], being classified as the earliest known polyplacophoran. However, the exact phylogenetic position of supposed Cambrian chitons is highly controversial, and some authors have instead argued that the earliest confirmed polyplacophorans date back to the [[Early Ordovician]].<ref name=Sigwart2007>{{cite journal |last1=Sigwart |first1=J.D. |last2=Sutton |first2=M.D. |date=October 2007 |title=Deep molluscan phylogeny: Synthesis of palaeontological and neontological data |journal=Proceedings of the Royal Society B: Biological Sciences |issue=1624 |volume=274 |pages=2413–2419 |pmid=17652065 |pmc=2274978 |doi=10.1098/rspb.2007.0701}} For a summary, see {{cite web |title=The Mollusca |publisher=University of California Museum of Paleontology |url=http://www.ucmp.berkeley.edu/taxa/inverts/mollusca/mollusca.php |access-date=2 October 2008 |archive-date=15 December 2012 |archive-url=https://www.webcitation.org/6CvnfcV0o?url=http://www.ucmp.berkeley.edu/taxa/inverts/mollusca/mollusca.php |url-status=live }}</ref> ''[[Kimberella]]'' and ''[[Wiwaxia]]'' of the Precambrian and Cambrian may be related to ancestral polyplacophorans. ''[[Matthevia]]'' is a Late Cambrian polyplacophoran preserved as individual pointed valves, and sometimes considered to be a chiton,<ref name=Runnegar1974>{{cite journal |first1=B. |last1=Runnegar | first2=J. Jr. |last2=Pojeta |date=October 1974 |title=Molluscan phylogeny: The paleontological viewpoint |volume=186 |journal=Science |issue=4161 |pages=311–317 |jstor=1739764 |pmid=17839855 |doi=10.1126/science.186.4161.311 |bibcode=1974Sci...186..311R |s2cid=46429653}}</ref> although at the closest, it can only be a stem-group member of the group.<ref name=Vendrasco>{{cite journal |last1=Vendrasco |first1=M.J. |last2=Wood |first2=T.E. |last3=Runnegar |first3=B.N. |year=2004 |title=Articulated Palaeozoic fossil with 17 plates greatly expands disparity of early chitons |journal=Nature |volume=429 |issue=6989 |pages=288–291 |pmid=15152250 |doi=10.1038/nature02548 |bibcode=2004Natur.429..288V |s2cid=4428441}}</ref>
[[File:Matthevia.JPG|thumb|right|Separate plates from ''Matthevia'', a Late [[Cambrian]] polyplacophoran from the Hellnmaria Member of the Notch Peak Limestone, Steamboat Pass, southern House Range, Utah are shown with a [[cent (United States coin)|US one-cent coin]] (19 mm in diameter).]]