Editing Living fossil (section)

=== Operational definition ===
An operational definition was proposed in 2017, where a 'living fossil' lineage has a slow rate of evolution and occurs close to the middle of morphological variation (the centroid of morphospace) among related taxa (i.e. a species is morphologically conservative among relatives).<ref name="Herrera-Flores 2017">{{cite journal |doi=10.1111/pala.12284 |title=Macroevolutionary patterns in Rhynchocephalia: is the tuatara (Sphenodon punctatus) a living fossil? |journal=Palaeontology|volume=60 |issue=3 |pages=319–328 |year=2017 |last1=Herrera-Flores |first1=Jorge A. |last2=Stubbs |first2=Thomas L. |last3=Benton |first3=Michael J. |doi-access=free |bibcode=2017Palgy..60..319H }}</ref> The scientific accuracy of the [[morphometric]] analyses used to classify [[tuatara]] as a living fossil under this definition have been criticised however,<ref name="Vaux 2019">{{cite journal |doi=10.1111/pala.12402 |title=Tuatara and a new morphometric dataset for Rhynchocephalia: Comments on Herrera-Flores et al. |journal=Palaeontology|volume=62 |issue=2 |pages=321–334 |year=2019 |last1=Vaux |first1=Felix |last2=Morgan-Richards |first2=Mary |last3=Daly |first3=Elizabeth E. |last4=Trewick |first4=Steven A.|bibcode=2019Palgy..62..321V |s2cid=134902015 }}</ref> which prompted a rebuttal from the original authors.<ref name="Herrera-Flores 2019">{{cite journal |doi=10.1111/pala.12404 |title=Reply to comments on: Macroevolutionary patterns in Rhynchocephalia: is the tuatara (Sphenodon punctatus) a living fossil? |journal=Palaeontology|volume=62 |issue=2 |pages=335–338 |year=2019 |last1=Herrera-Flores |first1=Jorge A. |last2=Stubbs |first2=Thomas L. |last3=Benton |first3=Michael J. |bibcode=2019Palgy..62..335H |hdl=1983/846d212a-6eb6-494e-855f-e0684bede158 |s2cid=133726749 |url=https://research-information.bris.ac.uk/ws/files/198134843/Full_text_PDF_accepted_author_manuscript_.pdf }}</ref>