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Macroevolutionary patterns in Rhynchocephalia: is the tuatara ( Sphenodon punctatus ) a living fossil?
Author(s) -
HerreraFlores Jorge A.,
Stubbs Thomas L.,
Benton Michael J.
Publication year - 2017
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/pala.12284
Subject(s) - biology , lineage (genetic) , cretaceous , mesozoic , paleontology , clade , living fossil , extant taxon , macroevolution , evolution of mammals , morphology (biology) , evolutionary biology , zoology , phylogenetics , biochemistry , structural basin , gene
The tuatara, Sphenodon punctatus , known from 32 small islands around New Zealand, has often been noted as a classic ‘living fossil’ because of its apparently close resemblance to its Mesozoic forebears and because of a long, low‐diversity history. This designation has been disputed because of the wide diversity of Mesozoic forms and because of derived adaptations in living Sphenodon . We provide a testable definition for ‘living fossils’ based on a slow rate of lineage evolution and a morphology close to the centroid of clade morphospace. We show that through their history since the Triassic, rhynchocephalians had heterogeneous rates of morphological evolution and occupied wide morphospaces during the Triassic and Jurassic, and these then declined in the Cretaceous. In particular, we demonstrate that the extant tuatara underwent unusually slow lineage evolution, and is morphologically conservative, being located near the centre of the morphospace for all Rhynchocephalia.