Living fossil

A living fossil is a <a href="/facts/Deprecation/1aQL7rnP">deprecated</a> term for an <a href="/facts/Extant_taxon/YK8uj7qU">extant taxon</a> that <a href="/facts/Phenotypically/vxWXKGLj">phenotypically</a> resembles related <a href="/facts/Species/oDg6b96r">species</a> known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant <a href="/facts/Clade/XefyYmWn">clade</a>. Living fossils commonly are of species-poor lineages, but they need not be. While the <a href="/facts/Body_plan/TykqU5bY">body plan</a> of a living fossil remains superficially similar, it is never the same species as the remote relatives it resembles, because <a href="/facts/Genetic_drift/lvoEEctX">genetic drift</a> would inevitably change its chromosomal structure.
Living fossils exhibit <a href="/facts/Punctuated_equilibrium/7keGQrc9">stasis</a> (also called "bradytely") over geologically long time scales. Popular literature may wrongly claim that a "living fossil" has undergone no significant evolution since fossil times, with practically no <a href="/facts/Molecular_evolution/lmMbqfzH">molecular evolution</a> or <a href="/facts/Morphology_(biology)/Nl3B0myy">morphological</a> changes. Scientific investigations have repeatedly discredited such claims.
The minimal superficial changes to living fossils are mistakenly declared as an absence of evolution, but they are examples of <a href="/facts/Stabilizing_selection/3kLN5cE7">stabilizing selection</a>, which is an <a href="/facts/Evolutionary_process/TuWap5IK">evolutionary process</a>—and perhaps the dominant process of <a href="/facts/Morphological_evolution/gl4ysPCa">morphological evolution</a>.
The term is currently deprecated among paleontologists and evolutionary biologists.

Living fossil open-in-new

Living fossil