Ghost lineage

Phylogeny of ichthyosaurs. Thick horizontal lines signify the existence of a fossil record for the respective time and taxa. Thin lines represent ghost lineages.

A ghost lineage is a hypothesized ancestor in a species lineage that has left no fossil evidence, but can still be inferred to exist or have existed because of gaps in the fossil record or genomic evidence.[1][2] The process of determining a ghost lineage relies on fossilized evidence before and after the hypothetical existence of the lineage and extrapolating relationships between organisms based on phylogenetic analysis.[3] Ghost lineages assume unseen diversity in the fossil record and serve as predictions for what the fossil record could eventually yield; these hypotheses can be tested by unearthing new fossils or running phylogenetic analyses.[4]

Ghost lineages and Lazarus taxa are related concepts, as both stem from gaps in the fossil record.[2] A ghost lineage is any gap in a taxon's fossil record, with or without reappearance, while a Lazarus taxon is a type of ghost lineage wherein a species is believed to have gone extinct due to an absence of it in the fossil record, but then reappears after a period of time.[2] Examples of Lazarus taxa include the famous coelacanths, as well as the Philippine naked-backed fruit bat.[5]

  1. ^ Lorente-Galdos B, Lao O, Serra-Vidal G, Santpere G, Kuderna LF, Arauna LR, et al. (April 2019). "Whole-genome sequence analysis of a Pan African set of samples reveals archaic gene flow from an extinct basal population of modern humans into sub-Saharan populations". Genome Biology. 20 (1): 77. doi:10.1186/s13059-019-1684-5. PMC 6485163. PMID 31023378.
  2. ^ a b c Wedel M (May 2010). "Ghost lineages". University of California Museum of Paleontology. Retrieved November 4, 2019.
  3. ^ Norell MA (January 1993). "Tree-Based Approaches to Understanding History; Comments on Ranks, Rules and the Quality of the Fossil Record" (PDF). American Journal of Science. 293 (A): 407–417. Bibcode:1993AmJS..293..407N. doi:10.2475/ajs.293.a.407.
  4. ^ Dingus L, Rowe T (1998). The Mistaken Extinction: Dinosaur Evolution and the Origin of Birds. New York: W. H. Freeman.
  5. ^ Gentle L (6 November 2015). "Meet the Lazarus creatures – six species we thought were extinct, but aren't". The Conversation. Retrieved 2019-12-04.