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A ghost lineage is a phylogenetic lineage that is inferred to exist (inferred-existence) but has no fossil record.[1]
Ghost lineages are commonly confused with Lazarus taxa, but there is a difference. For example, coelacanths (see below) are a Lazarus taxon, and the gaps in its fossil record are referred to as ghost lineages.[2]
Name
editIn 1992, an article stated: These additional entities are taxa [groups] that are predicted to occur by the internal branching structure of phylogenetic trees....I refer to these as ghost lineages because they are invisible to the fossil record.[1] Phylogenetic trees constructed based on fossil records and Darwin’s theory of evolution often give an indication that species with similar phenotypes existed although its fossil has not been discovered.[3][4]
Examples
editWhen looking back at extinct organisms, there are some groups of organisms (or lineages) that have gaps in their fossil records. These organisms or species may be closely related to one another, but there are no traces in the fossil records or sediment beds that might shed some light on their origins. A classic example is the coelacanth, a type of fish related to the lungfishes and to primitive tetrapods. It seems that coelacanths have also been around for the past 80 million years, but have failed to leave us any fossils to look at. The reason for this is their environment, which is deep water near volcanic islands; therefore, these sediments are hard to get to, giving these coelacanths an 80 million year gap or ghost lineage.[2] Another ghost lineage was that of the averostran theropods, a ghost lineage now reduced considerably thanks to the discovery of Tachiraptor.[5]
Duration and diversification
editIt is possible that the gaps in one organism's evolution can help us identify events in the fossil record. This can be done by calculating an actual ghost lineage's duration through intervals of time. It shows how the ghost lineage duration will go down as diversity goes up, helping to better understand when and maybe why the gaps happened.[6]
See also
editReferences
edit- ^ a b Norell, Mark A (1992). Taxic Origin and Temporal Diversity: The Effect of Phylogeny, in Extinction and Phylogeny. Columbia University Press, New York. pp. 89–118.
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suggested) (help) - ^ a b http://www.ucmp.berkeley.edu/taxa/verts/archosaurs/ghost_lineages.php
- ^ Norell, Mark A.; Novacek, Michael J. (1992-03-27). "The Fossil Record and Evolution: Comparing Cladistic and Paleontologic Evidence for Vertebrate History". Science. 255 (5052): 1690–1693. doi:10.1126/science.255.5052.1690. ISSN 0036-8075. PMID 17749423.
- ^ Norell, Mark A (1993). "TREE-BASED APPROACHES TO UNDERSTANDING HISTORY: COMMENTS ON RANKS, RULES, AND THE QUALITY OF THE FOSSIL RECORDS" (PDF). American Journal of Science. 293-A: 407–417.
- ^ Langer, Max C.; Rincón, Ascanio D.; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W.M. (8 October 2014). "New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes". Royal Society Open Science. 1. Royal Society: 140184. doi:10.1098/rsos.140184. PMC 4448901. PMID 26064540. Retrieved 17 October 2014.
- ^ Cavin, Lionel; Forey, Peter L. (2007-04-22). "Using ghost lineages to identify diversification events in the fossil record". Biology Letters. 3 (2): 201–204. doi:10.1098/rsbl.2006.0602. ISSN 1744-9561. PMID 17284405.