Living fossil

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The coelacanths were thought to have gone extinct 65 million years ago, until a living specimen belonging to the order was discovered in 1938.

A living fossil is a living species (or clade) of organism that appears to be similar to a species otherwise known only from fossils, typically with no close living relatives. Normally the similarity is only by an imagined physical resemblance, between two different species, one extinct, the other extant. It is an informal non-scientific term, mostly used in the lay media.

These species have survived major extinction events, and generally retain low taxonomic diversities. A species that successfully radiates (forming many new species after a possible genetic bottleneck) has become too successful to be considered a living fossil.


Fossil and living ginkgos
170 million-year-old fossil Ginkgo leaves
Living Ginkgo biloba plant

A subtle difference is sometimes made between a "living fossil" and a "Lazarus taxon". A Lazarus taxon is a taxon (either one species or a group of species) that suddenly reappears, either in the fossil record or in nature (i.e. as if the fossil had "come to life again"), while a living fossil is a species that (seemingly) has not changed during its very long lifetime (i.e. as if the fossil species has always lived). The average species turnover time (the time a species lasts before it is replaced) varies widely among the phyla, but averages about 2–3 million years. So, a living species that was thought to be extinct (e.g. the coelacanth, Latimeria chalumnae) could be called a Lazarus taxon instead of a living fossil. Coelacanths disappeared from the fossil record some 80 million years ago (upper Cretaceous). Of course, species do not just appear out of nothing, so all living Lazarus species (excluding disappearing and reappearing red list species) are nonetheless considered living fossils, if it can be shown they are not Elvis taxa.

Lastly, the term "living fossil" misleadingly appears to suggest that the organism has somehow "stopped evolving". Tadpole shrimp (Triops) are often presented as "living fossils", though a genetic study released in 2013 demonstrated the radiating diversity of notostracans in the genera Triops and Lepidurus: "Our work shows that organisms with conservative body plans are constantly radiating, and presumably, adapting to novel conditions... I would favor retiring the term ‘living fossil’ altogether, as it is generally misleading,” the author observed to the popular scientific press.[1] It should be noted that several recent studies pointed out that the morphological conservatism of coelacanths is a myth that is not supported by actual paleontological data.[2][3] In addition, it was shown recently that studies concluding that a slow rate of molecular evolution is linked to morphological conservatism in coelacanths are biased by the a priori hypothesis that these species are ‘living fossils’[4]

Some living fossils are taxa that were known from fossils before living representatives were discovered. The most famous examples of this are the coelacanthiform fishes Latimeria chalumnae and Latimeria menadoensis and the dawn redwood, Metasequoia, discovered in a remote Chinese valley. Others include glypheoid lobsters, mymarommatid wasps, eomeropid scorpionflies, and jurodid beetles, all of which were first described from fossils, but later found alive (2 species, 10 species, one species, and one species respectively). Others are a single living species that has no close living relatives, but is the survivor of a large and widespread group in the fossil record. Perhaps the best-known example is Ginkgo biloba, though there are others, such as Syntexis libocedrii (the cedar wood wasp).The dinoflagellate Dapsilidinium pastielsii is also such an example, which was first described as a fossil dinocyst from the Eocene.[5]



The term was coined by Charles Darwin in his On the Origin of Species, when discussing Ornithorhynchus (the platypus) and Lepidosiren (the South American lungfish):

Other definitions[edit]

Other definitions denoting living fossils:

The coelacanth for example, is a marine fish. The Mesozoic coelacanth species lived in salt and fresh water. Osmoregulation in Latimeria is handled by urea retention. Urea retention is considered to indicate fresh water ancestry. This means that the coelacanth lineage evolved from freshwater to saltwater.
The resemblance between Peripatus and Aysheaia (an early Cambrian animal from the Burgess Shale) would be striking (both are classified in the Tardipolypoda (Tardigrada and Onychophora), were it not that Aysheaia was a marine animal, while Peripatus lives in tropical leaf mould.
More primitive trapdoor spiders, such as this female Liphistius sp., have segmented plates on the dorsal surface of the abdomen and cephalothorax, a character shared with scorpions, making it probable that after the spiders diverged from the scorpions, the earliest unique ancestor of trapdoor species was the first to split off from the lineage that contains all other extant spiders.
Some paleontologists believe that living fossils with large distributions (such as Triops cancriformis) are not real living fossils. In the case of Triops cancriformis (living from the Triassic until now), the Triassic specimens lost most of their appendages (mostly only carapaces remain), and they have not been thoroughly examined since 1938.
Oxpeckers are morphologically somewhat similar to starlings due to shared plesiomorphies, but are uniquely adapted to feed on parasites and blood of large land mammals, which has always obscured their relationships. This lineage forms part of a radiation that includes Sturnidae and Mimidae, but appears to be the most ancient of these groups. Biogeography strongly suggests that oxpeckers originated in eastern Asia and only later arrived in Africa, where they now have a relict distribution.[6] The two living species thus seem to represent an entirely extinct and (as Passerida go) rather ancient lineage, as certainly as this can be said in the absence of actual fossils. The latter is probably due to the fact that the oxpecker lineage never occurred in areas where conditions were good for fossilization of small bird bones, but of course, fossils of ancestral oxpeckers may one day turn up enabling to test this theory.



Ginkgos have not only existed for a long time, but also have a long life span, with some having an age of over 2,500 years. Six specimens have even been known to survive the atomic bombing of Hiroshima, 1 to 2 kilometers from ground zero; they still live there today.

Some of these are informally known as "living fossils".






See also[edit]


  1. ^ "Diversification in Ancient Tadpole Shrimps Challenges the Term 'Living Fossil'" Science Daily accessed 2 April 2013; Ed Yong, [ "The Falsity of 'Living Fossils'", The Scientist accessed 2 April 2013.
  2. ^ Friedman M, Coates MI, Anderson P (2007). "First discovery of a primitive coelacanth fin fills a major gap in the evolution of lobed fins and limbs". Evolution & Development 9 (4): 329–37. doi:10.1111/j.1525-142X.2007.00169.x. PMID 17651357. 
  3. ^ Friedman M, Coates MI (2006). "A newly recognized fossil coelacanth highlights the early morphological diversification of the clade". Proc. R. Soc. B. 273 (1583): 245–250. doi:10.1098/rspb.2005.3316. PMC 1560029. PMID 16555794. 
  4. ^ Casane D, Laurenti P (Feb 2013). "Why Coelacanths are not "Living fossils" : a Review of Molecular and Morphological Data". BioEssays 35 (4): 332–8. doi:10.1002/bies.201200145. PMID 23382020. 
  5. ^ a b Mertens, K.N., Takano, Y., Head, M.J., Matsuoka, K. (2014). Living fossils in the Indo-Pacific warm pool: A refuge for thermophilic dinoflagellates during glaciations. Geology
  6. ^ a b Dario Zuccon, Anne Cibois, Eric Pasquet & Per G. P. Ericson (2006). "Nuclear and mitochondrial sequence data reveal the major lineages of starlings, mynas and related taxa" (PDF). Molecular Phylogenetics and Evolution 41 (2): 333–344. doi:10.1016/j.ympev.2006.05.007. PMID 16806992. 
  7. ^ On the Origin of Species, 1859, p. 107.
  8. ^ "The University of Chicago Medical Center: ''Scientists find lamprey a 'living fossil' ''". 2006-10-26. Retrieved 2012-05-16. 
  9. ^ Chambers, T.C., Drinnan, A.N. & McLoughlin, S. 1998. Some morphological features of Wollemi Pine (Wollemia nobilis: Araucariaceae) and their comparison to Cretaceous plant fossils. International Journal of Plant Science, 159: 160-171.
  10. ^ McLoughlin S., Vajda V. (2005). "Ancient wollemi pines resurgent". American Scientist 93: 540–547. doi:10.1511/2005.56.981. 
  11. ^ "Why Is the Okapi Called a Living Fossil". The Milwaukee Journal. Jun 24, 1954. 
  12. ^ Switek, Brian. "Repost: The Pelican's Beak - Success and Evolutionary Stasis | Wired Science". doi:10.1007/s10336-010-0537-5. Retrieved 2013-06-10. 
  13. ^ Morelle, Rebecca. "Rediscovered Hula painted frog 'is a living fossil'". BBC News. Retrieved 4 June 2013. 

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