Free Scientific Articles

This page features some free downloadable open access scientific articles (in alphabetic order by author) that are selected by The Sixth Extinction website. Do you know another open access scientific article that should be placed here? Or have you written an scientific article that you want to share here? If so, contact this website. Soon more articles will be added here!

The Sixth Extinction Republications Biology Letters Public Library of Science (PLoS)
Proceedings of the National Academy of Sciences (PNAS) Other free scientific articles



The Sixth Extinction Republications

The Sixth Extinction Republications are papers, articles and books about extinct species and subspecies or about extinction and the current biodiversity crisis in general. The originals have been edited and republished by The Sixth Extinction and are free to download from this website. These papers, articles and books are all licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.


Biology Letters

Biology Letters publishes short, highly-innovative, cutting-edge research articles and opinion pieces accessible to scientists from across the biological sciences. This Royal Society journal is characterised by stringent peer-review, rapid publication and broad dissemination of succinct high-quality research communications. All Biology Letters content is free to access online one year after publication.


Public Library of Science (PLoS)

The Public Library of Science (PLoS) is a nonprofit organization of scientists and physicians committed to making the world's scientific and medical literature a public resource. The articles in PLoS journals will be published only after they have undergone a rigorous and constructive peer-review process that will be managed by academic editors in collaboration with experienced professional editors.

The articles presented here are open-access articles distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

  • Bunce, M., Szulkin, M., Lerner, HRL., Barnes, I., Shapiro, B., et al. (2005). Ancient DNA Provides New Insights into the Evolutionary History of New Zealand's Extinct Giant Eagle. PLoS Biology 3(1): e9. doi:10.1371/journal.pbio.0030009. [download pdf] - [go to article on PLoS BIOLOGY].

  • Cardillo, M., Purvis, A., Sechrest, W., Gittleman, J.L., Bielby, J., et al. (2004). Human Population Density and Extinction Risk in the World's Carnivores. PLoS Biology 2(7): e197. doi:10.1371/journal.pbio.0020197. [download pdf] - [go to article on PLoS BIOLOGY].

  • Driscoll, C.A., Yamaguchi, N., Bar-Gal, G.K., Roca, A.L., Luo, S., et al. (2009). Mitochondrial Phylogeography Illuminates the Origin of the Extinct Caspian Tiger and Its Relationship to the Amur Tiger. PLoS ONE 4(1): e4125. doi:10.1371/journal.pone.0004125. [download pdf] - [go to article on PLoS ONE].

  • Heupink, T.H., Huynen, L, Lambert, D.M. (2011). Ancient DNA Suggests Dwarf and ‘Giant’ Emu Are Conspecific. PLoS ONE 6(4): e18728. doi:10.1371/journal.pone.0018728. [download pdf] - [go to article on PLoS ONE].

  • Lambert, D.M., Shepherd, L.D., Huynen, L., Beans-Picón, G., Walter, G.H., et al. (2009). The Molecular Ecology of the Extinct New Zealand Huia. PLoS ONE 4(11): e8019. doi:10.1371/journal.pone.0008019.[download pdf] - [go to article on PLoS ONE]

  • Ó Foighil D, Li J, Lee T, Johnson P, Evans R, et al. (2011). Conservation Genetics of a Critically Endangered Limpet Genus and Rediscovery of an Extinct Species. PLoS ONE 6(5): e20496. doi:10.1371/journal.pone.0020496. [download pdf] - [go to article on PLoS ONE].

  • Pask, A.J., Behringer, R.R., Renfree, M.B., (2008). Resurrection of DNA Function In Vivo from an Extinct Genome. PLoS ONE 3(5): e2240.doi:10.1371/journal.pone.0002240. [download pdf] - [go to article on PLoS ONE].

  • Russello, M.A., Poulakakis, N., Gibbs, J.P., Tapia, W., Benavides, E., et al. (2010). DNA from the Past Informs Ex Situ Conservation for the Future: An ''Extinct'' Species of Galápagos Tortoise Identified in Captivity. PLoS ONE 5(1): e8683. doi:10.1371/journal.pone.0008683. [download pdf] - [go to article on PLoS ONE].

  • Seabrook-Davison, M., Huynen, L., Lambert, D.M., Brunton, D.H. (2009). Ancient DNA Resolves Identity and Phylogeny of New Zealand's Extinct and Living Quail (Coturnix sp.). PLoS ONE 4(7): e6400. doi:10.1371/journal.pone.0006400. [download pdf] - [go to article on PLoS ONE].

  • Sodhi, N.S., Bickford, D., Diesmos, A.C., Lee, T.M., Koh, L.P., et al. (2008). Measuring the Meltdown: Drivers of Global Amphibian Extinction and Decline. PLoS ONE 3(2): e1636. doi:10.1371/journal.pone.0001636. [download pdf] - [go to article on PLoS ONE].

  • Wyatt, K.B., Campos, P.F., Gilbert, M.T.P., Kolokotronis, S-O., Hynes, W.H., et al. (2008). Historical Mammal Extinction on Christmas Island (Indian Ocean) Correlates with Introduced Infectious Disease. PLoS ONE 3(11): e3602. doi:10.1371/journal.pone.0003602. [download pdf] - [go to article on PLoS ONE].


Proceedings of the National Academy of Sciences (PNAS)

The Proceedings of the National Academy of Sciences of the United States of America (PNAS) is one of the world's most-cited multidisciplinary scientific serials. Since its establishment in 1914, it continues to publish cutting-edge research reports, commentaries, reviews, perspectives, colloquium papers, and actions of the Academy. Coverage in PNAS spans the biological, physical, and social sciences. PNAS is published weekly in print, and daily online in PNAS Early Edition. 

PNAS is a delayed open access journal, meaning they provide free access to its articles six months after print publication. The author(s) retains copyright to individual articles, and the National Academy of Sciences holds copyright to the collective work. Unlike the PLoS-articles, articles from PNAS cannot be distributed or reproduced directly from The Sixth Extinction website. However, we will provide you links to recommended individual acticles. You can access, read or download the following articles on the PNAS-website.

  • newAnchukaitis, K.J., Evans, M.N. (2010). Tropical cloud forest climate variability and the demise of the Monteverde golden toad. PNAS 107 (11) 5036-5040; doi:10.1073/pnas.0908572107. [go to article on PNAS-website].

  • Baker, Ilan J., Leon J. Huynen, Oliver Haddrath, Craig D. Millar, and David M. Lambert. (2005). Reconstructing the tempo and mode of evolution in an extinct clade of birds with ancient DNA: The giant moas of New Zealand. PNAS 102 (23) 8257-8262; published ahead of print May 31, 2005, doi:10.1073/pnas.0409435102. [go to article on PNAS-website].

  • Bunce, M., T. H. Worthy, M. J. Phillips, R. N. Holdaway, E. Willerslev, J. Haile, B. Shapiro, R. P. Scofield, A. Drummond, P. J. J. Kamp, and A. Cooper. (2009). The evolutionary history of the extinct ratite moa and New Zealand Neogene paleogeography. PNAS 106 (49) 20646-20651; published ahead of print November 18, 2009, doi:10.1073/pnas.09066601069. [go to article on PNAS-website].

  • newCheng, Tina L., Sean M. Rovito, David B. Wake, and Vance T. Vredenburg (2011). From the Cover: Coincident mass extirpation of neotropical amphibians with the emergence of the infectious fungal pathogenBatrachochytrium dendrobatidis.PNAS 108 (23) 9502-9507; doi:10.1073/pnas.1105538108. [go to article on PNAS-website]

  • newChiba, S. Roy, K. (2011). Selectivity of terrestrial gastropod extinctions on an oceanic archipelago and insights into the anthropogenic extinction process. PNAS 108 (23) 9496-9501; doi:10.1073/pnas.1100085108. [go to article on PNAS-website]

  • Cooper, A., C Mourer-Chauviré, G K Chambers, A von Haeseler, A C Wilson, and S Pääbo. (1992). Independent origins of New Zealand moas and kiwis. PNAS 89 (18) 8741-874. [go to article on PNAS-website].

  • Feeley, Kenneth J. and Miles R. Silman. (2009). Extinction risks of Amazonian plant species. PNAS 106 (30) 12382-12387; published ahead of print July 14, 2009, doi:10.1073/pnas.0900698106. [go to article on PNAS-website].

  • Hubbell, Stephen P., Fangliang He, Richard Condit, Luís Borda-de-Água, James Kellner, and Hans ter Steege. (2008). Colloquium Paper: How many tree species are there in the Amazon and how many of them will go extinct? PNAS 105 (Supplement 1) 11498-11504; published ahead of print August 11, 2008, doi:10.1073/pnas.0801915105. [go to article on PNAS-website].

  • newHuynen, L., Brian J. Gill, Craig D. Millar, and David M. Lambert. (2010). Ancient DNA reveals extreme egg morphology and nesting behavior in New Zealand’s extinct moa. PNAS 107 (37) 16201-16206; doi:10.1073/pnas.0914096107. [go to article on PNAS-website].
  • James, H.F., T W Stafford, Jr, D W Steadman, S L Olson, P S Martin, A J Jull, and P C McCoy. (1987). Radiocarbon dates on bones of extinct birds from Hawaii. PNAS 84 (8) 2350-2354. [go to article on PNAS-website].

  • Turney, Chris S.M., Timothy F. Flannery, Richard G. Roberts, Craig Reid, L. Keith Fifield, Tom F. G. Higham, Zenobia Jacobs, Noel Kemp, Eric A. Colhoun, Robert M. Kalin, and Neil Ogle. (2008). Late-surviving megafauna in Tasmania, Australia, implicate human involvement in their extinction. PNAS 105 (34) 12150-12153; published ahead of print August 21, 2008, doi:10.1073/pnas.0801360105. [go to article on PNAS-website].

  • newWake, D.B., Vredenburg, V.T. (2008). Colloquium paper: Are we in the midst of the sixth mass extinction? A view from the world of amphibians. Proc Natl Acad Sci USA 105(Suppl 1):11466–11473. [go to article on PNAS-website]


Other free scientific articles

  • Bunzel-Drüke, M. (2001). Ecological Substitutes for Wild Horse (Equus ferus Boddaert, 1785 = E. przewalskii Poljakov, 1881) and Aurochs (Bos primigenius Bojanus, 1827). Corrected reprint at

  • Castelli, Andrea (2010). Ibex Images from the Magdalenian Culture. PaleoAnthropology 2010:123-157. [download acticle from PaleoAnthropology website (pdf)].

  • newGill, B.J. (2007). Eggshell characteristics of moa eggs (Aves: Dinornithiformes). Journal of the Royal Society of New Zealand, 37:4, 139-150. DOI: 10.1080/03014220709510542.

  • newHoldaway R.N., and Jacomb, C. (2000). Rapid Extinction of the Moas (Aves: Dinornithiformes): Model, Test, and Implications. Science, 287:2250-2254. [go to article on Science].

  • newHoldaway, Richard N., Martin D. Jones & Nancy R. Beavan Athfield (2002). Late Holocene extinction of Finsch's duck (Chenonetta finschi), an endemic, possibly flightless, New Zealand duck. Journal of the Royal Society of New Zealand, 32:4, 629-651. DOI: 10.1080/03014223.2002.9517713.

  • newHuynen, L., Lissone, I., Sawyer, S., Lambert, D. (2008). Genetic identification of moa remains recovered from Tiniroto, Gisborne. Journal of the Royal Society of New Zealand, 38:4, 231-235. DOI: 10.1080/03014220809510557.

  • Lau, A. N., Peng, L., Goto, H., Chemnick, L., Ryder, O. A., and Makova, K. D. (2009). Horse Domestication and Conservation Genetics of Przewalski’s Horse Inferred from Sex Chromosomal and Autosomal Sequences. Molecular Biology and Evolution 26(1): 199–208. [go to article on Oxford Journals website].

  • Mona et al. (2010). Population dynamic of the extinct European aurochs: genetic evidence of a north-south differentiation pattern and no evidence of post-glacial expansion. BMC Evolutionary Biology 10:83. [download pdf] - [go to article on BioMed Central].

  • newRaxworthy, Christopher J. and Nussbaum, Ronald A. (2000). Extinction and extinction vulnerability of amphibians and reptiles in Madagascar. Amphibian and Reptile Conservation 2(1):15-23 (e10). [download pdf from ARC]

  • newStuart S.N., et al. (2004) Status and trends of amphibian declines and extinctions worldwide. Science 306:1783–1786. [go to article on Science].

  • newWood, J.R. (2008). Moa (Aves: Dinornithiformes) nesting material from rockshelters in the semi‐arid interior of South Island, New Zealand. Journal of the Royal Society of New Zealand, 38:3, 115-129. DOI: 10.1080/03014220809510550.


News Highlight

24 June 2012. The last Pinta giant tortoise (Chelonoidis abingdoni) Lonesome George dies. Read more: BBC News.


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