Gregory Retallack

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Gregory Retallack
RetallackBernardRanch.jpg
Greg Retallack, near Suplee, central Oregon, 1982
Born (1951-11-08) 8 November 1951 (age 74)
Hobart, Tasmania
CitizenshipAmerican and Australian
Alma mater Macquarie University,
University of New England (Australia)
Known for Paleopedology
Spouse(s) Diane Retallack, Director Eugene Concert Choir
Scientific career
Thesis A biostratigraphy for terrestrial Triassic rocks of Gondwanaland  (1978)
Doctoral advisor Rodney E. Gould
Website https://blogs.uoregon.edu/gregr/

Gregory John Retallack (born 8 November 1951) is an Australian paleontologist, geologist, and author who specializes in the study of fossil soils (paleopedology). He is a professor emeritus at University of Oregon and his research is primarily concerned with the fossil record of soils though Earth history. [1] His research has included investigations into climate change, the extinction of dinosaurs, the origins of upright walking humans. One controversial aspect of his career concerns the land vs. sea origin of Ediacaran-era fossils. He has written two well-received textbooks on paleopedology, and has appeared in numerous media shows. [2]

Contents

Biography

Retallack moved with his family from Hobart, Tasmania to suburban Sydney at age 4. [3] He grew up in Hurstville and then Epping. He attended The King's School, Parramatta, then studied biology and paleontology at Macquarie University. He received a BSc Hons with University Medal in 1974 from the University of New England (Australia) and a PhD in 1978 in geology from the same university. After a postdoctoral fellowship at Indiana University Bloomington he joined the faculty at the University of Oregon in 1981. He was a professor in the Department of Geological Sciences since 1992, and Director of the Condon Collection of the University of Oregon Museum of Natural and Cultural History since 2009. Since retirement in 2022 he has been a professor emeritus.[ citation needed ]

Retallack on Mount Cook, New Zealand, 1974 RetallackMtCook.jpg
Retallack on Mount Cook, New Zealand, 1974

A fossil collector since the age of 6, Retallack was outspoken concerning federal seizure in 1993 of Sue (dinosaur) the skeleton of Tyrannosaurus rex excavated by Pete Larson. [4]

Work

Evolution of life on land

Oligocene fossil soils of well-drained woodlands (red bands) and swamps (black spots) in the Painted Hills, Oregon PaintedHillspaleosols.jpg
Oligocene fossil soils of well-drained woodlands (red bands) and swamps (black spots) in the Painted Hills, Oregon

Retallack's research focuses on the study of paleosols (fossilized soils) to reconstruct ancient environments. In 1973, he proposed that paleosols preserved beneath fossil plant horizons could provide data on ancient plant communities that plant fossils alone could not reveal. [6] [7] He has applied this approach to various stages of evolutionary history, offering hypotheses that sometimes challenge established scientific understanding. [8]

Research findings

Retallack has used paleosols to investigate several major extinction and evolutionary events. Regarding climate change, he argued that the coevolution of grasslands and grazers over the past 50 million years drove global cooling via carbon biosequestration. [9] [10] In the field of human evolution, Retallack's fieldwork in Kenya concerning Proconsulidae (primates ancestral to humans) led him to suggest that the evolutionary transition to an upright stance occurred in woodland environments rather than in open savannas. [11]

He has also applied this methodology to mass extinction events. Studying the Cretaceous-Paleogene boundary in Montana, he hypothesized that acid rain resulting from an extraterrestrial impact contributed to the extinction of dinosaurs. [12] Similarly, his work in Antarctica on the Permian-Triassic boundary led to the hypothesis that the mass extinction was driven by a greenhouse gas crisis caused by methane released from coal instructions during massive volcanic events (flood basalts). [13] Furthermore, he has proposed a "woodland hypothesis" regarding the Devonian transition of vertebrates from fish to amphibians. [14]

In 2013, Retallack identified problematic fossils in Paleoproterozoic paleosols from South Africa, which he named Diskagma . He identified the species as a fungus comparable to the living Geosiphon . [15] Dated to 2.2 billion years old, these fossils would push back the record of life on land significantly from the previously accepted record of 1.2 billion years. [16] [17]

Retallack's work interpreting the Avalon and White Sea assemblages of the Ediacaran biota as lichens [18] has been challenged. [19] His proposal that Ediacaran fossils were preserved in subaerial paleosols, and thus not marine fossils, [20] [2] has been supported by a minority of researchers [21] but dismissed by other paleontologists. [22] [23] [24] Nature called it a "controversial claim" in a news report, in which paleontologist Guy Narbonne said "[I]t quickly became clear that there are simpler explanations for the features Retallack had validly noted, and most of us moved on to more promising explanations." [25] Retallack continues to maintain his position. [26] [27]

In 2020, Retallack and other researchers claimed to have found Dickinsonia fossils from Bhimbetka rock shelters, India. [28] However, in 2023 other researchers believed the material was actually the decayed remnants of a beehive. [29]

Media appearances

Retallack's work has been featured in several documentaries and science programs. His research on the Late Permian extinction appeared in the BBC's The Day the Earth Nearly Died [30] and the Science Channel's Miracle Planet . [31] Additionally, an episode of Prehistoric Predators on the National Geographic Channel covered his work on the Miocene of Panama. [32] [33] His findings regarding early life on land [20] were also discussed on radio programs broadcast by National Public Radio, [34] the Canadian Broadcast Corporation, [35] and Oregon Public Broadcasting. [36]

Paleosols (massive red bands) at horizons for Ediacaran fossils in Brachina Gorge, South Australia. BrachinaGorgepaleosols.jpg
Paleosols (massive red bands) at horizons for Ediacaran fossils in Brachina Gorge, South Australia.


Boards

Retallack has served as an associate or technical editor for such scientific journals as Geology, PALAIOS , and Journal of Sedimentary Research . His fellowships include the Geological Society of America, and the American Association for the Advancement of Science.

He served as the president and vice president of the Cordilleran Section of the Paleontological Society, of the Oregon Academy of Sciences, [37] and of the University of Oregon Chapter of the Society of Sigma Xi.

Reception

In Soils of the Past, David Fastovsky concludes "it is requisite for all persons trying to understand paleosols". [38] Of A Colour Guide to Paleosols, Daniel Yaalon concludes "Highly recommended for students and researchers alike for an introductory insight to paleopedology and to whet and refine their skills in paleosol interpretation." [39] Both reviews however baulked at the unfamiliarity of soil science terminology and classification in these texts. [38] [39]

Retallack's approach to the description and interpretation of paleosols has been widely adopted. [40] Some controversy concerned use of modern soil taxonomies for paleosols, [41] but Retallack's approach has since been validated by development of additional geochemical proxies for soil taxonomic criteria. [42] Retallack's confirmation of abrupt paleoenvironmental change on land at the Cretaceous-Tertiary [12] and Permian-Triassic boundaries, [13] has been supported by later research on extinction.[ citation needed ]

Awards and honors

Retallack has been honored for his research, including the Stillwell Award of the Geological Society of Australia, for best paper in the society journal in 1977, Ingerson Award of the Geochemical Society in 2015, and the Antarctica Service Medal of the U.S. National Science Foundation in 1999.[ citation needed ] He has been an invited lecturer throughout the U.S., and also to Germany, England, China, Thailand and India.

Bibliography

Textbooks

Selected publications

References

  1. ↑ Retallack, G. J. (2019). Soils of the past: an introduction to paleopedology (3rd ed.). Chichester, United Kingdom: Wiley. ISBN   978-1-119-53040-4.
  2. 1 2 Jones, N. (February 2013). "Soil or sea for ancient fossils". Nature Geoscience. 6 (2): 84. Bibcode:2013NatGe...6...84J. doi: 10.1038/ngeo1713 .
  3. ↑ Retallack, G.J. (2022). "Curriculum Vitae".
  4. ↑ Retallack, Greg J. (1993). "Fossils are for everyone". Newsweek. 121: 8. Archived from the original on 6 April 2025.
  5. ↑ Retallack, G. J.; Bestland, E. A.; Fremd, T. J. (2000). Eocene and Oligocene paleosols and environmental change in central Oregon. Boulder, Colorado: Geological Society of America Special Paper 344. ISBN   978-0-8137-2344-0.
  6. ↑ Retallack, G. J. (1973). "Stratigraphy, palaeobotany and environmental analysis of an area around Pittwater, north of Sydney, N.S.W.". BSC Honours Thesis, University of New England. Armidale, New South Wales.
  7. ↑ Retallack, G. J. (1977). "Triassic palaeosols in the upper Narrabeen Group of New South Wales. Part II: Classification and reconstruction". Journal of the Geological Society of Australia. 24 (1–2): 19–35. doi:10.1080/00167617708728964.
  8. ↑ Retallack, G. J. (1997). "Palaeosols in the upper Narrabeen Group of New South Wales as evidence of Early Triassic palaeoenvironments without exact modern analogues". Australian Journal of Earth Sciences. 44 (2): 185–201. Bibcode:1997AuJES..44..185R. doi:10.1080/08120099708728303.
  9. ↑ Retallack, G. J. (2013). "Global cooling by grasslands in the geological past and near future". Annual Review of Earth and Planetary Sciences. 41: 5.1–18. doi:10.1146/annurev-earth-050212-124001.
  10. ↑ Driese, Steven G. (2021). "Soils, Chemical Weathering, and Climate Change in Earth History". In Hunt, Allen (ed.). Hydrogeology, Chemical Weathering, and Soil Formation. Advancing Earth and Space Sciences.
  11. ↑ Retallack, G. J. (2007). "Paleosols". In Henke, W.; Tattersall, I. (eds.). Handbook of paleoanthropology, Volume 1. Principles, methods and approaches. Vol. 1. Berlin: Springer Verlag. pp. 383–408.
  12. 1 2 Retallack, G. J. (2004). "End-Cretaceous acid rain as a selective extinction mechanism between birds and dinosaurs". In Currie, P. J.; Koppelhus, E. B.; Shugar, M. A.; Wright, J. L. (eds.). Feathered dragons: studies on the transition from dinosaurs to birds. pp. 35–64.
  13. 1 2 Retallack, G. J.; Jahren, A. H. (2008). "Methane release from igneous intrusion of coal during Late Permian extinction events". Journal of Geology. 116 (1): 1–20. Bibcode:2008JG....116....1R. doi:10.1086/524120. S2CID   46914712.
  14. ↑ Retallack, G. J. (2011). "Woodland hypothesis for Devonian evolution of tetrapods". Journal of Geology. 119 (3): 235–358. Bibcode:2011JG....119..235R. doi:10.1086/659144. S2CID   128827936.
  15. ↑ Retallack, G. J.; Krull, E. S.; Thackray, G. D.; Parkinson, D. (2013). "Problematic urn-shaped fossils from a Paleoproterozoic (2.2 Ga) paleosol in South Africa". Precambrian Research. 235: 71–87. Bibcode:2013PreR..235...71R. doi:10.1016/j.precamres.2013.05.015.
  16. ↑ Peter Byrne (24 April 2014). "Early Life in Death Valley". Quanta Magazine. Retrieved 8 May 2014. Reprinted in ScientificAmerican.com
  17. ↑ Gregory Retallack (September 2013). "Problematic urn-shaped fossils from a Paleoproterozoic (2.2 Ga) paleosol in South Africa". Precambrian Research. 235: 71–87. Bibcode:2013PreR..235...71R. doi:10.1016/j.precamres.2013.05.015.
  18. ↑ Retallack, G. J. (1994). "Were Ediacaran fossils lichens?". Paleobiology. 20 (4): 523–544. Bibcode:1994Pbio...20..523R. doi:10.1017/S0094837300012975. S2CID   129180481.
  19. ↑ Waggoner, B. (1995). "Comment on "Were Ediacaran fossils lichens?"". Paleobiology. 21 (3): 397–398. Bibcode:1995Pbio...21..393W. doi:10.1017/S0094837300013373. S2CID   82550765.
  20. 1 2 3 Retallack, G. J. (2013). "Ediacaran life on land". Nature. 493 (7430): 89–92. Bibcode:2013Natur.493...89R. doi:10.1038/nature11777. PMID   23235827. S2CID   205232092.
  21. ↑ Knauth, L. P. (2013). "Not all at sea". Nature. 493 (7430): 28–9. doi: 10.1038/nature11765 . PMID   23235825.
  22. ↑ Xiao, S. H. (2013). "Muddying the waters". Nature. 493 (7430): 28–29. doi: 10.1038/nature11765 . PMID   23235825.
  23. ↑ Waggoner, B. M. (1995). "Ediacaran Lichens: A Critique". Paleobiology. 21 (3): 393–397. Bibcode:1995Pbio...21..393W. doi:10.1017/S0094837300013373. ISSN   0094-8373. JSTOR   2401174. S2CID   82550765.
  24. ↑ Waggoner, B. M.; Collins, A. G. (2004). "Reductio Ad Absurdum: Testing The Evolutionary Relationships Of Ediacaran And Paleozoic Problematic Fossils Using Molecular Divergence Dates". Journal of Paleontology. 78 (1): 51–61. Bibcode:2004JPal...78...51W. doi:10.1666/0022-3360(2004)078<0051:RAATTE>2.0.CO;2. S2CID   8556856.
  25. ↑ Switek, Brian (12 December 2012). "Controversial claim puts life on land 65 million years early" . Nature. doi:10.1038/nature.2012.12017. S2CID   130305901 . Retrieved 19 November 2013.
  26. ↑ Antcliffe, Jonathan B.; Hancy, Anthony D. (2013). "Reply to Retallack (2013): Ediacaran characters" . Evolution & Development. 15 (6): 389–392. doi:10.1111/ede.12048. ISSN   1525-142X.
  27. ↑ Callow, Richard H. T.; Brasier, Martin D.; Mcilroy, Duncan (2013). "Discussion: "Were the Ediacaran siliciclastics of South Australia coastal or deep marine?" by Retallack et al., Sedimentology, 59, 1208–1236" . Sedimentology. 60 (2): 624–627. doi:10.1111/j.1365-3091.2012.01363.x. ISSN   1365-3091.
  28. ↑ Retallack, Gregory J.; Matthews, Neffra A.; Master, Sharad; Khangar, Ranjit G.; Khan, Merajuddin (1 February 2021). "Dickinsonia discovered in India and late Ediacaran biogeography" . Gondwana Research. 90: 165–170. Bibcode:2021GondR..90..165R. doi:10.1016/j.gr.2020.11.008. ISSN   1342-937X. S2CID   229451488.
  29. ↑ Meert, Joseph G.; Pandit, Manoj K.; Kwafo, Samuel; Singha, Ananya (1 May 2023). "Stinging News: 'Dickinsonia' discovered in the Upper Vindhyan of India not worth the buzz" . Gondwana Research. 117: 1–7. Bibcode:2023GondR.117....1M. doi:10.1016/j.gr.2023.01.003. ISSN   1342-937X. S2CID   255846878.
  30. ↑ "The day the Earth nearly died". Youtube. 12 March 2009. Retrieved 21 August 2013.
  31. ↑ "Death and rebirth". Youtube. 9 June 2009. Retrieved 21 August 2013.
  32. ↑ Retallack, G. J.; Kirby, M. X. (2007). "Middle Miocene global change and paleogeography of Panama". PALAIOS. 22 (6): 667–679. Bibcode:2007Palai..22..667R. doi:10.2110/palo.2006.p06-130r. S2CID   56409337.
  33. ↑ "Terror raptor". Youtube. Retrieved 21 August 2013.
  34. ↑ "Land creatures may not have come from the sea". National Public Radio. Retrieved 21 August 2013.
  35. ↑ "Fossils could preserv oldest land life". Canadian Broadcast Corporation. Retrieved 21 August 2013.
  36. ↑ "Evidence of the oldest life on land". Oregon Public Broadcasting. Retrieved 21 August 2013.
  37. ↑ "The Oregon Academy of Science". Oregon Academy of Science. Archived from the original on 7 August 2013. Retrieved 21 August 2013.
  38. 1 2 Fastovsky, D. E. (1991). "Book Reviews". Sedimentology. 38 (1): 181–184. Bibcode:1991Sedim..38..179.. doi:10.1111/j.1365-3091.1991.tb01867.x.
  39. 1 2 Yaalon, D. H. (1998). "Book Review". Sedimentary Geology. 116 (3–4): 275–280. Bibcode:1998SedG..116..276Y. doi:10.1016/S0037-0738(97)00105-X.
  40. ↑ Driese, S. G.; Nordt, L. C. (2012). New frontiers in paleopedology and terrestrial paleoclimatology. Tulsa, Oklahoma: Society for Sedimentary Geology. ISBN   978-1-56576-322-7.
  41. ↑ Nettleton, W. D.; Olson, C. G.; Wysocki, D. A. (1998). "Paleosol classification: problems and solution". Catena. 41 (1–3): 61–92. doi:10.1016/S0341-8162(00)00109-0.
  42. ↑ Nordt, L.; Driese, S. G. (2010). "A modern soil characterization approach to reconstructing physical and chemical properties of paleo-Vertisols". American Journal of Science. 310 (1): 37–62. Bibcode:2010AmJS..310...37N. doi: 10.2475/01.2010.02 . S2CID   129449965.
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