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Oxygen isotopes suggest elevated thermometabolism within multiple Permo-Triassic therapsid clades

  1. Kévin Rey  Is a corresponding author
  2. Romain Amiot
  3. François Fourel
  4. Fernando Abdala
  5. Frédéric Fluteau
  6. Nour-Eddine Jalil
  7. Jun Liu
  8. Bruce S Rubidge
  9. Roger MH Smith
  10. J Sébastien Steyer
  11. Pia A Viglietti
  12. Xu Wang
  13. Christophe Lécuyer
  1. Univ Lyon, Université Lyon 1, Ens de Lyon, CNRS, UMR 5276 LGL-TPE, France, France
  2. University of the Witwatersrand, South Africa
  3. Univ Lyon, Université Lyon 1, CNRS, UMR 5023 LEHNA, France, France
  4. Institut de Physique du Globe de Paris, France
  5. Centre de Recherches en Paléobiodiversité et Paléoenvironnements, UMR 7207 CNRS-MNHN-UPMC, Museum National d’Histoire Naturelle, France
  6. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, China
  7. Iziko South African Museum, South Africa
  8. Institute of Geology and Geophysics, Chinese Academy of Sciences, China
  9. Institut Universitaire de France, France
Research Article
Cite this article as: eLife 2017;6:e28589 doi: 10.7554/eLife.28589
6 figures and 1 additional file

Figures

δ18Op differences between Permian therapsids and other tetrapods.

Differences in δ18Op values between therapsids and stereospondyls (white symbols) and between therapsids and parareptiles (black symbols) from the same localities are plotted against their corresponding palaeolatitude. A theoretical framework based on modern temperature gradient (0.6 ± 0.1°C/°Lat; see Appendix 1) and phosphate-water-temperature oxygen isotope fractionation (Lécuyer et al., 2013) predicts various δ18Op value differences. The lighter orange and red areas correspond to the uncertainty of the temperature gradient. Dap.: Daptocephalus; Tap.: Tapinocephalus.

https://doi.org/10.7554/eLife.28589.003
δ18Op differences between Early to Middle Triassic therapsids and other tetrapods.

Differences in δ18Op values between therapsids and stereospondyls (white symbols) and between therapsids and archosauriforms (black symbols) from the same localities are plotted against their corresponding palaeolatitude. A theoretical framework based on a lower-than-today thermal gradient (0.4 ± 0.1°C/°Lat; see Appendix 1) and phosphate-water-temperature oxygen isotope fractionation (Lécuyer et al., 2013) predicts various δ18Op value differences. The lighter orange and red areas correspond to the uncertainty of the temperature gradient.

https://doi.org/10.7554/eLife.28589.004
δ18Op differences between Middle to latest Triassic therapsids and other tetrapods.

Differences in δ18Op values between therapsids and stereospondyls (white symbols) and between therapsids and archosauriforms (black symbols) from the same localities are plotted against their corresponding palaeolatitude. A theoretical framework based on a lower-than-today thermal gradient (0.5 ± 0.1°C/°Lat; see Appendix 1) and phosphate-water-temperature oxygen isotope fractionation (Lécuyer et al., 2013) predicts various δ18Op value differences. The lighter orange and red areas correspond to the uncertainty of the temperature gradient.

https://doi.org/10.7554/eLife.28589.005
Phylogeny of sampled therapsids.

Phylogeny of the sampled therapsids plotted alongside a stratigraphic scale, based on proposed therapsid phylogenies (Ruben and Jones, 2000; Hillenius and Ruben, 2004; Gebauer, 2007; Cisneros et al., 2012; Liu, 2013; Ruta et al., 2013) and their biostratigraphic ranges (Kammerer et al., 2011; Kemp, 2012; Ruta et al., 2013; Huttenlocker, 2014; Day et al., 2015; Viglietti et al., 2016). The thickest parts of the bold lines represent the age range uncertainty of the localities where the samples come from. Species identified as endotherm-like are written in bold and red. Node numbers refer to clades quoted in the text: 1: Neotherapsida; 2: Dicynodontoidea; 3: Lystrosauridae; 4: Kannemeyeriiformes; 5: Epicynodontia; 6: Eucynodontia.

https://doi.org/10.7554/eLife.28589.006
Isotopic preservation assessment.

δ18Oc18Op differences between teeth and bones plotted against the structural carbonate content (wt%) of apatite. Samples that have δ18Oc18Op differences higher than 14.7‰ are considered doubtful as regards potential diagenetic alteration (see text). For carbonate contents (wt%) higher than 13.4%, the δ18Oc values are considered to be inherited from inorganic diagenetic processes. A high difference between δ18Oc and δ18Op is interpreted as the result of a microbially-mediated alteration of the apatite phosphate or too high δ18Oc values resulting from the addition of inorganic carbonate or isotopic exchange with an external source of inorganic carbon. The grey crosses refer to previously published South African bone and tooth samples (Rey et al., 2016).

https://doi.org/10.7554/eLife.28589.007
Appendix 1—figure 1
Expected latitudinal variation of the δ18Op difference between vertebrate taxa of various physiologies and ecologies.

Based on modern relationships between climate and phosphate-water-temperature oxygen isotope fractionation (Lécuyer et al., 2013) the following δ18Op values differences are predicted: (1) corresponds to a terrestrial endotherm compared to a terrestrial ectotherm; (2) corresponds to a terrestrial endotherm compared to a semi-aquatic ectotherm; The vertical range (3) corresponds to terrestrial animals having similar thermometabolism; (4) corresponds to the difference between a terrestrial and a semi-aquatic animals having a similar thermometabolism.

https://doi.org/10.7554/eLife.28589.009

Additional files

Supplementary file 1

Stable oxygen isotope compositions of phosphate (δ18Op) and carbonate (δ18Oc) of Permo-Triassic tetrapod teeth and bones reported along with their stratigraphic position, estimated age, palaeolatitudes and their carbonate content.

Asterisks represent diagenetically altered values.

https://doi.org/10.7554/eLife.28589.008

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