Research ArticlePALEONTOLOGY

Eggshell geochemistry reveals ancestral metabolic thermoregulation in Dinosauria

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Science Advances  14 Feb 2020:
Vol. 6, no. 7, eaax9361
DOI: 10.1126/sciadv.aax9361
  • Fig. 1 Simplified archosaur phylogeny illustrating the taxa investigated in this and previous clumped isotope studies.

    Extant ectotherms are blue; extant endotherms are orange. Maiasaura represents the major dinosaurian subclade Ornithischia, which is traditionally thought to represent the sister taxon to a Theropoda + Sauropoda clade as shown in (14) but in some recent phylogenies is placed as sister to Theropoda (13). Asterisk indicates taxonomic uncertainty for the Romanian eggshell sample, which may derive from a titanosaur sauropod (either the dwarf taxa Magyarosaurus or Paludititan or a larger titanosaurian) or the dwarf hadrosauroid Telmatosaurus (39).

  • Fig. 2 Clumped isotope [Δ47(abs)] value (calculated using the Gonfiantini parameters) versus temperature relationship of extant eggshell.

    Data from this study, other biogenic carbonates analyzed between 2010 and 2018 at Yale University (8, 5659), the calibration of laboratory precipitated carbonates from (8), and the extant eggshell carbonate calibration from (6). Error bars are SE for Δ47 (smaller than the symbols) and the range of expected body temperatures. Calibration lines, solid line; 95% confidence error envelope, shaded line; and 95% prediction envelope, dashed-dotted lines.

  • Fig. 3 Petrographic microscope images of dinosaur eggshell from this study.

    (A) Well-preserved Troodon eggshell from Devil’s Coulee, Alberta, Canada [Tyrrell Museum of Palaeontology (TMP) 2008.75.51]. (B) Well-preserved Troodon eggshell from Lost River Ranch, Alberta, Canada (TMP 2003.81.1). (C) Well-preserved Troodon eggshell fragment from Wann’s Hill, Alberta, Canada (TMP 1995.21.4). Arrows and horizontal lines point to the approximate boundary between the mammillary and prismatic layers. Presence of two calcitic layers is diagnostic of nonavian theropods. (D) Maiasaura hadrosaur eggshell from Devil’s Coulee, Alberta, Canada, with intermediate preservation (TMP 2009.153.1). The diagnostic radiating tabular units are indicated by the white arrow. (E) Romanian eggshell (oospecies Megaloolithus cf. M. siruguei, TMP 1991.175.2) from Tuştea locality, Romania, with intermediate preservation. Diagnostic radiating acicular crystals indicated by white arrow. (F) Poorly preserved lambeosaurine hadrosaur eggshell fragment from Wann’s Hill, Alberta, Canada (TMP 1988.121.41). Scale bars, 500 μm.

  • Fig. 4 Bulk trace metal concentrations in eggshells and mollusks with CL images of fossil eggshell.

    (A) Fe and Mn concentrations (ppm) in extant and fossil eggshells and fossil mollusks. Letters in the graph refer to specific CL images. (B to E) CL images of fossil eggshell thin sections in cross section used to assess preservation. (B) Well-preserved Devil’s Coulee Troodon, (C) Romanian eggshell (oospecies Megaloolithus cf. M. siruguei) with intermediate preservation, (D) Maiasaura from Devil’s Coulee with intermediate preservation, (E) poorly preserved lambeosaurine from Wann’s Hill, Alberta, Canada. Scale bars, 1 mm. Luminescence correlates with increased Mn concentrations in (A).

  • Fig. 5 Log body mass (kg) versus Δ47-derived body temperature estimates of fossil dinosaurs and mollusks.

    We present data from this study and (5, 6) in the context of model-based body temperature estimates from (2) (black dashed curve). Note that this model provides an illustrative example for the possibility of gigantothermy, but it has been debated (7). Diagonal-hatched symbols are specimens with moderate calcite preservation, while the rest are well preserved. Estimates of ambient MAT are taken from the literature (17, 18, 20, 21) for the latitudes of Late Cretaceous sites in Haţeg Basin, Romania (green bar), and Alberta, Canada (blue/pink bar). For Alberta, ambient warm season temperatures are also estimated from Δ47 in freshwater mollusks (shell symbols). Δ47 temperature error bars are 1 SE, and body mass error bars indicate a range of estimated sizes (11, 37, 60). Extant bird body temperature range is from (12). Asterisk indicates taxonomic uncertainty for the Romanian eggshell sample, which may derive from a titanosaur sauropod or the hadrosauroid Telmatosaurus (39).

  • Table 1 Criteria for characterization of fossil eggshell preservation.

    EggshellLocalityMn
    (ppm)
    Fe (ppm)CL image %
    luminescent
    Preservation test*Final preservation
    characterization
    Low-trace
    metals
    % Lum.Microstructure1° Aragonite
    Troodon formosus
    (Theropod) TMP
    2008.75.127
    Devil’s Coulee,
    AB, Canada
    60760.5✓✓✓✓✓✓NAWell preserved
    Maiasaura
    peeblesorum
    (Hadrosaur)
    TMP 2009.153.1
    Devil’s Coulee,
    AB, Canada
    156074111.3✓✓NAModerately preserved
    Hypacrosaurus
    stebingeri
    (Hadrosaur)
    TMP 1989.69.10
    Devil’s Coulee,
    AB, Canada
    42912313NAXNANANAPoorly preserved
    Troodon formosus
    (Theropod) TMP
    1995.21.4
    Wann’s Hill,
    AB, Canada
    99540.6✓✓✓✓✓✓NAWell preserved
    Indeterminate
    lambeosaurine
    (Hadrosaur) TMP
    1988.121.41
    Wann’s Hill,
    AB, Canada
    3265162373XXXNAPoorly preserved
    Troodon formosus
    (Theropod) TMP
    2003.81.1
    Lost River
    Ranch, AB,
    Canada
    6280✓✓✓✓✓✓NAWell preserved
    Magyarosaurus
    dacus (Sauropod)
    TMP 1991.175.2
    Tuştea, Haţeg
    Basin,
    Romania
    795615✓✓NAModerately preserved
    Gastropod W20Wann’s Hill,
    AB, Canada
    79297NA✓✓NANA✓✓Well preserved
    Bivalve TMP
    2009.149.5
    Milk River, AB,
    Canada
    21821NA✓✓NANA✓✓Well preserved

    *If the sample passed, it received a “✓✓”; partially passed, a “✓”; or failed, a “X.” NA indicates that either test was “not applicable” (e.g., original biomineral was calcite) or “not available” (e.g., no thin sections available).

    †Average of duplicates run to test stability of mass spectrometer.

    Supplementary Materials

    • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/7/eaax9361/DC1

      Supplementary Materials and Methods

      Fig. S1. Fossil localities in southern Alberta, Canada.

      Fig. S2. Paleogeographic map.

      Fig. S3. Clumped isotope [Δ47(abs)] value versus temperature relationship of laboratory-precipitated carbonate calibration data.

      Fig. S4. X-ray diffraction spectra of fossil mollusks.

      Fig. S5. Photomicrographs of dinosaur eggshell samples.

      Table S1. Specimen descriptions, localities, and isotopic values.

      Data S1. Raw data for both carbonate samples and standards and CO2 standards.

      References (6175)

    • Supplementary Materials

      The PDF file includes:

      • Supplementary Materials and Methods
      • Fig. S1. Fossil localities in southern Alberta, Canada.
      • Fig. S2. Paleogeographic map.
      • Fig. S3. Clumped isotope Δ47(abs) value versus temperature relationship of laboratory-precipitated carbonate alibration data.
      • Fig. S4. X-ray diffraction spectra of fossil mollusks.
      • Fig. S5. Photomicrographs of dinosaur eggshell samples.
      • Legend for data S1
      • Table S1. Specimen descriptions, localities, and isotopic values.
      • References (6175)

      Download PDF

      Other Supplementary Material for this manuscript includes the following:

      • Data S1 (Microsoft Excel format). Raw data for both carbonate samples and standards and CO2 standards.

      Files in this Data Supplement:

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