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Reply to: Egg pigmentation probably has an Archosaurian origin

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Data availability

All data supporting the findings of this study are available within the paper (Fig. 1), and its Extended Data (Extended Data Fig. 1, Extended Data Table 1).


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We thank D. E. G. Briggs for assistance with the manuscript, and M. Fabbri and J. Gauthier for suggestions.

Author information

J.W., T.-R.Y. and M.A.N. discussed Shawkey and D’Alba’s concerns. J.W. designed and performed the experiments, analysed the data, and created the figure. J.W. wrote the manuscript, which was reviewed by all authors.

Correspondence to Jasmina Wiemann.

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The authors declare no competing interests.

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Extended data figures and tables

Extended Data Fig. 1 Crocodylus siamensis outer and inner eggshell surfaces.

a, The outer eggshell surface (n = 1), which contains the highest pigment concentrations in eumaniraptorans is uncoloured/white. b, c, The inner eggshell surface (n = 2) shows a reddish tint (b), which reflects chorioallantoic tissues and vascularity (c) protruding into the innermost layers of the eggshell. The inner eggshell surface in b is manually cleaned of adjacent chorioallantoic tissue, whereas the inner eggshell surface in c is left untreated. Chorioallantoic tissues (c) are commonly vascularized, and therefore saturated in blood-derived haem, which represents, when dechelated, protoporphyrin. In this case, traces of protoporphyrin recovered from Crocodylus siamensis eggshell would not be homologous with eumaniraptoran eggshell protoporphyrin.

Extended Data Table 1 Information on added taxa (n = 4), catalogue numbers, ages, localities, and egg colours

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Fig. 1: Raman spectroscopic and statistical analysis of an eggshell pigmentation versus an egg colour signal.
Extended Data Fig. 1: Crocodylus siamensis outer and inner eggshell surfaces.


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