Varricchio-Suppl Mat

Five tables on: 1) the gas conductance of an average Troodon egg from MOR 299 and 750, 2) the gas conductance of a weighted (by sample size) average Troodon egg from MOR 299 ad 750, 3) chi-square test results for for uniform pore distributions in MOR 299 and 750, 4) chi-square test results for pore distribution comparison of Troodon eggs MOR 750 and 299, and 5) chi-square test for uniform distribution for average Troodon egg

Evaluating deformation in <i>Spheroolithus</i> dinosaur eggs from Zhejiang, China

<div><p>Lack of stratigraphic context for dinosaur eggs inhibits understanding of dinosaur reproductive biology and the taphonomic processes of egg preservation. Past taphonomic work suggests two features, compression ridges (sharp edge of broken eggshell around egg circumference) and deformation asymmetry (proportion of crushed to rounded sides of the egg), as geopetal structures. We examined these features across a large sample of <i>Spheroolithus</i> eggs from the Cretaceous of Zhejiang, China, to test their utility. On 103 isolated eggs, we determined asymmetry ratios (crushed side egg height divided by rounded side egg height) and observed an average asymmetry ratio of 0.71. Additional observations of <i>in situ</i> eggs demonstrate the stratigraphic downside as more rounded and less fractured, the stratigraphic upside as flatter with heavier fracturing and compression ridges as parallel to original bedding plane. Burial-caused fractures on the upper side of the egg allowed sediment to partially fill, subsequently supporting the bottom portion. Examining these features within 16 clutches allowed differentiation of biotic versus taphonomically altered arrangements. Three common clutch arrangements include planar (minimal egg overlap), offset (extreme overlap) and agglomerate (randomly arranged, closely packed). Analysis of egg strike and dip across clutches favours planar clutches as the principal configuration for <i>Spheroolithus</i> clutches.</p></div