Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils
Figure 4
Stylized reconstruction of adult and embryo of Chaohusaurus in comparison to a derived ichthyopterygian.
(A), adult based on AGM I-1 and CHS-5. Rectangle indicates the approximate range preserved in AGM I-1. Colored silhouettes of embryo are placed in approximate positions of embryos 1 and 2, with embryo 3 displaced to avoid overlap with embryo 2. The extent of the maternal tail tip, in gray, is based on AGM-CH-628-22. Scleral ring is based on AGM-CHS-3. (B), embryo based on embryo 2 and neonate 1 of AGM I-1. Elements in gray are missing. (C), the derived ichthyopterygian Stenopterygius with one embryo in birth position and three in body cavity, reconstructed based on SMNS 6293 (Staatliches Museum für Naturkunde, Stüttgart, Germany). Scale bars are 5 cm. See fig. S3 for a high resolution image.