Figure 2 in Ontogeny and evolutionary significance of a new acrotretide brachiopod genus from Cambrian Series 2 of South China

Figure 2. Ontogenetic development of ventral valve of Palaeotreta shannanensis gen. et sp. nov. from the Shuijingtuo Formation of southern Shaanxi. A–H, ventral valves demonstrating pedicle foramen forming stage (T1); A–D, juvenile with unrestricted pedicle notch, ELI-XYB S4-3 AU-06; E–H, small valve with pedicle opening, ELI-XYB S4s-3 AV-04; I–P, ventral valves demonstrating pedicle foramen-enclosing stage (T2); I–L, adult with enclosed pedicle foramen, ELI-XYB S4-3 AU-01; L, interior view, noting vascula lateralia (tailed arrow); M–P, larger valve with very short intertrough, ELI-XYB S4-3 AU-08.