Figure 9. Ontogenetic development of pedicle foramen of Palaeotreta zhujiahensis from the Shuijingtuo Formation of western Hubei. A, enlarged pedicle notch of Figure 8A; B, juvenile with unrestricted pedicle notch, showing raised propareas (arrows), ELI-AJH 8-2-3 AC-11; C, posterior view of Figure 8B; D, 'U'-shaped pedicle notch, note the growth of propareas at the posterior margin of metamorphic shell (arrow); E, F, 'U'-shaped pedicle foramen is soon to be enclosed, note the growth of propareas (arrow); G, enclosed pedicle foramen with short intertrough, ELI-AJH 8-2-D AD2-12; H, larger adult showing pedicle foramen outside the metamorphic shell, ELI-AJH 8-2-3 CD2-02; I, enlargement of propareas growing at the posterior margin of metamorphic shell and lateral sides of pedicle foramen of G; J, lateral view of I, note propareas growth (arrow); K, posterior view, showing pedicle foramen mostly located outside the metamorphic shell, box indicates the area shown in L, ELI-AJH 8-2-3 AC-22; L, enlarged view showing propareas growth (arrow); M, enlargement of propareas at the posterior margin of metamorphic shell, note pedicle foramen (arrow), ELI-AJH 8-2-1 AE-09; N, pitting structures on metamorphic shell, ELI-AJH 8-2-1 AE-09; O, P, enlarged secondary columnar layer, ELI-AJH 8-2-1 AE-09, ELI-AJH 8-2-1 CE-03.

Published as part of Zhang, Zhiliang, Holmer, Lars E., Chen, Feiyang & Brock, Glenn A., 2020, Ontogeny and evolutionary significance of a new acrotretide brachiopod genus from Cambrian Series 2 of South China, pp. 1569-1588 in Journal of Systematic Palaeontology 18 (19) on page 1581, DOI: 10.1080/14772019.2020.1794991, http://zenodo.org/record/10932614