A New Geinitziid Forewing Reveal the Biostratigraphyic Correlation between Daohugou and Shar Teg

The family Geinitziidae is a significant component of Mesozoic terrestrial ecosystems, offering unique potential for biostratigraphic correlation. This family exhibited a global distribution and high diversity during the Jurassic. In China, geinitziid fossil records are increasingly diverse. The Daohugou biota has yielded abundant geinitziid fossils, including Sinosepididontus, Shurabia, and Geinitzia, providing crucial evidence for exploring the morphology of the group. The Middle Jurassic Haifanggou Formation in Inner Mongolia and the Shar Teg sequence in Mongolia exhibited strong insects taxonomic similarity. For instance, the genus Sinosepididontus is only found in these two successions. However, the lack of species-level diagnostic taxa has limited more precise stratigraphic correlation. This study reports a complete forewing of Geinitziidae from the Haifanggou Formation at the Daohugou locality. Its venation characteristics are identical to those of the holotype of Sinosepididontus shartegicus Aristov et al., 2009, discovered in the Shar Teg sequence. The discovery of S. shartegicus at Daohugou provides the first species-level link between these two biotas. This significantly strengthens their biotic link and supports a more precise regional stratigraphic framework. Based on regional geological data, we correlate the Shar Teg sequence with the Haifanggou Formation, and the overlying Ulan Malgait sequence with the Tiaojishan Formation. Recently, a new geinitziid specimen belonging to Geinitzia was found in the Yangshuzhuang Formation at the Jiyuan Basin, Henan Province, Central China, indicating the widespread distribution of Geinitziidae in the Middle Jurassic. With the Yanliao region as the central area, the family Geinitziidae spread at least southward to central China and northwestward to the Shar Teg region in the Middle Jurassic.