Original paper
Mummified Dicroidium (Umkomasiales) leaves and reproductive organs from the Upper Triassic of South Australia
Unverfärth, Jan; McLoughlin, Stephen; Bomfleur, Benjamin
Palaeontographica Abteilung B Volume 304 Issue 5-6 (2022), p. 149 - 225
192 references
published: Dec 20, 2022
manuscript accepted: May 4, 2022
manuscript received: Feb 27, 2022
Abstract
The Leigh Creek Coal Measures incorporate unusually low-rank coals from the Upper Triassic of South Australia. Associated fluviolacustrine deposits contain well-preserved, partly mummified plant remains dominated by corystosperm seed ferns. The assemblage comprises seven species of Dicroidium, including D. odontopteroides, D. lineatum, D. dubium, D. zuberi, and Dicroidium spp. A, B and C, and associated reproductive organs, including various fragments of cupulate structures (Umkomasia sp. cf. U. quadripartita and Fanerotheca sp. cf. F. waldeckiformis) and pollen organs (Pteruchus africanus), all having excellent cuticle preservation. Based on a comprehensive analysis of more than 550 individual specimens, we (1) document diagnostic epidermal and cuticular features for foliage and reproductive organs, (2) provide an identification key for the Dicroidium species present, and (3) infer affiliations between reproductive organs and particular leaf species based on correspondence in epidermal anatomy and cuticle micromorphology and on mutual-occurrence data. Collectively, the Leigh Creek material contributes towards a more robust and realistic systematic classification of Umkomasiaceae, offers a rare chance for whole-plant reassembly of individual species, and refines reconstruction of the Dicroidium-dominated forest ecosystems in the middle to high latitudes of the Late Triassic greenhouse world.
Keywords
Corystosperms • Umkomasia • Fanerotheca • Pteruchus • cuticle analysis • whole-plant reconstruction • Gondwana