Fossil Record 20(2): 201-213, doi: 10.5194/fr-20-201-2017
A Burmese amber fossil of Radula (Porellales, Jungermanniopsida) provides insights into the Cretaceous evolution of epiphytic lineages of leafy liverworts
expand article infoJulia Bechteler, Alexander R. Schmidt§, Matthew A. M. Renner|, Bo Wang, Oscar Alejandro Pérez-Escobar, Alfons Schäfer-Verwimp#, Kathrin Feldberg, Jochen Heinrichs¤
‡ Department of Biology and GeoBio-Center, Ludwig Maximilian University, Menzinger Straße 67, 80638 Munich, Germany§ Department of Geobiology, Georg August University, Goldschmidtstraße 3, 37077 Göttingen, Germany| Royal Botanic Gardens and Domain Trust, Mrs Macquaries Road, Sydney, NSW 2000, Australia¶ State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, No.39, East Beijing Road, Nanjing 210008, China# Mittlere Letten 11, 88634 Herdwangen-Schönach, Germany¤ Ludwig-Maximilians-Universität Münchenen, München, Germany
† Deceased author
Open Access
DNA-based divergence time estimates suggested majorchanges in the composition of epiphyte lineages of liverworts during theCretaceous; however, evidence from the fossil record is scarce. We presentthe first Cretaceous fossil of the predominantly epiphytic leafy liverwortgenus Radula in ca. 100 Myr old Burmese amber. The fossil's exquisite preservationallows first insights into the morphology of early crown grouprepresentatives of Radula occurring in gymnosperm-dominated forests. Ancestralcharacter state reconstruction aligns the fossil with the crown group ofRadula subg. Odontoradula; however, corresponding divergence time estimates using the softwareBEAST lead to unrealistically old age estimates. Alternatively, assignmentof the fossil to the stem of subg. Odontoradula results in a stem age estimate ofRadula of 227.8 Ma (95 % highest posterior density (HPD): 165.7–306.7) and a crown group estimate of176.3 Ma (135.1–227.4), in agreement with analyses employing standard substitutionrates (stem age 235.6 Ma (142.9–368.5), crown group age 183.8 Ma (109.9–289.1)). The fossil likely belongs to the stem lineage of Radula subg.Odontoradula. The fossil's modern morphology suggests that switches from gymnosperm toangiosperm phorophytes occurred without changes in plant body plans inepiphytic liverworts. The fossil provides evidence for strikingmorphological homoplasy in time. Even conservative node assignments of thefossil support older rather than younger age estimates of the Radula crowngroup,involving origins for most extant subgenera by the end of the Cretaceousand diversification of their crown groups in the Cenozoic.