Abstract Detail

A synthesis of new paleontological and phylogenomic perspectives on gymnosperm evolution

Herendeen, Patrick [1], Herrera, Fabiany [2], Shi, Gongle [3], Ichinnorov, Niiden [4], Takahashi, Masamichi [5], Crane, Peter [6].

Diverse Gymnosperm-dominated floras from the Early Cretaceous of Mongolia and China.

Fossils and molecular evidence suggest that all extant and crown conifer families were established by the Early Cretaceous, coeval with the early radiation of angiosperms. In addition, Bennettitales, Ginkgoales, Umkomasiales, and Gnetales were significant floristic elements across Asia during that time. However, recognition of the lineages that lead to extant conifers (e.g., Cupressaceae s. l., Pinaceae) and other gymnosperm groups remains incomplete, mostly due to a partial and inadequately understood fossil record. Exceptionally preserved fossils from the Aptian-Albian (~100-125 Mya) of central Mongolia (e.g., lignified seed and pollen cones, foliage, and wood) and newly discovered permineralized (chert) plants from Inner Mongolia (China) provide a remarkable glimpse of the gymnosperm diversity during this key time in plant evolution. The new fossils show that conifers and other gymnosperm groups dominated the central Mongolian and northern Chinese landscape, from permanently flooded to more drained environments. The floras were composed of archaic and crown conifers lineages, including the voltzian plant Krassilovia and its associated Podozamites leaves, the stem pinaceous taxon Schizolepidopsis, and also Pityostrobus and one the oldest records of Picea (spruce). Three additional taxa show affinities with the subfamilies Cunninghamioideae (Elatides, Pentakonos) and Taiwanioideae (Stutzeliastrobus) of the Cupressaceae s.l. The new fossils also reveal that the enigmatic ginkgophyte Umaltolepis has a peltate, cupulate seed-bearing organ, unlike any other ginkgoalean fossil. At least four Umkomasia species are recognized from the lignite and chert deposits and provide a better understanding of the reproductive architecture of the seed-bearing structures of the enigmatic corystosperms. At least three Bennettitales leaves and associated scales and ovulate organs provide new ecological information on this extinct group. At least four seed types of the Bennettitales, Erdtmanithecales, and Gnetales (the BEG group) are also recognized. Together, all these fossils show that gymnosperms still dominated large areas of Asia during the rise of the angiosperms. Those plants show considerable morphological diversity as well as adaptations for wind pollination and ovule protection during the Early Mesozoic. The underappreciated architectural commonalities among the reproductive structures of the major groups of gymnosperm plants present in these floras will likely add a significant understanding of seed plant evolution.

1 - Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, United States
2 - Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022.0, United States
3 - Nanjing Institute Of Geology And Palaeontology, Chinese Academy Of Sci, 39 East Beijing Road, Nanjing, 32, 210008, China
4 - Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar-51, P.O. Box 260 8050, 2-cho, Ikarashi, Nishi-ku, Niigata, Japan
5 - 100-1 Kanabachitama-Cyo Sekiya Cyuou-Ku, Niigata, 15, 951-8165, Japan
6 - Oak Spring Garden Foundation, Oak Spring, Upperville, VA, 20184, USA

Keywords:
none specified

Presentation Type: Colloquium Presentations
Session: C04, A synthesis of new paleontological and phylogenomic perspectives on gymnosperm evolution
Location: 102/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 1:45 PM
Number: C04002
Abstract ID:975
Candidate for Awards:None