The Jambi gigantopterids and their place in gigantopterid classification

Abstract

The gigantopterids are a pan-palaeotropical Late Palaeozoic (to Early Mesozoic) plant group with unknown affiliations. Two gigantopterid species, both sole representatives of their respective genera, are known from the Early Permian Mengkarang Formation of Jambi (Sumatra, Indonesia). Through an emendation of the Jambi gigantopterids, based on the old and newly collected material, and a subsequent analysis of the leaf morphology of several gigantopterid genera, we conclude that the Jambi species are similar to the other gigantopterids, but do not appear to be related to them directly. We propose a possible scenario for the evolution of gigantopterid leaf morphology, based on marginal leaf growth, with implications for the validity of the gigantopterids as a natural group.

Depositional settings and changing composition of the Jambi palaeoflora within the Permian Mengkarang Formation (Sumatra, Indonesia)

“…The Asselian (Lower Permian) Mengkarang Formation of western Sumatra (Suwarna, Suharsono, Amiruddin, & Hermanto, ) hosts diverse fossil plant assemblages known collectively as the Jambi palaeoflora. This flora is typified by various examples of early origination of seed fern taxa (Booi, Van Waveren, & Van Konijnenburg‐Van Cittert, , ; Booi, Van Waveren, Van Konijnenburg‐Van Cittert, & De Boer, ), in situ silicified araucarioid tree trunks associated with Cordaites leaves (Booi, Van Waveren, & Van Konijnenburg‐Van Cittert, ), and the presence of Euramerican ferns and equisetales, and Cathaysian lycophytes (Van Waveren, Iskandar, Booi, & Van Konijnenburg‐Van Cittert, ). Originations consist of the earliest gigantopterids, like Palaeogoniopteris and Gothanopteris (Booi et al, ), while early appearances include (presumed) peltasperm genera such as Comia and Rachiphyllum (Booi et al, ).…”

“…Isotopic age evaluations from the base and the top of the section give insight in the accumulation rate and, consequently, the time of appearance of the various palaeofloral associations along the section. This detailed analysis enables the placement of the very early or first occurrences of seed ferns, described by Booi et al (, , ), into a palaeoclimatological context.…”

Late Permian (Lopingian) Terrestrial Ecosystems: A Global Comparison With New Data From the Low Latitude Bletterbach Biota

“…The Cathaysian flora developed in a tropical wet/humid climate of equatorial to tropical latitudes, and was characterised by the dominance of sphenophytes, ferns, and pteridosperm-grade seed plants, including gigantopterids. Records of this association are found in China, Laos, Korea, Japan, Thailand, Indonesia and Malaysia (Glasspool et al, 2003;Booi et al, 2009). The Euramerican flora, dominated by conifers, ginkgophytes and ferns (DiMichele et al, 2008), evolved in tropical to seasonally tropical climates, and is best documented in Europe and North America.…”

Reevaluation and taxonomic clarification ofGigantopteridiumandCathaysiopterisof western equatorial Pangea and their biogeographical significance

“…Terminology.-Morphology of specimens was characterized using descriptive terminology outlined by Booi et al (2009). Following these definitions, the venation of the leaf was ordered hierarchically, beginning with the central vein such that the midvein is considered primary or first order venation with successive secondary (second order) venation arising from the primary and tertiary (third order) venation arising from the primary as well as secondary veins.…”