The Middle Jurassic represents a critical greenhouse climate epoch in Earth's evolutionary history. During this period, the Pangea supercontinent underwent extensive breakup, and terrestrial plants experienced significant radiation and diversification, fundamentally shaping the landscape of Mesozoic terrestrial ecosystems. Located on the southern margin of Eurasia, the Iranian Plateau is a key component of the Cimmerian microcontinent and serves as a vital biogeographic hub linking European and Central Asian floras, making it an ideal region for comparative research on Eurasian palaeophytogeography.
Although previous studies have documented fossil plants from Iran, systematic and comprehensive investigations of Middle Jurassic floras from the Tabas and Kerman basins in central Iran remain lacking. The biodiversity, palaeoecology, and systematic relationships of these floras with coeval Eurasian assemblages are poorly understood, hindering a holistic understanding of vegetation evolution on the southern Eurasian margin during the Middle Jurassic.
Recently, an international research team led by Professor WANG Yongdong from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS) conducted a multidisciplinary integrated study on the Middle Jurassic floras of Central Iran. The research clarified the floral composition, palaeoecological and palaeoenvironmental conditions, and Eurasian palaeobiogeographic affinities of the region, challenging the long-standing classical hypothesis of widespread homogeneous Middle Jurassic vegetation across Eurasia by Vakhrameev. The findings have been published in the international geoscience journal Palaeogeography, Palaeoclimatology, Palaeoecology.
The study was first-authored by Dr. Mohammad Taghi Badihagh, a special research assistant at NIGPAS, and corresponded by Professor WANG Yongdong. It was jointly completed by palaeobotanists from Poland, Germany, Romania and Italy. The team integrated newly obtained fossil materials from Exploration Well 233 in the South Kochak-Ali area of Iran and compiled published palaeobotanical data from 21 fossil localities in the region, establishing a comprehensive palaeoflora dataset for the Middle Jurassic (early Bajocian) Hojedk Formation in Central Iran consists of Kerman and Tabas basins.
A total of 93 macrofossil taxa belonging to 37 plant genera were identified. The flora is dominated by ferns (35.62%), nilssonialeans (25.82%), and conifers (12.09%), while sphenopsids, seed ferns (pteridosperms), ginkgophytes, and bennettitaleans constitute subordinate components. Lycopsid fossils are extremely rare and only found in a few localities, indicating their marginal ecological role in the contemporary vegetation.
Multi-proxy evidence from sedimentology, palaeobotany and palynology indicates that central Iran was dominated by a warm temperate to subtropical humid climate during the Middle Jurassic. The palaeoenvironment consisted of a complex landscape of fluvial, deltaic, swamp and tide-influenced coastal settings. Frequent sea-level fluctuations drove alternating marine and terrestrial sedimentation, forming a stratigraphic sequence of interbedded coal seams and terrigenous clastic rocks.
Using quantitative methods including the Sørensen-Dice similarity index and network analysis, the team systematically compared the floral assemblages of Central Iran with coeval floras from the Alborz Mountain, Afghan Block, Europe, and Central Asia. The results of statistical analyses reveal a close floral affinity between the Tabas and Kerman basins as an integral unit with an strong biogeographic links with Alborz Mountain and Afghan Block, confirming that these terranes all belong to the Cimmerian microcontinent during the Middle Jurassic.
In contrast, significant floral differences exist between Central Iran and most coeval regions in Europe and Central Asia. This indicates that regional environmental heterogeneity and basin sedimentary evolution, rather than palaeolatitudinal gradients, served as the primary controlling factors of regional vegetation composition. The study does not support the widely accepted model of uniform Eurasian Middle Jurassic vegetation proposed by Vakhrameev, and reveals the complex evolutionary characteristics of terrestrial vegetation on the southern Eurasian margin during the Middle Jurassic.
This study provides fundamental data for reconstructing the palaeovegetation and palaeoenvironmental evolution of the Cimmerian microcontinent and partitioning Middle Jurassic palaeophytogeographic regions of Eurasia. It also offers new empirical evidence for understanding the responses of terrestrial ecosystems to tectonic and climatic evolution during the breakup of Pangea.
The research was jointly supported by the Key Program of the National Natural Science Foundation of China, the National Major Science and Technology Project for Deep Earth Exploration, the ANSO Talent Scholarship of the Chinese Academy of Sciences, and the Open Project of the State Key Laboratory of Palaeobiology and Stratigraphy.
Reference: Mohammad Taghi Badihagh, Maria Barbacka, Dieter Uhl, Mihai Emilian Popa, Giovanni Giuseppe Scanu, Yongdong Wang*. A comprehensive synthesis of the Middle Jurassic flora of Central Iran: Integrating new data and approaches for unravelling the Eurasian palaeobiogeography. Palaeogeography, Palaeoclimatology, Palaeoecology, 2026, 701:114112. https://doi.org/10.1016/j.palaeo.2026.114112
Fig.1 Showing the position of Iran in relation to the Northern Hemisphere and a detail showing Jurassic outcrops in the Tabas Block and the location of well No. 233.
Fig.2 Represented Middle Jurassic floral composition in Central Iran, Tabas Basin. Specimens come from well No. 233 from the South Kochak–Ali area.
Fig.3 Diversity and abundance of the Middle Jurassic palaeovegetation elements of Central Iran (Tabas and Kerman basins. The filled black boxes indicate the absence of taxa. Ferns represent the most diverse component of the flora at the species level, whereas among gymnosperms, Nilssoniales exhibits the highest species diversity.
Fig.4 Palaeogeographic position of the Middle Jurassic flora of Central Iran and coeval floras from Europe and Mid–Asian (modified from Thierry, 2000). The numbers roughly indicate the European and Mid–Asian floras.
Fig.5 Network analysis illustrating taxonomic connectivity among Middle Jurassic floristic assemblages across Europe and Mid–Asia. Node size (circles) represents individual sites and reflects taxonomic richness. Numbers inside the nodes represent the number of shared and common taxa between localities. Edge thickness corresponds to the strength of connectivity, with thicker lines indicating a higher number of shared taxa between localities. Nodes and edges are colour–coded by geographic region
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