Evidence map›Paper›PMID 42308614›Full record

ArticleAnnals of botany2026

Fossil ferns of the Asian tropics: Salvinia and Acrostichum macrofossils and diverse fern spores from the early Eocene Ghazij Formation (Balochistan, Pakistan).

Edward J Spagnuolo, David Shaw, Peter Wilf, Scott L Wing, Munir Ul-Haq, William C Clyde

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Article in Annals of botany, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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6 authors.

Edward J SpagnuoloDepartment of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA.ORCID 0000-0001-6720-900X
David ShawBiostratigraphic Associates (UK) Ltd, Stoke-on-Trent ST6 8NE, UK.
Peter WilfDepartment of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, USA.
Scott L WingDepartment of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA.
Munir Ul-HaqGeological Survey of Pakistan, Shehzad Town, Islamabad M3G7+4HH, H-8/1 H 8/1 H-8, Pakistan.
William C ClydeDepartment of Earth Sciences, University of New Hampshire, Durham, NH 03824, USA.

Funding

Geological Society of America EAR-2323037Mid-Continent Paleobotanical ColloquiumNational Science Foundation DGE-1255832National Science Foundation EAR-1925755National Science Foundation EAR-9902905New York Botanical GardenPaleontological SocietyPennsylvania State UniversityPennsylvania State University Department of Geosciences
6 · The paper itself

Abstract

backgroundFerns are most taxonomically and ecologically diverse in the tropics, but Cenozoic tropical fern fossils are rare, limiting understanding of fern evolution and biodiversity through time. Both Salvinia (Salviniaceae) and Acrostichum (Pteridaceae) are widely distributed ferns that are most diverse and abundant near the equator. Salvinia and Acrostichum macrofossils and spores have a rich Cenozoic record from subtropical and temperate regions, but only a handful of fossils have been discovered in the tropics, and few are from Asia. Here we report new fossil Salvinia and Acrostichum macrofossils and a diverse fern-spore assemblage from the early Eocene Ghazij Formation (Balochistan, Pakistan), palaeolatitude 0-5°N.

methodsAs part of a larger study of the Ghazij flora, we collected 29 fern macrofossils and 39 palynology samples from multiple localities. The fern fossils were compared with similar extinct and extant vascular plants and systematically described. KEY

resultsSalvinia dashtensis sp. nov. is described from four localities in the upper Ghazij Formation based on vegetative leaves, submerged rhizomorphic leaves, and inflated submerged structures (floats), along with Salvinia microspore massulae. These Salvinia occurrences serve as important freshwater palaeoenvironmental indicators. Acrostichum pinnae are identified at one locality in the upper Ghazij Formation from their characteristic reticulate secondary venation, forming rectangular to hexagonal polygons without freely ending veinlets. Acrostichumsporites spores are also identified. Spores of a total of 21 palynotaxa representing ten pteridophyte families (Gleicheniaceae, Lindsaeaceae, Lygodiaceae, Matoniaceae, Polypodiaceae, Pteridaceae, Osmundaceae, Schizaeaceae, Salviniaceae, and Thelypteridaceae) record a diverse fern assemblage from various ecological niches and the first occurrences of Pteris, Baculatisporites, and Verrucosisporites for Palaeogene Indo-Pakistan.

conclusionsThe Salvinia and Acrostichum occurrences from the Ghazij Formation provide rare fossil examples of extant fern genera in the ancient tropics and represent some of the only fern fossils for all of Palaeogene tropical Asia.

Indexed as

FernsFossilsBiodiversityBiological EvolutionPakistanPteridaceaeSporesTropical ClimateAcrostichumEocenefernsPakistanpalynologyPteridaceaeSalviniaSalviniaceaespores

Identifiers

PMID42308614
PMCPMC13275028

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