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Rashmi Srivastava and Mitsuo Suzuki

This paper describes five species of dicotyledonous fossil wood from the lower Oligocene Tsuyazaki Formation in Tsuyazaki, Fukuoka Prefecture, northern Kyushu: Rhus palaeojavanica (Anacardiaceae), Alnus scalariforme (Betulaceae), Hamamelis prejaponica (Hamamelidaceae), Magnoliaceoxylon palaeogenica (Magnoliaceae) and Sonneratia kyushuensis (Sonneratiaceae). This brings the number of species described from the Tsuyazaki locality to 19. Among these 19 species modern equivalents of all species, except for Sonneratia, occur in temperate to subtropical forests. Sonneratia is found today in mangrove vegetation of tropical to subtropical regions. The presence of Sonneratia may suggest a warmer climate in Kyushu during the early Oligocene.

Pieter Baas, Steven R. Manchester, Elisabeth A. Wheeler and Rashmi Srivastava

Wood of Connaroxylon dimorphum (Connaraceae, Oxalidales) from the Deccan Intertrappean Beds of India (KPg Boundary 65–67 MY BP) is described. It is characterized by parenchyma-like fiber bands alternating with normal fibers, septate and nonseptate fibers, vessel-ray pits with strongly reduced borders, uniseriate rays of square and upright cells, and radial tubules in the center of ray cells that are arranged in a herringbone pattern. The overall wood anatomy strongly resembles Melastomataceae p. p., Lagerstroemia p. p. (Lythraceae) and Connarus (Connaraceae). However, the shared radial tubules of Connarus and the fossil strongly tilt the evidence of botanical affinities towards this genus. This would represent the second and by far the oldest fossil wood record of the Connaraceae, also considerably older than the earliest fossil records of the family’s other plant parts, and one of the oldest fossils of the order Oxalidales.

Elisabeth A. Wheeler, Rashmi Srivastava, Steven R. Manchester and Pieter Baas

Associate-editor Michael Wiemann

ABSTRACT

Background and approach – The Deccan Intertrappean Beds of Central India contain a diverse assemblage of fossil plants, including petrified woods from 15 localities. These beds are dated at c. 67–64 Ma, i.e. latest Cretaceous–earliest Paleocene and span the K-Pg boundary, a significant time in angiosperm history. At this time, the Indian tectonic plate was halfway on its journey from Gondwana to its collision with Asia, and relatively close to the equator. We provide descriptions in IAWA Hardwood List codes for 47 species of Deccan fossil woods, based on our examination of thin sections of these woods, mostly holotypes that are housed at the Birbal Sahni Institute of Palaeobotany, Lucknow, India. An appendix lists all validly published Deccan wood species of which we are aware, including 52 that we were not able to examine.

Main results – The Deccan fossil woods described herein include the oldest known occurrences of some orders, families or genera viz. Lamiales (Lamia-ceae), Achariaceae (Hydnocarpus-like wood), Anacardiaceae, Simaroubaceae (Ailanthus-like and Simarouba-like woods), subfamily Leeoideae (Vitaceae), subfamily Myrtoideae (Myrtaceae), subfamily Planchoideae (Lecythidaceae), tribe Castilleae (Moraceae), tribes Grewioideae and Sterculioideae (Malvaceae). These first fossil records are discussed with reference to other macrofossil and pollen records of the same or related clades. They complement recent work on the oldest known Olea and Connaraceae also documented by Deccan woods.

For the Deccan woods we examined, we could confirm the earlier taxonomic assignment at least down to order or family level for 29 taxa. Ordinal level affinities are ambiguous for eight of the taxa. In two cases, we revised the taxonomic assignment to other families; for another eight, the original assignment was found to be incorrect, but we are unable to suggest alternative affinities.

Evolutionary implications – Only 3% of all Deccan woods have scalariform perforations and the incidences of so-called specialized features in the Baileyan sense are high, so these woods have a remarkably “modern” aspect. This is anomalous in comparison with contemporaneous fossil woods from higher paleolatitudes, and seemingly they are more “derived” than the recent flora. In these respects, the Deccan woods constitute a unique assemblage. The low incidence of scalariform perforations suggests xeric conditions, while – in contrast – the low incidence of distinct growth ring boundaries suggests an aseasonal everwet climate. It is speculated that convergent xylem specialization, especially the selection for simple perforations, was enhanced by the climatic conditions found at low paleolatitudes with high temperatures as would characterize the Deccan Intertrappean Beds at the K-Pg boundary.

Pieter Baas, Rashmi Srivastava, Steven R. Manchester and Elisabeth A. Wheeler

Strangely configured vessels composed of few elements interconnected in a sphere- or ring-like structure are reported from the type specimen of Amooroxylon deccanensis Bande & Prakash, a large fossil trunk from the Deccan Intertrappean Beds of central India (late Cretaceous-early Paleocene, about 66 MY before present). In the recent flora, circular vessels have been found mainly in association with branching nodes, axillary buds, wound callus, and pathogens, and they have been artificially induced by auxin. The presence of circular vessels in this fossil trunk showing no signs of branching or trauma makes this record highly unusual.

Rashmi Srivastava, Elisabeth A. Wheeler, Steven R. Manchester and Pieter Baas

The wood of Oleoxylon deccanense, reported informally in 1981 from the Deccan Intertrappean Beds of central India, is re-examined. We provide a formal diagnosis for the species and a more detailed description. The similarity to wood from species groups of the modern genera Chionanthus and Olea leads us to infer that this fossil taxon probably belongs to the monophyletic drupaceous subtribe Oleinae of the olive family, Oleaceae (Lamiales), although affinities with Rhamnaceae and Rutaceae cannot be wholly excluded. Since the fossil is from a late Maastrichtian-Danian horizon (65–67 MY BP) this would imply that a member of the Oleaceae was part of the flora that inhabited India several million years prior to the tectonic impact of India with Asia. The seemingly modern appearance of this and other Deccan fossil woods is briefly discussed.