The occurrence of a range of vessel diameters across a ring greater than × 5 (referred to here as graduated-porous) is not completely equivalent to ring-porosity as defined in the IAWA features list. Trees with graduated porous wood occur mainly in the mid-latitudes. A limiting factor relating to temperature (winter temperature extremes below -40° C) defines the northern occurrence of these trees, preventing them from being an important element in the boreal forest. Towards the equator, numbers fall off steeply where winter temperatures stay above freezing. In the mid-latitudes, where these trees are most prevalent (40-100% of the tree flora), percentages vary inversely with precipitation amount, a relations hip that has potential applicability in interpreting fossil assemblages. Occurrence of this character is consistent with its interpretation as an adaptation allowing high conduction rates early in the growing season that is particularly favoured in drier climates of the mid-latitudes. Trees with graduated-porous wood occur in the tropics, where they appear to be most common in dry-climate areas. Some tropical woods that display a range of vessel diameters but have narrow and wide vessels arranged in a random pattern (rather than showing a radial sequence from wide to narrow) may serve as indicators of climates that are seasonal with respect to precipitation but not temperature. Well-founded climate estimates based on fossil wood depend upon understanding more about the way wood is preserved in the fossil record; graduated-porosity (or ring-porosity) is itself a character that may influence likelihood of preservation.
Data on fossil dicotyledonous wood were assembled in order to 1) test the Baileyan model for trends of specialisation in dicotyledonous wood anatomy by addressing the question - were 'primitive' wood anatomieal features (as defined by the Baileyan model) more common in the geologie past than at present?, 2) infer, on a broad geographie scale, past climatie regimes, and long term climatic change, and 3) assess the extent of knowledge of fossil dicotyledonous woods. The resulting database has information on 91 anatomieal features for over 1200 fossil dicotyledonous woods. The incidence of selected anatomical features was plotted through time (by geologie epoch) for the world and for two regional groupings (roughly corresponding to the Laurasian and Gondwanan supercontinents). For comparison to the fossil wood record, the incidence of wood anatomie al features in the Recent flora was obtained from the 5260 record OPCN database for extant dicotyledonous woods.
Clarnoxylon blanchardii gen. et sp. nov. is a new taxon for fossil wood with a suite of features diagnostic of the Juglandaceae. It occurs at two Middle Eocene (c. 43-44 million years b.p.) localities in the Clarno Fonnation of central Oregon, USA. Clarnoxylon resembles the Platycaryeae and the Hicorieae in having exclusively simple perforation plates and solid pith. However, the common occurrence of crystalliferous idioblasts in the rays, but not in the axial parenchyma, and the cooccurrence at Clarno of platycaryoid fmits and pollen unaccompanied by hicorioid fmits indicate that Clarnoxylon has affinities with the Platycaryeae. Differences between Clarnoxylon and Platycarya support previous suggestions that short vessel elements, helical thickenings, and vascular tracheids are derived characters of Platycarya. These differences are also in accord with the ecological adaptation of the extant genus Platycarya to a temperate climate contrasting with the tropical Middle Ebcene setting of Clarnoxylon.
Two species of fossil angiosperm wood are described from the Oligocene of northwestern Bohemia in the Czech Republic. One specimen from Kadan–Zadní vrch Hill is identified as Cercidiphylloxylon kadanense Prakash et al. Because of its superior preservation, the specimen is designated as an epitype to the original holotype specimen of the species and genus. Cercidiphylloxylon kadanense is known only from the locality of Kadan–Zadní vrch Hill, and it represents the oldest fossil wood of true Cercidiphyllum Sieb. & Zucc. Three other wood specimens from Zichov are attributed to Liquidambaroxylon speciosum Felix. Modern wood of some species of Cercidiphyllum Sieb. & Zucc., Liquidambar L., Altingia Noronha, Corylopsis Sieb. & Zucc., Distylium Sieb. & Zucc., and Hamamelis L. was examined to determine how to distinguish the wood of Cercidiphyllum (Cercidiphyllaceae) from similar woods of Hamamelidaceae. The number of bars in the scalariform perforation plates of the vessels is about 40 in Cercidiphyllum, and about 20 in the Hamamelidaceae. Rays are variable, even at intra-specific level, and are not suitable for distinguishing these woods. These criteria were found to be useful in evaluating affinities of the fossil woods.
angiosperm fossilwoods have been described from its Late Cretaceous ( i . e ., Milanez 1935 ; Torres & Rallo 1981 ; Nishida & Nishida 1987 ; Mourier et al. 1988 ; Nishida et al. 1990 ; Franco et al. 2015 ; Egerton et al. 2016 ). In particular, the fossil record of angiosperm woods in central
; Bhandari & Colin 1999 ; Whatley & Bajpai 2000 ; Bajpai & Whatley 2001 ; Dogra et al . 2004 ) and plant megaremains ( Guleria & Srivastava 2001 ). The fossilwoods of five taxa were described systematically from near Anjar, Kutch district ( Guleria & Srivastava 2001 ). Keeping in mind the poor
was thought that the Deccan Traps were younger (Eocene) and so, not surprisingly, the woods were identified by their general similarity with present-day Indian woods. Almost all Deccan woods were assigned either extant generic names or fossilwood generic names formed by adding - oxylon to an extant
The Tambopata region of the southern Peruvian Amazon supports a high diversity of both woody plants and forest types. Woods collected from low riverside vegetation, floodplain forest, clay-soil forest on an upper terrace, sandy-soil forest, and swamp forest provide an opportunity to test for significant differences in quantitative anatomical characters among forest types. Vessel-element length in floodplain-forest trees is significantly greater than in the other forest types. Specific gravity is lower in the two early-successional associations (low riverine forest and mature floodplain forest). Vessel diameter and density do not show significant differences among forest types and may be responding to overall climate controls. These two characters, however, show a pattern of variation within a transect extending back from the river along a gradient of increasing substrate and forest age; in addition, sites characterized by frequent flooding or presence of standing water lack vessels in the wider-diameter classes. The six characters analyzed show distributions that are, with the exception of wood specific gravity, significantly nonnormally distributed, a consideration that may be important in representing characteristics of assemblages of taxa. The degree of variability seen in some of the quantitative characters shows the importance of either basing analysis on adequate sample sizes or identifying robust indicators that can be used with small samples.
As the phylogeny and evolution of angiosperms is being completely rewritten by molecular data, there is renewed interest in the earliest fossil record of the group. A putative Jurassic Angiosperm wood, Suevioxylon zonatum Kräusel is revisited. We reinvestigated the type material (specimen and five thin sections) with light microscopy and SEM. This reappraisal indicates that Suevioxylon zonatum is actually a poorly preserved softwood and not an angiosperm.