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Conifer remains including petrified wood resembling Sequoia, and leafy shoots and seed cone scales of Glyptostrobus (Cupressaceae s.l.) were found in the late Paleocene Fort Union Formation (Tongue River Member) in the Powder River Basin of Wyoming, northwestern USA. These findings indicate either a wider distribution of both Sequoia and Glyptostrobus in the late Paleocene compared with narrow habitat of modern genera, or possibly that Glyptostrobus-like cones were borne on trees with wood resembling that of Sequoia. The well-preserved wood is assigned to the new species Sequoioxylon carneyvillense sp. n. while the cone fragments and foliage are assigned to Glyptostrobus europaeus (Brongniart) Unger. Wood anatomical features of extant cupressaceous genera including Glyptostrobus, Metasequoia, Sequoia, Sequoiadendron and Taxodium were studied to provide more information for the identification of fossils.

Petrified wood is important evidence of forest type and past climate. Studies from mainly the Neogene of Turkey described many fossil woods, and revealed valuable information about the paleoenvironment structure and climate. This is the first occurrence of plant macrofossils belonging to the Middle Miocene Climate Optimum, a crucial period in Earth's history, found in Turkey. The purpose of the present study is to investigate, for the first time, the Middle Eocene Climate Optimum of Turkey through the first identification of two paleoxylotomical findings of Lutetian age from Central-North Turkey. After working on the thin wood sections, a new fossil genus of Lauraceae, Actinodaphnoxylon gen. nov. was described with a type species of Actinodaphnoxylon zileensis sp. nov. Another coniferous specimen was described as Pinuxylon cf. P. tarnocziense. These species indicate the presence of warm, humid rainforest and lower mountain forest 40–41 million years ago in the middle Black Sea region (Tokat-Zile) of North-Central Turkey.

Descriptions, comparisons and affinities are given for the following Late Eocene–Early Miocene new, to Egypt, records: Palmoxylon compactum Sahni, Palmoxylon geometricum Sahni, Palmoxylon indicum Sahni, Palmoxylon pondicherriense Sahni, Palmoxylon pyriforme Sahni, Palmoxylon rewahense Sahni and Palmoxylon wadiai Sahni. Comments on the geologic ages of the compared Palmoxylon species, Indian Plate migration, palaeogeography and palaeoclimates are given.

Hundreds of silicified standing stumps have been discovered within a lignitic horizon in the middle of the Tienen Formation near Hoegaarden in northeast Belgium. The anatomical features of the fossil stumps, as those of the numerous silicified secondary xylem remains collected since the last century from this area, demonstrate that they all belong to a single taxodiaceous taxon. The stumps bear characteristics shared by Taxodioxylon gypsaceum and Glyptostroboxylon tenerum, but affinities with the latter appear closer. They are attributed to Glyptostroboxylon sp. Calibration of the sedimentological, stratigraphical and organic carbon isotope data reveals that these taxodiaceous fossil trees developed in a swampy lowland environment most probably during the Initial Eocene Thermal Maximum at ca. 55 Ma.

A permineralized specimen of Prototaxites Dawson collected from the Upper Devonian Cleveland Shale in Cuyahoga County, Ohio, is grayish black, resembling decorticated, petrified wood. Cellulose acetate peels and ground sections show only the medullary region, consisting of wide and narrow, densely crowded tubes, almost all running parallel, and some oblique, to the long axis of the specimen. The tubes are thick-walled, two-layered, with longitudinal furrowa on the inner surface, septate, showing successive branching, some branches anastomosing. Thin-walled septate branched filaments are present in the intertubal spaces and also cover the tubes; small areas of disintegrated tubes are present all over. Structural details of the tube wall observed with SEM, coupled with other characters, when compared with the structurally known species of Prototaxites, warrant a new name for the Cleveland specimen: P. clevelandensis sp. nov.

Thirteen species of petrified wood have been assigned previously to the genus Paraphyllanthoxylon which was established by Bailey (1924) as representative of the section Phyllanthoideae of the family Euphorbiaceae. Madel (1962) considered the genus Paraphyllanthoxylon representative of only the Glochidion wood group of the section Phyllanthoideae. This necessitates the establishment of a new genus, Phyllanthoideoxylon , for fossil woods which have characteristics in common with several of the other wood groups in the section Phyllanthoideae. The thirteen previously identified species of Paraphyllanthoxylon are reviewed and compared with the characteristics of the genus. Eleven of these species are retained in Paraphyllanthoxylon Bailey (emend. Madel), one ( P. bangalamodense ) is assigned to Phyllanthoideoxylon nov. gen. and one ( P. keriense ) is transferred to Bridelioxylon Ramanujam.

A collection of petrified wood from the Lower Pliocene Ogallala Formation in western Oklahoma was examined. All specimens appear to be of the same taxon and exhibit features of extant Robinia species. To date, four fossil wood species of Robinia have been described. The relationship of Robinioxylon zuriensis Falqui to Robinia is doubtful because of the lack of diagnostic critical features. The remaining three, Robinia alexanderi Webber, Robinia breweri Prakash, Barghoorn and Scott, and Robinioxylon zirkelii (Platen) Muller-Stoll and Madel do show affinity to Robinia and all have been noted as structurally similar to R. pseudoacacia . The Oklahoma woods and these three fossil species show considerable overlap in quantitative features and are identical in qualitative features. Examination of different sections (and specimens) of extant Robinia pseudoacacia wood reveals quantitative and qualitative variation similar to that found amongst the petrified woods. Robinia alexanderi , Webber, R. breweri Prakash, Barghoorn and Scott, R. zirkelii (Platen) Muller-Stoll and Madel, and the Oklahoma specimens are considered to be conspecific as the differences between these fossil wood species are no different from those accounted for by variation within a single living species, R. pseudoacacia .

This investigation identifies the abundant petrified wood found in the basal Diablo Member of the Palm Spring Formation, Anza Borrego Desert State Park. Three families of temperate hardwood trees are recognized from the fossil wood cell structure. The Lauraceae represented by Umbellularia , the Salicaceae with specimens of Populus and Salix , and the Juglandaceae represented by Juglans . A review of the paleontologic and paleomagnetic literature establishes the base of the Diablo Member at approximately 3.8 m.y.B.P. with continued deposition for 1.2 m.y. The unique paleobotanical assemblage found in the Diablo Member together with the floral ecology of present-day equivalents reflects a temperate climate with ocean influence and predominantly winter rainfall in this region during the Lower Pliocene Epoch.