Cretaceous Wood Research Articles

Similarities and Differences in Dicotyledonous Woods of the Cretaceous and Paleocene. San Juan Basin, New Mexico, Usa

Fossil wood is common in the Late Cretaceous and Early Paleocene of the San Juan Basin, New Mexico. Six types of dicotyledonous wood are recognized: Paraphyllanthoxylon arizonense Bailey, Paraphyllanthoxylon anasazi sp. nov., Plataninium piercei sp. nov., Metcalfeoxylon kirtlandense gen. et sp. nov., Chalkoxylon cretaceum gen. et sp. nov., Carlquistoxylon nacimientense gen. et sp. nov. Woods with the characteristics of Paraphyllanthoxylon arizonense Bailey are the most common and occur in the Cretaceous Kirtland Shale and the Paleocene Ojo Alamo Sandstone and Nacimiento Formation. This wood type's characteristics are stable from the Cretaceous to the Paleocene. There were no significant differences in the vessel diameters, vessel densities, ray sizes, or estimated specific gravities of the P. arizonense woods from the Late Cretaceous (Kirtland Shale) and Early Paleocene (Nacimiento Formation and Ojo Alamo Sandstone). Based on the samples examined for this study, dicotyledonous woods were more diverse in the Cretaceous (five types) than in the Paleocene (two types) of the San Juan Basin. Diameters of the Cretaceous woods examined ranged from 14-40cm indicating they were trees rather than shrubs; diameters of the Paleocene woods examined ranged from 10-80cm. All the woods have generalized structure with combinations of features seen in more than one extant family, order, or subclass. Information from databases for fossil and extant woods indicates that some combinations of features (e. g., solitary narrow vessels, low vessel density and scalariform perforation plates, as seen in Metcalfeoxylon kirtlandense and Chalkoxylon cretaceum), while relatively common in the Cretaceous, represent strategies of the hydraulic system that are extremely rare in the Tertiary and at present. None of the dicotyledonous woods have distinct growth rings, although some samples of Paraphyllanthoxylon arizonense from the Paleocene show variations in vessel density and vessel diameter that may correspond to seasonal variations in water availability.

Dicotyledonous woods from the Upper Cretaceous of southern Illinois

Five species of fossil dicotyledonous wood are described from an Upper Cretaceous (Maestrichtian; locality in Alexander County, IllinoiS. U.S. A.Paraquercimum cretaceum has structure similar to the Fagaceae (evergreen Oak-Lithocarpus) and Casuarinaceae and represents the earliest known occurrence of this structural type (large solitary pores and uniseriate and large multiseriale rays).Paraphyltanthoxyhin illirioisense and Icacinoxylon alternipunctata are species of genera represented at other Cretaceous and Early Tertiary localities In large diameter trees.Parabombacaceoxylon magniporosum has large diameter pores and scalariform perforation plates, a combination of characters that is extremely rare in the extant flora.Paraapocynaceoxylon barghoorni has a combination of characters represented in extant Apocynaceae. These five species lack growth rings, have high vulnerability indices (mean vessel diameter divided by mean number of vessels per square millimeter, and a relatively high proportion of ray parenchyma. They lack specialized wood anatomical characters, and a compilation of vessel element lengths in these and other Cretaceous woods indicates that short vessel elements (a derived character) were less frequent in the Cretaceous than in extant dicotyledonous trees.

Angiosperm Wood from the Upper Cretaceous of Central California: Part I

This paper is the first in a series about a collection of 40 Upper Cretaceous woods from central California. The wood is in the form of fragments of stems and roots embedded in nodules of collophane rich in microorganisms, pollen, and spores. Two new species are described: Ulminium pattersonensis and Ulminium mulleri. Evidence presented indicates that these two specimens are similar to woods of the Lauraceae and fall well within the range of variation of woods of that family. Because the taxonomy of the Lauraceae is in need of revision, meaningful comparisons of fossil plant parts with modern taxa were found to be unfeasible.

ANGIOSPERM WOOD FROM THE UPPER CRETACEOUS OF CENTRAL CALIFORNIA: PART I

This paper is the first in a series about a collection of 40 Upper Cretaceous woods from central California. The wood is in the form of fragments of stems and roots embedded in nodules of collophane rich in microorganisms, pollen, and spores. Two new species are described: Ulminium pattersonensis and Ulminium mulleri. Evidence presented indicates that these two specimens are similar to woods of the Lauraceae and fall well within the range of variation of woods of that family. Because the taxonomy of the Lauraceae is in need of revision, meaningful comparisons of fossil plant parts with modern taxa were found to be unfeasible.

The Basal Rocks of the Tertiary at Uloa, Zululand, South Africa

AbstractAt Uloa in Zululand a nodule bed is the basal formation of a thin group of Tertiary sediments that rests on nearly horizontal Senonian silty mudstones. It contains mammillary, botryoidal, and cylindrical nodules, remanié Lower and Upper Cretaceous mollusca all ferruginized and partly pyritized, silicified Cretaceous wood, worn Tertiary sharks' teeth, and cetacean bone, phosphatized nodules of both Upper Cretaceous and Victoriella-bearing Eocene, and Tertiary glauconitic sandstone pebbles dated at 55 million years.A coquina-like limestone (“Pecten Bed”) overlies the irregular upper surface of the nodule bed disconformably. Consideration of some of the megafossils, the absence of larger Foraminifera, and the presence of Orbulina universa suggest that the “Pecten Bed” is Middle to Upper Miocene in age.Alternations of coarse and fine grained calcarenite layers that overlie the “Pecten Bed” disconformably, may be of youngest Miocene age.The nature of the Tertiary rocks suggests shallow water sedimentation from the Eocene to latest Miocene, with several periods of transgression and regression, and slight epeirogenic or eustatic movement only.