Article

Una nueva Podocarpácea fértil (Coniferal) del Cretácico inferior de Patagonia

AMEGHINIANA (Impact Factor: 1.17). 01/1990;

ABSTRACT The new genus, Morenoa fertilis from the early Cretaceous beds of the Baqueró Formation (Santa Cruz Province, Argentina) is here described. This conifer is referred to the family Podocarpaceae on account of its vegetative as well as reproductive male organs that include bisaccate pollen grains. The ultrastructure of the leaf cuticle (of the Elatocldus type) and the pollen grains (of the Podocarpidites type) was studied with transmission electron microscopy. Comparision with fossil and extant taxa of the family are also made, including the other three fossil genera known in fertile state from the same formation. The excellent preservation of the closed pollen sacs permitted the recognition of still inmature tetrads and a high inner content of Ubisch bodies. Epiphyllous fungi were also recognized on the leaf epidermis suggesting a mild and humid climatic regime.Some degradation of the leaf cuticles was observed, possibly related in part to fungal activity.

0 Followers
 · 
86 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sphenobaiera huangii (Sze) Hsü is typical Early Mesozoic fossil foliage of Ginkgoales in China. It has been recorded from the Upper Triassic to the Lower Jurassic. The cuticular anatomy is investigated based on material from the type locality, Lower Jurassic Hsiangchi Formation, Zigui County, Hubei Province. The specimens are similar to S. huangii, but contain new information about leaf morphology and cuticular anatomy. Lower and upper cuticle is investigated using light and electron microscopy (LM, SEM, and TEM). Many features are described for the first time, including general structures of lower and upper cuticle, stomata, papillae, and cuticular ultrastructure. At the ultrastructural level, two layers have been distinguished in both lower and upper cuticle, including a homogeneous outer layer with granules and a heterogeneous inner layer with fibrils. Based on a literature comparison between S. huangii and other relevant species of Sphenobaiera, S. huangii may represent the best-known taxon in the genus Sphenobaiera in both leaf morphology and cuticular structures. This study provides the first detailed ultrastructural data on the leaf cuticle of Sphenobaiera, one of the oldest foliage taxa of Ginkgoales, and offers further evidence for potential discussion on the taxonomic relationships of S. huangii with other ginkgoalean taxa.
    American Journal of Botany 04/2005; 92(4):709-21. DOI:10.3732/ajb.92.4.709 · 2.46 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Two new conifer morphospecies represented by a secondary xylem are reported for the Lower Cretaceous Baqueró Group (Santa Cruz Province, Argentina). Agathoxylon sp. is characterized by poorly defined growth rings, predominantly uniseriate pitting in the radial wall of the tracheids, cross fields with 1-6 pits and uniseriate rays. These features are shared with the leafy branches described for the unit as Araucaria grandifolia Feruglio emend. Del Fueyo and Archangelsky. The second taxon, Brachyoxylon sp. cf. B. boureaui, possesses poorly defined growth rings, mixed wood with predominantly uniseriate radial pitting, cross fields with 8-26 pits and uniseriate rays. These taxa represent the first fossil woods described for Baqueroan strata.
    Anais da Academia Brasileira de Ciências 07/2012; 84(3):617-26. DOI:10.1590/S0001-37652012005000047 · 0.88 Impact Factor
  • Review of Palaeobotany and Palynology 08/1995; 87(2):81-323. DOI:10.1016/0034-6667(95)93235-X · 1.66 Impact Factor