Ezequiel Ignacio Vera

Fossil woods (Coniferales) from the Baqueró Group (Aptian), Santa Cruz Province, Argentina

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.

A new specimen of Millerocaulis (Osmundales: Osmundaceae) from the Cerro Negro Formation (Lower Cretaceous), Antarctica

A new petrified stem of Millerocaulis Erasmus ex Tidwell emend. Vera, collected in the Aptian Cerro Negro Formation outcrops of Livingston Island (Antarctica), is described in detail. This specimen is probably conspecific with Millerocaulis australis (Vera), from the same unit, but it is smaller than the holotype and only known specimen of the latter species. Furthermore, differences between several characteristics of both specimens are observed. A discussion based on biological aspects of this group of plants is given, taking into account the ontogenetic variability. A conservative referral of the new specimen to M. australis is preferred over the proposal of a new morphotaxon for the inclusion of the new materials.

New Species of Conifer Wood from the Baqueró Group (Early Cretaceous) of Patagonia

1Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Angel Gallardo 470, C1405DJR Buenos Aires, Argentina. 2Área de Paleontología, Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, C1428EGA Buenos Aires, Argentina. EZEQUIEL I. VERA1,2 SILVIA N. CÉSARI1