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Abstract: Dichotomous rachises bearing Eremopteris golondrinensis Archangelsky foliage in organic connection with probable microsporangiate structures were collected in the mid to late Permian La Golondrina Formation at Laguna Castellanos locality in southern Patagonia. The fertile bodies are receptacles slightly curved distally that bear 4–5 sessile, erect and oblong to elliptic sporangia-like bodies parallel to each other. They are fused laterally and apparently are enveloped by a delicate layer of conjunctive tissue that holds them together and have no visible dehiscence marks. These structures are here interpreted as putative microsporangiate organs. The novel information allows the emendation of the diagnosis of E. golondrinensis by adding new data on the morphology of the frond and its reproductive organs. As the genus Eremopteris has recently been emended excluding this species, a new genus, Kladistamuos with a new combination, K. golondrinensis is proposed here. Kladistamuos is therefore considered to be another SW Gondwana plant fossil of a putative ‘pteridospermous’ affinity, having distally attached fertile organs that differentiate it from the Euramerican species of Eremopteris. [Copyright &y& Elsevier]

Two types of coniferous ovulate cones borne on leafy twigs are described from the Lower Cretaceous Kachaike Formation in Santa Cruz Province, Argentina. The fossils are impressions and compressions with well-preserved cuticles. Morphology, anatomy, and ultrastructure were studied using LM, SEM, and TEM. Ovulate cones were assigned to Athrotaxis ungeri (Halle) Florin of the taxodiaceous Cupressaceae and Kachaikestrobus acuminatus gen. et sp. nov. of the Cheirolepidiaceae. This latter taxon is characterized by terminal elongate cones borne on twigs with Brachyphyllum leaves, cone scales densely and helically disposed, broad bracts with an accentuated acuminate apex fused at their bases to eight-lobed ovuliferous dwarf shoots shorter than the bracts, and an epimatium covering at least one ovule that has preserved only the outer integument and the megaspore membrane. The ultrastructure of the bract and ovuliferous dwarf shoot cuticle is composed of three layers. Comparisons of K. acuminatus with other cheirolepidiaceous ovulate cones showed closest resemblance to Hirmeriella muensteri (Schenk) Jung. These Patagonian cone scales appear to have some of the most ancestral characters in the family. By the early Albian, A. ungeri and K. acuminatus were part of a plant assemblage dominated by ferns and a few subordinate angiosperms. The finding of A. ungeri in the Kachaike Formation extends its distribution during the Lower Cretaceous in Patagonia. These fossils also show that at that time, the taxodiaceaous Cupressaceae and the Cheirolepidiaceae still were well represented in southern South America. [ABSTRACT FROM AUTHOR]