Postcranial functional adaptations in the South American Miocene borhyaenoids (Mammalia,Metatheria): Cladosictis,Pseudonotictis and Sipalocyon

Three Santacrucian borhyaenoids, Cladosictis patagonica, Pseudonotictis pusillus and Sipalocyon gracilis, are analyzed from a functional-adaptive perspective. Five extant placentals and one marsupial model are also examined in order to interpret the locomotor adaptations of these fossils. Pseudonotictis pusillus is the smallest of the Santacrucian borhyaenoids and is known from fragmentary remains; from its small size, dental specializations and elbow anatomy, this species was certainly not far ecologically from an extant weasel. The postcranium of Sipalocyon gracilis, although poorly known, suggests climbing capabilities, and the pseudo-opposable pollex indicates skilful manipulative behaviour. Cladosictis patagonica was an active predatory form, short-legged and able to climb, although it was a less specialized arboreal form than the contemporaneous Prothylacinus patagonicus; the proportions of its limbs recall that of a living South American marten, the tayra. The pseudo-opposable pollex of Cladosictis, as in Sipalocyon, indicates skilful manipulative behaviour.     

Elchaxylon,a new corystosperm based on permineralized stems from the Late Triassic of Argentina

Artabe, A.E. & Zamuner, A.B., March 2007. Elchaxylon, a new corystosperm based on permineralized stems from the Late Triassic of Argentina. Alcheringa 31, 85‐96. ISSN 0311-5518.

Anatomically preserved stems of Late Triassic corystosperms from the Río Blanco Formation of Argentina are described and assigned to Elchaxylon zavattieriae gen. et sp. nov. The polyxylic gymnospermous axes have two discontinuous cambial rings, which develop centrifugal secondary xylem and centripetal secondary xylem around the mesarch primary xylem bundles. The centrifugal undivided pycnoxylic secondary xylem incorporates uniseriate rays, uni- to biseriate radial pitting either alternate or opposite, and one or two simple pits in each cross-field. Atypical secondary growth is restricted to localized development of centripetal secondary xylem (inverted xylem). Elchaxylon could represent a basal member of the rhexoxyloid lineage. This basal clade is characterized by limited centripetal secondary xylem, lack of perimedullar bundles, and modest development of centrifugal xylem.

Analia E. Artabe [aeartabe@museo.fcnym.unlp.edu.ar] and Alba B. Zamuner [azamuer@museo.fcnym.unlp.edu.ar]. División Paleobotánica, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque SN, 1900 La Plata, Argentina and Consejo Nacional de Investigaciones Científicas y Técnicas; received 20.5.2005, revised and accepted 14.9.2005.     

Palaeontology of the Cerros Bayos section,Roca Formation (Danian), La Pampa Province,Argentina

Palynofloras from an outlier of Tertiary sediments in the One Tree Hill area north of Adelaide are nonmarine and correlate with similar assemblages from Middle Eocene North Maslin Sands from Maslin Bay and Golden Grove. Although there are similarities with time-equivalent Lower Nothofagidites asperus Zone palynofloras in the Gippsland Basin, a number of species in the South Australian palynofloras do not extend below the Late Eocene in the Gippsland sequences. This indicates earlier appearances for these species in southcentral Australia. The sediments overlie a highly weathered bedrock palaeosurface, indicating that a phase of significant weathering occurred prior to the Middle Eocene. A number of selected taxa are illustrated and their distribution in the palynofloras is discussed. Two new species, Proteacidites mildenhallii and Proteacidites parrawirrensis, are described and one species, Rhoipites byfieldensis, is emended.     

Rhexoxylon cortaderitaense (Menéndez) comb. nov., a species of permineralized stems newly assigned to the Corystospermaceae,from the Triassic of Argentina

Bodnar, J., June, 2008. Rhexoxylon cortaderitaense (Menéndez) comb. nov., a species of permineralized stems newly assigned to the Corystospermaceae, from the Triassic of Argentina. Alcheringa 32, 171–190. ISSN 0311-5518.

Anatomically preserved stems of Late Triassic corystosperms from the upper Cortaderita Formation in San Juan province, Argentina are described and assigned to Rhexoxylon cortaderitaense (Menéndez) comb. nov. These specimens were originally attributed to conifers, a group not closely related to corystosperms. The silicified axes preserve features of the cortex, pith, and secondary vascular system. Like all Rhexoxylon species, these axes have two discontinuous cambial rings that develop centrifugal secondary xylem (normal secondary xylem) and centripetal secondary xylem (inverted secondary xylem). Both types of xylem are separated by a band of parenchymatous tissue developed by a remnant cambium. The centrifugal xylem is divided by parenchymatous rays following differential cambial activity. The secondary xylem is pycnoxylic with uniseriate rays; tracheids have mainly biseriate and alternate bordered pits on radial and tangential walls, and one simple oval pit in cross-fields. The distinctive feature of R. cortaderitaense is the conspicuous amount of centripetal secondary vascular tissues not forming perimedullar bundles, this being interpreted as an apomorphic trait. This interpretation of the character modifies previous hypothesized phylogenetic relationships of corystosperm wood taxa.     

Fossil wood of the Mimosoideae from the early Paleocene of Patagonia,Argentina

Brea, M., Zamuner, A.B., Matheos, S.D., Iglesias, A. & Zucol, A.F., December, 2008. Fossil wood of the Mimosoideae from the early Paleocene of Patagonia, Argentina. Alcheringa 32, 427–441. ISSN 0311-5518.

An anatomically preserved mature stem from the Salamanca Formation (early Paleocene) at Palacio de Los Loros, central Patagonia, Argentina, is described and assigned to Paracacioxylon frenguellii sp. nov. The material was preserved by siliceous permineralization and shows features of the secondary xylem typical of subfamily Mimosoideae. This species represents the oldest record of the genus and of the Leguminosae along the western border of Gondwana, and is the world's second oldest record of Leguminosae wood. The species is characterized by ring-porous to semi-ring-porous vessels that are solitary, in multiples of 2–4 and clustered, simple perforation plates, alternate and vestured inter-vessel pitting, homocellular 1–6 seriate rays, tyloses, crystals and diffuse apotracheal, vasicentric paratracheal and confluent axial parenchyma. Paracacioxylon frenguellii has anatomical similarities to Acacia Miller. The presence of Paracacioxylon frenguellii associated with pulvinate leaves suggests that the legumes might have been a component of mesothermal forests developed along the western margin of the Golfo San Jorge Basin during the early Paleocene.     

Graptolite fauna of the Hungshihyen Formation (Early Ordovician), eastern Yunnan,China

Ordovician graptolite-bearing strata in eastern Yunnan were deposited in nearshore, shallow-water environments. Graptolites are systematically described from three sections through the Hungshihyen Formation in eastern Yunnan Province, China: (1) Hongshiya section near Ercun village, Kunming; (2) Liujiang section, Luquan; and (3) Guihuaqing Reservoir section, Luquan. The graptolite fauna, characterized by the predominance of deflexed forms, includes ten species in two genera: Baltograptus turgidus (Lee), B. varicosus (Wang), B. yunnanensis (Li), B. calidus (Ni), B. enshiensis (Ni), Baltograptus sp. cf. B. deflexus (Elles & Wood), Baltograptus sp. cf. B. bolivianus (Finney & Branisa), Baltograptus sp. A, Baltograptus sp. B and Corymbograptus v-fractus minor (Li). A detailed morphological study of these southern Chinese graptolite faunas suggests that Baltograptus wudingensis (Li) is a junior synonym of B. turgidus (Lee); Baltograptus kunmingensis (Ni) is a junior synonym of B. varicosus (Wang); and Baltograptus triangulatus (Ni) is a junior synonym of B. yunnanensis (Li). The B. varicosus Biozone is newly recognized within the middle part of the Hungshihyen Formation, replacing the former Didymograptus deflexus Biozone. This interval is well correlated to the Baltograptus jacksoni Biozone in Britain, the Tetragraptus akzharensis, ‘Baltograptus cf. deflexus’ and Didymograptus bifidus (lower part) biozones in NW Argentina (eastern Cordillera), and the Acrograptus filiformis and Didymograptellus eobifidus biozones in northern Guizhou, South China. Accordingly, the interval is of mid-Floian age, rather than late Floian as previously proposed.     

First fossil pollen record of the Northern Hemisphere species Aglaoreidia cyclops Erdtman, 1960 in Australia

Sánchez Botero, C.A., Oboh-Ikuenobe, F.E. & Macphail, M.K., 2013. First fossil pollen record of the Northern Hemisphere species Aglaoreidia cyclops Erdtman, 1960 in Australia. Alcheringa 37, 1–5. ISSN 0311-5518.

Aglaoreidia cyclops Erdtman, 1960 is a fossil pollen species associated with upper Eocene to lower Oligocene freshwater deposits in Europe and North America. Specimens preserved in upper Eocene lignites near Norseman, Western Australia, are the first record of this Northern Hemisphere species both in Australia and the Southern Hemisphere. This new report widens the biogeographic distribution originally considered for this species. The stratigraphical and environmental characteristics of A. cyclops also make it an excellent stratigraphic indicator of upper Eocene freshwater deposits in Western Australia.

Carlos A. Sánchez Botero [casmwc@mail.mst.edu], Francisca E. Oboh-Ikuenobe [ikuenobe@mst.edu] Department of Geological Sciences and Engineering, Missouri University of Science and Technology, 129 McNutt Hall, Rolla, MO 65409, USA; Mike Macphail [mike.macphail@anu.edu.au] Department of Archaeology and Natural History, College of Asia and the Pacific, Australian National University Canberra, ACT 0200, Australia. Received 12.10.2012; revised 6.3.2013; accepted 7.3.2013.     

New Archaeocyatha from the Early Cambrian of the Mt. Wright area,New South Wales

An archaeocyathan fauna from a single limestone lens in the upper Cymbric Vale Formation at Mt. Wright shows species in common with the historic Ajax Mine fauna of the Flinders Ranges, South Australia. The Cymbric Vale fauna is considered equivalent to the lower Sanashtykgol ‘horizon’ of the Altay Sayan fold belt of Siberia.

New taxa described are the genera Hyptocyathus (Inessocyathacea, Hyptocyathidae fam. nov.), Aporosocyathus (Annulocyathidae), Wrighticyathus (Sigmocyathacea, Wrighticyathidae fam. nov.), Flexicyathus (Porocoscinidae) and Bractocyathus (Polycoscinidae), and the species Erugatocyathus cymbricensis and Veronicacyathus concavus.