The species of the brachiopod genus Terebratella d'Orbigny, which does not correspond to any one reported hitherto from the upper Eocene-? lower Oligocene La Meseta Formation of Seymour Island, West Antarctica but showing a strong affinity to the Recent T. inconspicua (Sowerby), is described.
Epifaunal organisms (bryozoans, foraminifera, serpulid polychaetes, cirripeds, octocorals), scratch marks and borings (brachiopod pedicle attachment traces and gastropod, phoronid, sponge and algal boreholes) were recognized on the brachiopod shells from the Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula. They are rare and occur only on about 10% of shells. It is probable that environmental conditions were not suitable for epibionts whose requirements were to be higher than those of brachiopods. The rarity of epifauna on the dead shells can be explained by their rapid burial.
Defining species boundaries, due to morphological variation, often represents a significant challenge in paleozoology. In this paper we report results from multi− and univariate data analyses, such as enhanced clustering techniques, principal coordinates ordination method, kernel density estimations and finite mixture model analyses, revealing some morphometric patterns within the Eocene Antarctic representatives of Palaeeudyptes penguins. These large−sized birds were represented by two species, P. gunnari and P. klekowskii , known mainly from numerous isolated bones. Investigations focused on tarsometatarsi, crucial bones in paleontology of early penguins, resulted in a probability−based framework allowing for the “fuzzy” partitioning the studied specimens into two taxa with partly overlapping size distributions. Such a number of species was supported by outcomes from both multi− and univariate studies. In our opinion, more reliance should be placed on the quantitative analysis of form when distinguishing between species within the Antarctic Palaeeudyptes .
Planktonie foraminifera of the genera Chiloguembelina Loeblich and Tappan. Globigerina d'Orbigny and Globorolalia Cushman are reported from glacio-marine sediments of the Low Head Member (Polonez Cove Formation, Oligocene) of King George Island (South Shetland Islands). West Antarctica. The foraminifer assemblage comprises two stratigraphically important species: Globigerina angiporoides Hornibrook and Chiloguembelina cubensis (Palmer), which indicate the Upper Eocene — Lower Oligocene age. Taking into account specific composition, this planktonie assemblage may tentatively be correlated with the Globigerina angiporoides Zone of New Zealand. Australia. South Pacific and South Atlantic, which belongs to the Lower Oligocene (see Jenkins 1985).
Whale bones from the upper Eocene — ?lower Oligocene La Meseta Formation of Seymour (Marambio) Island, West Antarctica, are assigned to the Archaeoceti. They most probably belong to an undetermined genus of the family Basilosauridae Cope. 1867; subfamily Dorudontinae Barnes and Mitchel. 1978.
Fossil bird remains assignable to ratites (palaeognathous birds) are described from the Paleogene strata of the La Meseta Formation of Seymour Island, Antarctic Peninsula. This record sheds new light on Gondwana's avian history.
Here are reported the first certainly indigenous agglutinated foraminifera known for the Eocene La Meseta Formation on Seymour Island, West Antarctica. The specimens were identified as Textularia sp. and occur in the upper portion of the unit, just below the contact with the overlying post-Eocene deposits. Despite being rare, the specimens are interpreted as autochthonous or parautochthonous due to their overall good preservation, fragility, and lack of sedimentary filling. The La Meseta Formation seems to have passed through a major diagenetic dissolution of calcareous microfossils, but the present findings suggest that indigenous agglutinated foraminifera can be found at least in some of its strata.
Basing on isolated vertebrae, fossil fishes of the order Gadiformes have been first discovered in sediments of the La Meseta Formation (upper Eocene — ?lower Oligocene) on Seymour (Marambio) Island, West Antarctica. This is one of the oldest and the only locality with the Gadiformes skeletal remains in the Southern Hemisphere. Other poorly preserved centra have been determined as Teleostei (order incertae sedis).
The synsacrum is an important element of the axial skeleton in birds, both volant and flightless. Little is known about the maturation of this complex bone in penguins. In this work, the supposedly ontogenetically youngest known synsacrum of early penguins was described. The analysis of this specimen, collected within the Eocene La Meseta Formation of Seymour (Marambio) Island, Antarctic Peninsula, revealed that this bird had attained at least the fledging stage of growth. Studies of three mature synsacra recovered from the same formation focused on the synsacral canals and, using indirect reasoning, their contents. These analyses revealed that the lumbosacral intumescence of the spinal cord and its extensions, the transverse canals, had been developed roughly like those in extant penguins (and also swifts and cormorants). The neural spine extensions (a non−nervous tissue) tracing the transverse grooves of the dorsal wall of the synsacral canal are currently considered as involved in the control of walking. The presented data suggest that such a sense organ gained its current penguin configuration by the late Eocene.