Diversity of pseudo-toothed birds (Pelagornithidae) from the Eocene of Antarctica

2015 ◽  
Vol 89 (5) ◽  
pp. 870-881 ◽  
Author(s):  
Marcos Cenizo ◽  
Carolina Acosta Hospitaleche ◽  
Marcelo Reguero
Keyword(s):  
Terminal Group ◽  
Lower Eocene ◽  
Early Oligocene ◽  
Large Size ◽  
La Meseta Formation ◽  
Size Type ◽  
Giant Size ◽  
Phylogenetic Affinities ◽  
The Antarctic ◽  
Seymour Island

AbstractThe Antarctic pelagornithid record is restricted to few isolated remains from the Eocene of Seymour Island in the Antarctic Peninsula. Here we report the oldest Antarctic pseudo-toothed bird. It is represented by an incomplete humerus lacking its proximal end, which comes from the lower Eocene levels of the La Meseta Formation (Seymour Island). This new specimen facilitates a review of all known pelagornithids from this continent. Antarctic pelagornithids were classified into two morphotypes that exhibit a mix of putative plesiomorphic and derived characters. Considering the worldwide pelagornithid record and according to estimated wingspans, four approximate size-types were identified. The oldest Antarctic specimens (two fragmentary humeri, middle Ypresian) were assigned to morphotype 1 and correspond to the large size-type. The younger materials (Bartonian/?Priabonian) here assigned to morphotype 2 (some cranial remains, fragmentary tarsometatarsus and humerus) correspond to the giant size-type and represent one of the largest known pseudo-toothed birds. Even though species level phylogenetic affinities of Pelagornithidae remain poorly resolved, three key evolutionary events can be recognized: (1) the disappearance ofDasornisin the Early Eocene and the appearance of more advanced forms with a trend to the specialization of large soaring capacity, (2) the origin ofPelagornissensu lato species in the early Oligocene, and (3) the appearance and dominance of a highly specialized terminal group at Mio/Pliocene time span.

The youngest record of fossil land mammals from Antarctica; its significance on the evolution of the terrestrial environment of the Antarctic Peninsula during the late Eocene

1997 ◽  
Vol 71 (2) ◽  
pp. 348-350 ◽  
Author(s):  
S. F. Vizcaino ◽  
M. Bond ◽  
M. A. Reguero ◽  
R. Pascual
Keyword(s):  
Antarctic Peninsula ◽  
Present Note ◽  
Late Eocene ◽  
South American ◽  
Terrestrial Environment ◽  
Shallow Marine ◽  
Early Oligocene ◽  
La Meseta Formation ◽  
The Antarctic ◽  
Seymour Island

The record of fossil land mammals from Antarctica has been restricted previously to the middle levels of the Eocene-?early Oligocene La Meseta Formation in Seymour Island, Antarctic Peninsula. This mostly shallow-marine sequence was divided informally into seven subunits (Tertiary Eocene La Meseta or TELM 1 to 7) by Sadler (1988). Land mammals, representing South American lineages of marsupials, edentates, and ungulates were recovered from TELM 3, 4, and 5 (Marenssi et al., 1994; Vizcaíno et al., 1994). The purpose of the present note is to report the discovery of a well-preserved ungulate tooth from the uppermost level of the La Meseta Formation (TELM 7) and to discuss its paleoenvironmental implications.

Eocene crinoids from Seymour Island, Antarctic Peninsula: paleobiogeographic and paleoecologic implications

1993 ◽  
Vol 67 (2) ◽  
pp. 250-257 ◽  
Author(s):  
David L. Meyer ◽  
Tatsuo Oji
Keyword(s):  
Antarctic Peninsula ◽  
Surface Waters ◽  
Systematic Position ◽  
La Meseta Formation ◽  
Mode Of Life ◽  
The Antarctic ◽  
Favorable Temperature ◽  
A New Species ◽  
Seymour Island ◽  
Water Facies

On the basis of recent collections from the Upper Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula, the morphology, systematic position, taphonomy, and paleoecology of the isocrinid Metacrinus fossilis are investigated. A new species, Notocrinus rasmusseni, is described as the first comatulid crinoid known from the Antarctic fossil record. The systematic assignment of M. fossilis is maintained. Basal abrasion of calyxes and absence of long attached columns suggest that M. fossilis might have lost most of the column in adult stages and lived directly on the substratum, supported by some arms and a few cirri, similar to comatulids. About 10 percent of M. fossilis individuals show brachial regeneration, in contrast to regeneration frequencies of 70–90 percent among modern Japanese isocrinids. The anomalous occurrence of isocrinids in shallow-water facies of the La Meseta is attributed to a combination of reduced predation pressure, the presumed stalkless mode of life, and a favorable temperature regime in Antarctic surface waters prior to the onset of cooling at the close of the Eocene.

Note on the Antarctic Tertiary brachiopods and museum registry of specimens described by E. F. Owen, 1980

1989 ◽  
Vol 63 (6) ◽  
pp. 955-955
Author(s):  
William J. Zinsmeister
Keyword(s):  
Natural History ◽  
Austral Summer ◽  
British Museum ◽  
Late Eocene ◽  
British Antarctic Survey ◽  
La Meseta Formation ◽  
The Antarctic ◽  
Seymour Island

During the course of fieldwork by a joint Argentine-American expedition to Seymour Island (Elliot et al., 1975) during the austral summer of 1974-1975, a number of brachiopods were collected from the Late Eocene La Meseta Formation. A representative collection of these brachiopods was sent to E. F. Owen, Department of Palaeontology, British Museum (Natural History) for study. Owen (1980) published a revision of the brachiopods from Seymour and nearby Cockburn Islands. The study was based on material collected by W. N. Croft of the Faulkland Islands Dependencies Survey (now British Antarctic Survey) and the material which I sent.

Late Eocene gadiform (Teleostei) skull from Seymour Island, Antarctic Peninsula

1991 ◽  
Vol 3 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Joseph T. Eastman ◽  
Lance Grande
Keyword(s):  
Antarctic Peninsula ◽  
Late Eocene ◽  
Climatic Conditions ◽  
Convincing Evidence ◽  
Posterior Half ◽  
Antarctic Region ◽  
La Meseta Formation ◽  
The Antarctic ◽  
First Time ◽  
Seymour Island

On the basis of a skull from the late Eocene La Meseta Formation on Seymour Island, Antarctic Peninsula, a gadiform fish is reported from the Antarctic region for the first time. This specimen, the most completely preserved fossil teleost cranium yet described from Antarctica, provides convincing evidence for the presence of Gadiformes in a far southerly location under temperate climatic conditions 40 m.y. ago. The exoccipital condyles, supraoccipital and lambdoidal crests, and post-temporal and supratemporal fossae are well preserved, as are the roofing bones on the posterior half of the skull. Comparative osteological study indicates that these features are very similar in appearance to those of merlucciids (hakes) and gadids (cods).

Antarctomithrax thomsoni,a new genus and species of crab (Brachyura; Majidae) from the La Meseta Formation (Eocene) of Seymour Island, Antarctica

1994 ◽  
Vol 68 (1) ◽  
pp. 174-176 ◽  
Author(s):  
Rodney M. Feldmann
Keyword(s):  
Antarctic Peninsula ◽  
Late Cretaceous ◽  
New Genus ◽  
High Energy ◽  
Lower Latitude ◽  
Decapod Crustaceans ◽  
New Genus And Species ◽  
La Meseta Formation ◽  
The Antarctic ◽  
Seymour Island

The james ross basin, situated on the eastern margin of the Antarctic Peninsula, has yielded an extensive fauna of decapod crustaceans spanning Late Cretaceous through Eocene time. To date, 28 species in 22 genera and 18 families have been described (Feldmann, 1992; Feldmann, Tshudy, and Thomson, 1993), making this the most diverse fossil decapod fauna in the Southern Hemisphere. Within the basin, Seymour Island alone contains rocks of the Eocene age La Meseta Formation from which seven species of crabs, one galatheid, and one species of callianassid ghost shrimp have been described (Feldmann and Zinsmeister, 1984; Feldmann and Wilson, 1988; Feldmann, 1992). The fauna of the La Meseta is remarkable also because, although the organisms are preserved in rocks deposited in moderate- to high-energy, shallow-water habitats (Elliot and Trautman, 1982), many of the species represent early occurrences of taxa with living descendants that are characteristic of deeper water, lower latitude habitats (Zinsmeister and Feldmann, 1984).

An additional record of a placental mammal (Order Astrapotheria) from the Eocene of West Antarctica

1992 ◽  
Vol 4 (1) ◽  
pp. 107-108 ◽  
Author(s):  
J.J. Hooker
Keyword(s):  
Antarctic Peninsula ◽  
Present Note ◽  
Late Eocene ◽  
The Other ◽  
West Antarctica ◽  
La Meseta Formation ◽  
James Ross Island ◽  
The Subject ◽  
The Antarctic ◽  
Seymour Island

Recently, fossil land mammals have been recorded in the James Ross Island area, east of the Antarctic Peninsula, from the marine middle-late Eocene strata of Seymour Island. These include two endemic species of polydolopid marsupial: Antarctodolops dailyi Woodburne & Zinsmeister 1984, and Eurydolops seymourensis Case, Woodburne & Chaney 1988, and three partly determinate placentals identified as a tardigrade edentate, a sparnotheriodontid litoptern and a trigonostylopid astrapothere (Bond et al. 1989). The marsupials are represented by fragmentary jaw and complete dental material, the litoptern and astrapothere only by tooth fragments. All are recorded from Unit TELM 5 of the La Meseta Formation (Sadler 1988), the two ungulates at a lower level than the rest. The subject of the present note is a second tooth fragment from Seymour Island identified as an astrapothere. It is worth recording because such mammal remains are rare and it is from TELM 4, the unit below that yielding the other land mammals.

Review of fossil penguins from Seymour Island

1971 ◽  
Vol 178 (1053) ◽  
pp. 357-387 ◽  
Keyword(s):  
New Zealand ◽  
Indirect Evidence ◽  
Late Eocene ◽  
Valid Species ◽  
The North ◽  
Early Oligocene ◽  
North Eastern ◽  
The Antarctic ◽  
Early Late ◽  
Seymour Island

Two collections of fossil penguins have been made from Seymour Island, off the north-eastern end of the Antarctic Peninsula, one by a Swedish expedition in 1901-1903 and the other by a British expedition in 1946. The age has usually been considered early Miocene but is probably earlier, late Eocene now seeming most likely but still uncertain. Wiman in 1905 based six then new generic and specific names on the Swedish collection Anthropornis nordenskjoeldii and Delphinornis larsenii are considered valid. Pachypteryx grandis is a valid species but is transferred to Anthropornis. Eosphaeniscus gunnari is a valid species transferred to Palaeeudyptes , a genus otherwise known from New Zealand and Australia. Orthopteryx gigas and Ichtyopteryx gracilis are considered essentially indeterminate, as are two groups of bones not named by Wiman. Marples named genus and species Notodyptes wimani from the British collection. The species is accepted but transferred to the New Zealand genus Archaeospheniscus. Wimanornis seymourensis , new genus and species, is based on a British specimen. This penguin fauna is essentially similar to the early (late Eocene and early Oligocene) faunas known from New Zealand. In the probable absence of species in common, geographic proximity is not indicated. The ecological similarity and some indirect evidence suggest that despite the presence of relative gigantism these penguins lived in considerably warmer waters than those of the present Antarctic coast.

Short Note: An intriguing penguin bone from the Late Eocene of Seymour Island, Antarctic Peninsula

2008 ◽  
Vol 20 (6) ◽  
pp. 589-590 ◽  
Author(s):  
Piotr Jadwiszczak
Keyword(s):  
Antarctic Peninsula ◽  
Short Note ◽  
Late Eocene ◽  
New Genus And Species ◽  
Type Specimens ◽  
West Antarctic ◽  
Antarctic Convergence ◽  
La Meseta Formation ◽  
The Antarctic ◽  
Seymour Island

Penguins (Aves: Sphenisciformes) are interesting to both neontologists and palaeontologists (e.g. Davis & Renner 2003). The fossil record of these extremely specialized inhabitants of the Southern Hemisphere extends back to the Palaeocene epoch (Slack et al. 2006). Extinct penguins are known from localities within the range of their modern-day relatives (Fordyce & Jones 1990), and the oldest diverse assemblage comes from the Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula, the only such locality south of the Antarctic Convergence (Myrcha et al. 2002, Jadwiszczak 2006a). Several collections amounting to over three thousand bones (mainly isolated skeletal elements) have been acquired since 1901 from that formation, and 15 penguin species have been erected so far (Jadwiszczak 2006a, table 1, Tambussi et al. 2006). Only ten of them (grouped into six genera) appear to be taxonomically distinct, and their type specimens are tarsometatarsi (Simpson 1971, Myrcha et al. 2002, Jadwiszczak 2006a, 2006b, p. 296). Individuals from six species belonging to four genera most probably were not larger than those of Aptenodytes forsteri G.R. Gray, 1844, the heaviest and tallest extant penguin (Jadwiszczak 2001, table 3). Interestingly, representatives of all ten species may have co-existed in the West Antarctic during the Late Eocene epoch, just prior to the final break-up of Gondwana (Jadwiszczak 2006a). Presented here is an intriguing partial tarsometatarsus of a small-sized penguin from the Late Eocene of Antarctic Peninsula, probably representing a new genus and species.

First articulated teleost fish from the Paleogene of West Antarctica

1991 ◽  
Vol 3 (3) ◽  
pp. 309-316 ◽  
Author(s):  
Anna Jerzmańska
Keyword(s):  
Teleost Fish ◽  
Phylogenetic Relationships ◽  
Upper Eocene ◽  
West Antarctica ◽  
Lower Oligocene ◽  
La Meseta Formation ◽  
Similarities And Differences ◽  
The Antarctic ◽  
Precise Assessment ◽  
Seymour Island

Marambionella andreae gen. et sp. nov. from the La Meseta Formation (Upper Eocene–?Lower Oligocene) on Seymour Island is the first fossil clupeid found in Antarctica and the first articulated teleost from the Antarctic Paleogene. It shows a mosaic of similarities and differences compared with various clupeid genera. This and the uncertainty about the polarity of characters within clupeids do not allow precise assessment of the phylogenetic relationships of Marambionella.

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