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.

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.

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).

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.

scholarly journals New mammalian and avian records from the late Eocene La Meseta and Submeseta formations of Seymour Island, Antarctica

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8268
Author(s):  
Sarah N. Davis ◽  
Christopher R. Torres ◽  
Grace M. Musser ◽  
James V. Proffitt ◽  
Nicholas M.A. Crouch ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Global Climate ◽  
Late Eocene ◽  
Eastern Coast ◽  
Ice Cap ◽  
Postcranial Remains ◽  
Circumpolar Current ◽  
The Antarctic ◽  
Insight Into ◽  
Seymour Island

The middle–late Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life in the high latitudes responded to this climatic shift is provided by the fossil record from Seymour Island, near the eastern coast of the Antarctic Peninsula. While extensive collections have been made from the La Meseta and Submeseta formations of this island, few avian taxa other than penguins have been described and mammalian postcranial remains have been scarce. Here, we report new fossils from Seymour Island collected by the Antarctic Peninsula Paleontology Project. These include a mammalian metapodial referred to Xenarthra and avian material including a partial tarsometatarsus referred to Gruiformes (cranes, rails, and allies). Penguin fossils (Sphenisciformes) continue to be most abundant in new collections from these deposits. We report several penguin remains including a large spear-like mandible preserving the symphysis, a nearly complete tarsometatarsus with similarities to the large penguin clade Palaeeudyptes but possibly representing a new species, and two small partial tarsometatarsi belonging to the genus Delphinornis. These findings expand our view of Eocene vertebrate faunas on Antarctica. Specifically, the new remains referred to Gruiformes and Xenarthra provide support for previously proposed, but contentious, earliest occurrence records of these clades on the continent.

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.

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.

Record of Late Miocene glacial deposits on Isla Marambio (Seymour Island), Antarctic Peninsula

2009 ◽  
Vol 22 (2) ◽  
pp. 193-198 ◽  
Author(s):  
Sergio A. Marenssi ◽  
Silvio Casadío ◽  
Sergio N. Santillana
Keyword(s):  
Antarctic Peninsula ◽  
Late Miocene ◽  
Late Eocene ◽  
Weddell Sea ◽  
Volcanic Group ◽  
Lower Oligocene ◽  
La Meseta Formation ◽  
James Ross Island ◽  
Stratigraphic Sequences ◽  
Seymour Island

AbstractWe report and describe two new small diamictite outcrops on Isla Marambio (Seymour Island), Antarctic Peninsula. These rocks rest on an erosional unconformity on top of the Eocene La Meseta Formation and are unconformably covered by glaciomarine rocks of the ?Pliocene–Pleistocene Weddell Sea Formation. The lithology, fossil content and isotopic ages obtained strongly suggest that the rocks belong to the Hobbs Glacier Formation and support a Late Miocene age for this unit. Additionally, the dated basalt clast provides the oldest age (12.4 Ma) for the James Ross Island Volcanic Group recorded up to now. The here described diamictite cannot be confidently correlated with a glaciomarine unit previously assigned to the Late Eocene–Lower Oligocene taken as proof that initial expansion of ice on Antarctica encompassed the entire continent synchronously in the earliest Oligocene. However, it is now evident that there are likely to be more, short but important, stratigraphic sequences of key regional and Antarctic wide interest preserved on the plateau of Isla Marambio.

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.

Eocene microplankton from La Meseta Formation, northern Seymour Island

1992 ◽  
Vol 4 (3) ◽  
pp. 355-362 ◽  
Author(s):  
Christopher D. Cocozza ◽  
Ciara M. Clarke
Keyword(s):  
Late Eocene ◽  
Early Eocene ◽  
Shallow Marine ◽  
Dinoflagellate Cyst ◽  
Two Samples ◽  
Low Diversity ◽  
La Meseta Formation ◽  
Marine System ◽  
Near Shore ◽  
Seymour Island

Twenty two samples collected from the Tertiary La Meseta Formation of Cape Wiman, Seymour Island, Antarctic Peninsula yielded abundant and moderately diverse assemblages of marine palynoflora, dominated by dinoflagellate cysts, together with acritarchs and chlorophyta. The assemblages can be divided into three association: Association 1, characterized by low diversity dinoflagellate assemblage of late Early Eocene age which are dominated by Enigmadinium cylindrifloriferum; Association 2 characterized by more diverse dinoflagellate cyst assemblages, which show a marked decrease in the dominance of E. cylindrifloriferum, and an increase in relative abundance of Areosphaeridium cf. diktyoplokus; and Association 3 which is characterized by a decrease in dinoflagellate cyst diversity up section. Changes in dinoflagellate cyst dominance and diversity throughout the section suggests a gradation from a stressed, shallow marine palaeoenvironment to a more open near-shore, shallow marine system becoming progressively more nearshore up section. The assemblages are no older than late Early Eocene in age, and possibly as young as Mid–Late Eocene.

An Eocene tardigrade (Mammalia, Xenarthra) from Seymour Island, West Antarctica

1995 ◽  
Vol 7 (4) ◽  
pp. 407-408 ◽  
Author(s):  
Sergio F. Vizcaíano ◽  
Gustavo J. Scillato-Yané
Keyword(s):  
Antarctic Peninsula ◽  
West Antarctica ◽  
Shallow Marine ◽  
Lower Miocene ◽  
La Meseta Formation ◽  
Seymour Island

Carlini et al. (1990) reported the presence of Xenarthra (Mammalia) from the Eocene deposits of Seymour Island, Antarctic Peninsula, based on an ungual phalanx from locality RV 8200. The locality, referred to informally as “mammal site” by Woodburne & Zinsmeister (1984), is located at 64°14′21″S, 56°39′44″W at an elevation of 45 m in the middle levels of the shallow marine La Meseta Formation (TELM 5 of Saddler 1988). Carlini et al. (1990) initially identified the phalanx as a megatherioid sloth (Order Tardigrada). Marenssi et al. (1994) revised its identification to ?Tardigrada or ?Vermilingua, by comparison with a primitive myrmecophagid (Order Vermilingua) from the Lower Miocene of Patagonia, whose ungual phalanges are indistinguishable from those of primitive sloths (Carlini et al. 1992). We report a fragmentary tooth of a member of the Tardigrada (Family incertue sedis) confirming the presence of this group in the Eocene of Antarctica.

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