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

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.

1997 ◽  
Vol 71 (2) ◽  
pp. 348-350 ◽  
Author(s):  
S. F. Vizcaino ◽  
M. Bond ◽  
M. A. Reguero ◽  
R. Pascual

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.


1991 ◽  
Vol 3 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Joseph T. Eastman ◽  
Lance Grande

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).


1992 ◽  
Vol 4 (1) ◽  
pp. 107-108 ◽  
Author(s):  
J.J. Hooker

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.


2008 ◽  
Vol 20 (6) ◽  
pp. 589-590 ◽  
Author(s):  
Piotr Jadwiszczak

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.


1992 ◽  
Vol 4 (2) ◽  
pp. 235-237 ◽  
Author(s):  
Douglas J. Long

A nearly complete lower pharyngeal tooth-plate from a large (over 60 cm long) fossil wrasse (Perciformes: Labridae) was recently recovered from the middle to late Eocene La Meseta Formation on Seymour Island, Antarctic Peninsula. This find increases the number of teleosts from the Eocene of Antarctica to five taxa, and further illustrates the diversity of the ichthyofauna in the Eocene Weddellian Sea prior to wide-scale climatic change in the Southern Ocean. The fossil wrasse represents the first occurrence of this family in Antarctica, and is one of the oldest fossils of this family from the Southern Hemisphere. Wrasses are not found in Antarctic waters today, and probably became extinct during the Oligocene due to a combination of climatic change, loss of shallow-water habitat, and changes in the trophic structure of the Wedell Sea.


PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8268
Author(s):  
Sarah N. Davis ◽  
Christopher R. Torres ◽  
Grace M. Musser ◽  
James V. Proffitt ◽  
Nicholas M.A. Crouch ◽  
...  

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.


2015 ◽  
Vol 89 (5) ◽  
pp. 870-881 ◽  
Author(s):  
Marcos Cenizo ◽  
Carolina Acosta Hospitaleche ◽  
Marcelo Reguero

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.


1993 ◽  
Vol 67 (2) ◽  
pp. 250-257 ◽  
Author(s):  
David L. Meyer ◽  
Tatsuo Oji

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.


2011 ◽  
Vol 32 (3) ◽  
pp. 269-277 ◽  
Author(s):  
Piotr Jadwiszczak ◽  
Sandra Chapman

The earliest fossil record of a medium-sized penguinThe fossil record of Antarctic Sphenisciformes dates as early as the late Palaeocene Cross Valley Formation, Seymour Island, Antarctic Peninsula. However, the best known Antarctic locality for early penguin remains (mainly isolated bones) is the Eocene La Meseta Formation that outcrops in the northeast of Seymour Island. The analysis of an unstudied set of specimens collected there by members of the British Antarctic Survey in 1989 has resulted in identification of a distal humerus from the unit Telm3 (early Eocene) of the formation that is the oldest known bone attributable to a medium-sized (in the context of the entire Cainozoic era) penguin. This find suggests that the origin of these birds, in conjunction with an increase in taxonomic diversity of the Eocene Sphenisciformes, was related to the Early Eocene Climatic Optimum (EECO) or, more probably, the early phase of subsequent cooling.


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