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).

A New Cetacean from the Late Eocene La Meseta Formation Seymour Island, Antarctic Peninsula

1989 ◽  
Vol 46 (12) ◽  
pp. 2219-2235 ◽  
Author(s):  
Edward D. Mitchell
Keyword(s):  
New Species ◽  
Antarctic Peninsula ◽  
New Genus ◽  
Late Eocene ◽  
New Genus And Species ◽  
New Family ◽  
Lower Jaw ◽  
La Meseta Formation ◽  
Lobodon Carcinophagus ◽  
Seymour Island

The new genus and species Llanocetus denticrenatus is described based on a cranial endocast and portion of a dentary fragment bearing two teeth from the Eocene La Meseta Formation, Seymour Island, Antarctic Penninsula. Llanocetus new genus is designated the type genus for the new family Llanocetidae. The Llanocetidae is placed within the new infraorder Crenaticeti, co-ordinate with the new Mysticete infraorder Chaeomysticeti. Llanocetus denticrenatus new species shows relationship with both Archaeoceti and Mysticeti. Revision of archaeocete and mysticete classification includes proposal of the new taxa Kekenodontinae, Mammalodontidae, and the new ranks Protocetoidea, Remingtonocetoidea, Basilosauroidea, and Eschrichtioidea. The endocast shows evidence of intracranial retial hypertrophy, taken as evidence of enhanced diving abilities. The large deeply notched teeth are widely spaced on the lower jaw. I hypothesize that filter feeding in whales arose first in species in which teeth with deep notches, forming widey spaced tubercles, comprised part of a straining apparatus analogous to the serrated teeth of the phocid seal Lobodon carcinophagus.

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.

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.

Chathamirhynchia kahuitara, a new genus and species of Late Cretaceous rhynchonellide brachiopod from the Chatham Islands, New Zealand: shell structure, palaeoecology and biogeography

2007 ◽  
Vol 98 (3-4) ◽  
pp. 357-367 ◽  
Author(s):  
Daphne E. Lee ◽  
Neda Motchurova-Dekova
Keyword(s):  
New Zealand ◽  
Shallow Water ◽  
Volcanic Rock ◽  
Late Cretaceous ◽  
Shell Structure ◽  
New Genus ◽  
High Energy ◽  
New Genus And Species ◽  
Cardinal Process ◽  
Energy Environment

ABSTRACTA new rhynchonellide brachiopod has been collected from the Kahuitara Tuff (Campanian–Maastrichtian) of Pitt Island, Chatham Islands, New Zealand. Brachiopods are extremely rare in Cretaceous rocks from New Zealand, and this new genus and species is unlike any other rhynchonellide known from Australasia or elsewhere. Chathamirhynchia kahuitara is distinguished by its small size, strong ribbing, and well-developed sulciplicate folding, and internally by a large, robust cardinal process and raduliform crura. The shell structure of C. kahuitara is shown to be of typical fine fibrous ‘rhynchonellidine’ type. This brachiopod was probably strongly attached to volcanic rock or shells in a shallow-water, high-energy environment. Implications for the biogeography of brachiopods during the Late Cretaceous are briefly discussed.

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.

A new Tethyan migrant: Cretachlorodius enciensis n. gen., n. sp. (Crustacea, Decapoda), from the Maastrichtian type area

1996 ◽  
Vol 70 (2) ◽  
pp. 293-296 ◽  
Author(s):  
René H. B. Fraaye
Keyword(s):  
Late Cretaceous ◽  
New Genus ◽  
New Taxon ◽  
Decapod Crustaceans ◽  
New Genus And Species ◽  
Type Area

A new genus and species of crab is described from the late Maastrichtian Meerssen Member of the Maastricht Formation at the type area of the Maastrichtian Stage, SE Netherlands. This new taxon could well be the ancestor of the xanthid Prochlorodius-Chlorodiella group and its occurrence provides additional evidence of a late Cretaceous radiation among the decapod crustaceans.

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).

A new genus and species of sea pen (Octocorallia : Pennatulacea : Stachyptilidae) from the Antarctic Peninsula

2002 ◽  
Vol 16 (6) ◽  
pp. 919 ◽  
Author(s):  
Pablo J. López-González ◽  
Gary C. Williams
Keyword(s):  
New Species ◽  
Antarctic Peninsula ◽  
New Genus ◽  
South Shetland Islands ◽  
New Genus And Species ◽  
Antarctic Region ◽  
Diagnostic Features ◽  
Shetland Islands ◽  
The Antarctic ◽  
Southern Oceans

Only six of the thirty-three valid genera of sea pens have previously been recorded from the Southern Oceans (Subantarctic and Antarctic regions). The discovery of a new genus, Gilibelemnon, and new species, Gilibelemnon octodentatum, of stachyptilid sea pen is here reported from the South Shetland Islands, which makes a total of eight genera known to occur in the Southern Oceans and thirty-four genera of sea pens known worldwide. Diagnostic features of the new genus are described, including the presence of a clearly delimited dorsal and ventral naked track on the rachis, the calyces with eight long terminal teeth, the siphonozooids densely and irregularly distributed and the presence of three-flanged rods in the peduncle surface. A discussion of sea pen phylogeny and biogeography in the Antarctic region is also provided.

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