The Meyer Desert Formation is a glacigenic, mostly non-marine sedimentary sequence that forms the upper part of the Sirius Group in the central Transantarctic Mountains. It is notable for containing the youngest known macrofossils of terrestrial plants and palaeosols found anywhere in Antarctica, preserved at elevations of ~1,760 m above sea level and approximately 500 km from the South Pole. Some earlier works included it within a broader “Sirius Formation,” but this usage has been largely abandoned.
Biota
The Meyer Desert Formation preserves a short-lived Pliocene interglacial tundra in a marine-influenced Fjord. Mean summer temperatures reached ~4–5 °C for 1–2 months, with 24-hour daylight, permafrost, strong katabatic winds, very low precipitation, and a growing season of only 6–12 weeks.
The landscape was a low-relief, gravelly braided outwash plain with unstable moraines, scattered shallow ponds, and thin peat lenses. Vegetation consisted of prostrate Nothofagus shrubs, dense vascular cushion plants up to 30 cm across, moss hummocks, scattered buttercups, sedges, and rare mare's-tail in wet hollows. This setting was similar floral-wise to the windswept cushion bush and fellfields of Patagonia and Tierra del Fuego above 800–1000 m. The sequence hovewer was coastal, based on marine Diatom & Foraminifera, part of the "Beardmore Paleofjord", a major seaway extending at least 165 km through the Transantarctic Mountains from its juncture with the S Ross Sea, with the floral levels being probably a shoreline of an smaller inland sea incursion, whose best analogue is Glacier Bay National Park.
Fossil Nothofagus leaves show that intermittent warm periods allowed Nothofagus shrubs to cling to the Dominion Range as late as 3-4 Ma (mid-late Pliocene). After that, the Pleistocene glaciation covered the whole continent with ice and destroyed all major plant life on it. More recent data records similar floras at least until the Miocene in the Antarctic Peninsula. The Pliocene age of the sediments has been constested, with two major options, one being periods were the Wilkes & Aurora subglacial basins were ice-free and sea-inundated as recent as the early Pliocene, and the other suggesting is Miocene or older, and it´s Diatoms are wind contamination. Extant Springtails (Antarcticinella, Cryptopygus, Gomphiocephalus) that still live in the same region suggest hovewer that the ice covering of the region wasn´t until the Pliocene, as they have been isolated from each other at between 1.3 and 5.5 My.
Animals GenusSpeciesAffinity / familyImageAntarctotrechusballi CarabidaeChironomidae indet.Indet.MidgeCurculionidae indet."Morphotype 1"Listroderini (aff. Listroderes) "Morphotype 2"Listroderini (aff. Falklandius/Telurus) Cyclorrhapha indet.Indet.aff. CochliomyiaIndet.Leg inside Ranunculus acheneLepidoptera? indet.Indet.Eggs of Moth or ButterflyLymnaeidae indet.Indet.aff. ChilinaOsteichthyes indet.Indet.Freshwater taxon, likely a GalaxiidaeOstracod indet.Indet.Putatively non-marine ostracodsPisidiumsp.Sphaeriidae
Plants GenusSpeciesAffinity / familyImageCushion plants indet.Indet.Donatiaceae, Apiaceae, Caryophyllaceae or AsteraceaeCyperaceae indet."Morphotype 1"Sedges"Morphotype 2"SedgesHippurissp.HippuridaceaeMarchantiaceae indet.Indet.LiverwortNothofagidites (Fuscospora) lachmaniaeNothofagaceae (cf. Nothofagus)NothofagusbeardmorensisNothofagaceae (aff. Nothofagus gunnii)Poaceae indet.Indet.GrassPodocarpidites"sp. b"Podocarpaceae (Aff. Pilgerodendron or Lepidothamnus)Pottiaceae indet.Indet.Moss, other 4 unnamed types are foundRanunculussp.RanunculaceaeReniform seed indet.Indet.?Chenopodiaceae, ?Caryophyllaceae or ?MyrtaceaeTricolpitessp.Polygonaceae or Lamiaceae"sp. 2"Polygonaceae or Lamiaceae
References