The Prehistory & Fossils Of Antarctica
Antarctica’s fossil record speaks to vanished ages when the White Continent supported much greater diversity of terrestrial life—and a climate radically different from today’s ice-cap frigidity.
From fossilized leaves to the petrified eggs of great Mesozoic sea reptiles, the bedrock of Antarctica has turned up some remarkable prehistoric treasures.
Antarctica spent several hundred million years joined with other of today’s Southern Hemisphere continents as part of the great landmass called Gondwana (or Gondwanaland). Gondwana, which came to include modern-day Antarctica, South America, Africa, India, Madagascar, and Australia, likely formed some 600 million years ago through the restless hustle-and-bustle of plate tectonics that dictates Earth’s geology.
Some 335 million years ago, Gondwana merged with northern continents to form the supercontinent Pangaea. Pangaea began breaking apart about 200 million years ago, initially splitting into the northern landmass Laurasia and that trusty southern one, Gondwana. Roughly 180 million years ago, Gondwana began a very long and drawn-out rifting process itself. Evidence for some of its earliest rupturing can be found among basaltic outcrops in Antarctica, linked to similar formations in southern Africa.
Antarctica likely became fully isolated roughly 30 to 40 million years ago as Australia broke off, opening up the Tasman Passage or Seaway, and South America separated to create the Drake Passage. As Antarctica drifted southward, its developing polar climate—and the growth of its ice cover—were enhanced by the strengthening of the Antarctic Circumpolar Current, a great eastward flowing current that arose as Gondwana’s breaking-apart birthed a Southern Ocean stretching unimpeded around the lower part of the globe.
Both because of more northerly, even equatorial, positions, and because of fluctuations in atmospheric carbon dioxide and other climatic variability, Antarctica used to be a much balmier place. Temperate and even semi-tropical forests once flourished on the White Continent, and a great variety of terrestrial vertebrate life could be found here. Most of that biodiversity—from araucaria and beech trees to marsupials and hoofed mammals—withered away as ice and cold started locking Antarctica in.
Although most of Antarctica lies covered by ice sheets—making paleontological research mighty challenging indeed—exposed portions of the continent and its islands, as on the exposed bedrock of the Transantarctic Mountains or the coastal margins and islets of the Antarctic Peninsula—have yielded some amazing fossil discoveries. These have helped paint a picture of Antarctica’s deep past, not least its comparatively lush and life-filled days as part of Gondwana and Pangaea.
Antarctic fossils range from plants, crustaceans, cephalopods, starfish, and insects to fish, birds, mammals, and reptiles, not least those universally transfixing archosaurs of the Mesozoic, the dinosaurs.
Remote and largely ice-covered as it is, Antarctica has produced some hugely important fossil finds since it first fell under scientific scrutiny, including discoveries with bearing on our conception of the Earth’s prehistory in general.
Antarctica’s fossil heritage overlaps with its iconic annals of human exploration. In February 1912, Robert Falcon Scott and several companions from his British Antarctic Expedition noticed intriguing fossils along the Beardmore Glacier as they made their fateful push for the South Pole. When their bodies were found months later, those fossils were among their pared-down belongings—testament to the team’s commitment to having them scientifically assessed, despite their desperate condition staggering back from the Pole.
In 1914, Albert Seward, a botanist at Cambridge University, studied the 280- to 300-million-year-old fossils Scott and his men had collected, and identified them as the extinct tree Glossopteris. As Glossopteris fossils had also been located in Africa, South America, India, and Australia, the find helped Alfred Wegener iron down his theory of continental drift, and the bygone existence of the supercontinent Gondwana.
Fossils of a Late Cretaceous ankylosaur, Antarctopelta, found on James Ross Island off the Antarctic Peninsula in 1986 were the initial dinosaur remains identified in Antarctica.
The first dinosaur fossils identified on the White Continent proper were found in the Transantarctic Mountains—which separate the relatively young volcanic and sedimentary rocks of West Antarctica from the much older continental core (craton) of East Antarctica—on a 1990-1991 expedition. The Early Jurassic “thunder lizards” in question were two species brand-new to paleontologists: the theropod Cryolophosaurus ellioti and the sauropodomorph Glacialisaurus hammeri.
The same fieldwork also turned up nearby the fossilized remains of a pterosaur—a flying reptile contemporaneous with the dinosaurs—and a mammal-like synapsid of the tritylodont family.
The presence of Glossopteris fossils in Antarctica indicates temperate forests of Permian vintage. More recent plant fossils suggest the many eras of widespread greenery the White Continent enjoyed before its post-Gondwana-breakup drift poleward turned it into a giant ice cube.
Excavations amid the Antarctic Peninsula’s sedimentary rocks have revealed evidence for Cretaceous forests of conifers, gingkos, cycads, ferns, and other lush vegetation. The southern beeches, Nothofagus, show up in the Antarctic fossil record by the Late Cretaceous, another link between the White Continent and Gondwanan fossils and living Nothofagus species of South America, Australia, and New Zealand. There’s some speculation that this important Southern Hemisphere temperate-forest tree may have even evolved on the Antarctic Peninsula.
While one would presume that the Antarctic temperate forests of southern beeches and other trees would have declined beginning about 35 million years ago with the White Continent’s isolation, fossils of one extinct Nothofagus species, N. beardmorensis, recovered in the Transantarctic Mountains not far from the South Pole have been dated to a mere two or three million years old.
In 1982, the exceptionally rich and varied fossil site of Seymour Island, set off the northeastern coast of the Antarctic Peninsula, generated the very first evidence of land mammals in Antarctica: a marsupial of the extinct order Polydolopimorphia.
Paleontologists now suspect Antarctica, back in its supercontinent days, was a critical corridor for prehistoric marsupial dispersal, funneling these pouched mammals—which evolved 125 or more million years ago in North America—from South America to Australia, today their great modern stronghold.
Seymour Island has sepulchered all manner of prehistoric life across a broad swath of deep time. The Australian Antarctic Program rightly calls it “one of the most important fossil sites on Earth,” not least for being a rare place where the momentous Cretaceous-Paleogene (K-Pg) boundary, straddling the mass extinction event that killed off non-avian dinosaurs and many other forms of life at the close of the Cretaceous, is well preserved.
In 2019, fossils of a kind of plesiosaur known as an elasmosaur were collected on Seymour Island. Probably a member of the Aristonectes genus, this Antarctic elasmosaurid ranks as the largest known of its kind, perhaps spanning nearly 40 feet long and weighing 15-odd tons.
And speaking of hefty, a Late Eocene penguin species described in 2014 from Seymour Island fossils ranked among the biggest known. This “colossus penguin” stood some 6.6 feet tall and weighed better than 250 pounds, dwarfing the largest living penguin, the world-famous emperor. Imagine coming face to face with a penguin that looms above eye level: the sort of thrilling thought exercise that Antarctica’s geologic layers, and the biological relics they contain, can inspire.
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