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Natural Science Forum / Biology / Paleontology / February 2005Question
Has been digs done in Antarctic that given us a clearer picture of the fauna that inhabited Antarctica before it totally froze over. I heard about the findings on Seymour Island, that the fauna there around 35 million years ago being very similar to South America's. > Has been digs done in Antarctic that given us a clearer picture of the > fauna that inhabited Antarctica before it totally froze over. I heard > about the findings on Seymour Island, that the fauna there around 35 > million years ago being very similar to South America's. Seymour Island in the mid-late Eocene apparently was home to litopterns, astrapotheres, glyptodonts, small marsupials and whopping huge phorusrhacoid birds - so on the surface a pretty similar fauna to that of Paleogene South America. If we had decent terrestrial fossil assemblages known for Late Eocene Australia (we don't) - it wouldn't surprise me if some of these guys lived there as well... or maybe not but you never know. J.A. ,Woodburne, M.O. Camp; Chaney, D.S. 1987. A gigantic Phorhoracoid bird from Antarctica. Journal of Paleontology 61: 1280-1284 Hooker, J.J,(1992) An additional record of a placental mammal (Order Astrapotheria) from the Eocene of West Antarctica. Antarctic Science , 4:107-108 Cambridge University Press GOIN, E J., AND A. A. CARLINI. 1995. An Early Tertiary microbiotheriid marsupial from Antarctica. Journal of Vertebrate Paleontology 15:205-207. from journals.cambridge.org/article_S0954102095220297 "Fossil glyptodont from Seymour Island The Cenozoic strata of Seymour Island continue to yield new palaeontological discoveries. Judd Case, of St Mary's College of California, and co-workers from the US Antarctic Program, have recovered fragments of a glyptodon, an extinct, giant armadillo-like mammal. The remains, from Eocene sands are reported to be those of a species unusually large for the time and to resemble others found in Patagonia." Cheers Brian >>Has been digs done in Antarctic that given us a clearer picture of the >>fauna that inhabited Antarctica before it totally froze over. I heard [quoted text clipped - 12 lines] > J.A. ,Woodburne, M.O. Camp; Chaney, D.S. 1987. A gigantic Phorhoracoid > bird from Antarctica. Journal of Paleontology 61: 1280-1284 AHA! Perhaps this is the source of Richard Dawkins' claim of ratites in Antarctica. OK, it's not the Cretaceous, and it's not a ratite. But it's a big flightless bird (other than a penguin) in Antarctica. Closer than anything else so far. > Hooker, J.J,(1992) An additional record of a placental mammal (Order > Astrapotheria) from the Eocene of West Antarctica. Antarctic Science , [quoted text clipped - 15 lines] > Cheers > Brian > > J.A. ,Woodburne, M.O. Camp; Chaney, D.S. 1987. A gigantic Phorhoracoid > > bird from Antarctica. Journal of Paleontology 61: 1280-1284 [quoted text clipped - 3 lines] > a big flightless bird (other than a penguin) in Antarctica. Closer than > anything else so far. Oh wait! - there was a ratite birdie in Eocene Seymour Island... TAMBUSSI, C. P., J. I. NORIEGA,A.GAZDICKI,A.TATUR,M. REGHUERO, and S. F. VIZCAINO. 1994. Ratite bird from the Paleogene La Meseta Formation, Seymour Island, Antarctica. Pol. Polar Res. 15:15020-15026. but if there really is an honest to god Cretaceous Antarctic fossil ratite out there I'm surprised I've never heard of it before. (Probably Richard went for a joyride in his wife's TARDIS, ended up in Maastrichtian Antarctica, saw some ratites and put them in his book, forgetting the absence of present day fossil evidence...) Cheers Brian >>>J.A. ,Woodburne, M.O. Camp; Chaney, D.S. 1987. A gigantic Phorhoracoid >>>bird from Antarctica. Journal of Paleontology 61: 1280-1284 [quoted text clipped - 9 lines] > VIZCAINO. 1994. Ratite bird from the Paleogene La Meseta Formation, > Seymour Island, Antarctica. Pol. Polar Res. 15:15020-15026. Dang. Now I have to find a copy. No apparent pdfs around, which is no surprise considering the age. How much material? How is it identified as a ratite? > but if there really is an honest to god Cretaceous Antarctic fossil > ratite out there I'm surprised I've never heard of it before. [quoted text clipped - 5 lines] > Cheers > Brian If placental mammals had lived in Australia before it broke off from Antartica 45 million years ago. Why did they go extinct? > If placental mammals had lived in Australia before it broke off from > Antartica 45 million years ago. Why did they go extinct? Nobody knows. How would you tell? There was a fossil of a Condylarth, an early form of Placental Mammal found in Murgon, in South-Eastern Queensland. "The first evidence we have of marsupials in Australia comes from the 55 million year old fossil site at Murgon in southern Queensland. This Murgon site has yielded a range of marsupial fossils, many with strong South American connections. At Murgon there is also evidence of a placental mammal, known as a condylarth. Placental mammals were also found in North America and South America at this time." http://www.cultureandrecreation.gov.au/articles/1998/07/fossils.htm > There was a fossil of a Condylarth, an early form of Placental Mammal > found in Murgon, in South-Eastern Queensland. [quoted text clipped - 9 lines] > > http://www.cultureandrecreation.gov.au/articles/1998/07/fossils.htm Yes, I know. What's your point? You were asking why placentals became extinct in Australia. I said we don't know and will probably never know, because we are likely never to have the data necessary to tell us. By the way, you need to learn to quote the post you're responding to. > If placental mammals had lived in Australia before it broke off from > Antartica 45 million years ago. Why did they go extinct? Who knows?...between the latest Paleocene/early Eocene sites in southeastern Qld and the Late Oligocene Riversleigh fossil motherlode theres something like a 30 million gap with no decent terrestrial Australian mammal record. Obviously something really really bad happened to Australia in that gap. My guess - being situated right next to a newly formed psychrosphere in the Late Eocene wasn't a particularly pleasant experience. Note that it wasn't just the terrestrial (non-bat) eutherians that vanished - lots of other Australian stuff vanished as well - microbiotheriid marsupials, possible ameridelphian opossums (*Djarthia*), salamanders, softshell turtles... Additionally, the insanely high number of weird australidelphian clades, many of them short-lived, present in the Oligo-Miocene Riversleigh deposits is the sort of "boom-bust" explosive diversification one expects not long after a (in this case regional) mass extinction event. Cheers Brian > My guess - being situated right next to a newly formed psychrosphere in > the Late Eocene wasn't a particularly pleasant experience. [quoted text clipped - 8 lines] > deposits is the sort of "boom-bust" explosive diversification one > expects not long after a (in this case regional) mass extinction event. I just found it something I previously have not known about Australian prehistory today, thanks Brian. |
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