Megafauna Extinction In Australia Essay, Research Paper
Megafauna Extinction In Australia Site Name: Cuddie SpringsGeographical Position: Northwestern New South Wales Archeological Sequence and Dates: Cuddie Springs has been excavated as a source of Fossil bone for a very long time, but starting in 1990 it has also shown cultural material as well. First it was excavated by Judith Furby, John Dodson, and Ian Prosser from the School of Geography at the University of New South Wales and then by Richard Fullager and Robert Jones of the Australian Museum.Finds and Associations: The most important finds at Cuddie Springs are found in asecure stratigraphic sequence that consists of megafaunal bones and artifacts occurring together and dated from 19 300 years and going back to at least 29 570 plus or minus 280 years, which is considered a minimum age for the oldest evidence of co-existence. These dates, done with radiocarbon dating, are considered fairly accurate ‘given the lack of evidence for rapid deposition, proximity to the limit of radiocarbon dating, and rudimentary pre treatment of charcoal.’ Among the sediment has been found Ochre and many stone tools, mainly flakes, cores and scrapers, most of which are made of silcrete, but also quartzite, quartz, feldspar porphyry, conglomerate and chert. As time went on, there is evidence that quartzite became less popular for tools and chert became more popular. There has also been found grindstones with starch residues, a probable cylcon and other artifacts with reworked edges containing blood and hair. Since 1992, DNA testing on the blood and hair found have taken place and have been identified as Macropus titan and Diprotodon. Interpretation: The fact that the stone tools contains DNA of extinct megafauna clearly shows that not only did megafauna exist at the time of human occupation, but that Aborigines were at least scavenging the carcasses dead megafauna and possibly were taking part in butchering trapped animals or hunting them and then carrying some bones back to their camp. Because of the amount of charcoal found and the presence of hearths, Cuddie Springs is considered a camp site.Also, environmental evidence taken from Cuddie Springs shows a decreasing tree, shrub and grass cover but a rise in saltbrush as the glacial maximum approached. This evidence agrees with environmental evidence taken from Ulungra Springs, located approx. 180 km to the southwest. Site Name: Lancefield swampGeographic Position: Southwest edge of Lancefield, a small agricultural town located in VictoriaArcheological Sequences and Dates: Lancefield swamp has been excavated since the early 1970’s by Gillespie, Horton, Ladd, Macumber, Rich, Wright, and Thorne.Finds and Associations: The swamp has a 0.2 meter thick bone bed, 1.5 meters below the surface. In this layer, the bones of six extinct megafaunal species were found. The dates on this level are approximately 26 kbp, which shows that humans co-existed with megafauna for over 7,000 years. Another relevant find at Lancefield is the climatic evidence. At approximately 26 kbp, Lancefield swamp changed from a period of erosion to a swamp, where gradually over a meter and a half of sediment accumulated. Among the megafauna present are: Macropus titan, which can attribute for 90% of the bones found, Protemnodon anak, Protemnodon cf. Brehus, Sthenurus occidentalis, Diprotodon, Genyornis, and Dromaius. All of which, except for Dromaius, are now extinct. A noticeable lack of juveniles is found in the M. titan bones. Other artifacts found at Lancefield swamp consist of a large quartzite blade, found in 1974 by P. G. Macumber, and in the present-day surface soils, numerous artifacts of the Holocene small tool tradition are found. The dating was done primarily by Radio-carbon dating, coming from two distinct samples found in different parts of the swamp years apart. The dating of Lancefield swamp is accepted as accurate.
Interpretation: Because of the quality of the dates taken from Lancefield, it appears as if humans and megafauna co-existed for over 7,000 years, raising serious doubts about the theory that humans caused the rapid extinction of megafauna in Australia due to over-hunting. Also, because the climatic evidence agrees with other southeast Australian sites in the fact that a major hydrologic change occurred at 26,000 ybp, it leads us to believe that climatic changes had more to do with the extinction than the presence of man. This is not to say that humans didn’t play a part in the extinction of megafauna, but only that they were not the soul cause, possibly not even the main cause. Evidence taken from the animal remains found at Lancefield, specifically the bones of M. titan, show evidence of signs of drought. The lack of juveniles in the bones has also been observed in modern herds during drought and many of the remains also show signs of “lumpy jaw”, a disease seen more commonly during periods of droughts. One possible theory is that the recurring droughts forced the larger species to congregeate around the sources of water, which were slowly drying. As the animals became limited in their movements due to lack of other sources of water, they became restricted to smaller and smaller areas. Then the large herds quickly ate the available sources of food and doomed themselves to extinction. A possible problem with this theory is that not all of Australia became extremely arid at this time, but research points to a large extinction of megafauna across the whole continent and not just in the parts that experienced recurring droughts.Site Name: Lake Mungo.Geographical Position: Western New South Wales.Archeological Sequence and Dates: Bowler excavated Lake Mungo in the 60’s and 70’s. Thorne removed WLH 1 from her carbonate encrustation, and he also did work with Bowler on WLH 3.Finds and Associations: Two human skeletons were found at Lake Mungo along with numerous collections of shells, hearths, ochre, and stone tools. Lake Mungo is significant because the skeletons had undergone burial rituals. WLH 1 was first cremated and then her bones were crushed, and WLH 3 was buried with ochre surrounding his body, even more remarkable since the nearest natural occurance of ochre is over 10 km away. The date for WLH 1 is approximately 25 kbp, while the date for WLH 3 appears to be around 30 kbp. No fossils of megafauna are found at this site with a date co-existing with any human remains.Interpretation: Lake Mungo relates to the extinction of megafauna in the fact that it represents a archeological find that dates back at least 30 kbp without any signs of megafauna. It is unclear if this means that the megafauna were already extinct in this area at this time or if the humans simply drove them off. We do know that Lake Mungo was a large fresh water lake that would have been an ideal habitat for many of the species referred to as megafauna, since it provided a stable water source and an abundant supply of food. Because of the lack of megafauna around Lake Mungo at the time of human occupation, it appears that humans didn’t play a part in megafauna’s extinction. If humans had massively killed the megafauna, their would be archeological sites preserving their remains, due to the high amount of calcium carbonate found around the lake shores where humans camped. Because Lake Mungo would have made an excellent habitat for megafauna as well as humans, yet megafauna is clearly lacking, we can conclude that megafauna abandoned Lake Mungo before humans occupied it. One possible theory about Lake Mungo is that the megafauna left the area in search of food before it grew into the lake it was, and the megafauna never had reason to return. Another possible reason is that as humans approached their habitat, the megafuana gradually moved on rather than compete with the new species. Either way, there is no sign of humans and megafaunas interacting in any way.