Lancefield Swamp
Encyclopedia
The Lancefield Swamp is a rich fossil deposit from the Pleistocene
epoch
was discovered in the 19th century near Lancefield
, Victoria, Australia
.
The site consists of a bone bed lying directly atop a layer of fluvial
gravel between layers of clay (Gillespie et al. 1978). The layer of bones is estimated to contain the remains of perhaps 10,000 individual Pleistocene animals(Gillespie 1978). A total of at least 6 Megafauna
species are represented, although the majority of bones are from Macropus giganteus or Macropus titan.
Human artifacts were found in the bone bed and in the overlying clay. However, evidence of reworking by water flow has been noted (Gillespie 1978). Thus it appears possible such artifacts are intrusions.
The Lancefield Swamp fossil site is important in the debate over the time of and causes of the extinction of Australian Megafauna
. Humans are estimated to have arrived in Pleistocene
Australia
, or Sahul, at anything from 60 ka to about 45 ka.
Initial radiocarbon dates yielded estimates of 31ka, a comparatively young age approaching the Last Glacial Maximum
. Horton (2000) therefore claimed Lancefield as a decisive example of the survival of Australian Megafauna
for many thousands of years after the arrival of modern humans in prehistoric Sahul.
But when Lancefield Swamp was investigated by van Huet (1999) it was found that the bones had indeed been reworked by fast flowing water at some time after the animals had died. This conclusion was based upon observations that the bones show signs of post-depositional wear, that they are all disarticulated, that complete skulls are lacking (noted by Gillespie 1978), that the majority of bones are large and that they tend to be aligned along a common axis indicative of the direction of water flow. It thus appeared probable that lighter bones had been washed away whereas heavier bones remained in situ. Dating of Diprotodon
teeth (van Huet et al. 1998) from the bone bed yielded ages of 46-56 ka by means of ESR and a minimum of 32 ka by means of Carbon-14.
However, as result of excavations begun in 2004, Dortch et al. (2004) suggest that the Lancefield Megafauna remains have not in fact been disturbed since deposition. Thus it is hoped that dates assigned to the Lancefield bones bones are reliable and therefore represent their true age since burial. If age estimates turn out to be on the high side, say 60ka or greater, the Lancefield bones may contribute little to our understanding of the effects of human activities upon the Australian Megafauna
since such an age would pre-date the arrival of modern humans in Sahul by a wide margin.
On the other hand, if the dates are comparatively recent, say less than 35 ka, then humans would be exculpated as the causative agent. If however the estimate falls somewhere close to 46ka then human arrival and the final demise of the Megafauna
would appear to be closely associated.
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
was discovered in the 19th century near Lancefield
Lancefield, Victoria
Lancefield is a town in the Shire of Macedon Ranges Local government area in Victoria, Australia. The town is located north of the state capital, Melbourne and had a population of 1,184 at the 2006 census.-History:...
, Victoria, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
The site consists of a bone bed lying directly atop a layer of fluvial
Fluvial
Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...
gravel between layers of clay (Gillespie et al. 1978). The layer of bones is estimated to contain the remains of perhaps 10,000 individual Pleistocene animals(Gillespie 1978). A total of at least 6 Megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...
species are represented, although the majority of bones are from Macropus giganteus or Macropus titan.
Human artifacts were found in the bone bed and in the overlying clay. However, evidence of reworking by water flow has been noted (Gillespie 1978). Thus it appears possible such artifacts are intrusions.
The Lancefield Swamp fossil site is important in the debate over the time of and causes of the extinction of Australian Megafauna
Australian megafauna
Australian megafauna are a number of large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives...
. Humans are estimated to have arrived in Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, or Sahul, at anything from 60 ka to about 45 ka.
Initial radiocarbon dates yielded estimates of 31ka, a comparatively young age approaching the Last Glacial Maximum
Last Glacial Maximum
The Last Glacial Maximum refers to a period in the Earth's climate history when ice sheets were at their maximum extension, between 26,500 and 19,000–20,000 years ago, marking the peak of the last glacial period. During this time, vast ice sheets covered much of North America, northern Europe and...
. Horton (2000) therefore claimed Lancefield as a decisive example of the survival of Australian Megafauna
Australian megafauna
Australian megafauna are a number of large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives...
for many thousands of years after the arrival of modern humans in prehistoric Sahul.
But when Lancefield Swamp was investigated by van Huet (1999) it was found that the bones had indeed been reworked by fast flowing water at some time after the animals had died. This conclusion was based upon observations that the bones show signs of post-depositional wear, that they are all disarticulated, that complete skulls are lacking (noted by Gillespie 1978), that the majority of bones are large and that they tend to be aligned along a common axis indicative of the direction of water flow. It thus appeared probable that lighter bones had been washed away whereas heavier bones remained in situ. Dating of Diprotodon
Diprotodon
Diprotodon, meaning "two forward teeth", sometimes known as the Giant Wombat or the Rhinoceros Wombat, was the largest known marsupial that ever lived...
teeth (van Huet et al. 1998) from the bone bed yielded ages of 46-56 ka by means of ESR and a minimum of 32 ka by means of Carbon-14.
However, as result of excavations begun in 2004, Dortch et al. (2004) suggest that the Lancefield Megafauna remains have not in fact been disturbed since deposition. Thus it is hoped that dates assigned to the Lancefield bones bones are reliable and therefore represent their true age since burial. If age estimates turn out to be on the high side, say 60ka or greater, the Lancefield bones may contribute little to our understanding of the effects of human activities upon the Australian Megafauna
Australian megafauna
Australian megafauna are a number of large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives...
since such an age would pre-date the arrival of modern humans in Sahul by a wide margin.
On the other hand, if the dates are comparatively recent, say less than 35 ka, then humans would be exculpated as the causative agent. If however the estimate falls somewhere close to 46ka then human arrival and the final demise of the Megafauna
Australian megafauna
Australian megafauna are a number of large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives...
would appear to be closely associated.
See also
- Australian MegafaunaAustralian megafaunaAustralian megafauna are a number of large animal species in Australia, often defined as species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives...
- Lancefield, VictoriaLancefield, VictoriaLancefield is a town in the Shire of Macedon Ranges Local government area in Victoria, Australia. The town is located north of the state capital, Melbourne and had a population of 1,184 at the 2006 census.-History:...
- List of fossil sites (with link directory)