Megalania and aborigines overlapped temporally

[Surroundx]

Temporal overlap of humans and giant lizards (Varanidae; Squamata) in Pleistocene Australia

Abstract

An obvious but key prerequisite to testing hypotheses concerning the role of humans in the extinction of late Quaternary ‘megafauna’ is demonstrating that humans and the extinct taxa overlapped, both temporally and spatially. In many regions, a paucity of reliably dated fossil occurrences of megafauna makes it challenging, if not impossible, to test many of the leading extinction hypotheses. The giant monitor lizards of Australia are a case in point. Despite commonly being argued to have suffered extinction at the hands of the first human colonisers (who arrived by 50 ka), it has never been reliably demonstrated that giant monitors and humans temporally overlapped in Australia. Here we present the results of an integrated U–Th and 14C dating study of a late Pleistocene fossil deposit that has yielded the youngest dated remains of giant monitor lizards in Australia. The site, Colosseum Chamber, is a cave deposit in the Mt Etna region, central eastern Australia. Sixteen new dates were generated and demonstrate that the bulk of the material in the deposit accumulated since ca. 50 ka. The new monitor fossil is, minimally, 30 ky younger than the previous youngest reliably dated record for giant lizards in Australia and for the first time, demonstrates that on a continental scale, humans and giant lizards overlapped in time. The new record brings the existing geochronological dataset for Australian giant monitor lizards to seven dated occurrences. With such sparse data, we are hesitant to argue that our new date represents the time of their extinction from the continent. Rather, we suspect that future fossil collecting will yield new samples both older and younger than 50 ka. Nevertheless, we unequivocally demonstrate that humans and giant monitor lizards overlapped temporally in Australia, and thus, humans can only now be considered potential drivers for their extinction.

Source:

Price, Gilbert J., Louys, Julien, Cramb, Jonathan, Feng, Yue-xing, Zhao, Jian-xin, Hocknull, Scott A., Webb, Gregory E., Nguyen, Ai Duc and Joannes-Boyau, Renaud. (2015). Temporal overlap of humans and giant lizards (Varanidae; Squamata) in Pleistocene Australia. Quaternary Science Reviews 125: 98-105. [Abstract]

[Isengard]

I'm no expert but I would assume that humans caused their extinction by hunting out their prey species and burning their environments? Presumably they were pretty dangerous and not a great thing to hunt. Is monitor lizard good eating?

[Ian Thomas]

Cool. Is on must read list.

Just because first humans in Australia overlapped some MF which then disappeared doesn't mean humans 'caused' the disappearance. There was never a continuous occupation of prehistoric Oz by humans. Both the genetic record and archaeology show that humans at the time disappeared along with the MF. Later arrivals then re-colonised 'Sahul' as it's called. The thing that gets glossed over is that people are globally distributed and have means to cross oceans. When the last megalania or diprotodon karked it, that was it for them because Sahul was the only place where their kind lived. But there was always a reservoir of humans across the water who could sail the seas and take over empty lands after a mass extinction.

Am. J. Hum. Genet. 65:808–828, 1999
Peopling of Sahul: mtDNA Variation in Aboriginal Australian and Papua New Guinean Populations
Alan J. Redd and Mark Stoneking
Aboriginal Australians showed close affinities with populations from the subcontinent of India, whereas PNG highlanders showed more-ancient divergence from all populations with hints of ancient ties to African populations.

These estimates of net divergence correspond to a date of separation between PNG highlanders and Australian Aborginals of 40,678 years (95% CI = 34,128–47,228 years) and a date of separation of Aboriginal Australians from southern Indians of only 3,390 years (95% CI = 1,686–5,093 years)

In other words PNG was settled by Africans at around 40kyrs whereas the most recent (pre-Euro) settlement of Sahul was only about 3000 years ago (maybe just 1600yrs?). With no input from a resident population. This can only mean the previous (African?) residents in Sahul died out before new colonisers from India arrived. The date tallies with extinctions of fauna like Tassie Devils and Thylacines from the mainland. It all means whatever killed MF also killed people just as completely. We can speculate the process has been going on for a very long time, like since 50,000 years ago.
 

[molloch]

Aug 24, 2015 9:18:39 GMT 10 Ian Thomas said:

Cool. Is on must read list.

Just because first humans in Australia overlapped some MF which then disappeared doesn't mean humans 'caused' the disappearance. There was never a continuous occupation of prehistoric Oz by humans. Both the genetic record and archaeology show that humans at the time disappeared along with the MF. Later arrivals then re-colonised 'Sahul' as it's called. The thing that gets glossed over is that people are globally distributed and have means to cross oceans. When the last megalania or diprotodon karked it, that was it for them because Sahul was the only place where their kind lived. But there was always a reservoir of humans across the water who could sail the seas and take over empty lands after a mass extinction.

Am. J. Hum. Genet. 65:808–828, 1999
Peopling of Sahul: mtDNA Variation in Aboriginal Australian and Papua New Guinean Populations
Alan J. Redd and Mark Stoneking
Aboriginal Australians showed close affinities with populations from the subcontinent of India, whereas PNG highlanders showed more-ancient divergence from all populations with hints of ancient ties to African populations.

These estimates of net divergence correspond to a date of separation between PNG highlanders and Australian Aborginals of 40,678 years (95% CI = 34,128–47,228 years) and a date of separation of Aboriginal Australians from southern Indians of only 3,390 years (95% CI = 1,686–5,093 years)

In other words PNG was settled by Africans at around 40kyrs whereas the most recent (pre-Euro) settlement of Sahul was only about 3000 years ago (maybe just 1600yrs?). With no input from a resident population. This can only mean the previous (African?) residents in Sahul died out before new colonisers from India arrived. The date tallies with extinctions of fauna like Tassie Devils and Thylacines from the mainland. It all means whatever killed MF also killed people just as completely. We can speculate the process has been going on for a very long time, like since 50,000 years ago.
 

Not quite, you are generalising the abstract a bit too much here. What the paper says is that there was admixing of Indian genomes and substantial gene flow - but the genome of the Australian Aboriginals is still close to that of the PNG. A larger, more recent studysupported this:

www.pnas.org/content/110/5/1803.full

They show more clearly that the Australian Aboriginal genome shares its origin with the PNG genome, but has substantial gene flow around 4320 years - which matches pretty closely with the palaeo evidence for the dingo and archaeo evidence for technology changes. However, the dingo has its origins in SE Asia - not India - so the picture is probably a bit more complex. Indian people probably got here via PNG rather than a direct flight.

see also:

www.pnas.org/content/110/32/E2948.full

and

www.researchgate.net/publication/235681928_Palaeoanthropology_Of_humans_dogs_and_tiny_tools

(Note also - we have firm dates of 3500ish years for the minimum age of the dingo being in Australia. Presumably they didn't get here alone - so Sahul was inhabited from at least that point.)

[Surroundx]

I had assumed that they were referring to Megalania:

"“We can’t tell if the bone is from a Komodo dragon — which once roamed Australia — or an even bigger species like the extinct Megalania monitor lizard, which weighed about 500kg and grew up to six metres long,” Dr Price said."

Source: www.uq.edu.au/news/article/2015/09/giant-killer-lizard-fossil-shines-new-light-early-australians