Re: Triassic mammal-like reptiles?

[Phil Bigelow <bigelowp@juno.com>]

If there is enough matrix still attached to the specimen, perhaps spore
analysis would settle the matter.  Spore bearing plants occur in both
Triassic and lower Cretaceous times, but their respective species should
be quite different.

<pb>
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On Mon, 07 Nov 2005 11:23:04 +0100 K and T Dykes <ktdykes@arcor.de>
writes:
> <<Any chance the material was redeposited from a Triassic formation?  
> Are
> there any Triassic units near the Australian locality or in its
> subsurface?>>
> 
> The authors discussed such possibilities, Phil, and I think the 
> paper's
> hanging around on line: Thulborn T & Turner S (2003), The last 
> dicynodont:
> an Australian Cretaceous relict, Proceedings of the Royal Society B, 
> 270,
> p.985-993.  I don't seem to have saved a copy of the file, so I'll 
> just have
> to nip off and fetch the print...
> 
> Back again.  The relevant six fragments were found in 1914 in 
> north-central
> Queensland.  Somebody said they were very like stuff Broom was 
> sweeping up
> in Karoo, especially the dicynodonts.  They then hung around in the
> Queensland Museum, as various other things occurred; a couple of 
> world wars,
> depressions, energy crises, cold wars, weddings and assorted other 
> global
> catastrophies.  A bit later (85 years or so) somebody noticed them 
> lying
> around, had a look and went golly gosh!
> 
> "Adherent matrix, a yellow-brownish mudstone, betrays their most 
> likely
> source as the Allaru Formation, a thick (ca. 250 m) succession of 
> mudstones
> and siltstones which outcrop exstensively in the region of 
> Alderley..."
> (reference number omitted, p.985).  And from a bit later on the same 
> page:
> "There are no outcrops of pre-Cretaceous rocks in the vicinity of
> Alderley..."
> 
> On page 987 they pose the question: Is this a dicynodont?  Based on 
> the
> anatomy their answer is yes.  If the things had been found in 
> suitable
> Triassic strata, there'd be no reason for any doubt at all.
> 
> As this is unlikely sounding stuff, they begin addressing the age 
> issues on
> page 989.  Associated fossils include a bit of ?/Platypterygius/ 
> ichthyosaur
> (which doesn't mean much to me).  They mention the complete lack of
> pre-Cretaceous rocks  in the area: "(ie. on the entire 1 : 250 000
> geological map showing ALderley station..:"  The nearest Triassic 
> exposures
> are over 100km away.  There's one paragraph which summarises their 
> case on
> the age succinctly and clearly (same page):
> 
> "In short, we can find no reason to doubt that QMF15.990 originated 
> from the
> Rolling Downs Group.  It seems quite certainly to be Early 
> Cretaceous in age
> and was probably introduced into the marine environment by 
> flood-waters that
> also carried the carcases of sauropods, ankylosaurs and ornithopod 
> dinosaurs
> (Molnar 1991, 1996a,b)."
> 
> Although those dinos weren't furry, even I can  appreciate the age
> implications of their presence.  The best explanation presently 
> available is
> that these fragments come from a Lower Cretaceous dicynodont.  While 
> that
> sounds outrageously unlikely, they couldn't come up with a more 
> plausible
> conclsion.  And the authors certainly appear to have tried all 
> options.
> 
> 
> 


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