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Re: Ichthyosaurus fossilised in mid-birth ??

--- Phil Bigelow <bigelowp@juno.com> wrote:
 > On Fri, 22 Jul 2005 21:08:34 +0100 (BST) Aidan Karley
 > <aidan_karley@yahoo.co.uk> writes:
 > > 
 > > --- Roberto Takata <rmtakata@gmail.com> wrote:
 > > 
 > > > (Where was that ichthyosaur giving birth to a baby from?)
 > Liassic (lower Jurassic) beds near Holzmaden, southern Germany..
 > The specimen is stored at the Staatliches Museum fur Naturkunde. in
 > Stuttgart.
     I'll try to refresh my memory on it when I get back onshore.
 > > Maybe 
 > > not
 > > as improbable sounding as the "fighting protoceratops" reported 
 > > from
 > > somewhere in the vicinity of Mongolia
 > The burial has been interpreted to be the result of a sudden
 > dune
 > collapse.
 > The Ankie baby clutch is also thought to have been buried by a dune
 > collapse. 
     Something would have been necessary to change the structural
 strength of the dune to get a collapse flow of some metres of
 thickness. The normal lee scarp flows on aeolian dunes are what? - a
 few mm thick? I'm trying to work up a scenario to generate such a
 strength change. Base of the dune weakened by rapidly-rising water
 table (flash flooding adjacent to a wadi?) leading to collapse of the
 whole dune base by local liquefaction? But a rising water table
 bringing a weakened zone close to the surface would result in listric
 rotation of sediment blocks near the surface, wouldn't it? At least,
 that's how I read the various landslips I've seen around the coasts.
 Intuitively it doesn't gel. I need to get out the arid region
 sedimentology text books again (which attic are they stored in?).
     Would getting mired in a quicksand do the job? Been on the
 receiving end of that myself, and there's no arguing with memories of
 the clammy feel of the sand around your knees.
     Does anyone know what the stratigraphic context of the "fighting
 dinosaurs" specimen is. Sandstone immeidately, but I'm wondering what
 was below the sand while it was being deposited. My memories from
 Norrell's (?) 'Dinosaurs of the Flaming Cliffs' book is that the area
 is a mish-mash of sandstones, palaeosols, caliche beds and minor (?)
 fine clastics, and I'm thinking about possibilities of springs coming
 to the surface through an unconsolidated sand bed - instant predator
 Aidan Karley,
 Aberdeen, (well, several hundred miles out to sea from ...)

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