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Re: Sloping terrain Re: Woman against Abelisaur



Dann Pigdon <dannj@alphalink.com.au> wrote:


> Just because something died in a particular environment doesn't necessarily 
> mean it lived there
> habitually. Archaeopteryx remains are often found in aquatic sediments, for 
> instance, but what if
> that means they had a high probability of dying if they attempted to cross 
> large water bodies,
> rather than being proof that they always lived close to water?


In the case of _Archaeopteryx_, I don't believe anyone has seriously
suggested that it lived where it died - in salty lagoons.  There are
also fossil flora and invertebrate fauna (especially insects)
preserved at Solnhofen that could only come from a forested habitat
with access to freshwater.  If, as recently suggested, Archaeopteryx
could not fly, but only glide, then it is highly unlikely that it
would have endeavored to cross large bodies of water.  Even if it
could fly, then it still possible that the known specimens were found
a long way from their preferred habitat(s) - like the winged,
forest-dwelling insects on which _Archaeopteryx_ may have fed.  If
_Archaeopteryx_ had a high probability of dying if it attempted to
cross large water bodies, then it presumably wouldn't do so unless
compelled to (such as by drought, or other circumstances that led to a
decline in resources on its island habitat).


> Fossilisation after all tends to record a creature's death rather than it's 
> life. A creature that finds
> itself in an environment it isn't well suited to may well have a higher 
> probability of dying than
> usual.


True enough.  But in the case of _Paralititan_, the fossilized
individual negotiated tidal flats and tidal channels in order to reach
the spot where it came to grief.  The water was shallow, the
vegetation plentiful, and the ground firm.  Why wouldn't a sauropod be
"well suited" to such an environment?  Also, there is evidence that
the carcass was scavenged by a carcharodontosaur.  The
carcharodontosaur didn't die there - it only left a tooth behind.  So
the carcharodontosaur didn't succumb to the local environment, and
therefore is no reason to assume that the _Paralititan_ did either.
It might have...who knows?


As for the mired _Giraffatitan_, this is a different case altogether.
It's been suggested that it was driven to the lagoon in which it died
because of drought.  Larger individuals got stuck in the mud, but
smaller/lighter individuals could pull themselves out.  The fact that
a large specimen of _Giraffatitan_ (and _Janenschia_ too) show limb
bones in an upright, articulated position indicates that they were
mired in the mud, and therefore implies they were in an environment
they weren't well suited to.




Cheers

Tim