[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Prehistoric Times (Tanystropheus)
At 14.15 16/10/02 +0200, aspidel wrote:
As I repeatedly posted here, I basically agree with Tracy new
intepretation of the skull, so I have nothing to add now on this. Also the
reconstruction of the whole skeleton is nice.
> In the prolacertiform camp, Tracy Ford presented new reconstructions of
> the skull of Tanystropheus and provided new insight into its possible
There's a T. Ford's note about it, with line drawings, in Prehistoric Times
#56 I just received today.
Not easy to get PT in Italy, but fortunately a friend has a subscription,
so I rushed at his desk to look at the new issue.
Some concerns there are however for other sections of the paper : at p. 15
it is written that the cervicals are 11, while at p. 22 it is written they
are 10. Err... actually they should be 12.
I for one do not know how Tanystropheus swum, but I am not that sure that
the posture of the skeleton in fig 4 at p.15 (which represent a finding "as
preserved"), represents also a swimming posture as suggested again at
p.22. To my eyes it represents a taphonomic condition of post mortem
contraction of neck muscles/ligaments, as you can see in many long necked
vertebrates. See how the head is set off, along with the first cervicals,
from the rib bundles. some force bent the neck against the bundles and rip
off the head.
When swimming, undoubtedly Tanystropheus was a slow swimmer, and probably
the posterior limbs played a great role, given that the anterior ones were
reduced and with a poorly ossified carpus. The tail was not deep as in tail
propelled swimmers and mobility in its proximal third was hindered by wide
transverse processes. Haemal spines are very small and narrow in the distal
portion of the tail, not usual for a tail propelled swimmer.
Its sauropterygian contemporaries were nothosaurs and neusticosaurs, which
had long necks and long tails. They were very good swimmers even if quite
different from their plesiosaur successors.Nothosaurs used mainly the stout
forelimbs (not yet completely modified into paddles) for swimming, while
neusticosaurs were propelled mainly by the long and rather deep tail with
fan-like haemal spines. The long neck of triassic sauropterygians
(placodonts excluded it's obvious) had good lateral but little vertical
mobility (details on request, otherwise this posting becomes too long, in
short, these and the following assumptions rely on the overall vertebral
morphology and on the orientation of zygapophyses), the neck of
Tanystropheus had some vertical mobility but very little or no lateral
mobility. The Tschanz idea was that of a diver with a trident (I do not
know if this is good English, I mean the long stiff stick with one or more
pointed spears) to catch fishes.
Is really a great mistery but also a great fun wondering
about the possible eco-morpho-what else-types that will fit for
"The voice from the lake then asked "which is the strangest thing of all?"
Judisthira replied "Every day men see other men die, they see the chariots
with the >corpses and the fires, yet they keep living as they were
immortals, >this is the strangest thing of all"
Dipartimento di Scienze della Terra
Università degli Studi di Milano
Via Mangiagalli 34
I 20133 Milano
have a look at our Triassic website at