Re: Mamenchisaurus tail club

["Fam Jansma" <fam.jansma@worldonline.nl>]

You wrote:
>
>This is really exciting news.  I can't wait to see Mamenchisaurus restored
>with this new tail club and I wonder how its skull material compares with
>the skull material known from other mamenchisaurus species (I recall at
>least one other is known from skull material, saw it on a Discovery program
>years ago).
>
More species of Mamenchisaurus have cranial material preserved, here a short
list (all taken from the Polygot-website, has a few good
Mamenchisaurus-papers, you should check it out:
http://blackwidow.informatics.sunysb.edu/anatsci/browse.cfm ):
1) Mamenchisaurus youngi (skull lenght 51 cm, skull hight 31 cm, skull
breadth 19 cm)
- nearly complete skull, only lacking few elements on the posterior left
side
- lower jaws complete with only the midportions slightly damaged (lenght
(restored) 47 cm)
- the upper dentition is complete and the lower dentition nearly so
2) Mamenchisaurus sinocanadorum (lenght of specimen not given)
- just presented by a lower jaw with dentition, it was on the same show as
the one on which you saw that other Mamenchisaurus skull. I know, I saw the
same, but when they start talking about a Mongolian dig, you can see the
lower jaw of this (doubtfull) species of Mamenchisaurus
3) Mamenchisaurus jingyanensis (skull lenght 55 cm, skull hight 25 cm, skull
breadt 25 cm)
- nearly complete skull lacking nasal and jugal
- the right mandible has been damaged but the left is relatively well
preserved, lacking only the articular
- replacement teeth present in the empty alveoli, as well as some scattered
ones in the matrix from the upper dentition, the lower dentition is complete
4) Mamenchisaurus anyuensis
- the skull is only represented by 14 isolated teeth
These are the species that I know of that had cranial material, but more
species are described IIRC, but if they include any skull material....
>
> Its certainly an interesting skull, with just an amateurs
>perspective it looks like a cross between the Diplodocus and
>Camarasaurus-like skulls (which were the two kinds they debated putting on
>it all those years before skull material was known if I recall right).
>
It looked more slender though, more like the skull of M. jingyanensis, but
IIRC the skull was pretty crushed.
>
>Its also nice to see the amterial referred to an existing species instead
of
>creating a new one from it.  It seems to me this is done too often with
>Chinese sauropods.
>
Agreed, individual variation is often neglected, as well as sexual
dimorphism.
>
>One question though.  How could something sensitive enough to be a sense
>organ also function as a weapon (which would typically need to be tough and
>resitent to damage)?  The two purposes seem to be mutually exclusive.
>
The tailclub could very well be a pathological thing, when the end was
bitten by a Sinraptorid and got infected or something like that. It happened
to that famous tail-spike of a Stegosaurus-specimen which got completely
deformed due to the infection, so a similair condition might have occured
here.