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Re: Everything you know about the Iren Dabasu age is (right)



Tim Donovan wrote-

> Very simplistic comparison there.
> Regarding size, Segnosaurus overlaps with
> Therizinosaurus,

 Because the hindlimb specimen from Khermeen Tsav is
relatively small?

No, I didn't include the hindlimb in Therizinosaurus for our comparisons since it cannot be compared to any of ther specimen (with published information), so may not belong to the taxon. The smallest Therizinosaurus specimen I know of is IGM 100/17, a first manual ungual. I don't think I need to mention the uncertainties involved in comparing taxon sizes based on incomplete specimens, differing proportions, etc..


>while the named
> Iren Debasu taxa are smaller than Baynshiren or
> Nemegt taxa.  But then you
> have the Iren Debasu forearm which is in the
> Baynshiren size range.  Of
> course, this isn't very useful when we don't know
> the age of any of these
> specimens.
> Regarding abundance, we have one specimen of
> Erlikosaurus and Erlianosaurus,
> two of Neimongosaurus, four of Segnosaurus,

 Is that all? I count 5 localities which yield
Segnosaurus or something similar.

I know of the holotype (IGM 100/80) and a referred specimen (IGM 100/81) from Amtgay, a paratype (IGM 100/82) from Khara Khutul, and another paratype (IGM 100/83) from Baynsheen Tsav. Three localities. Which others do you have and what are your references? Currie (2000) also lists it as being from Urilge Khudag, but his reference for that (Barsbold and Perle, 1980) doesn't mention that locality, and every specimen described by the latter has a known locality.


>and four
> of Therizinosaurus.

 I thought there was one specimen from the Nemegt
Basin and two from Khermeen Tsav.

The holotype (PIN 551-483) is from the Nemegt Basin, three referred specimens (IGM 100/15, 100/16, 100/17) are from Khermeen Tsav. The tentatively referred hindlimb (IGm 100/45) is apparently also from Khermeen Tsav.


> How is Therizinosaurus rare again?

 AFAIK, it is only known from a few specimens from two
Nemegtian localities out of about ten, whereas all
localities long considered of Bayanshiree age have
yielded therizinosaurs.

Well, besides Segnosaurus from Amtgay, Khara Khutul and Baynsheen Tsav, we have Erlikosaurus from Baysheen Tsav and Enigmosaurus from Khara Khutul. What other Bayanshiree localities are you including, which segnosaur specimens are known from them, and what are your references?


> Or looking at it
> from a stratigraphic
> perspective, more than six Iren Debasu specimens,
> six Baynshiren specimens,

 How recent are these stats? Do they take into account
work of the mid-late '90s in Outer Mongolia?

They include all published specimens I'm aware of.

Mickey Mortimer