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You Hailu and Mazongshan
You Hailu kindly supplied me with a copy of his thesis, and so far, it
appears to be very interesting. While *Archaeoceratops* and his new
hadrosauroid are treated with a cladistic analysis, his new titanosaur is
not; the cladistic analysis of *Archaeoceratops* agrees with recent work
by Makovicky, and that of the hadrosauroid places it as the most basal
hadrosauroid, but it doesn't take many steps to place it in a trichotomy
with "iguanodontoids" proper and hadrosauroids. The new hadrosauroid is
very similar to both *Altirhinus* on one side and *Jinzhousaurus* on the
other, is short-snouted, and has a dentary more than 75% the jaw length,
as in *Ouranosaurus* and hadrosaurs but unlike the "generic" basal
hadrosaurs *Protohadros* or *Eolambia*, or the basal "iguanodontoid"
*Probactrosaurus gobiensis*. His new titanosaur is said to be very similar
to *Tangvayosaurus*, and the general placement compared to several basal
forms, including *Malawisaurus*, *Phuwiangosaurus*, and *Cedarosaurus*,
tends to agree with recent placement of *Tangvayosaurus* (=*Titanosaurus
falloti*) as a titanosauroid. *Opisthocoelicaudia* is not compared but
*Andesaurus* is. The most interesting thing about the skeleton is perhaps
the distal caudals which, rather than being truly biconvex, have small
mounds on both ends with well-defined rims and a pit dorsal to the mound
(the last is central in the facet, and they do not interlock); despite
this, You says they are not biconvex, which might be a matter of degree
rather than absolute condition; his new form might therefore be
intermediate between the amphiplatyan and biconvex conditions.
As a note, Mazongshan in Chinese translates to "Horse Mane Mountain", a
name You uses rather frequently; the name for his new hadrosauroid comes
from the Latin, _equus_ and _jubus_, respectively, dropping "mountain".
Stratigraphically, the level from which these forms as well as
*Nanshiungosaurus bohlini* derive appears to balance around the Albian,
based largely on palynological data; the fossils hail from beds relegated
to the Chijinbao or Dugou Formations, which are Early to Middle Cretaceous
in age, and part of the Xinminbao Group. *Archaeoceratops*, an
iguanodontid, and an ornithomimid are known from the lower, red, beds of
the Chijinbao; the middle, grey, beds of the Dugou yield an ornithomimid,
the new hadrosauroid, and the new titanosaur.
Jaime A. Headden
Little steps are often the hardest to take. We are too used to making leaps
in the face of adversity, that a simple skip is so hard to do. We should all
learn to walk soft, walk small, see the world around us rather than zoom by it.
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