Triceratops posture

[GSP1954@aol.com]

In all known quadrupedal dinosaur trackways the hindfeet nearly touch the 
midline or are separated by no more than one foot width. The handprints are 
often but not always a little further from the midline, being separated by 
one to two handprint widths. 

The very large trackways very probably correctly attributed to Triceratops 
(the only viable four toed alternative being a giant nodosaur so far not 
known from that time and place) has the touching the midline, so the legs 
sloped down and in from the hips, with the knee bowed out a little like in 
rhinos. The hand prints are somewhat further out being separated by two 
handprints, which places them immediately below the shoulder joints. The 
elbows probably were bowed out a little, which is true of rhinos and other 
ungulates. The substantial projection medial to the humerus head, which was 
also present in sauropods, would not have interfered with the ribs because 
the shoulder joint was located forward of the anterior ribs. There is no 
evidence that the arms were semi-sprawling during normal locomtion, although 
they may have been able to assume such a posture when drinking or during slow 
speed combat. This is detailed in the 2000 paper I co-authored with Per 
Christiansen in Paleobiology 26:450. 

The new Smithsonian mount has the hindfeet separated by about three or four 
foot widthes, causing the legs to splay out in a manner not compatible with 
any dinosaur trackway. The hands are separated by three or four hand widths, 
also much greater than observed. Some of the joints do not appear to be fully 
articulated. There are problems with the configuration of the scapular 
glenoid, which is often distorted by crushing but faces partly inwards in 3-D 
preserved examples of Triceratops and other ceratopsians large and small. I 
do not believe any of the well preserved glenoids were digitized. 

If moi ever gets a chance to design a Triceratops mount I'll plop the sucker 
directly onto the trackway, with any size differences accounted for. Should 
be the standard procedure in my humble opinion. 

GP