Where the Dinosaurs Are

OLD BONE ODORI
(my dance with dinosaurs)
page 5


BUILDING A BETTER STEGOSAURUS

ITC Stego

This is an ITC Stegosaurus, built in 1957.  As I recounted on the first page, this was my brother's model and I had to do some restoration of missing plates when I dug it out of storage in the early 1990's.  Since then I have put together new versions of the Tyrannosaurus and Brontosaurus kits in this series, re-released by Glencoe Models in the 1990's.  In doing so, I tried to make them more accurate in reflecting modern thinking regarding dinosaur posture as well as improving detail in many of the rather crudely cast pieces.   I have had a reissued Glencoe kit of this beast in my closet for a long time, and recently decided to see if I could make it into a more modern 21st century Stegosaurus. 

Little steg
NEW AND IMPROVED STEGOSAURUS

When I opened the box, my primary plan was to raise the tail off the ground as modern thinking says they weren't tail draggers.  I also wanted to make the tail spikes into a more horizontal  "thagomizer" instead of the old-fashioned upright configuration.  Then I took a closer look at the pieces and realized how much work was ahead.  As is typical of all of the kits in the ITC series, the vertebrae are narrow and oval rather than thick and round.  The articulations between the vertebral facets are only vaguely represented and if anyone really wanted to fix this central issue, they would probably be better off sculpting an entire model from scratch.  I decided to be content to try to enhance the disc demarcations between the bones and in a few places cut deeper grooves to depict intra-spinal articulations, but not to be obsessive about it. 

I always considered the skull of the Stegosaurus to be its blandest feature, and this old model is probably the reason. 

old head  old jaw

There is very little detail in the original.  A seam runs where there should be an opening and the mandible looks more like a lifeboat than a jaw.  I added some putty and went to work with my Dremel.  The orbits and nostrils were enlarged and I added fenestrae behind and above the eyes, as well as removing everything in the lower jaw that didn't look like a jaw.  I also carved out the underside of the skull so the poor thing would be able to swallow.

stego head work  new head and
                jaw

newhead

This is the new head, with all of the added openings

I cleaned up the neck and accentuated the cervical ribs.  I thought about adding osteoderms under the neck and making new ribs from sprue, but decided that would be too much trouble.  I may add them later.

As is typical of these kits, the ribs needed work. 

raw ribs  ribs to cut

There isn't anything to set the ribs apart from the vertebrae and there is a pretty obvious seam between the parts.  In the second image I show a sharpie line that gives an idea of where to apply the Dremel.  The plastic is fairly soft and shreds easily, which makes precise cuts tough.  Nonetheless, after a lot of cutting, puttying and sanding, there is at least a suggestion that there is a dividing line between the ribs and the vertebrae to which they attach.

new
                          ribs 


There has been some controversy over the position of the front limbs of Stegosaurus.  Some think that they are bent at the elbow and others believe that the front end was perched on fairly straight legs.  Either way, the head is supposed to be held fairly low, so I decided to stick with the bent position.*  While I didn't plan to do much in the way of putting the legs in a different pose, they needed a LOT of work.  The parts of the front legs didn't really line up with the joints and the rather crude casting quality made it tough to tell which bones were which.   At the elbows I had to decide how to show the radius and ulna as separate bones rather than a single messy clash of shapes.  Large seams that were almost extra joints had to be filled with putty.  Then there were the feet...  They consisted of softly formed clusters of toes with no delineation at all showing interphalageal joints.  I tried to deepen the gaps between the toes and used a cutting tool to make some rudimentary lines suggesting toes, but they still pretty much look as if this Stegosaurus is wearing mittens.  The feet are not the strongest part of this model. 

*As will be seen below, after putting the whole thing together, I changed my mind.

stego legs

A quick look at the hips and pelvis revealed what is probably the most amazing shortcut and incredible inaccuracy in this kit.  One of the basic and defining characteristics of all dinosaurs is the open acetabulum, or hip joint.  The opening is formed where the three bones of the pelvis, the pubis, ilium and ischium come together and the femur, or thigh bone is supposed to fit into that gap.   This model shows the femur butted into the underside of the iliac crest and there is no hip joint at all!  The rest of the pelvis is also a mess.  Stegosaurus is an ornithischian dinosaur, meaning that its pubis has an extension that runs backwards along the ischium rather than projecting forward in a large boot-shaped bone as seen in theropods such as the Tyrannosaurus.  In looking at this model I could never understand how the ornithischian pelvis was constructed and it was now evident why it always seemed so confusing.  The iliac rest looked pretty good aside from the slots on the underside for the misplaced femurs, but the lower pelvis parts are pretty much devoid of detail and consist of little more than Y-shaped blobs representing the smushed-together ischium and pubis. 

old pelvis

From the old version, the lack of a hip joint can be seen at the upper arrow and the fused, blobbish ischium and pubis is shown at the lower arrow.

I decided that I would need to get rid of the slots on the underside of the iliac crests, make heads for the femurs, and while I was at it, show the difference between the pubis and the ischium,


pelvis parts

In this picture a Sharpie has been used on the ischium/pubis to show the dividing line between the bones and where the acetabulum will be.  I have also cut the locating tab off of the end of the femur so that I can replace it with a plausible femoral head.

stego femora 

This kit has really heavy sprue and a couple of short lengths attached to the ends of the femurs make a nice basis for a head to articulate with an open acetabulum.

 stego pelvis parts

Some putty has been applied to the femurs and the demarcation between the pelvic bones as well as the open hip sockets are now pretty obvious.  There was still some drilling to do and those slots on the iliac rests still needed to be removed, but these parts make a much better pelvis!

Finally it was time to work on the tail, which was really the part I originally expected to alter the most.  The way the tail joined the body would need to be altered in order to have it up in the air instead of dragging on the ground.   The change in angle needed to happen over several inter-vertebral joints rather than in one place to avoid it appearing that the poor thing simply sat down too hard and broke it.  I began by cutting through the discs between the first five vertebrae at the base of the tail and inserting spacers made from number tabs scavenged from the model.  Once the discs were cut, the articulations between the neural spines bent easily.  I drilled a couple of holes into the center of the first few vertebrae and into the sacrum to allow me to insert pins to hold everything together. 

pelvis

1.  New disk spacers from number tabs.            
2.  Pin between tail and sacrum.                        
3.  Old femur insertion removed and puttied.      

All of the gaps were then puttied and sanded

tailbase



Finally, it was time to alter the "thagomizer".  The attachment tabs on the spikes were bent to allow an open angle between them and they were glued in place. 

thagomizer

At this point, the basic skeleton was complete and all that remained was the addition of the plates.  The largest plate, at the base of the tail, just didn't fit on its tab without running into the next tab and following plate.  I drilled a hole into it and another into the neural spine and used wire to attach it.   That worked well and it occurred to me that if I attached ALL of the plates that way, I could have them standing up or folded over, as the earliest depictions of Stegosaurus  showed them sloped downward like roof tiles.  However, that seemed like way too much work and I knew if I played with them too much, they would eventually break off and be really hard to reattach.  So the rest are glued onto the tabs projecting from the neural spines.

While I got down to work painting it with a coat of black primer, dark brown mixed with red for a second coat and a misting of medium gray with flat black washes and a little bit of medium brown dry brushing, I began to have misgivings about the way it looked.  As I said before, I had decided to leave the front legs bent and in modifying the hips I actually added at least a centimeter to the length of the femurs as well as moving their attachment points down from the iliac crest to the new sockets.  The end result was an animal that was really tipped forward with really long upper legs giving it a gigantic stride.  Before adding the plates and spikes, here is how it looked:

first pose

No matter how I looked at it, it seemed more like a skedaddling Scelidosaurus than the self-confident Stegosaurus I was trying to make.  My misgivings were confirmed when friends viewing some preliminary shots commented on the length of the stride and wondered if I had a reason for keeping the front legs bent.   The more I thought about it, then more I felt that I should probably make some changes.  Accuracy aside, there is another agenda here.  I am planning to re-build my original Stegosaurus as a somewhat different stegosaurid.  Most other members of the family are always shown with bent front legs and are all smaller than the North American Stegosaurus stenops on which this model is based.   They are all shorter, and bending the elbows will help with the illusion of a smaller animal.  I'm not sure when I will get to that project, but at least I am thinking ahead.

As far as the front legs were concerned, I had a hard time finding good images of skeletons with them straightened rather than bent.  There are plenty of pictures of life restorations in that configuration, but most museum skeleton displays don't seem to have been adjusted.  This summer I had gone to a display at the San Diego Natural History Museum where a Stegosaurus skeleton from the American Museum in New York was on display.  After taking a few pictures I was told that photography was verboten, but in reviewing my photos, I was delighted to find that I had gotten the shots I needed, and they showed the front legs in a vertical configuration!  To be honest, I was not that impressed with the way the joints articulated in that mount, but I decided to go ahead and make the necessary changes.  Clenching my teeth, I snapped the front legs off from the scapulas and used a wire cutter to do the same to the rear legs.  Of course, this caused the spine to snap at the the lumbar-sacral junction, so I used that as an opportunity to insert a long steel pin for future stability.  Next I used a razor saw to make the necessary angled cuts to separate each humerus from the ulna with its olecranon. 

new front

After some putty and sanding, new articulations were formed and reinforced with pins.

old elbow  new elbows
Old elbows                              New elbows

The femurs were easier to fix.  I chopped of the revised heads and made new ones with extra sprue, leaving them around one and a half centimeters shorter, then glued them back into the hips, using the base as a template for location.  Each of the feet has a pin that fits into the base, so the whole thing can be removed.  Some extra touch-up on the paint was all that remained.  As with any model, there are definitely ways to improve this beyond what I already did, but at this point there are no major issues eating at me.  I may still add some cervical ribs, but I will probably leave the legs alone unless there is some future revelation that determines once and for all that they are bent after all. 

Stegosaurus

Frontal





RESIN FATIGUE IN ALLOSAURS

It is 2014 and while I find it hard to believe, my Ants Allosaurus is twenty years old!  Although I tend to think of my models as fairly durable, I recently noticed that this one was starting to show its age.  Over the years I have have had to repair it a number of
times, most extensively when the right leg broke off during a move and required a metal pin in the hip socket to hold it in place and at the same time the head and first cervical vertebra snapped off and also needed a steel pin for stability.  The tail is quite a lever
arm and has broken in several places but I always just used superglue and kicker to repair it.  Over the past year or more I have tried to ignore an increasing sag there but finally had to admit that the tip was dropping to the level of the ankle as there was bending in the resin at multiple joints, not just loosening in the glue bonding the pieces together.  Pretty soon it would be regressing to become a tail dragger, a dinosaur depiction considered seriously out of date.  As I moved the tail up and down I realized that it would almost have to become a solid mass of superglue to have any hope of rigidity and that would be even uglier than having the tail touch the ground.   I briefly considered a wire support but discarded the idea on aesthetic grounds and besides there was the likelihood that it would continue to sag between the pelvis and any support and end up looking like a pony ready for the glue factory.

Allosag

With a little downward pressure the tail snapped off and a little bit of flexing showed where other loose joints were as they gave way.

Bobtail    Allotail

Then it was Dremel time, an always anxiety-provoking activity.  Holding parts like these steady while trying to drill directly through their centers without having the bit come popping out the side a few vertebrae down the line and avoiding snapping off transverse processes demands a steadier hand than I usually have.  The holes also have to line up with each other, something that can be tough to accomplish when the tip of the drill keeps skipping around on contact with the pieces.   I tried to make sure that the holes extended through at least a couple of vertebrae in each direction so that wire would provide some serious stability.

Listhesis  allowired

While I was at it, I decided to correct the listhesis between the two vertebrae on the right side of the largest hunk of tail .  (That's the poor alignment between the bones causing a step-off where the arrow is pointing) and those bones were not loose at all, so I had to cut them apart before drilling.  I then inserted lengths of stiff wire into the holes and slid the bones back over it like a string of pearls, adjusted the bend in a few places and exhaled.

allofixed

I am pretty happy with the way it looks now and wish I had used a lot more wire and pins when I built it in the first place or better yet, brass connectors like Brant Bassam recommends on his website but this fix may last a while and a complete retrofit would probably be more hassle than it is worth.  I'll know more in a few years if there are no new drags, sags or gravitationally induced snaps.





TYRANNOSAURUS EVOLUTION

My Tyrannosaurus skeleton is an ongoing project.  After several moves I noticed that a couple of toes were broken off and as long as I was gluing them back together I decided to adjust the arms.  They had been in the standard pose reaching forward with palms facing down.  Current thinking is that they are supposed to be hanging down and pronated so that the palms are facing inward.  Cutting through the elbow joints was a bit tougher than I anticipated and I ended up having to re-glue both entire forelimbs, including the scapulae back to the ribs without benefit of locating pins as I removed them when I first put the kit together.  Well, anything for accuracy, right?

newly armed rex

old arms        new arms
Old arms                                                      New arms

Come to think of it though, I should have added a furcula.  Next time!