Mosasaur Moment

Ross McMillan

Ross McMillan of Dallas is a paleosculptor who creates models of ancient creatures for researchers and scientific exhibits. Following is the account of making the Dallasaurus turneri model as told by Jan, his wife, researcher and active participant in the process.

Ross McMillan

On December 12, 2004 Ross spoke by phone with Mike Polcyn , a researcher with SMU’s Department of Geological Sciences, to discuss the recent discovery in Dallas County of a new species of early mosasaur. This “find” is quite significant as the skeletal bones date back to 92 million years ago.

The animal, Dallasaurus turneri is a new primitive mosasaur from the Middle Turonian of Texas.

Ross and I met with Mike to hear his idea for a sculpture. We examined the actual fossilized remains (vertebrae, etc.) sketched them and made measurements to determine proper placement on the skeleton.

Numerous points needed to be discussed with Mike before the start of the actual sculpture. For instance, while Dallasaurus was swimming were the legs held close to or away from the body? Another point in question was the general posture of the body and tail. Studying the motion of modern monitor lizards while swimming, it can be surmised that primary propulsion was provided by the tail. The muscles involved in the undulating motion were anchored immediately forward of the hips which suggests that the body, forward of that area would have been held fairly straight except during abrupt maneuvers such as sharp turns.

Jan McMillan

Our plan was to depict the animal while casually cruising his territory.

The skull and limbs are done separately from the body. The skull was fashioned from thermal plastic clay which hardens upon baking. This was shown to Mike, who pointed out areas that needed to be revised for this specific animal. Ross made the appropriate changes, and again had Mike examine it. Mike gave it the final ok. The skull was then “muscled up” with clay in preparation for skin detail that would be added later.

Moving past the skull to full body Ross started with a 3/16th’s piece of copper wire the length of the body (which serves as the spine) the basic body shape is made with aluminum foil and wired onto the copper, leaving room to later lay thermal hardening clay over this armature. The limbs are done by the same process but with thinner wires, cut to the length of the skeletal drawings. Over the following months the body shape was defined with particular attention given to the anatomical features which were specific to this animal.

Mike was consulted every step of the way by email, phone or when we were fortunate enough to have him “in person”.

Though they would be covered by skin, the placement and shape of muscles and certain organs was of critical importance to achieve an accurate portrayal of this little guy. When these underlying features were completed, the main body and tail were baked in a large specially designed oven in our studio. The smaller pieces are baked in our kitchen oven. I have actually baked more feet, hands and skulls in my oven than food!

Author’s note:
It is now June. You might wonder how in the world it could take up to six months to only get this far & my response is that it’s a good thing this artist (Ross) and this Scientist (Mike) are both perfectionist- to the end and only then (using my favorite line, “You know that you know”.

Ross McMillan talks about making the model for Dallasaurus, which is shown alongside fossil castings of much larger mosasaurs that existed later.

Finally satisfied, with all body parts properly secured, the entire animal is ready for the Skin detail. I will say that the skin detail took more time than almost any other aspect of the sculpture.

Fortunately, fossilized skin samples from other mosasaurs were able to serve as a guide in depicting a smooth, almost rectangular scale pattern (much like a modern day Iguana). After completion of the final skin detail, the head, body and tail went into the oven again this time as a complete piece. The legs were baked separately. (yes, in my oven)!

Another fortunate event was a visit from our good friend Keith Strasser, known worldwide as a premier paleosculptor. His experience was helpful during the final stages of the sculpt when proper ‘tweaking’ and a second ‘experienced eye’ can fine tune various areas. In addition it was quite fortuitous that Keith was here to help with the tedious task of molding & casting.

Whenever a paleo artist attempts to recreate a long extinct animal, a certain amount of artistic license will be exercised. If an actual sample of fossilized Dallasaurus skin is discovered, we may find that the scale pattern is slightly different than the one we have chosen.

Next, two-part RTV (room temperature vulcanizing) rubber molds were made of the body & limbs. *note: sounds simple but it took almost 40 hours to complete this chore. Using the molds, a casting of each piece was made from two-part resin. Because of weight constraints, the main body was hollow cast and later filled with expandable foam.

A 3/8” steel rod was inserted through the underside of the body between the hind legs and anchored firmly with two-part epoxy. The rod was then epoxied into a predrilled hole into a base that was cast from Hydrocal (a cement like plaster). The rod holds the sculpture suspended approximately 4 inches above the top of the base. The base was painted with various colors using an air brush. These colors were then toned down and blended using a series of translucent washes.

The legs were ready to be epoxied to the body and scale detail was sculpted at the seams to provide a smooth transition from legs to body.

Glass eyes from a taxidermy supply were epoxied into the eye sockets and eyelid detail was fashioned using two-part epoxy. After carefully masking the eyes & covering the base, the entire piece was primed with a lacquer based primer

Now it was time for the most fun part! The animal gets ‘dressed’.

The Painting.

Ross has quite an imagination, and an excellent, unmatchable sense of color and technique. He chose to paint the animal in a striped pattern of greens and blues, over a light yellow to tan base. Skin folds and scale detail were enhanced by the use of burnt umber, applied in multiple thin washes.

The final step was to disguise the metal support rod with artificial plant material resembling generic sea grasses of the Late Cretaceous.

The project lasted 10 months to the day. The Sculpture, Dallasaurus turneri, a/k/a “TODD”, was born on October 12, 2005. (Ross names all of his sculptures).

The actual time spent in research, casting, sculpting (and all the other stuff) was by our estimate, 800-1000 hours.

Another sculpture of Dallasaurus turneri is planned for the near future. By altering the body parts of the first sculpture, the 2nd piece can be finished in a shorter time period…probably not more than 3-400 hrs.

This sculpture was very much a labor of love. Every part of the project was a real delight (except maybe the molding & casting) for us.

It is particularly exciting for a paleo artist to have the opportunity to portray a new discovery.

Being able to work on this with a knowledgeable scientist, Mike Polcyn ensures the most up to date scientific accuracy. His understanding of the subject and attention to detail encouraged us throughout this time; not ignoring his availability by phone (even from other countries), e-mail and the countless miles between his house to ours to SMU.

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