Meet Jane, Juvenile Tyrannosaur

A juvenile tyrannosaur (a term referring to members of the dinosaur family Tyrannosauridae that includes T. rex, Nanotyrannus, Tarbosaurus, Gorgosaurus and Albertosaurus), “Jane” was discovered in June 2001, during a Burpee Museum expedition to the Hell Creek Formation of Carter County in Montana. Jane was initially found by two amateurs: Bill Harrison, a professor of foreign languages and literatures at Northern Illinois University; and homemaker Carol Tuck. Because Jane was discovered toward the end of the field season, excavation had to wait until the following year.

Over the course of seven weeks, approximately 12 feet of overburden was removed to expose the partially articulated skeleton of a small tyrannosaurid. During excavation, the specimen was "field" identified as Nanotyrannus lancensis because of the similarities in tooth and jaw morphology to the Nanotyrannus holotype skull (CMNH 7541) housed at The Cleveland Museum of Natural History. The specimen was removed in several plaster jackets, the largest being some 8 feet by 5 feet  and weighing 2 tons. The specimen was transported back to Rockford, Illinois, in August 2002. However, preparation did not begin until January 2003. A team of preparators with no formal training prepared the specimen, a process that took approximately 10,500 man hours.

Skeletal drawing by Burpee Museum of Natural History

Once prepared, the specimen was found to be 51 percent complete by bone count, with skeletal elements that include two-thirds of a disarticulated skull, several cervical vertebrae, several cervical ribs, several dorsal vertebrae and ribs, the right scapulocoracoid, the right humerus, complete hips and sacrum, mostly complete legs and feet, and about half the caudal series.
  Jane Skeletal drawing

After being prepared and molded/cast, Jane was studied by Burpee Museum Curator Michael Henderson and several well-known tyrannosaur paleontologists including Philip Currie, Robert Bakker and Jack Horner. This research is ongoing and a formal description of the specimen is being formulated.

When initially prepared, many characteristics were found that appeared distinct from T. rex, including a prominent lateral glenoid shelf on the scapula (shoulder joint), a narrow "Gorgosaurus-like" vomer (a bone on the roof of the mouth), an increased alveoli (tooth-socket) count in both the maxilla and dentary, and an unknown pneumatic foramen (opening) in the left quadratojugal (bone at the back of the jaw) also present in the holotype of Nanotyrannus (CMNH 7541).

The first two skeletal characters are now recognized as being the result of the animal’s young age and small size. It is now known that similar features are present in other small tyrannosaurids and are lost as the animals grow and mature. Also, histological work was done on Jane by Dr. Greg Erickson, who examined the growth rates of various tyrannosaurs. Based on his work, Jane is determined to have been 11 years old at the time of her death and still growing.

The presence of more tooth rows in the lower jaws of both Jane and Nanotyrannus has made the potential referral of either taxa to T. rex more difficult. However, new Tyrannosaurus specimens, including “Samson” at the Carnegie Museum in Pittsburgh and the re-prepared T. rex specimen at South Dakota School of Mines in Rapid City, South Dakota, show these same extra tooth placements in both the dentary and maxilla.

Thus, the presence of the unique jaw character seems to suggest that Jane and CMNH 7541 may indeed be the same type of dinosaur and may be different from T. rex. Additionally, unpublished data obtained from CT scans of the braincase of CMNH 7541, carried out by Dr. Larry Witmer at Ohio University, has revealed characters that suggest CMNH 7541 is not from a T. rex. Unfortunately, the braincase of Jane was not recovered with the specimen, so direct comparison of this region of the two skulls is not possible at this time.

Burpee Museum scientists continue to study Jane. CMNH eagerly awaits the results of their research. In the meantime, we’ll be conservative and simply call Jane a "juvenile tyrannosaur."

A cast of Jane went on display at CMNH on November 11, 2006.

Fun fact:

Jane has a pathological toe – a large "spongy growth" on the right toe of her left foot.  Originally diagnosed as a heal fracture, the element was CT scanned by radiologists at Rockford Memorial Hospital. The pathology was re-diagnosed as an osteomelitis with a Brody's Abscess (bone infection). In humans/mammals, such a bone infection can be quite debilitating: prior to the advent of antibiotics, it was 20 percent fatal in humans. This bone infection may have affected Jane's behavior.