THE BIG DISCOVERY
By Lesley Kool
Ask any palaeontologist and they will tell you that the best discoveries of the dig are usually made on the last day, when everyone is packing up. Fortunately the best discovery of the 2017 Eric the Red West dig was made on the second-to last day, so we had another day up our sleeve to return to the site to find more.
Up until that penultimate day the dig had been going along quite smoothly, with the occasional dinosaur jaw, dinosaur limb and a number of dinosaur vertebrae coming out of the main part of the fossil layer. Then great excitement ensued when a concentration of bones was recovered in a number of associated blocks of rock. It quickly became clear that this many bones, so close to one another had not been found at this site since its discovery in 2005 when Mike Cleeland and George Caspar found the remains of a small ornithopod dinosaur skeleton. Could these bones represent the remains of another small dinosaur?
After dig manager Steve Poropat drew a "mud map" of the position of the major blocks and the exposed bones within the fossil layer, the blocks of rock and all outlying fragments were carefully collected and transported back to camp for further study. As most of the bones were still encased in rock and only cross-sections were visible, it was difficult to identify individual elements. There were three large blocks, which contained most of the exposed bones, plus a number of smaller blocks. A careful reconstruction of the blocks could not be carried out at the camp so it was decided that the blocks should be transported back to my home, where I have a small preparation laboratory set up.
The following day, the rest of the crew returned to the site to make sure that they had retrieved all the fossiliferous rock surrounding the associated bones, whilst I returned home to work on the bone jigsaw.
I was able to ascertain how most of the bones fit back together again but there were a couple of specimens that appeared to be missing ends. Fortunately a visit from Wendy Turner the following week solved those problems. Wendy was one of the excavation crew members who had discovered the accumulated bones, and when she called in the following week, she had in her possession the last of the missing pieces of bone. She was also instrumental in helping me piece some of the more obscure bones together, which saved me many hours of head-scratching.
Because the discovery of an accumulation of bones is a rarity at the Eric the Red West site, lead researcher Dr. Tom Rich decided it would be worth scanning the blocks to see if any unexposed bones could be detected. Two of the three blocks were scanned using a Computed Tomography scanner, but revealed no evidence of internal bones.
Once the blocks had been scanned, the next step was to decide how to prepare the bones. Under normal circumstances, when individual bones are prepared, the bone is completely removed from the surrounding rock so that it can be studied in more detail. However, in this case, it was important that the association between the bones was preserved. It was decided that the bones would be exposed enough to be identified, but left in situ in the blocks. As some bones were shared by more than one block it was important to make sure that they were prepared with the same exposed aspect.
The preparation of the bones took around three months and yielded a number of surprises.
Firstly, there are eleven bones present in the blocks and they represent more than one dinosaur.
Six of the bones are from an ornithopod dinosaur (the small plant eating dinosaurs that are so common in Victorian Cretaceous rocks). A partial hip includes an ilium and ischium, which could possibly be from the same individual. An ulna and humerus (parts of the fore-limb) could also be associated. The bottom part of a tibia is also preserved, which is approximately the right size to be associated with the hip bones. A small centrum; part of a vertebra from the back bone of an ornithopod dinosaur was also preserved.
Four bones belong to a theropod (meat-eating) dinosaur: two metatarsals from the foot; a claw, probably from the hand of a theropod dinosaur and a slender rib bone called a gastralium is also preserved.
The eleventh bone is a piece of turtle carapace, which is a rare find at the Eric the Red West site, unlike the Flat Rocks site at Inverloch where turtle bones are quite common.
Once all the bones were exposed, the blocks were transported to the Preparation laboratory in Museums Victoria, Melbourne, where Collections Manager Tim Zeigler expertly glued them back together again and they are now on permanent display to visitors to the lab.
Although the bones did not turn out to be the remains of a second ornithopod dinosaur skeleton there is some evidence that at least some of the bones may have come from the same individual, and the discovery of more theropod dinosaur bones is always exciting. The Dinosaur Dreaming team intend to return to the Eric the Red site in the future to explore more of the fossil layer in the hope of finding more associated bones.
The blocks of fossiliferous rock recovered from the Eric the Red West site at the end of the 2017 field season, prior to preparation. Photographer: Lesley Kool
Preparation complete on the blocks. Annotated image identifying the various exposed bones. Photographer: Lesley Kool