Holly Woodward at work in the Museum Victoria Palaeontology lab.
Source: Museum Victoria
Holly Woodward, a PhD student in palaeontology at Montana State University, is spending a few weeks at Museum Victoria studying growth rates of Victorian polar dinosaurs.
Holly’s speciality is bone histology – the study of bone microstructure – which is amazingly well preserved in fossilised bone and reveals a surprising amount of information about dinosaur biology.
“You can look at dinosaur bone under the microscope to learn about how fast the dinosaurs grew, how old they were and whether they were fully grown when they died,” explains Holly. While in Melbourne she is preparing bone samples to borrow and study in fine detail when she returns to the USA. She will compare the tiny Victorian dinosaurs to her main study dinosaur, a 7-metre duckbill dinosaur from Montana.
“Australia used to be a lot closer to the South Pole so the dinosaurs might have experienced prolonged day or night, and I was wondering how that might be reflected in their bone histology.” Her research here, supported by a grant from the National Science Foundation and the Australian Academy of Science, builds upon the work of Dr Tom Rich and Dr Patricia Vickers-Rich on the dinosaurs that lived in Victoria 110 million years ago.
Under the microscope, the sliver-thin sections of bone show pockets and channels where there were bone cells and tiny blood vessels when the animal was alive. Furthermore, rings of bone – laid down annually much like tree rings – tell Holly about the patterns of growth; these have the potential to be quite different from other dinosaurs because of the extreme climate under polar conditions.
Sectioning the bone is a delicate and time-consuming job. First Holly removes a small piece from a leg bone. After embedding it in a plastic resin, she takes very thin cross-sections using a rock saw, then sands them until they are thin enough for light to pass through. The final step is to replace the removed piece with an exact replica which she casts and paints herself. This preserves the length of the bone so the overall shape and size remains for future studies.
Holly’s samples are from dinosaurs of various ages so will reveal much about their lifespan. She’s even looking at a special case – a dinosaur with a broken leg that healed poorly. By examining the bone microstructure, she will know how long this particular animal lived after its injury, and give us another small glimpse of life in Victoria during the Cretaceous.