Synchrotron radiation uncovers new information about the first vertebrates

An international research team has for the first time managed to map the complex structure of the vertebral column in the earliest tetrapods.

The international research team, including tetrapod expert Per Erik Ahlberg at Uppsala University, has managed to produce high-resolution X-ray images using high energy synchrotron radiation. These images made it possible for the scientists to reconstruct the vertebral columns in these long-gone animals in minute detail.

The vertebral column is a bone structure that exists in all tetrapods as well as in water-living vertebrates such as fish. Unlike tetrapods alive today with vertebra composed of only one bone, early tetrapods had vertebra made up of several parts.

For over a hundred years it has been believed that the early tetrapods had vertebra made up of three sets of bones – one at the front, one on top and one at the back. However, this traditional model has now proven to be the wrong way round.

The fossils were scanned at the European Synchrotron Research Facility (ESRF) in France. The bone that was previously believed to be the first bone in the pattern turned out to be the last. A seemingly trivial piece of knowledge which is of great importance to our understanding of the evolution of the vertebral column.

Another finding was that the Ichthyostega, one of the earliest tetrapods, had a number of small, previously unknown bones at the centre of its chest. These are nature’s first known attempts of creating a real breast bone. The structure strengthened the chest of the Ichthyostega so it was able to support its own body weight when moving around on land.

Next, the research team will try to establish how the vertebral chord affected movement patterns in these early tetrapods using sophisticated biomechanic analysis.

Reference: Stephanie E Pierce, Per E Ahlberg, John R Hutchinson, Julia L Molnar, Sophie Sanchez, Paul Tafforeau, and Jennifer A Clack. Vertebral Archtecture in the earliest stem tetrapods. Nature. Advance Online Publication 13 January 2013.