I’m sure many people, whether scientists or just the average person have always wondered about what kind of creatures or what the environment was like over 300 million years ago, before the dinosaurs roamed. So, specifically, the question to be answered today is: what were the trees like 374 million years ago? The answer: most definitely different from today’s tree!
Recently, scientists have discovered silicified trunks containing hundreds of tree-like structures in Northwest China. The team led by Hong-He Xu of the Nanjing Institute of Geology and Palaeontology travelled to Nanjing, China in order to study this amazing discovery. They studied the thick transverse and longitudinal sections of the trunk.
The researchers named this species the Xinicaulis lignescens, which translates to “new stem becoming woody”. What they found when they cut open the trunk was hundreds of xylems which is defined as a type of transport tissue in vascular plants that transports mainly water and nutrients. Today, in most trees, the xylem goes up through the center of the tree, and a new xylem grows around the old one, which is typically called the “growth ring” where this is used to estimate the age of the tree. The image below shows the comparison between X. lignescens (top) vs. today’s tree (bottom).
From the top picture above, the xylem are arranged on the outer area of the trunk compared to today’s common tree that have xylem filling the entire trunk. Hong-He Xu also discovered that the middle of the X. lignescens trunk was hollow and that the xylem strands were interconnected to each another like a web. Each of these xylems had its own set of “growth rings”. The tree therefore grows by continuously tearing the specific xylem apart and repairing it to allow the big parent tree to grow in size. This is a very complicated process!
Currently, Hong-He Xu and his team are studying how much carbon these trees could capture from the atmosphere as well as how this could have impacted the climate. By studying these rare fossils, we gain a piece of the puzzle of what the world was like in the past.
Ziyi Wang
