By Discovery News
Fossil trees that approached the heights of today’s tallest redwoods have been found in northern Thailand.
The longest petrified log measures 72.2 m, which suggest the original tree towered to more than 100 m in a wet tropical forest some 800,000 years ago.
The trees appear to have been closely related to a species alive today called Koompassia elegans, which belongs to the same family as beans, peas and black locust trees, explained lead author of the study Marc Philippe of France’s University of Lyon. That is to say, the ancient trees are not closely related to today’s tallest trees, which are the eucalyptus (gum trees) of Australia and sequoia (redwoods) of California. Both of those living trees can reach about 130 m in height.
Interestingly, there are no trees living today in Thailand that approach the size of the ancients.
“Highest trees nowadays in Thailand are almost 60 m,” says Marc Philippe.
”To my knowledge the highest tree yet recorded in Thailand is a Krabak tree, belonging to the Dipterocarpaceae (‘tropical oaks’), 58 m tall.”
The sediments in which the fossil trees were found suggest that they lived in a wet forest at the edge of a lowland plain. Today the fossil trees are at an elevation of 170 m above sea level and the climate flips between wet and dry seasons — what’s called monsoonal.
Marc Philippe says it’s possible there has been some uplift of the region since the trees fell.
Just how these buried trees were found is an interesting story in itself. A small section of a large petrified log was found more than 10 years ago by a villager in a reserve forest in the Ban Tak district of the Tak Province. The discovery was reported to officials of the National Park, Wildlife and Plant Conservation Department who came out to examine the log and survey the surrounding area. The log was then excavated to a length of 21 m without reaching the end. Ground penetrating radar was brought in and found that 30 m of trunk were still unexposed. Funds were found to excavate the whole trunk. At present, seven of nine discovered petrified trunks have been excavated.
“The result was the appearance of what is considered the world’s longest piece of petrified wood, with a length of 72.22 m, the researchers report.
“In 2006, the name of the park was changed to the Petrified Forest Park because of the fascinating discoveries.”
As to why there were big trees in the past that are unrelated to today’s giant trees, it appears to be just another case of what’s called convergent evolution. That’s where similar environmental factors lead to traits that are similar in unrelated species. Think rheas (South America), ostriches (Africa) and emus (Australia). All are large, unrelated flightless birds that evolved on different continents.
Researchers say they are not sure what drives trees to grow taller, but a dense forest and a competition for sunlight is part of it. It seems likely that over hundreds of millions of years that plants have been around there have been lots of very tall tree species, probably from every family of plant. It’s just an extremely very rare thing to get an entire petrified trunk to confirm it.