The discovery begins in the Tiruchirappalli district of the Tamil Nadu state in southern India. In 1978, in rocks almost seventy million years old, a collection of truly enormous bones were excavated by P. Yadagiri and Krishnan Ayyasami. The bones came from a time known as the Cretaceous period and they were clearly the bones of a dinosaur but they were larger than any other that had been discovered. The most notable bone in the collection was a truly gigantic tibia (shin bone) that was a staggering two metres long, taller than a person and more massive than the tibia of any other dinosaur.
The creature was named Bruhathkayosaurus matleyi, appropriately meaning huge bodied reptile and it belonged to a family of dinosaurs called the sauropods, a group famous for having tremendously long necks and tails, huge bodies and four pillar like legs. Bruhathkayosaurus would have been very similar to other sauropods in appearance except with one big difference; its size.
Since the day it was discovered, there was no denying how unfathomably, unimaginably immense Bruhathkayosaurus was. Its tibia alone was an astounding two metres long. This is twenty nine percent larger than the shin bone of the previous record holder, another dinosaur called Argentinosaurus. Bruhathkayosaurus was so huge it would have made even other dinosaurs look miniscule by comparison. Unfortunately, it must be mentioned that the same, record-breaking tibia has since been lost to science.
This is because the nature of the rocks in which it was discovered, combined with the effects of the monsoon weather on the soil, led to the bone disintegrating during the dry season, quite literally crumbling to dust. Therefore, the only evidence that remains of this impossibly immense dinosaur are a collection of photographs and sketches of the bones. While this is unfortunate, these pictures and descriptions still provide palaeontologists with the information needed to calculate its size and, in 2023, internationally renowned palaeontologists Gregory S. Paul and Asier Larramendi attempted to do just that.
It is worth noting that Gregory S. Paul is considered among the most influential palaeontologists in recent history. Not only has he authored and illustrated multiple, scientific dinosaur books, but he was also among the first palaeontologists to depict dinosaurs as active, warm-blooded animals and was one of the first to portray many carnivorous dinosaurs with feathers. These characteristics are now known to be present in many dinosaur species and are considered common knowledge among the scientific community.
Paul was also a consultant for the critically acclaimed and widely beloved Jurassic Park, both the movie as well as the original novel by Michael Crichton. Paul and Larramendi were able to calculate a weight range for Bruhathkayosaurus by comparing its shin bone to those of other, closely related sauropod dinosaurs. They also estimated the total femur length for Bruhathkayosaurus and once again compared the femur length to those of closely related dinosaurs. The results were beyond staggering.
The study found Bruhathkayosaurus may have weighed between 110 and 170 tonnes, with a mind-numbing 110-130 tonnes being considered the most likely. While a specific length was not provided, a reconstruction in the same paper indicates it may have been 35-40 metres long. This is truly incredible and makes Bruhathkayosaurus possibly the largest dinosaur ever discovered and indeed the largest land animal ever known. In fact, Bruhathkayosaurus was so huge that it may not only have been the largest land animal ever but also one of the largest animals to have ever existed. At 110-130 tonnes, Bruhathkayosaurus is equal in size to an average blue whale.
While the very biggest blue whales are known to reach 30 metres and weigh close to 200 tonnes, most blue whales do not reach such sizes and are closer to 100-150 tonnes in mass. Therefore, while Bruhathkayosaurus may not have been bigger than the absolute biggest blue whale ever recorded, it was certainly equal in size to most individuals and definitely longer. Further, we have a tremendously larger sample size of blue whales but only one specimen of Bruhathkayosaurus so it is very likely that some Bruhathkayosaurus may have actually grown larger than the biggest blue whales. While this is all certainly incredible, perhaps what is just as remarkable is that Bruhathkayosaurus may actually have roamed Sri Lanka, or at least the northern region of the island.
The reason for this is because, for much of its natural history, Sri Lanka was connected to the Indian subcontinent by a land bridge extending from the north of the island. This land bridge would not have been too different from the one that currently connects North and South America. Thus, the Northern Province, and some western regions, of Sri Lanka would have been connected to the south of India, allowing dinosaurs from the Indian subcontinent to spread across the land without obstruction. At this point in time, India itself was an enormous island and was separate from the rest of Asia.
The age of dinosaurs existed from 200-66 million years ago and Sri Lanka remained part of the Indian subcontinent throughout that time. In fact, it is only as recently as 15 million years ago that this land bridge began to disappear. The rise of sea levels prompted the land bridge to become submerged and it has been disappearing and reappearing for hundreds of thousands of years, submerging most recently around 10,000 years ago. However, during the age of the dinosaurs, the land bridge was fully present and dinosaurs like Bruhathkayosaurus, which lived in the very south of India, would have been able to cross into the north of Sri Lanka with ease.
Whether these dinosaurs actually spread throughout the rest of Sri Lanka is not known for certain but, considering how animals like elephants can travel hundreds of kilometres, it seems very likely that Bruhathkayosaurus would have been capable of spreading across all of Sri Lanka without much trouble. But if dinosaurs could migrate in and out of Sri Lanka so easily, why have we still not found fossils of them?
Unfortunately, the sedimentology of Sri Lanka does not make the fossilisation of such animals likely. Fossilisation is a very long, complex process and it is an exceptionally rare phenomenon that requires the correct type of soil for it to occur. Unfortunately, Sri Lanka does not have the soil that would encourage fossilisation. However, this does not mean fossils have never been discovered. For instance, plant fossils dating back to the Jurassic period have been discovered, as well as mammal fossils that are tens of thousands of years old.
However, the fossilisation of dinosaurs, especially huge ones the size Bruhathkayosaurus, is very unlikely to happen in Sri Lanka. Does that mean dinosaurs did not exist in Sri Lanka after all? The answer is they certainly did. Just because dinosaur fossils might not be preserved does not mean they did not roam the island. Dinosaurs have been found in every corner of the globe, even as far north as the Arctic Circle and as far south as Antarctica.
Therefore, it is almost certain that dinosaurs would have lived across all of Sri Lanka. The fact that Sri Lanka was so heavily connected to India also makes it extremely likely that dinosaurs from the south of India would have been able to spread into Sri Lanka quite easily, including Bruhathkayosaurus. It is humbling to think that possibly the largest dinosaur to ever walk the earth, and one of the biggest animals to ever exist, may have actually walked across this same island some seventy million years ago. Yet, perhaps what is just as overwhelmingly amazing is that Sri Lanka remains to this day a sanctuary for a tremendous diversity of the last dinosaurs on Earth; the birds.
Birds are the last living dinosaurs, and are descended from a group of small, carnivorous dinosaurs closely related to the famous Velociraptor. While this may be surprising at first, birds are indeed true dinosaurs the same way we humans are true primates. While the giant dinosaurs of the past may be gone, their legacy lives on in the myriad of birds that grace the skies of our planet today. With 34 endemic birds and a total of 468 bird species, Sri Lanka is a true haven for the last dinosaurs on Earth.
It is home to a variety of amazing species, such as the massive lesser adjutant, magnificent white bellied sea eagle and graceful greater flamingo, as well as countless others. While Sri Lanka may have once been home to the largest dinosaur ever to exist, this island’s greatest pride is not the dinosaurs of the past but the dinosaurs that still thrive here today.
Therefore, it is essential that we cherish the wonderful birds of this country while we still can. It is essential to understand the threats facing Sri Lanka’s birds and work together to find practical solutions that will allow these amazing animals to coexist peacefully alongside us. While the gargantuan Bruhathkayosaurus may be extinct, we can ensure that Sri Lanka’s birds, the island’s last dinosaurs, do not meet the same fate.
Writer David Jeevathithan Ambalavanar is a twenty-four-year-old from Jaffna who has been fascinated with the natural world and its history. He is currently reading for his Bachelor of Science Honour degree at Monash University Malaysia.
