Giants Of The Past

 

 

   Meet the true GIANTS  of the giant tortoise past. Introducing....

 

 

 

MEGALOCHELYS

 

Megalochelys Atlas skeleton on display at the AMNH. Photo by Clair Houck (Wikipedia)

 

 

  During the Miocene era and into the Pleistocene period of time (5million-10,000) there was a species of tortoise that made the modern Galapagos and Aldabra tortoises look like small Hermanns. The appropriately named Megalochelys or Colossochelys which means ‘Great Turtle’ is amongst the largest of any discovered Testudine animal, it is thought there were 7 subspecies.

 

  Megalochelys Atlas lived during the dry glacial period, with a range from Siwalik region in Western India to southern and eastern Europe and as far east as the Islands of Sulawesi and Timor in Indonesia. Other locations include Thailand and the southern Yunnan province of China.

 

   It had a carapace length of over 2m (6.5ft) and an approximate height of 1.8m (5ft 9), weight estimates range from 2000-4000kg but probably more to the lower end of the scale. The estimated total length of the tortoise was between 2.5-2.7m,

 

   It’s imense size made Megalochelys the largest known tortoise. The only larger turtles, in history, were the marine Archelon and Protostega or the freshwater Stupendemys from South America. A specimen of the upper part of Megalochelys Atlas humerus was measured and found to exceed the size of the same portion of the corresponding bone in the Indian Rhinoceros.

 

   Galapagos tortoises are the largest living species of tortoises today and the largest Galapagos individual, Goliath, had a carapace length of 137cm, width 103cm, height 69cm and a weight of 417kg, which is considerably smaller then Megalochelys Atlas..

 

   Megalochelys Atlas had elephantine feet similar to the Galapagos and Aldabra species, in order to be able to support its immense weight although, it is thought that Megalochelys closest living relative is the Sulcata or African Spurred tortoise, so it was probably a lot more armour plated than the island species of today. There is evidence of this by the very large Gular forks at the front of the shell which are common in Sulcata but are much less evident in Galapagos and Aldabra giants.

 

   Needless to say man, in the form of Homo Erectus, is the most likely cause of this animals extinction because as humans moved into the area they began to exploit the immense tortoise as a meat source until it was extinct on the mainland. It continued to survive on Timor until the Middle Pleistocene era about 10,000 years ago, when man arrived there too. Due to its massive size it would have been formidable prey for an animal predator to attack, until humans arrived equipped with tools and a group intelligence that allowed them to avoid the tough protective shells and pierce the softer vulnerable parts beneath. They found it relatively easy to hunt this slow creature and turtles as a group made up a large portion of the diet of early humans.

 

   It is likely that Atlas was a herbivore, like his modern day smaller relatives- the Sulcata and Indian Star tortoise but there is evidence that he was really Omnivorous, more like the Aldabra and Galapagos, who can behave like scavengers when they are hungry, and eat a carcase too.

 

   During the Miocene era the world environments were very different to how it is now. The tortoise would have thrived in warm humid conditions and with a strong monsoon season they would have had abundant vegetation to feed on. The diet of Megalochelys would probably of consisted of dried leaves on the forest floor and leafy flowering plants too, it was most commonly found in the outer mountain range of the Himalayas.

 

  It was a Cryptodidian tortoise, which means it pulls its head directly back into its shell, rather than folding it sideways and tucking it under the front Marginal Scutes, like animals such as the Eastern Long Necked Turtle.

 

   The fossils of Megalochelys were discovered in 1844 by Palaeontologists Hugh Falconer and Captain Proby Thomas Cautley. Parts of a shell specimen found in Indonesia were measured and they found Atlas had Costal Scutes that measures 1cm in thickness and the Bridge atatching Carapace to Plastron being 7cm thick. Interestingly modern Aldabra have a shell thickness of around 7.6cm but they are unique amongst giant tortoises, where most have traded thickness of shell to give them lighter weight, enabling them to move around easier.

 

  Continental tortoises are faced with a tougher life than the island species and there is more pressure on them to grow quickly and get out of hunting size as soon as possible. On the mainland there are more predators to hunt them, which will shorten life expectancy, especially if humans enter the mix. Megalochelys Atlas may have had the ability to live for 100-200 years, like the modern counterparts Galapagos and Aldabra giants but it is thought that this would be an exception rather than the rule.

 

   Galapagos and Aldabra tortoises have developed a symbiotic relationship with the local bird wildlife on their islands and the Finches will comedown and peck parasites and bugs from them if they stand up tall allowing them easy access, this process can take a couple of minutes. However this cleaning response is only seen in island tortoises. Other large species like the Sulcata or the Leopard tortoises do not exhibit this behaviour. It is thought that standing still for so long, in such a vulnerable position, would leave them too exposed to predator attack for continental animals. Island life is much more chilled.

 

 

 

 

And It's Slightly Smaller Relative....

 

TITANOCHELON

 

 

   Later tortoise Titanochelon was slightly smaller and up to 2m long, which is still larger than today’s giants. There are 10 known subspecies of Titanochelon and they lived in the area of Europe- France, Germany, Portugal and Spain, in the Iberian Peninsular and up to Switzerland and down to Greece.

 

   Analysis has shown that Titanochelon is most closely related to the Leopard tortoise, which is native to Africa, suggesting that Titanochelon has Africa origin, although it spent its days happily wandering through the area that was to become Madrid.

 

   It is known from 20 million years ago to their extinction around 2 million years ago, which is likely to be because of a climate cooling period, due to the onset of glaciation, at the beginning of Pleistocene.

 

   Visually it looks very much like the African Spurred or Sulcata tortoise. It was short, wide and strong, with a shell that was covered with bony tissue scales for protection.

 

Titanochelon was the largest tortoise to ever live in Europe.