A1.39 Geochelone atlas (land turtle) Pleistocene, Found in India, Size: 8 ft./2.5 m / Traits:
  • Cells have DNA
  • Cells have a nucleus in them
  • Cells have mitochondria
  • Multicellular
  • Cells are held together with collagen.
    Sexual reproduction
  • Early embryo forms as a hollow ball of cells called a blastula
  • This blastula opens into a tube “tail end first”
  • Has a head and is bilaterally symmetrical (you can draw one line down the middle)
  • Cells organize themselves into true tissues (muscle, nerves)
  • Cells organize themselves into true organs (heart, liver, stomach)
  • Has a hollow space between the gut and outer body wall where organs are (this space is called a coelem—pronounced “see-lome”
  • Segmented body
  • Internal bony skeleton
  • Backbone, Spinal chord and braincase
  • Had jaws
  • Had lungs
  • Had paired appendages
  • Had four legs
  • Amniotic egg (could lay eggs on land because of protective cover on egg)
  • Two openings in the roof of the mouth (“palatal openings”)
  • Has a shell
  • Braincase fused to the skull
  • Carotid artery (the big one in your neck) encased in bone
  • Vertical (straight back) retraction of head and neck into shell
  • Enlarged skull
  • High arch of shell.

Geochelone atlas is also known as Testudo Atlas. It was the largest land tortoise that has ever been discovered. Sometimes it is also called Colossochelys, which means “colossal shell.” This mighty creature weighted about 4 ½ U.S. tons. Its elephant-like legs sprawled out on all sides of its body in the typical reptilian fashion and supported the massive protective shell which was carried on its back. Cushioned pads on the soles of its feet spread the animal’s considerable weight evenly over the five, heavily-nailed toes of each foot—an arrangement similar to that seen in modern elephants.
Geochelone probably only ate plants, as do most of its modern relatives (though some are known to eat slugs and worms). It would have spent its time browsing and cropping leaves with its sharp toothless beak, without fear of being attacked. Because if a predator, such as one of the saber-toothed cats, did try to attack, Geochelone would have pulled its head and legs back into its shell and presented a solid bony box, which would have been almost impossible to move or turn over.
The modern relatives of this extinct tortoise, in terms of size and weight, is the Galapagos giant tortoise, Geochelone elephantopus, found on the Galapágos Islands, off the coast of Ecuador. But even this large animal is only 4 ft./1.2 m long—half the length of the Geochelone atlas—and weighs a mere 500 lbs./225 kg
(Adapted from Palmer, p.212)