How Did the Leatherback Turtle Evolve

Illustration of Archelon, the Leatherback Turtle's Closest Prehistoric Relative
Illustration of Archelon, the Leatherback Turtle's Closest Prehistoric Relative. DEA PICTURE LIBRARY/De Agostini Picture Library/Getty Images

The leatherback turtle is one of 7 species of sea turtles but it is the only species left in its family, Dermochelyidae. It looks much different from other sea turtles. So, how did the leatherback evolve?

Background on the Leatherback Turtle

The leatherback turtle is the largest sea turtle species and one of the largest marine reptiles. They can grow to a maximum length of about 6 feet and weight of about 2,000 pounds.

Their name came from the leather-like skin that covers their carapace, which easily distinguishes them from the six other sea turtle species that are still living. In addition, they have dark black or gray skin that is covered with white or pink spots. 

Leatherback turtles have a large range that extends throughout all but the coldest parts of the ocean.

How Long Has the Leatherback Existed?

The leatherback turtle has been in existence for about 100 million years. Below you can learn more about some of the earliest sea turtles.

Leatherback Turtle Ancestors:

Marine reptiles evolved about 300 million years ago. These animals looked like large lizards, and eventually evolved into dinosaurs, lizards, turtles, marine reptiles, crocodiles and even mammals.

Turtles in general have been around a long time - one of the first turtle-like animals is thought to be eunotosaurus, an animal that lived about 260 million years ago.

The first marine turtle is thought to be Odontochelys, who lived about 220 million years ago. This turtle had teeth, a relatively soft carapace and appeared to spend much of its time in the water. The next turtle appears to be Proganochelys, which evolved about 10 million years later. This turtle had lost the ability to hide its head in its shell and was much larger than Odontochelys.

It had a shell that was harder than that of previous turtles to better protect it from predators.

By about 100 million years ago, there were 4 sea turtle families - Cheloniidae and Dermochelyidae, which still contain species living today, and Toxochelyidae and Protostegidae, which went extinct about 50 million years ago.

The Leatherback's Closest Ancestor

Although the leatherback turtle is very large, it is dwarfed by its closest known ancestor, Archelon, which was the size of a small car (about 12 feet long). It propelled itself through the water using powerful front flippers. Notably, like today's leatherback, it had a leathery shell. This turtle lived during the late Cretaceous period around 65 million years ago, and was in the Protostegidae family.

The Only Remaining Species In Its Family

The leatherbackturtle is the sole surviving member of the Family Dermochelyidae, one of two families of sea turtles (Cheloniidae is the other). This family split off from the Prostegidae family about 100 million years ago.  

About 50 million years ago, most of the turtles in the Prostegidae family went exinct, but the leatherback family Dermochelyidae survived and thrived.  At this time there were several different species of leatherbacks.

 Competition between these species and with other marine animals led to the extinction of all but one species of sea turtle by 2 million years ago. This was Dermochelys coriacea, the leatherback that survives today. Its specialized diet of jellyfish seemed to be to this species' advantage, and it thrived until humans entered the picture. 

References and Further Information:

  • Spotila, J.R. 2004. Sea Turtles: A Complete Guide to Their Biology, Behavior and Conservation. The Johns Hopkins University Press. 227pp.
  • Strauss, B. Prehistoric Turtles: The Story of Turtle Evolution. Accessed November 29, 2015.
  • Strauss, B. Archelon. Accessed November 29, 2015.
  • Waggoner, B. 1995. The Cretaceous Period. University of California Museum of Paleontology.
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Kennedy, Jennifer. "How Did the Leatherback Turtle Evolve." ThoughtCo, Aug. 29, 2016, thoughtco.com/leatherback-turtle-evolution-2291977. Kennedy, Jennifer. (2016, August 29). How Did the Leatherback Turtle Evolve. Retrieved from https://www.thoughtco.com/leatherback-turtle-evolution-2291977 Kennedy, Jennifer. "How Did the Leatherback Turtle Evolve." ThoughtCo. https://www.thoughtco.com/leatherback-turtle-evolution-2291977 (accessed January 18, 2018).