What are the most surprising extinct animals

Extinct giant tortoise with surprising relatives

Giant tortoises are now only found in very few places in the wild, for example on the East Pacific Galapagos Islands and the Aldabra Atoll in the Indian Ocean. These reptiles, which weigh up to 400 kilograms and are more than a meter long, are said to have belonged to the animals that inspired Charles Darwin to his theory of evolution. Just a few centuries ago, giant tortoises were much more widespread: around 200 years ago they were found on the Mascarene Mountains east of Madagascar and until a few thousand years ago on many other islands, such as the Fiji Islands, the Bahamas, Cuba, Madagascar, Sicily or the Canary Islands.

Extinct giants

Of course, only fossil remains remain of the imposing land vertebrates. Since these species disappeared practically everywhere shortly after the arrival of humans, it stands to reason who is responsible for their extinction. A team led by Uwe Fritz from the Senckenberg Natural History Collections in Dresden have now taken a closer look at several 700 to 2,700 year old finds from seven Bahamas islands.

"We succeeded in sequencing ten almost complete mitochondrial turtle genomes from six of these islands," explains Fritz. This DNA data of the species Chelonoidis alburyorum compared it with other tortoises - and was a surprise.

Just one kind

The analyzes published in the journal "Scientific Reports" show that the Bahamas were only colonized by giant tortoises about 1.5 million years ago. Accordingly, there were morphologically very different types of turtles on the individual islands of the Bahamas. Genetically, the giant tortoises, which were exterminated before the arrival of the first Europeans, belonged to only one species that was closely related to the Galapagos giant tortoise.

According to the study, the very different shell shapes of the Galapagos giant tortoises must have emerged shortly after the archipelago was colonized, which, according to the findings of the international team, took place around two million years ago. "This contradicts the currently prevailing doctrine that the Galapagos giant tortoises belong to around 15 different species," says Fritz. "According to our results, all Galapagos tortoises must be grouped together into one species!" (red, February 15, 2021)