African Spurred Tortoise

Geochelone sulcata

After the Galapagos and Aldabra Tortoises, the African Spurred Tortoise takes the title as third largest in the world. These land giants dwell in drier regions of central and northern Africa where they subsist on a diet of fruits and vegetables. During the driest times of the year, the Tortoises build burrows and enter states similar to hibernation in order to keep from dehydration.

Breeding occurs during rainier parts of the year, and males will fight for the right to breed with females. During the copulation itself, females will be unable to move due to the weight of the male Tortoises. About two months after mating the female will dig a large nest and deposit 15-30 eggs into. They will incubate for an additional 8 months before the 2" hatchlings emerge. It will take the Tortoises fifteen years to reach sexual maturity. But, like their large Tortoise cousins, they can live over 100 years.

African Spurred Tortoises have experienced some drastic population drops. They've been losing their habitats due to urbanization and the spread of livestock, and have also been hunted for meat. African Spurred Tortoises are also collected for the pet trade when they are in their younger years. This makes re-population difficult, as they take so long to mature.

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IUCN Status : Vulnerable

Location : Africa

Size : Length up to 36in (90cm), Weight up to 200lbs (91kg)

Classification : Phylum : Chordata -- Class : Sauropsida -- Order : Testudines
Family : Testudinidae -- Genus : Geochelone -- Species : G. sulcata

Atlas Tortoise

Colossochelys atlas

In the past we have learned all about the massive prehistoric Sea Turtles that once swam the world's oceans, but we have yet to talk about what is possibly the largest land Turtle ever discovered. This creature is even larger than the Galapagos and Aldabara Tortoises-- it had a shell that could grow nearly 7ft long!

The appropriately named Atlas Tortoise lived during the Miocene and Pleistocene periods, and its fossils have been found in India, Pakistan, and Thailand. There is also speculation that they lived as far west as southern Europe. Like their closest modern relatives, they were slow moving, plant eating herbivores.

The Atlas Tortoise probably looked very similar to the Galapagos Tortoise, just longer, taller (nearly 6ft!), and heavier. Their massive, 1,000kg+ bodies were supported by thick, sturdy legs that could, along with the head, retract into the shell when threatened.

There is some controversy about the classification of this species, and it has gone by many names. When first discovered and named back in 1837, they were called Megalochelys sivalensis. Their current name was bestowed in 1844, but was flip flopped around to both Geochelone atlas and Testudo atlas, before coming back to the Colossochelys genus again. It is still sometimes referred to by all four of those genus names, confusing!

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Status : Extinct since the Pleistocene (around 1 million years)

Location : South Asia
Size : Shell Length up to 7ft (2.5m)

Classification : Phylum : Chordata -- Class : Reptilia -- Order : Testudines
Family : Testudinidae -- Genus : †Colossochelys -- Species : † C. atlas

Leopard Tortoise

Stigmochelys pardalis

The Leopard Tortoise, sometimes also referred to as the African Leopard Tortoise is a large, colorful species of reptile that can be found throughout the grassland and semi-arid regions of the African continent. They also happen to be popular in the pet industry.

What blows my mind about keeping these guys as pets is that they can grow to be over 2ft long! One typically thinks of pet reptiles as living in small little terrariums, but not these Tortoises! They are actually best kept in large outdoor pens in very warm, dry areas. And have I mentioned that they can live more than 50 years? That is a lifetime pet commitment right there!

While we're discussing size, I should also note that these are the fourth largest Tortoises in the entire world, and can weigh more than 50lbs. Surprisingly, even with all that weight, Leopard Tortoises are pretty good at getting around. They have small claws on their front feet that give them good maneuverability over bumpy terrain, and young Tortoises have even been observed making vertical climbs!

Leopard Tortoises are not listed by the IUCN, but pet industry demands have affected their wild numbers in some areas. It has been illegal to import them into the United States since 2000, which is definitely a good thing. Wild-caught Leopard Tortoises do not adjust well in captivity, carry several different parasites, and those that live often need a substantial amount of rehabilitation. Thankfully there are now captive breeders to supply those who feel that a giant long-lived Tortoise is the right pet for them.

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IUCN Status : Not Listed
Location : Africa
Size : Body length around 18in (45cm)

Classification : Phylum : Chordata -- Class : Sauropsida -- Order : Testudines
Family : Testudinidae -- Genus : Stigmochelys-- Species : S. pardalis

Proganochelys

Proganochelys quenstedti

Poor Proganochelys. For over 100 years it was the oldest turtle species ever discovered. its fossils dated back 210 million years! ...And then Odontochelys was found in 2008 with fossils 10 millions years older... and ruined that "oldest" distinction. Ah well, such is science! I'm sure even Odontochelys will be dethroned at some point; we still have such much to learn about the Earth's past.

Proganochelys fossils have been found in Germany and Thailand, and they show that this was a creature around 1m long. They look remarkably like the turtles that we have today, and even shed some light on how turtle got to be how they are.

Since it already has its shell, Proganochelys doesn't teach us much about shell evolution (Odontochelys helped a bit with that though!). It does, however, demonstrate how turtles lost their teeth very on in their evolutionary development. and it also has the large ear opening that is also found in modern turtles.

One big difference between Proganochelys and modern turtles is the retractability of the head. Our ancient friend simply could not do such a thing. But! They did have small spines on the neck to protect themselves with. Another cool difference? A spiny, clubbed tail!

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Status : Extinct, lived around 210 million years ago.
Location : Germany, Thailand
Size : Length up to 3.3ft (1m)

Classification : Phylum : Chordata -- Class : Sauropsida -- Order:  Testudines
Family : Proganochelidae -- Genus : Proganochelys -- Species : P. quenstedti

Cylindraspis Tortoises

Cylindraspis peltastes

There were five different Tortoise species within the Cylindraspis genus:

• Cylindraspis indica - Réunion giant tortoise
• Cylindraspis inepta - Saddle-backed Mauritius giant tortoise
• Cylindraspis peltastes - Domed Rodrigues giant tortoise
• Cylindraspis triserrata - Domed Mauritius giant tortoise
• Cylindraspis vosmaeri - Saddle-backed Rodrigues giant tortoise

All five have been extinct for around 200 years.

The Cylindraspis Tortoises were once found on the Mascarene Islands of Rodrigues, Réunion, and Mauritius (home of the Dodo). This small group of islands is located in the Indian Ocean, off the coast of Madagascar. They were first discovered by Europeans in 1507, and were colonized around a century later. When humans arrived, the Tortoises were abundant across the island chain, but within 100 years they were almost completely wiped out. A few decades after that they were gone entirely.

How and why did this fast extinction happen? Well, it is a story very similar to that of one of their more famous island neighbors-- the Dodo. These Tortoises were very large, and very slow moving. This made them easy targets for hunting, much like the Dodo. The Tortoises also required very little food and maintenance, which made them ideal creatures to take on boats as a food supply.

Some of the species saw a decline faster than others (the Réunion Giant Tortoise was nearly gone by 1730, for example). Most were eliminated by 1800, with the last individuals dying out by 1840.

Sadly, the Cylindraspis Tortoises are not the only island turtles to be negatively affected by humans, and even the popular Galapagos Tortoises have faced extinction (some subspecies are gone entirely). Hopefully modern conservation measures and learning from the past can prevent more Tortoises from going the way of the today's animals.

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IUCN Status : Extinct by 1840
Location : Mascarene Islands
Size : Varies

Classification : Phylum : Chordata -- Class : Reptilia -- Order : Testudines
Family : Testudinidae -- Genus : †Cylindraspis

Wattle-necked Softshell Turtle

Palea steindachneri

Wow, this week is becoming an unofficial Mascarene Islands theme week, and sort of by accident too! I came across today's animal while browsing around a site that listed the reptiles and amphibians of Hawaii. I zeroed in on a Softshell Turtle, as they are very interesting looking creatures... and what do you know, they've been introduced to Mauritius!

And though I found the animal in a Hawaiian context, they aren't native Hawaiians. The Wattle-necked Softshell Turtles are actually native to Vietnam and southern China, and were introduced to islands elsewhere. Interestingly, most of what we know of their biology and behavior comes from those Hawaiian individuals.

Wattle-necked Softshell Turtles belong to an entire family of Softshell Turtles, Trionychidae, but they are the only species in their genus. Like their cousins, they have flat shells covered with leathery skin rather than bony scutes. They also have long, retractable necks that have wattle clusters around the base (hence the name).

Unfortunately, like many other Softshell Turtles, the Wattle-necked Softshell Turtle is Endangered. This is due in part to their desirability in the food trade in Asia. Captive breeding farms have been set up to keep the wild Turtles from being hunted. But those farms may actually be hurting the Turtles, as they make the food more popular. The introduced populations in Hawaii and Mauritius may some day be the only populations left.

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IUCN Status : Endangered
Location : Southeast Asia, Hawaii, Mauritius
Size : Length up to 10in (25cm)

Classification : Phylum : Chordata -- Class : Reptilia -- Order : Testudines
Family : Trionychidae -- Genus : Palea -- Species : P. steindachneri

Odontochelys

Odontochelys semitestacea

Odontochelys is an extinct animal that was only just recently discovered (2008). It is pretty darn remarkable find, and represents the earliest Turtle that we know about.. it dates back to the Early Triassic over 220 million years ago!

Odontochelys is a transitional reptile. It shares many characteristics with modern turtles, but also demonstrates traits found in earlier reptiles. It has a plastron, which is the under part of a turtle's shell, but it has no carapace! It also has a turtle-like beak, but there are teeth inside it!

The find is helping scientists figure out how turtles evolved. The previous-oldest-fossil already had a carapace, so discovering a species without one gives clues as to where the shell actually came from. One theory is that shells came from the fusion of osteoderms, which are bony plates of armor in the skin. But Odontochelys has no osteoderms, yet it still has a plastron.

The other theory, which is now looking better, is that the plastron grew first (presumably to protect the aquatic turtles from underside attacks). Once the plastron was in place the turtles eventually evolved extensions from their ribs and backbone that fused together to form a full shell. However, it will be difficult to determine for sure until more transitional fossils are uncovered.

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Status : Extinct for around 220 Millions Years
Location : China
Size : Length up to 9.5in (24cm), Weight up to 4.5lbs (2kg)

Classification : Phylum : Chordata -- Class : Sauropsida -- Order : Testudines
Family : †Odontochelyidae -- Genus : †Odontochelys-- Species : †O. semitestacea

Eastern Long-necked Turtle

Chelodina longicollis

It's easy to see where this animal gets its name-- the Eastern Long-necked Turtle has a neck that can be nearly as long as their carapace! These necks are so long that they aren't pulled directly back into the carapace. They bend in sideways.

These Australian natives have flat carapaces that grow to around 8in in length and are colored in shades that range from black to brown to green. Their undersides (plastrons) are cream colored with very distinctive black lines.

You can find these Turtles living in slow moving freshwater streams and ponds. They have powerful webbed feet that allow them to dig and swim with ease, and they spend a good deal of time basking on rocks and logs. In the wild Long-necked Turtles are 100% carnivorous, feeding on insects, mollusks, tadpoles, fish, and other small creatures. When the Turtles themselves feel threatened, they secrete a stinky fluid from their musk glands. This gives them one of their other common names-- "Stinker."

Eastern Long-necked Turtles can be kept as pets, but they require a good deal of space, as well as a long commitment. These guys can live for decades!

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IUCN Status : Least Concern
Location : Australia
Size : Carapace length around 8in (20cm)

Classification : Phylum : Chordata -- Class : Sauropsida -- Order : Testudines
Family : Chelidae -- Genus : Chelodina -- Species : C. longicollis

Olive Ridley Sea Turtle

The Olive Ridley Sea Turtle is one of the smaller Sea Turtles; they have a carapace length of around 2ft. They also have the distinction of being the most abundant Sea Turtle on the planet, with about 800,000 females coming ashore to nest annually.

Lepidochelys olivacea

Olive Ridleys, named for their olive coloration, have a very large distribution and can be found in tropical waters around the world. They are a migratory pelagic Turtle, but they also can be spotted in coastal regions as well.

Olive Ridley Sea Turtles exhibit one of the most interesting nesting habits in the world. Once or twice a year, in waves triggered by some unknown event (Lunar Cycles? Wind? No one knows for sure), thousands of female Turtles come ashore in events called Arribadas. Each turtle lays around 100 eggs, and sometimes there are so many Turtles that they actually dig up previously laid nests in order to deposit their offpspring! One beach in India saw 200,000 females at a single event!

Despite the large population number, Olive Ridley Sea Turtles are considered to be Vulnerable by the IUCN. This is because the selected survey sites have shown a population decline over the last 2-3 generations. The Marine Turtle Specialist Group actually reports a 50% decline since the 1960s. The Olive Ridleys are at risk due to hunting, egg harvesting, bycatch, and habitat degradation. So while they are the most abundant of the Sea Turtles, they are also one of the most exploited. The Turtles are currently protected by numerous agreements and treaties, including CITES I.

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IUCN Status : Vulnerable
Location : Tropical waters worldwide
Size : Carapace Length up to 28in (70cm)

Classification : Phylum : Chordata -- Class : Reptilia -- Order : Testudines
Family : Cheloniidae -- Genus : Lepidochelys -- Species : L. olivacea

Archelon

The Archelon type specimen

I love covering extinct Turtles because they have such an interesting evolutionary history. Turtles have been around since the Triassic, dating back 220 million years. They've even had roughly the same body shape for the last 200 million of those years, with modifications being made to their teeth (losing them), their shells (going from soft to hard) and their size (varies completely!)

Today's Turtle, Archelon, definitely had a unique size. These giant Sea Turtles grew to be 12 feet long! Archelon lived during the late Cretaceous Period, and its fossils have been found primarily in South Dakota and Wyoming, which were once covered by shallow seas.

Once you get past its car-like size, you'll notice that Archelon did look quite a bit like our modern Sea Turtles. In fact, its closest living relative is the large (but not that large) Leatherback Sea Turtle. In fact, like the Leatherbacks of today, Archelon probably ate jellyfish and other soft-bodied sea creatures like squid.

Archelon did have two major differences though. The first was that its shell wasn't hard-- it was actually soft and leathery and supported by an internal bone structure. Secondly, they had remarkably broad, paddle-like flippers (modern Sea Turtles also have long flippers, but they are not nearly as broad proportionally).

They died out at the end of the Cretaceous Period, around 65 million years ago, and no Turtle since has come close to rivaling it in size!

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Status : Extinct for 65 million years
Location : North America
Size : Length around 12ft (3.6m), Weight up to 2tons

Classification : Phylum : Chordata -- Class : Reptilia -- Order : Testudines
Family : †Protostegidae -- Genus : †Archelon -- Species : A. ischyros