Triassic turtle evolution, new research


This video says about itself:

Evolution of the Turtle Shell (Illustrated)

30 May 2013

Evolution of the turtle shell based on developmental and fossil data. This animation is based on the work of Dr. Tyler Lyson, currently at the Smithsonian Institution.

The animation shows how various fossils, particularly Eunotosaurus and Odontochelys, bridge the morphological gap between a generalized animal body plan to the highly modified body plan found in living turtles.

The paper, published in Current Biology, can be found here.

Animation by Stroma Studios.

From the Washington Post in the USA:

How the turtle got its shell, a not-so ‘Just So’ story

By Sarah Kaplan

June 25 at 5:22 AM

Long, long ago, in a time so far in the past it preceded the dinosaurs and the continents, lived a tiny creature named “grandfather turtle.” It had many of the qualities of the turtles we know and love today: a boxy body, plodding legs, a long neck topped by a small, round head.

It was only missing one thing: a shell.

Thanks to the newly discovered fossil of that tiny creature, scientists say they have solved the story of how the turtle got its shell. But this is no Rudyard Kipling fable. It’s science.

The not-so “Just So” story, published in the journal Nature on Wednesday, tracks the evolution of the turtle body plan through millions of years of history. By examining fossils that spanned millennia and continents, researchers were able to figure out how the modern turtle’s unique shell evolved from what was just a brief expanse of belly bones about 240 million years ago.

The origin of the turtle shell has long bewildered scientists (this was, apparently, the one natural phenomenon Kipling hadn’t written a story to explain). Though they had fossils of turtle predecessors from the beginning and the end of the Triassic period, there was little evidence of what happened to ancient turtles during the intervening years. The bones of the 260 million-year-old Eunotosaurus, a reptilian creature found in South Africa, had wide, flat ribs and a sprawling, turtle-like figure, but it was far from the armor-encased animal we know today.

The next time a turtle ancestor popped up in the fossil record, the Odontochelys about 220 million years before present, it had a fully developed belly plate called a “plastron” that would eventually expand to enclose the turtle’s whole body, protecting it from attacks from above and below. (The first turtle with a true shell wouldn’t appear on the scene until about 6 million years after that.)

But there was nothing in the yawning 40 million-year void between the two ancient species to explain where that plastron came from.

“Hopefully we’ll find more,” Robert Reisz, a paleontologist at the University of Toronto, told National Geographic after the Odontochelys was first found in 2008. “We’re closing the gap, but there is still a big morphological gap between this turtle and its non-turtle ancestors.”

Enter Pappochelys, the hero of our story, ready and willing to fill that gap.

Pappochelys, whose name means “grandfather turtle,” lived about 240 million years ago in a warm sub-tropical lake, Hans-Dieter Sues, a co-author of the Nature study and curator at the Smithsonian Museum of Natural History in D.C., told NPR. Discovered in a limestone quarry near Stuttgart, Germany, it is the precise chronological and morphological midpoint between the two previously known fossils: about eight inches from tip to tail, it had slender legs and an oddly boxy body with a rib cage that looked like the beginnings of a “little bony house.”

This physiological setup was good for protection and also worked as “bone ballast,” according to Smithsonian, allowing the animal to control its buoyancy in the water.

In addition, the Pappochelys had a series of hard, shell-like bones lining its belly — the beginnings of the plastron that would turn up 20 million years later.

“It has real beginnings of the belly shell developing, little rib-like structures beginning to fuse together into larger plates and then ultimately making up the belly shell,” Sues told NPR.

Sues’s co-author, Rainer R. Schoch, a paleontologist at the Staatliches Museum für Naturkunde in Stuttgart, called Pappochelys a “transitional creature,” one that illustrates how ancient lizards became modern turtles.

“Transitional creatures are the most important contribution that paleontology can make to the study of evolution,” Schoch told Voice of America. “They are often unexpected and show surprising features.”

And, in Pappochelys case, they tell pretty good stories.

Largest colony of olive ridley turtles discovered in Gabon


This video says about itself:

28 July 2010

An Olive Ridley Turtle lays eggs on a moonlit night at Rushikuliya beach in Orissa, India. Feel privileged to view this rare insight into the private life of the Ridley Turtle!

The Olive ridley turtle (Lepidochelys olivacea), also known as the Pacific Ridley, is one of the smallest species of sea turtle. It is named for the olive-green color of its heart-shaped shell. Costa Rica is the one of the most important nesting sites. Ostional Beach in Guanacaste Province has the highest monthly concentration of these turtles. The “arribadas”—mass arrival and nesting—occur every month. October and November features the highest nesting rates (approximately 200 turtles per hour).

‘This clip of professionally-shot broadcast stock footage belongs to the archive of Wilderness Films India Ltd., and has been filmed on either Digital Betacam or 1080i HD.

From Wildlife Extra:

The Atlantic’s largest turtle breeding colony has been discovered

The central African country Gabon is providing an invaluable nesting ground for a vulnerable species of sea turtle considered a regional conservation priority say scientists from the University of Exeter

The scientists surveyed almost 600 km of Gabon’s coastline and uncovered the largest breeding colony of olive ridley turtles in the Atlantic. The results suggest that Gabon hosts the most important rookery for this species in the Atlantic, with estimates indicating that there could be up to 9,800 turtle nests per year compared with around 3,300 in French Guiana and 3,000 in Brazil.

Olive ridley turtles are one of the smallest of the sea turtles and are named for the greenish colour of their shell and skin. Although considered the most abundant of the marine turtles, there has been a net decline in the global numbers of the species, such that they are currently listed as ‘vulnerable’ by the International Union for Conservation of Nature (IUCN).

Although a considerable proportion of nesting occurs within protected areas in Gabon, a range of illegal activities and external pressures continue to exist highlighting the need for continued conservation efforts.

Dr Kristian Metcalfe, lead author from the Centre for Ecology and Conservation (CEC) at the University of Exeter said: “Conservation efforts for sea turtles can be hampered by their migratory life cycles, which carry them across jurisdictional boundaries and international waters. That makes this first population assessment which covered extensive areas of Gabon’s coast outside of monitored regions all the more valuable and worthwhile, and demonstrates the importance of focusing beyond intensively monitored beaches”.

The data generated as part of this study was used to inform the development of a new network of marine protected areas covering nearly a quarter of Gabon’s Exclusive Economic Zone.

Even after long years of nesting monitoring, there are still things that surprise us all. For the first time on Vamizi Island in Mozambique, on the turtle monitoring project that started over 10 years ago, four albino green turtle hatchlings were found on the island’s most successful nesting beach, two of which were still alive. What was even more interesting about these hatchlings, was their red eyes (lack of pigmentation), a common consequence of albinism: here.

Dutch wildlife video


This video by Clifton Buitink from the Netherlands is called Dutch Nature 2.0.

It features wildlife like a kingfisher, grey lag geese, a northern lapwing, turtles, frogspawn etc.

Galapagos tortoises freed on island where they had become extinct


This video is called World’s BIGGEST TORTOISE! The Giant Galapagos Tortoise, 5 fascinating facts.

From daijyworld.com:

207 giant turtles to be released in the Galapagos

Quito (Ecuador), May 23 (IANS): Administrators at Ecuador’s Galapagos National Park said 207 giant turtles will be released next month on the island of Santa Fe, where the native tortoises died out more than 150 years ago.

The turtles to be set loose on June 5 by the park directors and the Galapagos Conservancy group belong to the species Chelonoidis hoodensis, Spanish news agency Efe reported from the South American nation.

Native to the Galapagos island of Espanola, the Chelonoidis [hoodensis] is morphologically and genetically similar to the original Santa Fe turtle.

The aim of the initiative is to establish “a breeding population that fulfills a function in the ecosystem”, park management said.

“Once the turtles are introduced, a key part of this project is to assess changes in the ecosystem resulting from the presence of these chelonians, and to evaluate the interaction between the turtles and the island’s land iguanas, particularly in the use of shared resources like food,” Danny Rueda, Galapagos ecosystems director, said.

The turtles to be released on Santa Fe range in age from four to 10 and have been raised in captivity.

Around 40 of the turtles will be equipped with a GPS device that will relay data on their movements and activities.

Pirates and whalers depleted the population of turtles in the archipalago, leaving only 15 individuals that allowed park management and the Charles Darwin Foundation to start a breeding programme.

The eradication in 1971 of the goats that had been introduced to the islands contributed greatly to the recovery of the ecosystem.

The Galapagos Islands, located about 1,000 km west of the coast of continental Ecuador, were declared a World Natural Heritage Site in 1978.

Giant tortoises, new research


This video is about giant tortoises and turtles.

From the BBC:

The truth about giant tortoises

They’re big but tortoises used to be much bigger, and while they may be slow on their feet their minds may be surprisingly quick

Henry Nicholls

Reputation: Giant tortoises live on islands. They can be aged by studying growth rings on their shells, which is how we know they are the longest lived vertebrate on record. Charles Darwin found they moved a whole lot faster than he’d imagined.

Reality: Giant tortoises are a recent evolutionary innovation and used to be everywhere, not just on islands. It’s impossible to age them accurately unless you know when they hatched. They are actually pretty slow. Darwin was probably chasing them.

The largest tortoises in the world are to be found on the Seychelles in the Indian Ocean and in the Galápagos in the Pacific. But this truth has given rise to the false belief – often found in textbooks – that their large size is a product of island life. It almost certainly isn’t.

This much is evident from a cursory inspection of the fossil record. A typical Galápagos tortoise has a carapace around 100 cm long. If this is the benchmark for “giant”, it is clear that giant tortoises were not restricted to small islands. They were everywhere.

In the southern USA and Central America, for instance, there was a monster of a tortoise known as the southeastern giant tortoise (Hesperotestudo crassiscutata) that only went extinct around 12,000 years ago.

In Queensland, Australia there used to be a beast that goes by the name of Owen’s giant horned ninja turtle (Ninjemys oweni). Before you ask, yes, it was named after the ninja turtles of teenage mutant fame.

Then there was the real mother of all giants, the Siwaliks giant tortoise (Megalochelys atlas), which was tramping around what is now the Punjab in India until a few million years ago. It was around twice the size of a Galápagos tortoise.

In addition, a 1999 genetic analysis of Galápagos tortoises suggests their ancestors were probably pretty large before they left mainland South America several million years ago.

In fact, it’s been argued that being big was a necessary pre-adaption for the successful colonization of remote oceanic islands. If it finds itself in the water, a giant tortoise will bob along tolerably well, its long neck ensuring it doesn’t take on too much water.

If there used to be so many giant tortoises, where are they all now? A recent study by the International Union for Conservation of Nature indicates that giant tortoises have suffered a far higher incidence of extinction than more modestly sized tortoises and turtles.

“These slow moving and non-threatening animals required minimal effort to find,” wrote Anders Rhodin, director of the Chelonian Research Foundation and his colleagues.

Worse, giant tortoises can survive without food or water for long periods. That meant they could be stored – alive – to provide fresh meat many months down the line.

“Tortoises were, essentially, the earliest pre-industrial version of ‘canned food’,” they suggest. Early hominins opened their shells with stone-tool “can-openers”.

It is only because humans came late to the Seychelles and the Galápagos that we can still marvel at these creatures today.

In these isolated spots, giant tortoises have become reptilian representatives, their extreme longevity casting them as a living link to a lost world. But how long do they live, really?

It is often said that you can age a tortoise by counting growth rings on its shell. Unfortunately, this is only reliable for the first year or two and is useless for aging an animal that is fully grown – which for giant tortoises is at the age of around 20.

The only reliable method of aging a tortoise is to record its year of birth. In a few instances where this has been done for giant tortoises, it is clear they can live for 150 years or more.

Giant tortoises are not known for their speed. When in the Galápagos in 1835, Charles Darwin found that they moved faster than he’d imagined.

“One large one, I found by pacing, walked at the rate of 60 yards in 10 minutes, or 360 in the hour,” he wrote in his Zoology Notes. “At this pace, the animal would go four miles [6.4 km] in the day & have a short time to rest.”

More recently, researchers have been using tracking devices to record movements of Galápagos tortoises in more detail. It turns out they are not nearly so lively, most of the time making small movements around a relatively small patch.

“Our tortoises don’t usually move more than absolute max of 2 km per day,” says Stephen Blake, coordinator of the Galápagos Tortoise Movement Ecology Programme. “Darwin was probably chasing them.”

They might be slow, but they are also probably smarter than most people imagine.

Research on the South American red-footed tortoise (a not-too-distant relative of the giant tortoises in the Galápagos) shows they use landmarks to create cognitive maps of their surroundings. They can also follow the gaze of another tortoise and learn from the behaviour of others. It seems likely that giant tortoises are capable of similar cognitive feats.

Galapagos tortoises eat invasive plants


This 2014 video is called Galapagos Islands RARE ANIMALS – Giant Tortoise.

From Washington University in St. Louis, USA today:

Endangered tortoises thrive on invasive plants

3 hours ago

Most research on the role of introduced species of plants and animals stresses their negative ecological impacts. But are all introduced species bad actors?

In one fascinating case the answer might be no. The iconic giant tortoises of the Galapagos Islands are thriving on a diet heavy on non-native plants. In fact, the tortoises seem to prefer these plants to native ones.

Introduced plants began to increase in abundance on the Galapagos Islands in the 1930s as native highland vegetation was cleared for agriculture, and the rate of introductions has been increasing ever since.

The giant tortoises, for their part, seem headed in the opposite direction. Until the late Pleistocene epoch, they were found on all the continents except Antarctica. Today they survive in only two locations: the Aldabra Atoll in the Indian Ocean, and the Galapagos Archipelago in the eastern Pacific Ocean. In the Galapagos, all of the remaining subspecies are considered vulnerable or endangered.

But now in a surprising turn of events, field research in the Galapagos shows that introduced plants make up roughly half the diet of two subspecies of endangered tortoise. What’s more, these plants seem to benefit the tortoises nutritionally, helping them stay fit and feisty.

The research, published in the March issue of Biotropica, was conducted by Stephen Blake, PhD, an honorary research scientist at Washington University in St. Louis and Fredy Cabrera of the Charles Darwin Foundation in the Galapagos.

“Biodiversity conservation is a huge problem confronting managers on the Galapagos Islands, “Blake said. “Eradicating the more than 750 species of invasive plants is all but impossible, and even control is difficult. Fortunately, tortoise conservation seems to be compatible with the presence of some introduced species.”

Counting bites and bouts

The study was done on the island of Santa Cruz, an extinct volcano that is home to two species of giant tortoise, but also to the largest human population in the Galapagos. Farmers have converted most of the highland moist zones to agriculture and at least 86 percent of the highlands and other moist zones are now degraded by either agriculture or invasive species.

In earlier work, Blake had fitted adult tortoises on Santa Cruz with GPS tags and discovered that they migrate seasonally between the arid lowlands, which “green up” with vegetation only in the wet season, to the meadows of the highlands, which remain lush year-round.

“This struck us as pretty odd, ” he said, “since a large Galapagos tortoise can survive for a year without eating and drinking. This is why sailors would collect the tortoises to serve as a source of fresh meat aboard ship.”

“Why would a 500-pound animal that can fast for a year and that carries a heavy shell haul itself up and down a volcano in search of food?,” Blake said. ” Couldn’t it just wait out the dry season until better times came with the rains?”

The answer, of course, depends on the tortoise’s energy balance. But the only detailed study of tortoise foraging the scientists were aware of had been completed in 1980, “largely before the explosion of introduced and invasive species hit the Galapagos,” Blake said.

Over a period of four years, the scientists followed tortoises in the field and, during 10-minute “focal observations” recorded every bite the tortoises took, the plant species and which part they ate. As an additional measure of the fruits the tortoises were eating, the scientists also counted and identified seeds (sometimes more than 1,000) in tortoise dung piles.

Counts of bites and bouts (defined as all feeding on a given species during the focal observations) showed that tortoises actually spent more time browsing on introduced species than on native ones.

“We weren’t really that surprised,” Blake said. “Consider it from a tortoise’s point of view. The native guava, for example, produces small fruits containing large seeds and a small amount of relatively bitter pulp in a thick skin. The introduced guava is large and contains abundant sweet pulp in a thin, pliable skin.”

The team, which included Sharon Deem, a wildlife veterinarian and epidemiologist at the St. Louis Zoo, also assessed the tortoises’ health and nutritional status, weighing them by suspending them from a spring balance and taking blood samples.

All of the indicators the scientists studied suggest that introduced species in the diet have either a neutral or positive effect on the physical condition of the tortoises. Introduced species may even help tortoises to improve their condition during the dry season.

Since a return to “pristine” conditions is unlikely on the Galapagos, it is heartening to learn that this may not be all bad news for the islands’ charismatic megaherbivores.

Rare tortoise babies born on Galapagos island


This video says about itself:

5 March 2015

Baby tortoises were born on the Island of Pinzon, something that likely hasn’t happened since 1880. CNN’s Natalie Allen has this story.

From Associated Press:

Scientists cheered by birth of Galapagos tortoises in wild

Posted: Mar 14, 2015 5:33 AM Updated: Mar 17, 2015 8:36 AM

By GONZALO SOLANO

QUITO, Ecuador – For the first time in a century, babies of the endangered Pinzon giant tortoise have been born in the wild in the Galapagos islands, scientists said.

An expedition in 1970 found only 19 adult tortoises on the archipelago’s Pinzon island, averaging 70 years old, so scientists removed them to start a captive breeding program on Santa Cruz island. The program produced juveniles that were transplanted back to the island, which is the only place the species is found.

Danny Rueda, who is in charge of conservation and restoration of ecosystems in the Galapagos, told The Associated Press that in December six infant Pinzons were found to have been born on the island.

He said there are now 650 juvenile and adult tortoises on Pinzon.

Rueda said the reintroduction of the tortoise was helped by the 2012 campaign to eradicate rats that infested Pinzon and other islands in the archipelago after being introduced long ago by passing ships. The rats prevented the reproduction by tortoises and other species.

“Finding the six baby tortoises tells us that the process of eradicating rats succeeded,” he said.

“We have begun to see that the ecosystem has begun to restore itself” on Pinzon, Rueda added. “It is a process that takes a long time. But the first step is the birth of tortoises in their natural habitat, which a century ago did not happen.”

The Galapagos, an Ecuadorean territory in the Pacific about 1,000 kilometers (620 miles) from the mainland, was declared a World Heritage Site by UNESCO in 1978 because of its unique land and marine animals and vegetation. That flora and fauna helped inspire Charles Darwin’s theory of evolution.

See also here.