Tag Archives: sloth

Slothbot slowly, but surely monitors the environment

A two-toed sloth moves a cable at a cacao plantation in Costa Rica. Credit: M. Zachariah Peery.

The trend nowadays is to design robots that are faster, more agile, and life-like. While there are many upsides to this kind of approach, all that flashy movement consumes a lot of energy. Sometimes, slow and steady is better. Taking cues from one of the most energy efficient (and laziest) creatures in the animal kingdom, researchers at the Georgia Institute of Technology have devised the SlothBot — a hyper-efficient robot that continuously monitors environmental changes in the forest canopy for months.

Magnus Egerstedt, a professor at the School of Electrical and Computer Engineering at the Georgia Institute of Technology, was visiting Costa Rica when he was inspired by sloths to develop what he calls “a theory of slowness”. Sloths seem to be everyone’s “spirit animal” — eat, sleep, and hang out in trees all day (some sloths can spend their entire lives up in trees). These animals are famous for their extremely sluggish movement and slow metabolism, which compels sloths to rest as much as 22 hours a day. But the sloths are also masters of energy conservation, being capable of meeting their daily calorie needs with the equivalent of a small potato.

“The life of a sloth is pretty slow-moving and there’s not a lot of excitement on a day-to-day level,” said Jonathan Pauli, an associate professor in the Department of Forest & Wildlife Ecology at the University of Wisconsin-Madison, who has consulted with the Georgia Tech team on the project.

“The nice thing about a very slow life history is that you don’t really need a lot of energy input. You can have a long duration and persistence in a limited area with very little energy inputs over a long period of time.”

Gennaro Notomista shows the components of SlothBot on a cable in a Georgia Tech lab. Credit: Allison Carter, Georgia Tech.

Egerstedt previously developed control algorithms for swarms of wheeled or flying robots. But when Egerstedt had to develop an environmental monitoring robot for tree canopies, he could think of no better creature to emulate than one that lives all day in the trees.

“The thing that costs energy more than anything else is movement,” Egerstedt said. “Moving is much more expensive than sensing or thinking. For environmental robots, you should only move when you absolutely have to. We had to think about what that would be like.”

The SlothBot features a pair of photovoltaic panels that supply power, along with 3-D printed gearing and wire-switching mechanisms. The robot is actually comprised of two bodies connected by an actuated hinge. Each body has a driving motor connected to a rim on which a tire is mounted. Switching from one cable to another without failure was the biggest challenge that the researchers had to solve.

“It’s a tricky maneuver and you have to do it right to provide a fail-safe transition. Making sure the switches work well over long periods of time is really the biggest challenge,” said Gennaro Notomista, a graduate research assistant.

So far, the SlothBot prototype has been tested on a network of cables on the university’s campus. In the future, the researchers will mount a 3D-printed shell, which is meant to make the robot look like a cute sloth while offering protection from the rain and wind. Once this stage is complete, the SlothBot will be deployed in the tree canopy at the Atlanta Botanical Garden. Ultimately, the authors of the new study would like to see the SlothBot in a cacao plantation in Costa Rica, where real sloths also live.

 “The cables used to move cacao have become a sloth superhighway because the animals find them useful to move around,” Egerstedt said. “If all goes well, we will deploy SlothBots along the cables to monitor the sloths.”

The SlothBot was described in a study published in the journal IEEE Robotics and Automation Letters and presented at the International Conference on Robotics and Automation in Montreal.

Giant sloth.

Timeline for giant sloth extinction rewritten by new analysis

The giant sloth may have lived in the slow lane, but it went extinct much faster than previously estimated, a new study reports.

Giant Sloth Bones.

Lithic tool associated with giant ground sloth bones.
Image credits Gustavo Politis, Pablo Messineo.

Researchers at the National University of Central Buenos Aires, Olavarría, Stafford Research, and La Brea Tar Pits and Museum, report that the giant sloth went extinct before the Holocene, the current geological period.

Dirty collagen

Prior research had found that the giant sloth disappeared during the Pleistocene, the geological epoch spanning from about 2.5 million to 11 thousand years ago — the last period of repeated glaciations to grip the Earth (right before the Holocene). However, there was also some evidence pointing to the survival of this species in certain pocket areas (of today’s Pampas, Argentina) up to the Holocene.

The present study comes to invalidate that hypothesis: the giant sloths went completely extinct before the onset of the Holocene, it explains. This new paper used a more stringent testing technique to date the remains of giant sloths found at the Campo Laborde dig site in Argentina. The team recovered collagen from the remains — they note that a single bone had recoverable collagen — that they dated using the radiocarbon technique and used to establish the new timeline for the sloths’ extinction.

The study also provides a glimpse into what went wrong with earlier dating attempts: the collagen used in the current study had been heavily contaminated with compounds leaching from the soil around it. Earlier dating efforts had not taken this contamination into account, they explain, which fouled the results. The team used chemical purification techniques to clean up the collagen before running their analysis, and then extracted specific amino acids that could only have come from the sloth itself, the team explains.

Giant sloth.

Giant sloth.
Image credits Eden, Janine and Jim / Flickr

Their analysis shows that the giant sloth went extinct around 10,570 years ago. This would push the timeline of their disappearance out of the Holocene (previous research found that the animals went extinct around 9,730 years ago, which is during the Holocene).

It’s a distinction that might sound pedantic, but it’s actually quite significant. Humans are currently considered the driving force behind the extinction of many ancient megafauna species, including the giant sloth. The new findings don’t exonerate our ancestors, but they do suggest that they were only part of the problem; their hunting of the giant sloths certainly helped, but it likely happened during a time when the species was buckling, likely under environmental strain from changing climate patterns.

The findings also raise the possibility that other species of huge mammals, especially those in South America (but possibly other places around the globe as well) didn’t make it to the Holocene either. If the collagen in the remains those studies were based on is found to be contaminated, the findings could be off the mark by thousands of years.

The paper “A Late Pleistocene giant ground sloth kill and butchering site in the Pampas” has been published in the journal Science Advances.

10 of the Weirdest Prehistoric Creatures

Eons ago, many millennia before written history, bizarre animals roamed the Earth. The most renowned of these prehistoric creatures were the dinosaurs. Countless films have been made featuring these great reptiles. But during the various epochs of our world’s prehistory there existed many other weird and wonderful beasts. And many of them had names that were even weirder.

You will find some of these to be even more fascinating than dinosaurs. It was in this era before the dominance of mankind that life on Earth underwent a great deal of evolution. And, in fact, the Earth itself, its land masses and oceans, also evolved drastically.

Ichthyostega

Credit: Wikimedia Commons.

Credit: Wikimedia Commons.

Living in the late Devonian period, Ichthyostega was one of the earliest amphibian-like animals. It had the head and tail of a fish, and it needed to return to the water in order to breed. The feature which differentiated Ichthyostega from lobe-finned fish was the limbs. In Ichthyostega, the fins were jointed, with leg and toe bones. Ichthyostega‘s foot was odd by modern standards. It had eight toes.

Sharovipteryx

Sharovipteryx. Credit: Wikimedia Commons

Scientists believe Sharovipteryx to be an ancestral link to the winged reptiles the pterosaurs. Not classified as a true pterosaur itself, it lived in the early Triassic period over 240 million years ago. It’s in a class of its own. The creature’s remains have been unearthed at the Madygen Formation in Kyrgyzstan, Central Asia. It was a mere one foot in length. It had four appendages which seem to have possessed thin flaps of skin like wings. The two forelimbs were quite short, and the rear limbs were much longer. Some theorize this design enabled Sharovipteryx to jump with ease. Paleontologists believe its mode of transportation was more like gliding than true flying.

Longisquama

Longisquama. Credit: Wikimedia Commons.

Longisquama. Credit: Wikimedia Commons.

This creature was what has been called a diapsid. The diapsids were a reptilian subclass which eventually would evolve into the most important reptile subclass. But it began as a small group of climbing and gliding reptiles. The diapsids lived in forests located on the supercontinent Pangea during the Triassic period. Thus, Pangea was the place Longisquama would have called home.

The skeleton’s most stunning feature is a double row of long scale-like structures running along its back, forming six to eight pairs. It had one pair of scales for each of its pairs of ribs. The scales had a central hollow vein, like bird feathers. But unlike feathers, Longisquama‘s scales seem to have been formed of flat sheets and not genuine plumes. This is the creature featured in this article’s header image.

Stagonolepis

Illustration of an Aetosaur. Credit: Wikimedia Commons.

 

Stagonolepis was an aetosaur, sometimes also synonymically referred to as a stagonolepid. The Triassic world was filled with a vast variety of crocodilian species. The aetosaurs were unique among the early crocodiles since they were herbivorous. Unlike modern crocs, they were vegetarians. And Stagonolepis was one of the most prevalent of the stagonolepids at the close of the Triassic. Its long, narrow body was armor-coated, and it was capable of reaching a length of nine feet. Some artist renderings depict a creature which rather resembles a modern armadillo.

Casea

Credit: Wikimedia Commons.

Credit: Wikimedia Commons.

The caseids were another group of early reptiles. No reptile living today looked as odd as the Casea. The massive pig-like body, tiny head, overhanging upper jaw with peg-like teeth, and lower jaw with no teeth gave Casea a goofy look. These prehistoric creatures had large ribcages and were capable of reaching four feet long. Their prime occurred in the late Permian period. The term “casea” means “cheesy.”

Nothosaurus

Nothosaurus. Credit: Wikimedia Commons.

Nothosaurus. Credit: Wikimedia Commons.

Nothosaurs were related to the plesiosaurs but did not always have the best physical capabilities for coping with marine life. These reptiles did not have gills. So they had to come up to the surface for fresh air. Their long necks which would have easily been able to sneak into a school of fish were a big asset when it came to catching their prey.

Nothosaurus is one example of a nothosaur. Others such as Ceresiosaurus, Pachypleurosaurus, and Lariosaurus are also classified as nothosaurs. A good deal of our basic understanding of these marine reptiles comes from Dr. Oliver Rieppel of the Field Museum, Chicago, Illinois. Nothosaurus itself lived in the mid-Triassic, and its name’s meaning is translated as “false lizard.” Scientists have considered two possibilities as to how the animals gave birth to their offspring. The eggs were laid on the sandy shores like modern sea turtles. Or a Nothosaurus would give live birth to its young at sea just as some sharks do today.

Stegosaurus

3D Model of Stegosaurus

You know, it would be kind of unfair not to include at least one dinosaur in this list. (Although, cinema and literature have almost made them overrated.) What is so special or weird about Stegosaurus apart from the fact that it was a dinosaur? Well, it isn’t really. It is primarily included on this top ten list in order to clear up some misconceptions and mysteries surrounding its public consideration. Dwelling in the prehistoric Americas in the late Jurassic period, Stegosaurus had bony plates along its back and small ossicles covering its throat.

In relation to the creature’s mass, it has the smallest brain of all dinosaurs. Speaking of brains, here is another fun fact which some people still may have never heard. For a time, scientists were throwing out the hypothesis that a certain organ located in the tail of a Stegosaurus was responsible for performing some actions in the dinosaur’s posterior end.

However, the mass of nerves or whatever organ it may have been is no longer considered to have been a true brain. As for its renowned plates, scientists have made several speculations as to their function. They could have been for simple body defense when sparring with its peers or evading predators. They might have been for storing up heat during the day to then “burn up” after the sun went down. Or the plates even could have a means to attract mates.

Thylacosmilus

 

 

Artist Rendering of Thylacosmilus

 

Thylacosmilus obviously has the body style of a saber-toothed tiger. Interestingly enough, the animal also happened to be a marsupial. A marsupial is simply an animal which has a pouch of skin in which to carry its newborn young for a period. Modern marsupials include kangaroos and opossums. Living in the late Tertiary period, Thylacosmilus had strong, long-lived family relationships. Any restoration is far from perfect since a full skeleton has never been found.

Tsaidamotherium

Credit: Frontiers of Zoology.

Credit: Frontiers of Zoology.

Considered a pronghorn, Tsaidamotherium lived in the late Tertiary and bears some resemblance to the musk ox of present-day. Its body shape seems related to that of bovines. Tsaidamotherium was a grazing creature like many of its Miocene peers and lived on the Mongolian plains. It possessed one great cylindrical horn ontop its forehead and directly in the center. Another much smaller horn was located directly adjacent to it.

The likely function that its larger horn is supposed to have carried out was perhaps for display to attract a counterpart of the opposite gender. At first glance then, this creature could resemble the description of the mythical beast the unicorn. Dougal Dixon states this same relation in The World Encyclopedia of Dinosaurs and Prehistoric Creatures.

Megatherium

Artist Depiction of Megatherium. Credit: Wikimedia Commons.

 

As the name implies, this brute was a pretty large mammal. It was actually a giant ground sloth related to modern sloths. An inhabitant of South America during the Quaternary period, an adult standing on its hind legs could reach a height of 20 feet. Megatherium was previously regarded as a slow tree ripper. But recent studies show that its great claws might have been used for stabbing and killing. If this was the purpose of its claws, it would make the giant sloth the largest predator of the South American plains.

Ecosystems still feel the pain of ancient extinctions

The more researchers study ecosystems, the more we learn that an ecosystem behaves, in many ways, just like a living organism: thousands of years after human hunters wiped out big land animals like giant ground sloths, the ecosystems they lived in are still suffering from the effects, much like a body suffers from past trauma.

The giant sloth, imagined in happier days. Image: Jaime Chirinos/SPL

The giant sloth, imagined in happier days. Image: Jaime Chirinos/SPL

Humans wiping out species (directly through hunting or indirectly through habitat destruction) is not really a new thing. Early human hunters have posed a stress on environments for thousands if not tens of thousands of years, because they were so successful and the prey didn’t have enough time to adapt.

Most ecosystems rely on big animals to supply them with nutrients (read: dung fertilizing).

“If you remove the big animals from an ecosystem, you pretty much stop nutrients moving,” says Chris Doughty of the University of Oxford.

In order to understand the impact of this extinction, Doughty and his colleagues studied the distribution of phosphorous – a nutrient that plants need to grow; he analyzed the Amazon basin in South America, an area which was once the home of fantastically large animals, such as elephant-like gomphotheres and giant ground sloths.

Unfortunately for these spectacular animals though, some 12.500 years ago, humans moved to South America, and shortly after this, these animals went extinct due to extensive hunting and climate change. Today, the Amazon basin is home to a huge biodiversity, but there are no more truly big animals – and their extinction still has a massive effect on the distribution of phosphorous throughout the basin.

Using the relationship between animal size and phosphorous distribution, Doughty estimated how much phosphorus South America’s larger extinct animals would have transported 15,000 years ago. His model concluded that megafauna would have spread nutrients 50 times faster than today’s fauna. This happens because big animals carry more food around in their bellies and they also travel more searching for food. It’s just like blood vessels in the body:

When you get rid of big animals, it’s like severing the nutrient arteries.”, says Doughty. He thinks the same thing happened in North America, Europe and Australia, where most big animals have also been wiped out. “The idea that herbivores redistribute nutrients is not new, but the scale of this thinking is much, much bigger,” says Tim Baker at the University of Leeds in the UK.

If his model is correct, than it’s quite safe to assume that the Amazon is still recovering from this drastic event which severely altered the circuit of nutrients. With large herbivores gone from the area, it’s up to the humans to take their role – but we’re doing the complete opposite of what they’re doing.

amazon basin

“These megafauna would disperse nutrients, whereas humans concentrate them,” says Doughty. We spread fertiliser on small plots of productive farmland, and keep large animals like cows fenced rather than letting them roam freely. “There are probably more nutrients because of people, but they are very poorly distributed.”