Why don’t have turtles tail spikes like stegosaurs?


This 2017 music video is called Ankylosaurus | Dinosaur Songs | Pinkfong Songs for Children.

From North Carolina State University in the USA:

Why don’t turtles still have tail spikes?

Researchers explain why tail weaponry is rare

January 17, 2018

Summary: In a study covering 300 million years of evolutionary history, researchers have found four necessary components to tail weapon development: size, armor, herbivory and thoracic stiffness.

We’re all familiar with those awesome armored giants of the Jurassic and Cretaceous periods — Stegosaurus and Ankylosaurus — and their amazing, weaponized tails. But why aren’t similar weaponized tails found in animals living today? In a study covering 300 million years of evolutionary history, researchers from North Carolina State University and the North Carolina Museum of Natural Sciences found four necessary components to tail weapon development: size, armor, herbivory and thoracic stiffness.

“Weapons like tail clubs and bony spikes are found only in a few extinct animals — such as ankylosaurs, glyptodonts (large extinct armadillos) and in some ancient turtle species,” says Victoria Arbour, former postdoctoral student at NC State, current postdoctoral fellow at the Royal Ontario Museum and corresponding author of a paper describing the research. “These same weapons just don’t occur in modern-day animals, and we wanted to know why they were so rare even in the fossil record.”

Study co-author Lindsay Zanno, professor of biological sciences at NC State and head of paleontology at the NC Museum of Natural Sciences, agrees, “We kicked off this study with a simple observation: most animal weapons used for combat are located on the most critical part of the body for survival, the head, as opposed to more expendable ones such as the tail. Why, we asked, wasn’t evolution producing more animals with weaponized tails, when this would seem to be far less dangerous?”

To answer this question, Arbour and Zanno looked at a data set of 286 amniote species, both living and extinct, to see if there were patterns that pointed to the evolution of three specific types of tail weapons: bony spikes, a stiff tail or a bony knob at the tip of the tail. Amniotes refer to backboned, four-legged reptiles and mammals, as well as birds.

In the case of bony tail weaponry, the researchers found the animals had four things in common. First, they were usually large, weighing over 200 pounds (or 100 kilograms) — about the weight of the glyptodonts that used to roam South America or a living mountain goat — or were over three feet (a meter) long.

Second, armor was key. Ancient turtles, armadillos and armored dinosaurs were covered in some sort of hard carapace or bony plated armor. Thoracic stiffness — referring to a body that doesn’t bend side to side easily, perhaps so that it could easily counteract the forces needed to swing a large clubbed or spiked tail — was also important. Finally, every animal in the fossil record that developed elaborate tail weaponry was an herbivore, or vegetarian.

“It’s rare for large herbivores to have lots of bony armor to begin with,” Arbour says, “and even rarer to see armored species with elaborate head or tail ornamentation because of the energy cost to the animal. The evolution of tail weaponry in Ankylosaurus and Stegosaurus required a ‘perfect storm’ of traits that aren’t seen in living animals, and this unique combination explains why tail weaponry is rare even in the fossil record.”

Zanno continues, “This study is an elegant example of how the fossil record can be used to better understand the world around us today.”

Advertisements

Elephants in Borneo, why?


This video says about itself:

Saving the Borneo Elephant (full documentary) HD

The Bornean Elephant is a subspecies of the Asian Elephant, physically and behaviourally different from the elephants of mainland Asia. Known locally and commonly as ‘Bornean Pygmy elephants’, they are about a fifth smaller than mainland Indian elephants but similar in size to populations of Sumatra and the Malaysian Peninsula. They are generally more rotund in appearance with shorter trunks and a smaller rounder face, which makes their ears appear larger. They also have a long tail, which in some individuals reaches all the way down to the ground . Only some males display tusks, which are shorter and straighter than in the mainland elephants.

From the Instituto Gulbenkian de Ciencia:

New light on the mysterious origin of Bornean elephants

January 17, 2018

How did Borneo get its elephant? This could be just another of Rudyard Kipling’s just so stories. The Bornean elephant is a subspecies of Asian Elephants that only exist in a small region of Borneo. Their presence on this southeastern Asian island has been a mystery. Now, in a study published in Scientific Reports, a research team led by Lounès Chikhi from Instituto Gulbenkian de Ciência (IGC, Portugal) and CNRS, Université Paul Sabatier (France), and Benoit Goossens, from Cardiff University (Wales), and Sabah Wildlife Department (Malaysia), found that elephants might have arrived on Borneo at a time of the last land bridge between the Sunda Islands in Southeast Asia.

Until recently, two opposing theories have been under debate to explain the origin of Bornean elephants: they could have been recently introduced by humans, maybe 300 years ago, or they could have diverged from Asian elephants a long time ago. Indeed, there are historic records reporting that, in the 17th century, neighbour Sultans offered elephants as gifts to the Bornean Sultan. Current elephants would thus be non-native elephants that turned feral. On the other hand, about 15 years ago a genetic study showed that the DNA of Bornean elephants was very different from that of other Asian elephants, suggesting a very ancient separation, on the order of 300,000 years ago. However, no elephant fossils have yet been discovered in Borneo, even though fossils from other large mammals such as orang-utans have been found.

To shed light on the mystery of Bornean elephant’s origin, Chikhi and Goossens’ team used genetic data analysis and computational modelling to study the past demographic history of these animals. It is very difficult to track ancient demographic history of animals, even more when there are no fossil records to guide the work. “What we did was to create computational models for different scenarios that might have happened. Then, we compared the results from these models with the existing genetic data, and used statistical techniques to identify the scenario that best explained the current genetic diversity of the elephant population in Borneo”, explains Lounès Chikhi.

“Our results suggest that the most likely scenario to have occurred is a natural colonization of Borneo around 11,400 to 18,300 years ago. This period corresponds to a time when the sea levels were very low and elephants could migrate between the Sunda Islands, a Southeastern Asia archipelago to which Borneo belongs. We cannot exclude more complex scenarios, but a historical human introduction seems very improbable, and so does a very ancient arrival”, adds Reeta Sharma, researcher at the IGC and first co-author of the paper.

With less than 2000 individuals surviving today in an increasingly fragmented environment, and with regular news of poisoned or killed Bornean elephants, the future is grim for this endangered species. “Its very limited geographic distribution and reduced genetic diversity compromise the future of the population. Understanding their origins and past demography will be useful for the development of a long-term conservation strategy, especially at the time we, Sabah Wildlife Department, and partners are drafting a new 10-year State Action Plan for the Bornean elephant”, said Goossens. The researcher notes “in the light of the recent killings of elephants in the state for ivory trade and during conflicts, Sabahans must realise that it is their natural patrimony that is targeted, they need to stand for their wildlife and condemn those who kill those magnificent creatures. We should take pride of our wildlife, elephants are part of Sabah’s patrimony and we cannot afford losing more animals.”

Arkansas dinosaur tracks in the USA


This video from the USA says about itself:

Acrocanthosaurus atokensis was the largest meat eating dinosaur in North America of the early to mid Cretaceous period. The most complete specimen was discovered just 10 miles from the Museum of the Red River in Idabel and it is now the State Dinosaur of Oklahoma.

This video from 2011 includes interviews with one of the principal excavators, Cephis Hall and Dr. Kenneth Carpenter of the USU Eastern Prehistoric Museum, who with Dr. Phillip J. Currie in 2000 described the find. Also interviewed are: Henry Moy of the Museum of the Red River, Neil Larson of the Black Hills Institute, Kyle Davies of the Sam Noble Museum, and Michael Bergland of mnfx.com.

From the University of Arkansas, Fayetteville in the USA:

Digitally preserving important Arkansas dinosaur tracks

January 16, 2018

Scientists using laser-imaging technology have documented and digitally preserved the first known set of theropod dinosaur tracks in the state of Arkansas.

The tracks, discovered in 2011 in a working gypsum quarry near Nashville, Ark., have since been destroyed. But high-resolution digital scans taken over a period of two weeks in 2011 allowed a team of researchers to study the tracks and determine that they were made by Acrocanthosaurus, a large carnivorous dinosaur. The findings extended the known range of Acrocanthosaurus 56 miles east, to the western shore of an ancient inland sea.

“It actually confirms that the main genus of large theropods in North America was Acrocanthosaurus”, said Celina Suarez, an assistant professor in the Department of Geosciences who was part of the team that documented and studied the tracks. “It now has been found in Wyoming, Utah, Oklahoma, Arkansas and Maryland, a huge range.”

Results of the study were recently published in the journal PLOS ONE. Researchers also created a detailed, publicly accessible online map of the site and the tracks. Brian Platt, an assistant professor of geology from the University of Mississippi, led the study. Researchers from the University of Arkansas Center for Advanced Spatial Technology (CAST) provided the scanning equipment and expertise.

The Rush to Preserve the Site

After the tracks were discovered, researchers received a $10,000 Rapid Grant from the National Science Foundation to quickly document the site. The U of A’s vice provost for research and economic development and the J. William Fulbright College of Arts and Sciences provided matching grants, for a total of $30,000.

The mining company moved its operations to allow researchers a short window of time to document the find. Researchers used LiDAR, which stands for light detection and ranging, because traditional methods would have taken too long, said Suarez. “From a technical standpoint, it’s important that the ability to rapidly scan such a large area is available to paleontologists. It was invaluable for this project since we had such little time to work.”

The site had two different sized Acrocanthosaurus tracks, suggesting both adult and younger animals walked the ancient tidal flat about 100 million years ago, during the Cretaceous Period. It also contained tracks made by sauropods, long-necked plant-eating dinosaurs.

LiDAR uses a pulsed laser to measure distances to the earth in tiny increments, generating a data “point cloud” that is used to digitally recreate a physical space. In this case, the equipment was mounted on a lift over the site. By analyzing carbon and oxygen isotopes of the rock at the track surface, researchers determined that the track surface was indeed the surface that the animals stepped on, rather than an underlying layer that remained when the original surface eroded.

The digital reconstruction of the trackway site: http://trackways.cast.uark.edu/index.html

Costa Rican sea turtles studied with drones


This video says about itself:

25 April 2017

While conducting a drone survey in front of Playa Cabuyal on the Pacific coast of Costa Rica, we encountered a male East Pacific green turtle. Surprisingly, we were also able to identify that this was a male turtle as made evident by the size of its tail.

From Duke University in the USA:

Drones confirm importance of Costa Rican waters for sea turtles

Study is first to use drones to count sea turtles in waters near nesting habitat

January 16, 2018

Summary: A new drone-enabled population survey — the first ever on sea turtles — shows that larger-than-anticipated numbers of turtles aggregate in waters off Costa Rica’s Ostional National Wildlife Refuge. Scientists estimate turtle densities may reach up to 2,086 animals per square kilometer. The study underscores the importance of the Ostional habitat; it also confirms that drones are a reliable tool for surveying sea turtle abundance.

Hundreds of thousands of sea turtles come ashore to lay their eggs during mass-nesting events at Ostional National Wildlife Refuge on Costa Rica’s Pacific coast, making it one of the most important nesting beaches in the world.

Now aerial drones are giving scientists deeper insights into just how important the beach and its nearshore waters are.

Using a fixed-wing drone to conduct aerial surveys of olive ridley sea turtles in waters off Ostional during four days in August 2015, scientists from Duke University and the University of North Carolina at Chapel Hill (UNC-CH) estimate turtle densities there may reach as high as 2,086 animals per square kilometer during peak nesting season.

“These are extraordinary numbers, much higher than any of us anticipated,” said Seth Sykora-Bodie, a PhD student at Duke’s Nicholas School of the Environment, who co-led the study with Vanessa Bézy, a PhD candidate at UNC-CH.

“Our findings confirm drones can be used as a powerful tool to study sea turtle abundance at sea, and reveal incredible densities of turtles in Ostional’s nearshore habitat,” said Bézy. “The development of this methodology provides vital new insights for future conservation and research.”

Equipping the drone with a high-resolution digital camera with near-infrared vision and flying it just 90 meters above the ocean expanded the field of view and significantly increased image clarity, allowing the researchers to detect many turtles swimming just below the water’s surface. Observers relying only on visual sightings made from boats could easily miss these submerged animals because of their angle of view and the clarity of the water, Sykora-Bodie said.

The researchers published their peer-reviewed paper Dec. 18 in Scientific Reports. It is the first study to use unmanned aerial systems (UAS), or drones, to estimate the abundance of sea turtle populations.

Traditionally, scientists have collected this type of abundance data using mark-and-recapture studies, in-water surveys, and censuses of turtles observed on nesting beaches. These methods can be costly and time-consuming, incur potential risks to both the observers and the animals, and increase the likelihood that turtles may be missed or double-counted.

The new pilot study shows that using camera-equipped drones provides a safe, cost-effective and scientifically robust alternative.

“Because of the clarity of the images we can collect, and the greater flexibility we have in where, when and how we collect them, this approach provides us with better data for understanding population status and trends, which can then be used to inform management decisions and develop conservation measures tailored to individual populations, locations and time frames”, Sykora-Bodie said.

Olive ridleys are classified as vulnerable on the IUCN Red List of Threatened Species. One of the chief threats they face is being accidentally caught and killed by hooks and other fishing gear used by longline and trawl fisheries.

To conduct the newly published study, researchers from Duke’s Marine Robotics and Remote Sensing Labflew an eBee senseFly fixed-wing drone equipped with a near-infrared camera over a three-kilometer stretch of nearshore water twice daily — morning and evening — on four consecutive days during a mass-nesting event, or arribada, in August 2015. By analyzing the captured images, they identified 684 confirmed turtle sightings and 409 probable sightings.

Using methods that scientists regularly employ for estimating the population abundance of marine species based on surface sightings in traditional surveys, Sykora-Bodie and his colleagues then calculated a low-end daily estimate of up to 1,299 turtles per square kilometer in the surveyed area, and a high-end estimate of up to 2,086 turtles. Long-term surveys, coupled with further research on olive ridleys’ dive profile — how deep they dive, and how long they remain under water — will be needed to refine these estimates.

How Alaskan bears help plants


This video about Alaska is called The Land of Giant Bears.

From Oregon State University in the USA:

Great scat! Bears — not birds — are the chief seed dispersers in Alaska

January 16, 2018

It’s a story of bears, birds and berries.

In southeastern Alaska, brown and black bears are plentiful because of salmon. Their abundance also means they are the primary seed dispersers of berry-producing shrubs, according to an Oregon State University study.

The OSU team used motion-triggered cameras to record bears, birds and small mammals eating red berries of devil’s club, and retrieved DNA in saliva left on berry stalks to identify the species and sex of the bears. Researchers found that bears, while foraging, can disperse through their scat about 200,000 devil’s club seeds per square kilometer per hour. Rodents then scatter and hoard those seeds, much like squirrels hoard acorns.

The study was published today in the journal Ecosphere.

In most ecosystems, birds generally are thought of as chief dispersers of seeds in berries, said Taal Levi, an ecologist in OSU’s College of Agricultural Sciences and co-author on the study. The researchers found that birds accounted for only a small fraction of seed dispersal.

This is the first instance of a temperate plant being primarily dispersed by mammals through their gut, and suggests that bears may influence plant composition in the Pacific Northwest.

It was well-known that bears were dispersing seeds through their scat, Levi said, but it was not known that they were dispersing more seeds than birds, or the relative contribution of brown and black bears to seed dispersal, or whether the two species bears were eating berries at different times of the year.

“Devil’s club is extremely abundant in northern southeast Alaska, so it didn’t seem plausible that birds were dispersing all this fruit”, Levi said. “Bears are essentially like farmers. By planting seeds everywhere, they promote a vegetation community that feeds them.”

The researchers found that in the study area along the Chilkat and Klehini rivers in southeastern Alaska, brown bears dispersed the most seeds, particularly before salmon became widely available. They also found that after the brown bears switched from eating berries to salmon later in the season, black bears moved in and took over the role as principal seed dispersers. Black bears are subordinate to brown bears and avoid them.

The fruit on a devil’s club stalk is clustered into a cone containing berries. The researchers observed through the camera recordings that brown bears can swallow an estimated 350 to 400 berries in a single mouthful. Birds, on the other hand, consumed on average 76 berries per plant that they visited.

“That’s pretty remarkable,” Levi said. “When birds visit these shrubs, they take a few berries and fly off. They don’t eradicate the cones like a bear.”

Laurie Harrer, Levi’s co-author, swabbed devil’s club to retrieve environmental DNA from residual saliva left by animals and birds that ate the berries. Harrer, a master’s student in OSU’s Department of Fisheries and Wildlife, analyzed the samples to determine that female brown bears ate more berries than male brown bears, female black bears ate more than male black bears and brown bears ate more than black bears.

Brown bears, also known as grizzlies, are extinct in Oregon and California and are nearly extinct in Washington.

“The indirect effect of salmon is that they support abundant bear populations that then disperse a lot of fruit”, Levi said. “We’ve lost the salmon-bear ecosystem that once dominated the Pacific Coast. That has implications for the plant community. These seed dispersal pathways through brown bears are all but eliminated. The degree to which black bears can fulfill that role is not clear.”

Fluorescescent chameleons, new study


This video from the USA says about itself:

Wild Chameleons in Florida?!

26 April 2016

On this episode of Coyote’s Backyard, the team and new friend David Humphlett discover an animal NONE of them expected to find! In all of their trips to South Florida Coyote and the crew have seen their fair share of amazing creatures. Everything from Alligators and Crocodiles to invasive Pythons and Knight Anoles have crossed their paths, but tonight they find something extremely rare – an invasive but very WILD Veiled Chameleon! Get ready to meet one very cool color shifter!

Although Veiled Chameleons are native to the Arabian Peninsula they have established breeding populations in South Florida in recent years due to favorable climate conditions and an abundance of specimens released from the exotic pet trade. The Chameleon discovered in this video was not released back into the wild and was instead given to an educational/research group.

From the Ludwig-Maximilians-Universität München in Germany:

Zoology: Luminescent lizards

January 16, 2018

Chameleons are known to communicate with conspecifics by altering their surface coloration. Munich researchers have now found that the bony tubercles on the heads of many species fluoresce under UV light and form impressive patterns.

Biogenic fluorescence is mainly known from marine organisms, but is rare in terrestrial vertebrates. “So we could hardly believe our eyes when we illuminated the chameleons in our collection with a UV lamp, and almost all species showed blue, previously invisible patterns on the head, some even over the whole body”, says David Prötzel, lead author of the new study and PhD student at the Bavarian State Collection of Zoology (ZSM). To understand the phenomenon, the researchers used a variety of modern methods. Micro-CT scans showed that the pattern of fluorescence exactly matched the distribution of tubercles pattern on the skull. The tissue analyses yielded another surprise: “Our histological 3D reconstruction shows that the skin covering the tubercles on the skull is very thin and consists only of a transparent layer of epidermis”, explains Dr. Martin Heß from the BioCenter of Ludwig-Maximilians-Universität (LMU) in Munich. These patches effectively act as windows that enable UV light to reach the bone, where it is absorbed and then emitted again as blue fluorescent light.

“It has long been known that bones fluoresce under UV light, but that animals use this phenomenon to fluoresce themselves has surprised us and was previously unknown”, says Dr. Frank Glaw, Curator of Herpetology at the Bavarian State Collection of Zoology.

The tubercles fluoresce under UV light to form distinct patterns that represent certain species or species groups. In addition, the males in most species of the genus Calumma have significantly more fluorescent tubercles than the females. Therefore, the researchers suspect that this fluorescence is not a mere coincidence, but helps the chameleons to recognize conspecifics, and presents a consistent pattern in addition to their skin-based colour language — especially as blue is a rare colour and easily recognisable in the forest.

Dinosaurs, lies and truth


This video says about itself:

LIES About Dinosaurs You PROBABLY Still Believe!

8 January 2018

Check out these lies about dinosaurs you probably still believe! From the largest and most dangerous dinosaurs like Tyrannosaurus rex and Brontosaurus to smaller ones like velociraptors, here are the top 10 myths about dinos debunked!