Tag Archives: foot

Fossil Friday: bird encased in amber has an unique, “extreme” toe

The bird’s hyper-elongated third toe is longer than its whole lower leg, the authors report.

Bird in amber.

The fossilized bird, encased in amber. Image credits Linda Xing et al., (2019), Cell Biology.

Researchers in China have discovered a new species of ancient bird preserved in amber– and it’s packing one seriously impressive toe. The fossilized beast, which lived around 99 million years ago, likely used the appendage to draw food out of tree trunks. According to the team, it’s the first time such a food structure has been observed in either living or extinct birds.

Bigtoe

“I was very surprised when I saw the amber,” says first author Lida Xing at China University of Geosciences (Beijing). “It shows that ancient birds were way more diverse than we thought. They had evolved many different features to adapt to their environments.”

The fossils include two isolated wings, an isolated foot with wing fragment, and two partial skeletons, most of them from juvenile individuals. The fossils date back to the Cretaceous period and were found encased in amber in 2014 in the Hukawng Valley of Myanmar. It was christened Elektorornis chenguangi. The new species’ most distinctive feature is its very, very long third toe measuring 9.8 millimeters. It is a full 41% longer than its second toe and 20% longer than its tarsometatarsus, the main bone in the lower legs of birds. Comparison to 20 other extinct bird species from the same time and 62 living birds showed that, showed that Elektorornis chenguangi is the only species so far discovered to evolve this foot structure.

Elektorornis chenguangi is part of a group of extinct birds called Enantiornithes, the most abundant type of bird known from the Mesozoic era. To the best of our knowledge, the Enantiornithines became extinct during the Cretaceous-Paleogene extinction event about 66 million years ago (the one where all the dinosaurs died) and left no living descendants behind. Elektorornis means “amber bird”.

Bird leg.

A 3D reconstruction of the birds’ leg.
Image credits Linda Xing et al., (2019), Cell Biology.

Based on the measurements they’ve taken of the fossils, the team reports that Elektorornis was smaller than a sparrow and that it was arboreal (i.e. it liked trees as opposed to the ground or water surfaces). The bird’s foot measures 3.5 centimeters in length, and weighs 5.5 grams.

“Elongated toes are something you commonly see in arboreal animals because they need to be able to grip these branches and wrap their toes around them,” says co-author Jingmai O’Connor at the Chinese Academy of Sciences. “But this extreme difference in toe lengths, as far as we know, has never been seen before.”

During the Mesozoic area, the Hukawng Valley of Myanmar was heavily forested with trees that produced resin as a defensive mechanism. The area is famed for its amber and fossil-bearing amber bits to this day, all thanks to those trees. The oldest known bee and a feathered dinosaur tail, among many others, have been discovered in amber from this valley. The team obtained the amber from a local trader, who didn’t know what animal this weird foot belonged to.

“Some traders thought it’s a lizard foot, because lizards tend to have long toes,” Xing says. “Although I’ve never seen a bird claw that looks like this before, I know it’s a bird. Like most birds, this foot has four toes, while lizards have five.”

As to why the bird needed such a long leg, the team still can’t say for sure. The only animal today to sport similar digitation is the aye-aye, a lemur that uses its long middle fingers to fish larvae and insects out of tree trunks for food. The team suspects Elektorornis chenguangi used its toe in a similar way.

“This is the best guess we have,” O’Connor says. “There is no bird with a similar morphology that could be considered a modern analog for this fossil bird. A lot of ancient birds were probably doing completely different things than living birds. This fossil exposes a different ecological niche that these early birds were experimenting as they evolved.”

The paper “A New Enantiornithine Bird with Unusual Pedal Proportions Found in Amber” has been published in the journal Current Biology.

Hominin talus.

New research suggests humanity’s ancestors began walking upright earlier than believed

New research shows that one ancestor of modern humans was walking upright much more often than we believed.

Ardi.

The skull of the Ardipithecus ramidus specimen nicknamed “Ardi”.
Image credits T. Michael Keesey / Flickr.

One immediately-distinguishable feature of humans is the way we move about —  we’re unique among mammals in that we consistently walk upright. Since it’s such a distinguishing feature, anthropologists are very interested in finding out when our ancestors picked up the habit.

New research from the Case Western Reserve University School of Medicine suggests that at least one of our ancestors relied on bipedal walking much more than previously believed.

Early walker

“Our research shows that while Ardipithecus was a lousy biped, she was somewhat better than we thought before,” said Scott Simpson, a professor of anatomy at Case Western who led the study.

The findings come from an analysis Simpson’s team performed on fragments of a 4.5 million-year-old female Ardipithecus ramidus. This specimen was discovered in the Gona Project study area in the Afar Regional State of Ethiopia. Hip, ankle, and hallux (big toe) bones belonging to the ancient female showed that Ar. ramidus was far better adapted to bipedalism than previously thought, but still far from perfect.

Fossil evidence from this stage of humanity’s past are rare, so we have a pretty dim idea of what was going on at the time. As such, Simpson’s research — although seemingly a simple pursuit involving an ankle of all things — actually goes a long way into fleshing out our understanding of  Ardipithecus locomotion, as well as the timing, context, and anatomical details of ancient upright walking.

Previous research has shown that Ardipithecus was capable of walking upright and climbing trees — but the fossils that research was based on lacked the anatomical specializations seen in the Gona fossil examined by Simpson. This suggests that the species saw a wide range of adaptations as they transitioned to modern, upright walking as seen in modern humans.

“Our research shows that while Ardipithecus was a lousy biped, she was somewhat better than we thought before,” says Simpson.”The fact that [it] could both walk upright […] and scurry in trees marks it out as a pivotal transitional figure in our human lineage.”

Hominin talus.

A freshly-found fossil A. ramidus talus.
Image credits Case Western Reserve University School of Medicine

The team says that certain adaptations in the specimen’s lower limbs are tell-tale signs of bipedality. Unlike monkeys and apes, for example, our big toes are parallel with the others. The team worked to reconstruct the foot’s range of motions by analyzing the area of the joints between the arch of the foot and the big toe. While joint cartilage no longer remains for the Ardipithecus fossil, the surface of the bone has a characteristic texture which shows that it had once been covered by cartilage.

Having all toes neatly parallel to one another allows the foot to function as a propulsive lever when walking. Ardipithecus had an offset grasping big toe useful for climbing in trees, but the team’s analysis showed that it was also used to help propel the individual forward when walking — in other words, it’s a mixed-use tool, indicative of a transition towards bipedalism. The team also reports that Ardipithecus’s knees were aligned directly above its ankles when it stood. This latter characteristic is also similar to what you’d see in a modern (bipedal) human, and stands in contrast to what you’d see in a (non-bipedal) chimp, for example, whose knees are “outside” the ankle, i.e., they are bow-legged, when they stand.

The paper “Ardipithecus ramidus postcrania from the Gona Project area, Afar Regional State, Ethiopia” has been published in the Journal of Human Evolution.

Why smoking weed gives you the munchies — blame your hormones

Scientists have zoomed in on why cannabis makes people hungry — the so-called “munchies”. Aside from solving a long-standing curiosity, this could lead to treatments for appetite loss in chronic illness, researchers say.

Yum yum.

The Munchies

As anyone who’s ever had a taste of the Devil’s grass (a.k.a. cannabis) can attest, one of the after-effects is a sudden and strong desire for food — especially sweets. However, while this effect has been observed for decades, its cause and mechanism were not known. But with the surge of cannabis legalization measures (both for recreational and medical purposes), understanding the “munchies effect” became even more important.

“We all know cannabis use affects appetite, but until recently we’ve actually understood very little about how or why,” explained Jon Davis, Ph.D., researcher in the Department of Integrative Physiology and Neurosciences at Washington State. “By studying exposure to cannabis plant matter, the most widely consumed form, we’re finding genetic and physiological events in the body that allow cannabis to turn eating behavior on or off.”

Scientists already knew that the psychological effects of cannabis (the “high”) are caused by a family of compounds called cannabinoids, particularly delta-9 tetrahydrocannabinol (THC). But the ability of THC to stimulate appetite is much less understood.

The Hunger Hormone

Davis and colleagues designed a study on rats, with a vapor exposure system to mimic how people often consume cannabis. This way, they were able to control the dosage, which was closely monitored throughout the study. First, researchers observed that even a brief exposure to cannabis prompted rats to eat a meal — even right after they’d eaten.

“We found that cannabis exposure caused more frequent, small meals,” stated Davis. “But there’s a delay before it takes effect.”

Then, the team observed a surge in a hormone called ghrelin. Ghrelin, often called the “hunger hormone,” regulates appetite and plays a significant role in the distribution and rate of use of energy. When the stomach is empty, ghrelin is secreted as a message to the brain that it’s time to look for food. It seems that cannabis stimulates ghrelin secretion, which in turn makes us hungry.

In order to confirm that this was the cause of the increased appetite, researchers then administered a second drug which inhibits ghrelin production — and cannabis no longer stimulated eating.

Of course, there are a few distinctions to be made here. For starters, it’s a rat study, and there’s no guarantee that the same effect is carried out similarly on humans — although Davis is cautiously confident that this will be the case. Secondly, there is a myriad of different cannabis strains out there, each with its own THC concentration and individual characteristics. In this study, researchers only used marijuana grown at the University of Mississippi, which has an extremely low THC concentration (about 7.8%). Commercial marijuana often reaches THC concentrations over 20%. This makes it harder to assess if the effect is uniform across all strains, or how it may relate to other properties like THC content.

However, this is yet another compelling argument in the case for the medicinal use of cannabis. While some of the drug’s purported benefits have certainly been overstated, there is still a case to be made for some medical properties of marijuana — in this case, Davis says, as a way to promote appetite. Patients undergoing taxing clinical treatments often find it hard to maintain a healthy appetite.

“Something that we want to pursue in my lab is seeing whether the effect of THC concentrations could cause different results — meaning, maybe they would eat a little sooner or delay feeding a little longer,” Davis told Inverse. “Having said that, I’m absolutely confident that when people are going to inhale or vaporize marijuana, they are going to have an increase in appetite.”

The results are currently under review.

Scientific Reference: Investigating the Neuroendocrine and Behavioral Controls of Cannabis-Induced Feeding Behavior. JF Davis, PQ Choi, J Kunze, P Wahl, Washington State University Pullman. Presented July 2018, Society for the Study of Ingestive Behavior, Bonita Springs, FL.

elephant

Elephants walk on their tip-toes and it’s literally killing them in captivity

elephant

Credit: Pixabay

The elephant is known in popular culture as a wise animal, not an elegant one. You’d be surprised to find out, though, that African elephants walk on their tippy-toes despite having a huge foot which measures 4.4 feet (1.34 m) in circumference.

Elephants on high heels

Olga Panagiotopoulou, an evolutionary morphologist at the University of Queensland, Australia, wanted to get to the bottom of an oddity. Many captive elephants are plagued by foot problems which not only changes their gait in an awkward way but in time can grow in a disease. Every year, elephants from zoos and conservation sites need to be euthanised because there’s nothing that can treat them, Panagiotopoulou said.

The debate has come up with two primary candidate explanations: either the captivity itself is driving the elephants to change their gait and ultimately ruin their feet or something in the environment is to blame. The two are so well connected, however, that it’s very difficult to single out the leading factor.

Testing elephant walking is very challenging but Panagiotopoulou and colleagues found a way. They trained five African elephants (Loxodonta africana) from a park in South Africa to walk over a platform that was fitted with pressure sensors. When an elephant walked over the platform, the researchers could then map the load distribution along the foot.

The results of the tests made on African elephants were then compared to those made on Asian elephants (Elephas maximus) in a zoo in England using the same pressure plates. This analysis revealed that when elephants walk in wild or semi-wild environments, they put the most pressure on the outside toes of their front feet and the least pressure on their heels. The outside of their feet is, not coincidentally, where most instances of disease occur.

Because zoos and certain conservation park often have harder surfaces, even asphalt, the findings seem to explain why captive elephants have to deal with sore feet on a daily basis.

“We know that elephants in captivity get diseases that we don’t see in wild individuals as much, but the major question for conservation purposes is what can we do to prevent them,” Panagiotopoulou told ABC Australia.

It’s not like we can release elephants in the wild overnight. Captive environments are crucial to elephant conservation in Africa where poachers are having a field day. Since 2007, the African savanna lost 30 percent of its elephants to cut-throat poaching.

Instead, Panagiotopoulou is proposing the wide scale introduction of pressure plates to monitor the health of elephant feet. If an animal is at risk, future development of foot disease might be avoided through trimming.

“You can change the trimming approach to move the weight away from the part of the foot that is injured or can even create elephant orthotics to stop disease progression,” she said.

Rhinos also experience similar difficulties. They might also walk on their tippy-toes and we’ll soon learn when Panagiotopoulou and colleagues use pressure plates to study their gait as well.

Findings appeared in the journal Royal Society Open Science.