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Sperm counts in men from North America, Europe, Australia, and New Zealand have dropped by over 50 percent over the past 40 years.

Sperm Count is Decreasing in Rich Nations—and No One Knows Why

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 Over the past 40 years, sperm counts in men from North America, Europe, Australia, and New Zealand have dropped by over 50 percent, researchers announced on Tuesday.


 Researchers examined 7,500 studies conducted between 1973 and 2001. They selected 185 studies with consistent counting methods and performed analyses on data from almost 43,000 men.


 Their findings,
 <a href="http://dx.doi.org/10.1093/humupd/dmx022">
 released in
 
 Human Reproduction Update
 
</a>
 , showed that sperm concentration fell from 99 million per milliliter to 47.1 million per milliliter during the span of the study, indicating a 52.4% decline in sperm concentration and a 59.3% decline in total sperm count for men in these nations. What’s more, the scientists found that the decrease in sperm count is not slowing. As sperm counts have implications for morbidity and mortality, these results raise potential concerns for health and fertility.


 While previous studies on sperm count were criticized for not accounting for confounding variables like age, sexual activity, or infertility, this study used consistent sperm count methods and broad data sets from many locations to address these concerns.

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 The study did not directly address causes for the decline, though in interviews with
 <a href="https://www.newscientist.com/article/2141784-sperm-count-has-fallen-by-nearly-60-per-cent-in-richer-countries/#link_time=1501018098">
 New Scientist
 </a>
 , study author Shanna Swan of the Icahn School of Medicine at Mount Sinai indicated that since the decline occurred in these specific nations, there may be a causal relation with chemicals. The impact of chemicals, like phthalates that are often found in
 <a href="https://www.nytimes.com/2017/07/12/well/eat/the-chemicals-in-your-mac-and-cheese.html?_r=1">
 food packaging and make their way into nearly every brand of macaroni and cheese
 </a>
 , has been called into question lately by data that suggests they may interfere with testosterone production and endocrine systems.


 Here’s Kate Kelland,
 <a href="https://www.scientificamerican.com/article/sperm-count-dropping-in-western-world/">
 reporting
 </a>
 for Scientific American:

<blockquote>

 “This study is an urgent wake-up call for researchers and health authorities around the world to investigate the causes of the sharp ongoing drop in sperm count,” said Hagai Levine, who co-led the work at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Jerusalem.


 The analysis did not explore reasons for the decline, but researchers said falling sperm counts have previously been linked to various factors such as exposure to certain chemicals and pesticides, smoking, stress and obesity.


 This suggests measures of sperm quality may reflect the impact of modern living on male health and act as a “canary in the coal mine” signaling broader health risks, they said.

</blockquote>

 But it’s not all bad news—47.1 million sperm per milliliter is still well above the 15 million sperm threshold that is considered low from a fertility standpoint. The study revealed no clear decline in sperm count for men in South America, Asia, or Africa, but the authors note that far fewer studies have been conducted in these regions.


 For now, the question of what is causing sperm count decline is still open, but the evidence of the trend is increasingly apparent.

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 Image credit:
 <a href="https://www.flickr.com/photos/82066314@N06/9233907080/">
 Iqbal Osman / (CC BY 2.0)
 </a>

An obvious decrease in sperm count amongst richer nations is showing no sign of slowing.

Scientists Have New Understanding of How Animals See Color

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 A few years ago, Professor Liz Tibbetts stumbled upon something surprising.  She noticed that wasps had striking facial features—including fake eyelines and distinctive marks.  At the time, people didn’t believe that wasps were able to see this kind of fine scale variation, but in the years since, her wasps have become a model system of how individual identities are displayed and perceived even in animals with tiny brains.
 

 “Animals use color in every context in very meaningful ways, you can look at social behavior, partners, enemies, or you can look at reproductive behavior, sexual selection, mate choice, escaping behavior and crypsis—every aspect of their life is impacted by color,” said Mark Hauber, Professor of Animal Behavior at the University of Illinois, Urbana-Champaign and one of the authors of a new review paper on the biology of color.
 

 Researchers know that animals are able to see and produce colors that humans cannot, specifically in the ultraviolet and infrared zone, but until recently they were not able to view the world as animals themselves see it. In the paper released in
 <a href="http://dx.doi.org/10.1126/science.aan0221">
 Science
 </a>
 this week, scientists showed that we are starting to understand how animals produce color and integrate information about it, and what implications that has for evolution. “We have tools which allow us to see how the bird sees a fruit item or how a predator sees an egg in a nest, instead of seeing the world through photographs,” said Hauber.
 
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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/wasp.width-990_F7TR5xm.jpg"/>
<figcaption>Scientists didn’t believe that wasps were able to see fine scale variation, but they have become a model system of how individual identities are displayed and perceived even in animals with tiny brains.
 
 </figcaption>
</figure>

 Colors can emerge from pigments and chemicals (like traditional paints, or the fluorescence that gives us highlighters) or from structures (in which physical features manipulate light and allow us to perceive colors), and different species sometimes develop very similar features.  Humans, for instance, experience pigmentation changes due to the
 <a href="https://doi.org/10.1016/j.cell.2007.10.055">
 same signaling molecule as stickleback fish
 </a>
 .
 

 We perceive light and color through hue, saturation, and lightness using cones and rods.  Other animals experience different portions of the light spectrum, according to the paper. Birds have three cone types and can see in the ultraviolet. Certain types of fish can see different colors based on what they eat and many can see infrared light.
 

 A group of scientists ranging from evolutionary biologists to behavioral ecologists and anthropologists collaborated at a workshop in Berlin, exploring the role of color across animals.  By collectively examining hundreds of species, they examined color on scales as small as nanoscale features and cellular mechanisms, and as large as fully visible arrays. The team connected the sensory, cognitive, and neural bases of color in animals with the adaptive and evolutionary implications of coloration. “We can now ask questions about color from every angle, from the evolutionary to the mechanistic, to the perceptual and developmental aspects,” said Hauber.
 
<aside class="pulledquote">
 We can now ask questions about color from every angle, from the evolutionary to the mechanistic, to the perceptual and developmental aspects.
 </aside>

 The team pieced together a full picture due to advances in technology such as spectrophotometry, digital imaging, and computational tools that allow scientists to better quantify the full spectrum of colors, not just those visible to humans. The methods reveal the way that nanoscale features interact with light, how animal colors change over time, and what causes coloration.
 

 They also drew from advances in neuroscience and genetics, illuminating the way animals perceive color and the genetic changes that allow unrelated species to develop parallel or convergent phenotypes, which in this context means they developed similar observable colored features (like the fish and humans). Connecting these concepts allows scientists to ask questions about how one animal may develop camouflage based on what its predators can see, how great reed warbler birds distinguish their own eggs from parasitic cuckoo eggs, or about why some wasps can distinguish faces. “People are using these tools understand how social structures for instance in starlings effects colorfulness of females,” said Hauber.  “The more equitable and social a starling species is, the more colorful a female starling is because sexual selections works both ways.”
 

 This roadmap allows us to understand how our animal counterparts see color, and will help scientists develop new biomaterials or bio-inspired designs with applications for design, architecture, medicine, clothing, or security.  Beyond obvious applications for camouflage, by understanding how color is produced in nature, researchers can generate new materials with higher energy efficiency or that perform multiple functions, much like the colors present in animals.
 

 Hauber says scientists now need to explore pattern generation and recognition, diving deeper into how creatures like wasps can recognize facial features, and understanding the neurological aspects, and even probing color production in plant species.  “Both in insects with tiny brains and with monkeys and humans with facial recognition, we need to have a model for how color and pattern are perceived.”
 
</section>

 Photo credit:
 <a href="https://www.flickr.com/photos/slgc/5994915303/">
 slgckgc / Flickr (CC BY 2.0)
 </a>

Alcohol May Boost Memory Formation After Learning

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 Drinking may not be so bad for your memory after all.
 

 In fact, a study released this week in
 <a href="https://www.nature.com/articles/s41598-017-06305-w">

 Nature Scientific Reports
 
</a>
 suggests that drinking alcohol right after learning something new might actually help your brain store that information more effectively than if you remained sober.
 

 While previous studies have examined the role of alcohol in memory formation, this study was one of the first to test this outside of a lab setting. The team from the University of Exeter studied 88 adults between the ages of 18-53.  Participants were asked to conduct the study in their own homes, and half were told to drink as much as they wanted. The other half had to remain sober. The sober and drinking groups had similar backgrounds in terms of age, body mass index, typical drinking habits, and incidence of blackouts.
 
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/4873748610_9d69c16d52_o.width-990_O8V4seV.jpg"/>
<figcaption>Researchers compared the performance of adults who drank as much as they wanted and those who did not drink during the evening on specific memory tasks for words learned before the evening began.
 
 </figcaption>
</figure>

 For participants, the study started—sober—at 6 pm. They first listened to 24 words that seemed similar to real words, but had extra letters (like frenzylk). At 7 pm, they were asked to remember the words based on the first few letters (an example prompt was frenzy_ _).  Around 8 pm, for half of the participants, the drinking began. And drink they did. The average person consumed about six drinks worth of alcohol.
 

 Two hours later, at 10 pm, participants were given a second, image-based task to test memory retention during drinking. They were shown 128 images and asked to categorize them as indoor or outdoor items. They were then presented with 192 images (some of which overlapped with the first 128), and asked whether each image was old (from the first set), similar (showed an old item in a new position), or new (had not appeared before).
 

 The next morning, after a night of drinking, the participants who consumed more alcohol answered correctly more often for the first task than those who drank less. The scientists had hypothesized that the memory boost would occur because drinking alcohol blocked individuals’ ability to form new memories while imbibing, leaving more resources to encode memories developed before. Beth Mole described the results for
 <a href="https://arstechnica.com/science/2017/08/booze-boosts-the-brains-ability-to-remember-info-learned-before-drinking/">
 Ars Technica
 </a>
 :
 
<blockquote>

 They were partly right. The drinkers did indeed perform better at the made-up word challenge. The sober group showed an ever-so-slight decline in remembering the words between the evening and morning tests. But the drinkers scored statistically significantly better the next morning than they did in the evening—not just the same as the evening. This hints at the idea that alcohol doesn’t simply help reduce forgetfulness; it may instead firm up freshly formed knowledge and enhance memory.
 

 Still, the results of the image-based memory challenge were not so crystal clear. Drinkers didn’t do worse than the sober folks. They all did about the same in both evening and morning tests.
 
</blockquote>

 If people who drank had scored worse on the image tests, the researchers would have had evidence to support their hypothesis that memory formation suffers while drinking, giving the brain time to consolidate older memories. That part, though, remains unsolved.
 

 Originally, the team had hoped to conduct the tests in an even more realistic setting for binge drinking like bars or clubs, but the businesses weren’t keen on the idea. “The most available option was to test participants in their homes during a drinking session that preceded a night out,” the researchers wrote.
 

 The team’s next experiments will explore how sleep may work together with alcohol to improve our memories. Alcohol, the researchers wrote, may boost the patterns in slow wave sleep—also known as deep sleep—that help us encode memories. If there is a link, it could explain the boozy memory boost and has been ignored by most other studies.
 
</section>

 Photo credit:
 <a href="https://www.flickr.com/photos/tegg/4873748610/">
 Pete Berlin / Flickr (CC BY-NC 2.0)
 </a>

“Ape Who Went to College” Dies

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 Chantek, the beloved orangutan who was one of the first apes to learn sign language, has passed away at age 39.
 

 Chantek rose to fame after “attending university,” living with anthropologist Lyn Miles at the University of Tennessee for nine years. Miles and other caretakers taught him over 150 words in American Sign Language, as well as important human skills like cleaning his room, using the bathroom, and directing a car route.
 
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/chantek-1.width-990_2IV9LbC.jpg"/>
<figcaption>39-year-old Chantek was known for having an engaging personality.
 
 </figcaption>
</figure>

 His tenacity for learning made him the star of a 2014 PBS documentary “
 <a href="http://www.pbs.org/video/my-wild-affair-ape-who-went-college-1/">
 The Ape Who Went to College
 </a>
 .” In many ways, Chantek was raised much like a human. In fact, he sometimes referred to himself as an “orangutan person.”
 

 Chantek was among a special group of apes who knew ASL, including Koko, the gorilla, and Washoe, the chimpanzee.
 

 The BBC described the friendly ape:
 
<blockquote>

 Zoo Atlanta said that Chantek frequently used sign language to communicate with keepers but “he was shy about signing with individuals he did not know and often chose forms of communication which are more typical of orangutans, such as vocalisations and unique hand gestures”.
 

 “Chantek will be deeply missed by his family here at Zoo Atlanta,” said Hayley Murphy, vice president of the zoo’s animal divisions.
 

 “He had such a unique and engaging personality and special ways of relating to and communicating with those who knew him best. It has been our privilege to have had him with us for 20 years.”
 
</blockquote>

 Orangutans typically live about 35-45 years in the wild. Chantek was born at the Yerkes National Primate Research Center in Georgia. He returned to the Atlanta Zoo to live out his later years with other orangutans, including his friends 34-year-old female Madu and playful 10-year-old male Dumadi. While the cause of death has not been announced, he was being treated for heart disease, a leading cause of death among captive orangutans.
 

 Miles shared an example of his communication abilities
 <a href="http://www.bbc.com/news/av/uk-politics-40860444/he-asked-me-to-get-the-car-and-take-him-home">
 with the BBC
 </a>
 : “The last time I saw him not too long ago he asked me for meat cheese bread [a cheeseburger] and for me to get the car and take him home.”
 
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 Watch the incredible story of Chantek, the orangutan raised as a human child on an American university campus during the '70s and '80s.
 </div>
</section>

 Photo credit:
 <a href="https://twitter.com/ZooATL/status/894681378834571266">
 Zoo Atlanta / Twitter
 </a>

Can Government Keep Up with Artificial Intelligence?

Artificial intelligence research is moving quickly. Can the government move quickly enough to effectively regulate it?

Anyone Can Be Trained to Hallucinate, and That’s Teaching Scientists About Perception

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 Hallucinations are often distressing—a suggestion that something is amiss in our brains. But new research suggests we’re all susceptible to hallucinations, and that may not be such a bad thing.


 In a paper released last week in
 <a href="http://science.sciencemag.org/content/357/6351/596">

 Science
 
</a>
 , a team from Yale University set out to understand how we interpret the world around us—in short, how we determine what’s real and what’s not. They suspected that people who regularly hallucinate perceive the world based on what they expect to happen, while others, who don’t hallucinate, would rely more what their senses are telling them is happening in the world.


 To determine that, authors Phil Corlett and Al Powers began by conditioning participants to hear a tone when they were shown a checkerboard pattern. Then they slowly removed the actual sound and asked people when they heard it. Participants who regularly heard voices were five times more likely to say they heard a tone when there wasn’t one, and they were 25-30% more confident in their choice. But they weren’t alone in hearing things. In fact, all of the participants experienced some induced hallucinations during the experiment.


 “I did not expect that people who did not have a psychotic illness would perform so similarly to people who did hear voices,” Powers says. “They were very, very alike.”


 “Really healthy people that don’t hallucinate in their everyday lives—graduate students, and postdocs, and highly accomplished people—were very, very susceptible to this effect, even the ones who didn’t hear voices. They were more susceptible to it than I expected,” Corlett says. The study contributes to the idea that schizophrenia, much like autism, may exist as a spectrum, the authors say.

<h2>
 Hearing Things
</h2>

 Powers personally experienced the phenomenon when testing the software for the experiment. He was surprised to find that, despite his deep knowledge of the process and mechanisms, the effect still worked on him. “At the beginning, it was quite exciting,” he says, though he admitted that “it’s concerning, to be honest.”


 He and Corlett compared four groups: those with diagnosed psychoses who either did or did not hallucinate and those not diagnosed with psychoses who either did or did not hallucinate. Each of the groups contained 14-15 people. Most of these participants were relatively easy to recruit. But they needed to find people who experience hallucinations as part of daily life yet haven’t been diagnosed with a psychiatric disorder. So they turned to the Connecticut Psychics’ Association, specifically to psychics who regularly hear voices.

<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/5323813967_ca7a703466_o.width-990_lcMBW3d.jpg"/>
<figcaption>Vincent van Gogh frequently suffered from psychotic episodes of hallucinations and delusions.
 
 </figcaption>
</figure>

 Many of the study participants who hallucinate but haven’t been diagnosed as psychotic tend to lead normal lives. The hallucinations don’t seem to interfere, like for a police officer in her 50s who heard daily narrations of her activities as she worked.


 Powers and Corlett wanted to know if people diagnosed with psychoses had brains that operated differently than the other subjects. To do that, they had to make people who don’t typically hallucinate…hallucinate. And that’s why they turned to a famous technique originally used on dogs—Pavlovian conditioning. The team conditioned participants to associate a checkerboard pattern with a 1-kHz tone, which sounds like the bleep over a swear on late-night TV. Initially, the scientists sprinkled in lots of 1-kHz tones that they were certain the participants could hear. Then, as the task went on, they changed their intensity and often removed them entirely. Like in a hearing test at the doctor, participants were asked to press a button when they heard the tone. In an added twist, participants could indicate how confident they were about their response. Meanwhile, their brains were examined using magnetic resonance imaging (MRI).

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 The researchers found the psychics’ descriptions of their hearings incredibly similar to the accounts of their psychotic hallucinating patients. That reinforced to Corlett and Powers that mental symptoms like hallucinations and delusions may exist on a continuum, from manageable occurrences to increasingly severe and disruptive clinical cases.


 Meanwhile, the group with known psychosis but no regular hallucinations responded differently. While most participants were unable to tell real tones from imagined ones, those in the psychotic, non-hallucinating group were more quickly and confidently able to determine the change.



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 Corlett thinks this is because most of the people in the psychotic non-hallucinators group experience delusions, a phenomenon separate from hallucinations where they have trouble connecting different clues from their environment. “They have a real problem picking up the contingency between the checkerboard and the tones,” he says. “The importance of including this group is to say that what we found isn’t simply attributable to psychosis, but particular to hallucinations.”


 Using MRI neuroimaging, the team was able to tie the underlying mechanism that causes auditory hallucinations to those used in normal perception. In other words, hallucinations prey on the same processes that allow us to see and hear. “We’re able to say that hallucinations are not just foreign, scary, unrelatable things, but are in fact a process or an alteration of a process that we ourselves undergo every day in deciding what surrounds us,” Powers says.

<h2>
 Role of Cultural Stigmas
</h2>

 Psychosis is typically defined as active hallucinations or delusions coupled with significant clinical distress, but there is still some debate over where the boundaries are. Up until now, schizophrenia has primarily been treated as a one condition, but Corlett and Powers think a symptom-by-symptom approach may serve patients better. Their work provides further evidence that there may not be one not one type of schizophrenia but many.


 The study’s findings also suggest that cultural or religious attitudes toward hallucinations may influence whether they are benign or disruptive, says anthropologist Tanya Luhrmann of Stanford, who studies unusual sensory experiences and their cultural implications. “It opens the possibility that if people with psychosis learn to expect to different things from their hallucinations, they might have different hallucinations,” she says. “The content [of hallucinations] has something to do with prognosis—the more mean and negative the voices, the worse the outcome.”


 In the U.S., we tend to assume that psychotic experiences are inherently negative, but in her work, Luhrmann has found that that’s not always the case in other cultures. Evidence by other scientists and anthropologists suggests that the more negatively one perceives their voices, the worse their outcome.

<div class="pullquote">

 “These hallucinations, either with neural feedback or with some kind of more spiritual training, might benefit these patients.”

</div>

 Luhrmann was intrigued by those who hallucinate frequently, but don’t show signs of psychosis, like the psychics. She, like Powers and Corlett, is curious about how their experiences differ from other hallucinators based on the stigma attached to their voices—or lack thereof. In some other cultures, like the people in Ghana that Luhrmann recently visited, those who hear voices undergo extensive training to take control of them. Globally, grassroots support groups for individuals who hear voices are becoming more common, empowering people to name their voices, share their experiences, and develop more positive relationships with the voices they hear. Intervoice, one such network based in the U.K., provides forums for people to share their stories without judgement and emphasizes auditory hallucinations as a meaningful human experience.


 By framing these experiences as significant and potentially benevolent, we can help hallucinators understand and take charge of their hallucinations. “This gives us more confidence that training these hallucinations, either with neural feedback or with some kind of more spiritual training, might benefit these patients,” Luhrmann says.


 Powers and Corlett hope they have also paved the way towards better diagnoses by pairing participant accounts of their experiences with computational modeling based on brain imaging. The individualized information could help psychiatrists determine the best way to treat patients based on where their symptoms and behaviors are on the psychosis spectrum.


 “We can use this objective measure to show somebody, ‘Yes, you’re having these odd experiences, they’re different from the people who don’t have a need for care in these ways,’” Corlett says. Understanding these differences could also help them identify who may develop a psychotic illness and who may not.


 The psychiatrists also want explore new therapies. Understanding the specific mechanisms that underlie hallucinations may help the team determine who would respond well to drugs, like those based on the cholinergic neurotransmitter system. Cholinergic neurotransmitters relate to our ability to reconsider prior expectations. These therapeutic drugs, which are based on the same active ingredient in belladonna or nightshade that can cause hallucinations, were initially rejected when they were administered broadly. But this could give researchers the means to determine who might respond well to the drugs.


 Ultimately the researchers have a better understanding of “what the neural mechanisms for hallucinations in the context for mental illness might be,” Corlett says. Knowing that these symptoms exist on a spectrum, and having the tools to recognize individual differences, “can be used to treat people more effectively in the future,” Powers says.


 Photo credits:
 <a href="https://www.flickr.com/photos/63002317@N08/8635598350/">
 eitsch723/Flickr (CC BY-NC-SA 2.0)
 </a>
<a href="https://flic.kr/p/97rWpZ">
 Estudio de Arquepoética y Visualística Prospectiva/Flickr (CC BY-NC-SA 2.0)
 </a>

We may all be susceptible to hallucinations—and they’re not that different from how our brain interprets actual events.

Hybrid Dinosaur May Change How We Understand Dinosaur Evolution

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 The mysterious
 
 Chilesaurus
 
 —the dino with the seemingly mismatched features—finally has a home on the family tree.
 

 The dinosaur confused paleontologists at first. Its bird-like hips and flat teeth are reminiscent of
 
 Stegasaurus
 
 , but its head, arms, and legs are more similar to
 
 Velociraptor
 
 . Paleontologists originally put the kangaroo-sized creature in the same suborder as
 
 Velociraptor
 
 . But now, paleontologists are recognizing it as a link between dinosaurs like the
 
 T. rex
 
 and others like
 
 Triceratops
 
 . The findings, released this week in the Royal Society journal
 <a href="http://rsbl.royalsocietypublishing.org/lookup/doi/10.1098/rsbl.2017.0220">
 Biology Letters
 </a>
 , may change our understanding of dinosaur evolution.
 
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<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/chilesaurus_nt_small-1.width-990_bVqZgOx.jpg"/>
<figcaption>Artistic rendering of the puzzling Chilesaurus.
 
 </figcaption>
</figure>

 Here’s Pallab Ghosh, interviewing Barron for
 <a href="http://www.bbc.com/news/science-environment-40890714">
 the BBC
 </a>
 :
 
<blockquote>

 “We had absolutely no idea how the ornithischian body plan started to develop because they look so different to all the other dinosaurs. They have so many unusual features,” the Cambridge scientist said.
 

 “In the 130 years since the ornithischian group was first recognised, we have never had any concept of how the first ones could have looked until now.”
 
</blockquote>

 Ornithischians, like
 
 Triceratops
 
 and
 
 Stegasaurus
 
 , were long considered a monolithic branch on the dinosaur family tree, while saurischians were thought to include two branches, theropods—like
 
 T. rex
 
 and
 
 Velociraptor
 
 —and sauropods—like
 
 Brachiosaurus
 
 .
 

 But in March, Matthew Baron of Cambridge University and his colleagues published findings in
 <a href="http://www.nature.com/nature/journal/v543/n7646/full/nature21700.html?foxtrotcallback=true">
 Nature
 </a>
 that challenged long-standing assumptions. By examining the features of
 
 Chilesaurus
 
 that overlapped with members of both the theropod and ornithician dinos, the researchers realized that the newly discovered species bridged the carnivorous and herbivorous saurichians. Their analysis resulted in moving theropods from Saurischia and into a class of bird-limbed dinosaurs now known as Ornithoscelida (which formerly contained ornithischians like
 
 Triceratops
 
 ).
 
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://staging.pbs.org/wgbh/nova/media/images/dinos.width-990_74ikOMr.jpg"/>
<figcaption>Chilesaurus gave the scientists evidence to rethink dinosaur classification, providing a link between theropods and ornithischians.
 
 </figcaption>
</figure>


 Chilesaurus
 
 lived during the late Jurassic period, around 150 million years ago, in what is now Chile. It stood at about seven to ten feet tall. The specimen was
 <a href="http://www.smithsonianmag.com/science-nature/meet-chilesaurus-new-raptor-dinosaur-vegetarian-diet-180955101/">
 discovered in 2004
 </a>
 by seven-year-old Diego Suarez on a hike with his parents (who happened to be geologists), leading to its moniker of
 
 Chilesaurus diegosuarezi
 
 .
 

 Baron and his team analyzed over 450 characteristics of dinosaurs and compared existing species to the perplexing hodgepodge
 
 Chilesaurus
 
 fossil. By noting feature-by-feature similarities, they reevaluated the family tree and concluded that the new dinosaur may bridge the
 
 Triceratops
 
 branch with the
 
 T. rex
 
 branch.
 

 Understanding where
 
 Chilesaurus
 
 sits in dinosaur lineage has apparently taught Baron and his colleagues a lot about dinosaur evolution. The species may be one of the first to consume plants for sustenance, for example. Scientists have long wondered how this transition occurred, and whether herbivorous dinosaurs first developed the beaks used to graze on plants or the
 <a href="http://www.latimes.com/science/sciencenow/la-sci-sn-dinosaur-missing-link-20170815-story.html">
 stomachs needed to digest them
 </a>
 . The
 
 Chilesaurus
 
 ‘s bird-like hips indicates that the gut led the way.
 

 By reorganizing the dinosaur tree, paleontologists have also added further evidence that birds are indeed dino descendants: previously, the theropods we view as birds’ ancestors were not considered relatives of the bird-limbed group, but with the new evidence—and reorganization—they’re all on the same part of the family tree.
 
</section>

 Image credits:
 <a href="https://commons.wikimedia.org/wiki/File:Chilesaurus_NT_small.jpg">
 Nobu Tamura/Wikimedia Commons (Public Domain)
 </a>
 ,
 <a href="https://commons.wikimedia.org/wiki/User:LadyofHats/gallery1">
 LadyofHats/Wikimedia Commons (Public Domain)
 </a>

Bianca Datta

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