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12 Surprising Effects of Daylight Saving Time

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Every March, clocks “spring forward” across much of the United States, robbing people of one precious hour of sleep. While hearing those same people complain about being tired is one not-so-surprising effect of Daylight Saving Time, the possibility of a longer prison sentence for those going before a judge on “sleepy Monday” is less expected. Here are 12 surprising effects of Daylight Saving Time—the good, the bad, and the scientifically ambiguous.

1. INCREASED SPENDING

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In 2016, JP Morgan Chase decided to look into the economic consequences of Daylight Saving Time (DST) by examining Los Angeles and Phoenix, two cities that are large, relatively close to each other, and have stable weather. Critically, Phoenix doesn’t observe DST while Los Angeles does [PDF].

Among their findings, DST was “associated with a 0.9 percent increase in daily card spending per capita in Los Angeles at the beginning of DST.” Perhaps more surprising, the end of DST was associated with a per capita daily spending reduction of 3.9 percent.

2. A HIGHER RISK OF HEART ATTACKS

Many studies have shown that DST is associated with an increase in heart attacks, with one study showing a 24 percent increase in the number of heart attacks on the Monday after DST at a group of Michigan hospitals. According to the University of Michigan, Mondays are bad for heart attacks in general (researchers believes the stress of beginning a new workweek and changes to the sleep-wake cycle are the reason why), but DST makes everything worse. Interestingly, the Tuesday following the end of DST was associated with a 21 percent drop in patients.

3. MISSED APPOINTMENTS

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Somewhat relatedly, a 2017 study found that the percentage of missed medical appointments increased significantly following DST. But as with heart attack risk, the missed appointments decreased in the fall—at least temporarily.

4. MORE CAR ACCIDENTS ... MAYBE (AT LEAST FOR A FEW DAYS)

Another field where studies aren't as consistent as one might expect is traffic accidents. In 2001, an American study found that there was a significant increase in accidents on the Monday after the shift to DST. A 2018 New Zealand study echoed the sentiment, finding that on the first day of DST road accidents increased 16 percent. In contrast, a Swedish study found that DST didn’t have any important effect in that country.

Of course, there’s more to DST than just those first couple days. After DST has gotten started, there’s more light on the road later in the day. Several studies have found this light reduces accidents substantially, so much so that one study concluded that a year-round DST would reduce motor vehicle occupant fatalities by 195 per year.

It’s so complicated that a 2010 analysis in Minnesota listed 10 studies that found positive effects of DST on road safety, and six studies that showed negative effects in both the spring and fall changes.

5. LONGER PRISON SENTENCES

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Researchers frequently use DST to study sleep deprivation in populations, as it’s a period of time when we all wake up an hour before we’re used to. One of these studies focused specifically on judicial punishment in U.S. federal courts [PDF]. The researchers looked at “sleepy Monday” (the Monday after the time change) and compared the sentence lengths to other Mondays. They found that on “sleepy Monday,” judges handed out 5 percent longer sentences. But don’t think you can get a lighter sentence during the fall switch; the researchers found no effect on sentencing at that time. But the researchers point out that this probably isn’t limited to judges—even managers may find themselves in the mood for doling out harsher punishments.

6. MORE MINING INJURIES

According to one study of mining injuries from 1983 to 2006, the Monday directly after the switch to DST was associated with 5.7 percent more workplace injuries and 68 percent more workdays lost because of injuries, indicating that there are more injuries that are more severe after the switch [PDF]. There isn’t, however, a corresponding decrease in the fall.

7. FEWER KOALA COLLISIONS

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One study decided to look at how DST affected human-wildlife interaction, specifically koala-vehicle collisions [PDF]. Because koalas are largely nocturnal, they often cross the road in the evening or at night. By shifting traffic patterns to times when it wasn’t dark, the researchers found that DST could “decrease collisions with koalas by 8 percent on weekdays and 11 percent at weekends” (although the difference between weekend and weekdays wasn’t significant, the researchers proposed that a slight increase in morning collisions lessened the benefit during the weekday). The researchers hope that further study can be done on human-animal interactions and DST.

Koalas aren’t the only ones crossing a road that benefit from DST; pedestrians might be safer as well. One study found “no significant detrimental effect on automobile crashes in the short run” and in the long run was associated with “a 8 to 11 percent fall in crashes involving pedestrians ... in the weeks after the spring shift to DST.” Meanwhile another study found that a year-long DST would mean 171 fewer pedestrian fatalities a year.

8. DECREASED SATISFACTION WITH LIFE IN GENERAL (AND INCREASED USE OF THE WORD TIRED)

In both the UK and Germany, studies have shown that life satisfaction deteriorates in the first week after the switch to DST in the spring. One study even quantified the deterioration in Germany with money. For the entire sample, the cost was calculated to be €213 (about $262), but for people in full employment—with relatively inflexible schedules—that increases to €332 ($408). And for the men in the sample, the cost of transition was €396 ($487).

Meanwhile, a Facebook analysis looked at the "feelings" people were sharing on the platform. On the Monday after the start of DST, the use of the word tired increased by 25 percent, with similar increases for “sleepy” and “exhausted” (as well as “wonderful” and “great”). In just the period from 5 a.m. to 12 p.m. on Monday, “feeling tired” usage increased an average of 86 percent, from a 12 percent increase in the non-DST Arizona up to a 231 percent increase in Delaware. By Thursday, “tired” is back to normal.

9. SLEEPIER KIDS (MAYBE)

The studies surrounding DST and school children are surprisingly inconclusive. On the one side, a 2009 article in Sleep Medicine looked at 469 Germans from 10 to 20 years old and divided them up into ‘larks’ (those who go to bed early and wake up early) and ‘owls’ (those who go to bed late and wake up late). They found that after the DST transition the group was sleepier for three weeks after the transition, with owls showing higher daytime sleepiness, and proposed that tests shouldn’t take place in the week following the switch over to DST.

A 2017 article in Economics of Education Review, however, looked at 22,000 Europeans students and found that, at least for low-stakes tests, the effect wasn’t statistically significant.

10. MORE CYBERLOAFING ON THE JOB

A woman gets caught cyberloafing at work
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Another study looked at people’s Google search trends for the Mondays before the switch to DST, immediately after the switch, and a week after, with a specific focus on sites like Facebook, YouTube, and ESPN (i.e. entertainment sites that people probably aren’t Googling for their jobs). They found that on the Monday after the switch, people searched for 3.1 percent more entertainment websites than the Monday before DST, and 6.4 percent more than the subsequent Monday. While the researchers caution they can’t be sure this was all "cyberloafing," the fact that there was nothing else special about these Mondays meant it very likely was [PDF].

11. MISTIMED INSULIN SHOTS

It might seem that in this age of smartphones and connected devices that figure it all out, the twice-yearly ritual of finding all the clocks to change is a thing of the past. But that’s not necessarily true. In a 2014 article in the Journal of Diabetes Science and Technology, the authors pointed out an easy clock to miss: insulin pumps. Because most commercial pumps aren’t GPS-enabled and lack internal time change mechanisms, they have to be manually set up. The study authors discuss an international college student with an insulin pump that came from a country that didn’t observe DST, meaning the clock was an hour off. They say that no significant harm resulted, but it just serves as a reminder to make sure you check all your clocks.

12. HIGHER ENERGY BILLS

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One of the main rallying cries for DST is that it saves energy, but studies have been mixed. In 1975 the Department of Transportation issued a report about whether a short-lived, year-long DST experiment had been worthwhile [PDF]. They declared “modest overall benefits might be realized by a shift from the historic six-month DST system,” but cautioned that these benefits were difficult to isolate. Optimistically, though, they said DST might help reduce 1 percent of electricity use.

But as modern researchers have noted, electricity usage has shifted since then. Chief among the changes: Only 46 percent of the new single family households completed in 1975 had air conditioning, compared to 93 percent in 2016 [PDF].

Indiana provided a good place to test this change, because in 2006 they decided to observe DST as an entire state (individual counties had observed DST before). A study ultimately concluded that while DST does save electricity in lighting, this is more than offset by increased demands for heating and cooling, resulting in Indiana households being hit by $9 million per year in higher electricity bills [PDF]. However, the study only looked at residential electricity consumption, not commercial or industrial.

Around the same time, the Department of Energy also looked into DST and found that during a four-week extension, electricity use decreased about half a percentage point per day. Ultimately, Stanton Hadley at the Oak Ridge National Laboratory told Live Science, “I could see the answer being either way.”

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10 Scientific Benefits of Being a Dog Owner
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The bickering between cat people and dog people is ongoing and vicious, but in the end, we're all better off for loving a pet. But if anyone tries to poo-poo your pooch, know that there are some scientific reasons that they're man's best friend.

1. YOU GET SICK LESS OFTEN.

Dog snuggling on a bed with its person.
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If cleaning commercials are to be believed, humanity is in the midst of a war against germs—and we shouldn't stop until every single one is dead. In reality, the amount of disinfecting we do is making us sicker; since our bodies are exposed to a less diverse mix of germs, our entire microbiome is messed up. Fortunately, dogs are covered in germs! Having a dog in the house means more diverse bacteria enters the home and gets inside the occupants (one study found "dog-related biodiversity" is especially high on pillowcases). In turn, people with dogs seem to get ill less frequently and less severely than people—especially children—with cats or no pets.

2. YOU'RE MORE RESISTANT TO ALLERGIES.

Child and mother playing with a dog on a bed.
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While dog dander can be a trigger for people with allergies, growing up in a house with a dog makes children less likely to develop allergies over the course of their lives. And the benefits can start during gestation; a 2017 study published in the journal Microbiome found that a bacterial exchange happened between women who lived with pets (largely dogs) during pregnancy and their children, regardless of type of birth or whether the child was breastfed, and even if the pet was not in the home after the birth of the child. Those children tested had two bacteria, Ruminococcus and Oscillospira, that reduce the risk of common allergies, asthma, and obesity, and they were less likely to develop eczema.

3. YOU'LL HAVE BETTER HEART HEALTH.

Woman doing yoga with her dog.
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Everything about owning a dog seems to lend itself to better heart health. Just the act of petting a dog lowers heart rate and blood pressure. A 2017 Chinese study found a link between dog ownership and reduced risk of coronary artery disease, while other studies show pet owners have slightly lower cholesterol and are more likely to survive a heart attack.

4. YOU GET MORE EXERCISE.

Person running in field with a dog.
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While other pets have positive effects on your health as well, dogs have the added benefit of needing to be walked and played with numerous times a day. This means that many dog owners are getting 30 minutes of exercise a day, lowering their risk of cardiovascular disease.

5. YOU'LL BE HAPPIER.

Woman cuddling her dog.
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Dog owners are less likely to suffer from depression than non-pet owners. Even for those people who are clinically depressed, having a pet to take care of can help them out of a depressive episode. Since taking care of a dog requires a routine and forces you to stay at least a little active, dog owners are more likely to interact with others and have an increased sense of well-being while tending to their pet. The interaction with and love received from a dog can also help people stay positive. Even the mere act of looking at your pet increases the amount of oxytocin, the "feel good" chemical, in the brain.

6. YOU HAVE A MORE ACTIVE SOCIAL LIFE.

Large bulldog licking a laughing man.
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Not only does dog ownership indirectly tell others that you're trustworthy, your trusty companion can help facilitate friendships and social networks. A 2015 study published in PLOS One found that dogs can be both the catalyst for sparking new relationships and also the means for keeping social networks thriving. One study even showed that those with dogs also had closer and more supportive relationships with the people in their lives.

7. YOUR DOG MIGHT BE A CANCER DETECTOR.

Man high-fiving his dog.
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Your dog could save your life one day: It seems that our canine friends have the ability to smell cancer in the human body. Stories abound of owners whose dogs kept sniffing or licking a mole or lump on their body so they got it checked out, discovering it was cancerous. The anecdotal evidence has been backed up by scientific studies, and some dogs are now trained to detect cancer.

8. YOU'LL BE LESS STRESSED AT WORK.

Woman working on a computer while petting a dog.
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The benefits of bringing a dog to work are so increasingly obvious that more companies are catching on. Studies show that people who interact with a pet while working have lower stress levels throughout the day, while people who do not bring a pet see their stress levels increase over time. Dogs in the office also lead to people taking more breaks, to play with or walk the dog, which makes them more energized when they return to work. This, in turn, has been shown to lead to much greater productivity and job satisfaction.

9. YOU CAN FIND OUT MORE ABOUT YOUR PERSONALITY.

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The kind of dog you have says a lot about your personality. A study in England found a very clear correlation between people's personalities and what type of dogs they owned; for example, people who owned toy dogs tended to be more intelligent, while owners of utility dogs like Dalmatians and bulldogs were the most conscientious. Other studies have found that dog owners in general are more outgoing and friendly than cat owners.

10. YOUR KIDS WILL BE MORE EMPATHETIC.

A young boy having fun with his dog.
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Though one 2003 study found that there was no link between pet ownership and empathy in a group of children, a 2017 study of 1000 7- to 12-year-olds found that pet attachment of any kind encouraged compassion and positive attitudes toward animals, which promoted better well-being for both the child and the pet. Children with dogs scored the highest for pet attachment, and the study notes that "dogs may help children to regulate their emotions because they can trigger and respond to a child's attachment related behavior." And, of course, only one pet will happily play fetch with a toddler.

A version of this story originally ran in 2015.

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16 Prehistoric Creatures You’ll See In Jurassic World: Fallen Kingdom
Chris Pratt meets the vicious T. rex in Jurassic World: Fallen Kingdom (2018)
Chris Pratt meets the vicious T. rex in Jurassic World: Fallen Kingdom (2018)
Universal Pictures and Amblin Entertainment, Inc. and Legendary Pictures Productions, LLC.

The sequel to 2015’s Jurassic World ups the ante with a huge roster of dinosaurs, pterosaurs, and marine reptiles. While some are familiar favorites (see: T. rex), others have never been seen in a major motion picture before. Pull off your nostalgia goggles and let’s take a look at what modern science has to say about the long-gone animals of Jurassic World: Fallen Kingdom.

1. TYRANNOSAURUS

Lived: 68 to 66 million years ago in North America

Diet: Carnivore

Maximum Length: 40 feet

Name Means: “Tyrant lizard”

Apparently, the most popular dinosaur of all time wasn’t above cannibalism: Multiple Tyrannosaurus rex bones have bite marks on them that match the teeth of other tyrannosaurid species. Debate has arisen over the issue of T. rex plumage. University of Alberta paleontologist Scott Persons recently compared tiny skin impressions left behind by Tyrannosaurus and its close cousins Gorgosaurus, Daspletosaurus, and Tarbosaurus. These reveal that the dinos had pebbly scales, but the samples contain no evidence of feathers. Keep in mind though that the skin impressions only represent small patches of the dinosaurs’ tails, necks, abdomens, and pelvises—so Tyrannosaurus might’ve had feathers elsewhere on its body. For the record, Persons thinks the giant carnivore would still look “pretty cool and plenty scary” with a little fuzz. “[Nobody] ever complained that tigers weren’t scary, and they’re fluffy,” he said.

2. APATOSAURUS

Artistic interpretation of an individual of A. louisae arching its neck down to drink
Public Domain, Wikimedia Commons

Lived: 155 to 150 million years ago in North America

Diet: Herbivore.

Maximum length: 80 feet

Name means: “Deceptive lizard”

In 1879, an unidentified sauropod (a long-necked dinosaur) was found in Wyoming. At first, this creature was given the name Brontosaurus excelsus but in 1903, paleontologist Elmer Riggs rechristened it as Apatosaurus excelsus (the Apatosaurus had been described before the Brontosaurus, so the name had precedence). A few scientists now think the Brontosaurus and Apatosarus actually are distinct and the much better-known name ought to be reinstated for that particular group, but others disagree. Regardless, Apatosaurus was pretty awesome. Some of its bones were pneumatic and the body contained a number of air sacs. Such traits would’ve made the big plant-eater very lightweight for an animal of its size. Apatosaurus may have also been able to break the sound barrier by cracking its sinuous tail like a bullwhip.

3. TRICERATOPS

Lived: 68 to 66 million years ago in North America

Diet: Herbivore

Maximum length: 29 feet

Name means: “Three-horned face”

Give credit where it’s due: Look at the baby Triceratops in Fallen Kingdom and you may notice that the horns above its eyes curve backward ever so slightly. This is scientifically accurate. The brow horns of Triceratops newborns were tiny bumps which bent backward during the adolescent years. Then they changed course and bowed forward while the animals matured. Puncture wounds and lesions on the skulls of adult Triceratops tell us these animals locked horns in head-to-head combat. Triceratops was constantly replacing its teeth, which were arranged in tight clusters and most likely used to shear through fibrous vegetation.

4. SINOCERATOPS

Lived: 75 to 66 million years ago in China

Diet: Herbivore

Maximum length: 19 feet

Name means: “Chinese horned face”

A newcomer to the Jurassic Park films, Sinoceratops first came to light during a 2008 fossil-hunting excursion into China’s Shandong Province. It belongs to the same family as Triceratops and was the first member of this group to be found in Chinese rock. Small, forward-bending horns lined the top of its frill, which was proportionally smaller than that of Triceratops. A single cone-shaped horn sat over the nostrils.

5. ALLOSAURUS

Lived: 155.7 to 150 million years ago in North America and Portugal and possibly elsewhere

Diet: Carnivore

Maximum length: 28 (or possibly 35) feet

Name means: “Different lizard”

In one of the trailers for Fallen Kingdom, a running Allosaurus falls flat on its face. The dinosaur was no stranger to injury in real life. Cracked ribs, broken arms, and badly-infected toes are just a few of the medical maladies that Allosaurus skeletons have been preserved with. Selected as Utah’s official state fossil in 1988, Allosaurus is one of the most commonly found predatory dinos in the American west. Strong neck muscles may have allowed the carnivore to disembowel prey by pulling its head backward in a falcon-esque tugging motion. And here’s something we’d really like to see on the silver screen: According to a 2015 study, Allosaurus could possibly open its jaws at a nightmarish 92-degree angle.

6. MOSASAURUS

Lived: 70 to 66 million years ago in Europe and North America

Diet: Carnivore

Maximum length: 56 feet

Name means: “Lizard of the Meuse River” (It was first discovered along this European river in 1764.)

Mosasaurus wasn’t a dinosaur; it’s more closely related to snakes and monitor lizards than it is to any of the other creatures you’ll read about here. Both Jurassic World flicks show the marine reptile leaping high out of the water to snag unwary prey. According to mosasaur expert Michael J. Everhart though, these animals didn’t have the tail strength or speed to pull off such an athletic feat. Mosasaurus is the most famous member (and the namesake genus) of the mosasaur superfamily. Late in the age of dinosaurs, these were some of the ocean’s major predators. They probably swam like gigantic crocodiles, keeping their flippers pressed against the body. Fossil evidence tells us that mosasaurs gave birth to live young at sea and at least some of them had vertically-fluked tails.

7. PTERANODON

Lived: 88 to 80.5 million years ago in central North America

Diet: Carnivore (probable fishing specialist)

Maximum wingspan: 20 feet (or possibly 24 feet)

Name means: “Toothless wing”

Here’s another non-dinosaur for you. Good old Pteranodon was a kind of North American pterosaur. What’s that, you ask? Pterosaurs were flying reptiles that patrolled the skies from 228 to 66 million years ago. Long before birds or bats took to the air, pterosaurs became the first vertebrate animals to ever achieve powered flight. The good people of Kansas designated Pteranodon itself as one of their official state fossils in 2014. Back in this animal’s heyday, there was a vast inland sea which covered most of the Great Plains, splitting North America in two. Pteranodon may have behaved like a modern albatross, using its narrow wings to soar for vast distances on air currents above the ocean waves. The creatures were apparently keen on seafood: Pteranodon skeletons are sometimes found with masses of fish bones in their throats and stomachs. We may never know how they captured prey, but one idea can be dismissed outright: Not a single known pterosaur had opposable toes, so Pteranodon couldn’t have grabbed things with its feet like the genetically-engineered flyers in Jurassic World do.

8. CARNOTAURUS

Bryce Dallas Howard and Justice Smith are trapped by the Carnotaurus in 'Jurassic World: Fallen Kingdom' (2018)
Universal Studios and Amblin Entertainment, Inc. and Legendary Pictures Productions, LLC.

Lived: 72 to 69 million years ago in Argentina

Diet: Carnivore

Maximum length: 25 feet

Name means: “Meat-eating bull"

Carnotaurus didn’t show up in the first four Jurassic Park movies, but Michael Crichton wrote the horned creature into his 1995 novel The Lost World. The book depicts Carnotaurus as a nocturnal hunter that can change colors like an overgrown cuttlefish. There’s no reason to put any stock in this idea, but the real Carnotaurus was not without its quirky attributes—including its forelimbs. While T. rex gets a lot of flack for its meager arms, those of Carnotaurus are proportionately smaller, and the Argentine dino didn’t even have any wrist bones. On the flip side, Carnotaurus’s strong legs and powerful tail would’ve made it a gifted sprinter. Skin impressions reveal that its back, neck, and tail were studded with bony knobs, much like the ones Carnotaurus shows off in Fallen Kingdom.

9. GALLIMIMUS

Lived: 70 million years ago in Mongolia

Diet: Probable omnivore

Maximum length: 20 feet

Name means: “Chicken mimic”

Gallimimus belongs to an ostrich-like family of dinosaurs known as the ornithomimids. Though it lacks plumage in the Jurassic movies, real ornithomimids were covered in fuzzy down as youngsters and the adults grew long feathers on their arms. Gallimimus and its brethren couldn’t fly, but their showy, wing-like forelimbs could’ve been used to help them attract mates. Ornithomimids compensated for their lack of teeth by swallowing rocks, which ground up food in the stomach. Exactly what they ate is unclear, though most paleontologists think the ostrich mimics were either omnivorous or herbivorous.

10. BRACHIOSAURUS

Lived: 155 to 140 million years ago in North America

Diet: Herbivore

Maximum length: 72 feet

Name means: “Arm lizard”

Even though it’s poorly represented in the fossil record, Brachiosaurus is well-known to the general public. This is largely due to its breakout role in the first Jurassic Park movie. The Brachiosaurus in that classic film hold their elongated necks in an almost vertical position, and this depiction might not be too far off. A 2010 biomechanical analysis argued that browsing on treetops would’ve been a more energy-efficient option for Brachiosaurus-like sauropods than holding their necks horizontally and eating ground-level plants. It’s interesting to think about the behemoth’s cardiovascular system: In order to pump blood up that lengthy neck and into the head, Brachiosaurus may have required a gigantic heart weighing in the neighborhood of 880 pounds.

11. ANKYLOSAURUS

Lived: 68 to 66 million years ago in North America

Diet: Herbivore

Maximum length: 21 feet

Name means: “Curved lizard”

We know this formidable animal had a backside covered in bony plates; yet because no one’s ever found a complete Ankylosaurus skeleton, scientists disagree about how the armor was arranged. The 19-inch-wide club on its tail was probably a weapon. Using CT scans and anatomical measurements, a Canadian research team estimated that a large Ankylosaurus club could strike its target with enough force to break bones. Evolution made some of the tail vertebrae in these dinosaurs stiff and inflexible so they could support their heavy clubs. A hammer needs its handle after all.

12. STYGIMOLOCH

Lived: 68 to 66 million years ago in North America

Diet: Probable herbivore

Maximum length: 10 feet

Name means: “Styx devil”

It’s kind of ironic that Stygimoloch is mentioned by name in Fallen Kingdom’s promo videos. Paleontologist John R. “Jack” Horner has worked as a consultant for all five Jurassic Park films. He thinks that Stygimoloch is nothing more than the juvenile version of the thick-headed dinosaur Pachycephalosaurus, which lived at the same time and place. (You may remember the latter’s cameo in 1997's The Lost World: Jurassic Park.) This would render the name Stygimoloch invalid. Horner’s argument is supported by the trademark feature of both dinos: the iconic domes on the top of their craniums. Stygimoloch’s skull bones were not fully fused together, suggesting the animal had a lot of growing to do. CT scans have also shown that Stygimoloch’s dome was significantly thinner than that of Pachycephalosaurus. Perhaps these dinos used their special skulls to flank each other—or maybe the thick noggins were designed for heavy-duty headbutts. For his part, Horner has proposed that these were used for identification.

13. STEGOSAURUS

Mounted skeleton of Stegosaurus stenops in right lateral view at the Natural History Museum, London.
Susannah Maidment et al. & Natural History Museum, London, CC BY 4.0, Wikimedia Commons

Lived: 155 to 150 million years ago in North America and Portugal

Diet: Herbivore

Maximum length: 23 feet

Name means: “Roof lizard”

Nobody knows what to make of the bony plates on Stegosaurus’s back. If self-defense was their purpose, why do they project upward from the spine, leaving the flanks of this vegetarian wide open? And why do the plates of other spiky-tailed dinosaurs in its family have radically different shapes? One hypothesis is that these bizarre accessories were used to attract mates—much like the peacock’s gaudy tail feathers. Maybe they also helped the small-headed herbivores recognize other members of their own kind from afar. The quartet of spikes on Stegosaurus’s tail were almost certainly used to ward off attackers. Live Stegosaurus got plenty of mileage out of these weapons: One survey, which compared 51 individual spikes, reported that just under 10 percent had been broken and re-healed at the tip.

14. COMPSOGNATHUS

Lived: 150 million years ago in Germany and France

Diet: Carnivore

Maximum length: Four feet

Name means: “Elegant jaw”

Only two skeletons of this dinosaur have ever been discovered, both of which were found with the remains of tiny lizards tucked inside their rib cages. That’s a pretty far cry from the scene in The Lost World: Jurassic Park where a swarm of “Compies” gobble up the man who’s been tormenting them with a cattle prod. But we digress. Named in 1859, Compsognathus used to be the smallest type of non-avian dinosaur known to science. It no longer retains this title, as the creature would’ve dwarfed some more recently-discovered dinos like the 15-inch Mongolian Parvicursor.

15. BARYONYX

Bryce Dallas Howard and Justice Smith encounter the Baryonyx in 'Jurassic World: Fallen Kingdom' (2018)
Universal Pictures and Amblin Entertainment, Inc. and Legendary Pictures Productions, LLC.

Lived: 130-125 million years ago in England, Spain, and Portugal

Diet: Carnivore

Maximum length: 25 feet

Name means: “Heavy claw”

Sail-backed Spinosaurus was the main villain in 2001's Jurassic Park III—a casting choice that irked plenty of fans. Baryonyx was a close relative of this beast who now joins Jurassic World: Fallen Kingdom’s Mesozoic ensemble. Preserved stomach contents have shown that Baryonyx ate fish as well as the herbivorous dinosaur Iguanodon. On each hand, Baryonyx had a 12-inch hooked claw that served an unknown purpose. (Artists like to imagine it as a fishing tool.) The animal’s conical teeth look well-equipped for grabbing hold of slippery prey. Despite the narrowness of its snout, Baryonyx’s jaws were able to withstand a great deal of bending and torsion.

16. VELOCIRAPTOR

Chris Pratt with a baby Velociraptor in 'Jurassic World: Fallen Kingdom' (2018)
Universal Pictures and Amblin Entertainment, Inc. and Legendary Pictures Productions, LLC.

Lived: 85 to 70 million years ago in Mongolia and China

Diet: Carnivore

Maximum length: 7 feet

Name means: “Swift thief”

Velociraptor stood less than two feet tall at the hip and weighed around 55 pounds. Michael Crichton’s description of the animal was inspired by its bigger cousin, Deinonychus. Even that dinosaur was smaller than the man-sized predators of Jurassic Park, though. Both Velociraptor and Deinonychus were dromaeosaurs: bird-like carnivores with bony rods in their tails and sickle-shaped toe claws. (When we say “bird-like,” we mean it: Dromaeosaurs are thought to be some of our feathered friends’ closest relatives. Many had plumage; Velociraptor itself came with sizable feathers on each arm.)

The notion that they hunted in packs can be traced back to the maverick paleontologist John Ostrom of Yale. During the 1960s, he worked at a Montana dig site where four Deinonychus were found around the body of a larger herbivore named Tenontosaurus. Ostrom’s belief that dromaeosaurs hunted in organized groups gained traction with scientists and novelists alike. A newer interpretation of the data is that the dinos lived alone and at most occasionally came together to mob vulnerable plant-eaters.

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