A time shift can be defined as an occurrence where a current era is briefly supplanted by another era in the time line. Most cases involve a short return to the past, though there have been recorded cases of people somehow jumping into a future world.
Evidence of time shifts abounds throughout history. Beneath the incidents and anecdotal tales lies the shimmering possibly for a new branch of physics.
Time shifts, also called time slips, have been recorded back to the days of the ancient Sumerian. We need not travel back as far as 6,000 years to scrutinize the records of ancient cylinder scrolls, however, to unravel the mysteries surrounding these astounding vagaries in the time stream.
Time shifts can be documented as three distinctly different types of temporal anomalies:
1.A person (or persons) actually passes through some type of eddy, loop or portal in time and experiences a past or future environment that exists briefly before they re-enter their current time stream.
2.A person (or persons), snatched by a time vortex or time cloud, are never seen or heard from again. These are not normal missing persons cases of the kind found on every police blotter. But that they were, for the people disappearing often vanished before astonished witnesses. Sometimes massive manhunts and search parties have been mounted, all to no avail.
3.A third type of time shift involves objects or animals out of time. Impossible artifacts or extinct animals that have no business existing in our modern world. A subset to that is a contemporary animal suddenly appearing in an odd place and then vanishing again without a trace.
Now that we have outlined the types of time shifts that are most common, let us turn to some actual events.
Slipping into the Past
An Australian woman named Lyn related this strange experience that happened not once, but six times during her stay in a small Australian town:
In 1997 Lyn lived in a small outback town that was built in 1947 and had changed little since that time.
"'I was driving toward the main intersection of the town, when suddenly I felt a change in the air. It wasn't the classic colder feeling, but a change, like a shift in atmosphere. The air felt denser somehow. As I slowed at the intersection, I seemed to be suddenly transported back in time to approximately 1950. The road was dirt, the trees were gone and coming toward me to cross the intersection was an old black car, something like a Vanguard or old FJ Holden. As the car passed through the intersection the driver was looking back at me in total astonishment before he accelerated. From what I could see he was dressed in similar 1950s fashion, complete with hat.' 
This is a classic time shift experience. In many cases people from the other era see the unintentional interloper from another time as well.
"'This whole episode lasted perhaps twenty seconds and was repeated at least five times during my time there, always at the exact spot. I tried to make out the registration plate number but the car was covered in dust.'
Lyn wondered if there is someone out there still living who remembers seeing a strange sight at the intersection back in the 50s...of a weird car with a bug-eyed woman at the wheel. 
Jenny Randles and Time Storms
The British author, Jenny Randles, meticulously researched the phenomenon of time shifts in, Time Storms: Amazing Evidence for Time Warps, Space Rifts, and Time Travel.
The following are some of the true incidents she catalogues in her breakthrough book:
*Oxford, Maine, 1975 - At 3 a.m. on October 27, David Stephens, 21, and an 18-year-old friend were in a wooded area when they heard a strange sound. They got in their car to go investigate, and the vehicle was soon enveloped in a colored glow. There was a blink in reality and the two instantly found themselves about a mile away with the car pointing in the opposite direction. They subsequently suffered various physical abnormalities, including severe disorientation.
*Somerset, England, 1974 - On July 28, Peter Williamson was having a barbecue in his backyard garden, which was interrupted by a heavy electrical storm. His dog, spooked by the threatening atmosphere, cowered under a tree. Peter went to rescue the animal. There was a bright flash - and Peter vanished into thin air! Police were called and a thorough investigation and search were conducted, without success. At 8 a.m., three days later, Peter was found in some nearby bushes with one foot in a pond - as if he had just appeared there out of nowhere.
*Linhares, Brazil, 1981 - On April 20, Jorge Ramos, who was a representative for a chemical company, left his home at 6 p.m. to travel a few miles to a meeting. He never arrived. His Volkswagen was found on a side road a few miles from his home; the key was still in the ignition and all his business and personal effects were in the car. Police investigations could not account for what happened to Jorge or where he was. Five days later, his wife received a frantic call from Jorge. He said that while driving his car he was covered in a strange white glow after which he found himself in a dreamy, floating state. He came to standing by an unfamiliar road and sought help. To his shock, he discovered that the date was now April 25 - and he was 600 miles from home! 
Time shifts like these happen with an odd regularity. Although this phenomenon can occur at any moment any place on Earth, there are particular areas that seem to have more than their fair share of anomalous temporal behavior.
People Teleported by Time
Perhaps one of the most celebrated cases of time and location shifts is that of the documented events surrounding one Gil Perez, the so-called teleported man.
Gil Perez, a Spanish [civilian guard] stationed at the governor-general's palace during the Spaniards' early years in the Philippines, was surprised when he found himself one day not in Manila, but in Mexico City.
Wearing a uniform of the Malacanang guards, Perez suddenly appeared in Mexico City's Plaza Mayor on October 24, 1593. Claiming he had no idea how he got there, the 'teleported man' only said that the Philippine governor-general at that time, Don Gomez Perez Dasmarinas, was assassinated. His statement was confirmed two months later when the Manila galleon arrived in Mexico, relaying the news about Dasmarisas' literal axing in a mutiny by Chinese rowers.
Although many historians question the validity of Perez's mysterious disappearance, which was documented only a century later, he could very well be one of history's first recorded teleported men. 
The curious case of one Mr. Hawkins was related by Eula White, a young girl who lived in rural Alabama during the 1920s:
'In those days, Eula says, 'rural Alabama was still kind of backward. Little electricity, and horses and wagons the only transportation for many farm folk. I remember it was a bright summer day. Early that morning the other women and I had gathered on the front porch of the Hawkins' farmhouse to shell quite a few bushels of peas and beans.
'About mid-afternoon we were still on the porch shelling peas. We looked up and saw Mr. Hawkins approaching the house. Thrown across the saddle in front of him was a large white, cloth sack of flour, and cradled in his left arm was a brown bag of other groceries. We watched as he rode up to the gate, and he stopped there, waiting for someone to open it. One of the boys ran to the gate and opened it. Then, in full view of all of us women and children, Mr. Hawkins vanished! He just disappeared, instantly!
'We sat there for a second or so, just astonished. Then, terrified, we began screaming. After a few minutes, we calmed down, but were still shaking and confused. We just didn't know what to do. So after a while we went back to shelling peas. Mrs. Hawkins made one the boys close the gate.
'About a half hour later, we looked up and again saw Mr. Hawkins riding toward the house with that same white sack of flour across the saddle in front of him and that same brown bag of groceries in his left hand. Again he rode up to the gate without a sound and stopped. None of us had the nerve to open the gate. We were all just too afraid to move. We just sat there staring at him, waiting to see what would happen next. Finally, to our relief, Mr. Hawkins spoke: 'Well, is someone going to open the gate for me?' Mr. Hawkins got there before he arrived.' 
As I had mentioned, although most people that experience a time shift into the past or witness a past event, some shift into the future. The following is one of those cases:
Daisy and her friend Rick were driving to another friend's house in September of 2004 in Rick's beat up old truck. 'Suddenly, the truck's engine died and Rick and I were stranded on a deserted highway in the middle of the night,' Daisy says. 'We were surrounded on both sides of the road by cornfields that stretched into the distance.
'Rick began a desperate effort to restart the truck, but nothing seemed to work. We decided to walk to the nearest town about two miles away to find a payphone to call our friend. We walked for what seemed like hours and the town was nowhere in sight.
'However, just when desperation was about to grip us, we saw a light, a gloriously bright light, shining over the steep hill ahead of us. We ran up the hill that blocked us from the light and were flabbergasted by what we saw. Just over the hill, Rick and I saw what could only be described as a futuristic city with lights streaming out of every window of the massive, metallic towers. In the middle of the futuristic city was a huge silver dome.
'I stared at the city, stunned, until Rick elbowed me, which pulled me out of my trance and he pointed to the sky. Hovering above the city were hundreds of hovercraft. One flew toward us with amazing speed.
'Rick and I were so scared that we took off running back to the broken down truck. I never looked back, but I felt someone watching me the whole way. When we got back to the truck, it started without difficulty. Rick and I took off as fast as we could in the opposite direction. We never went back or spoke of it again to this day.' 
Objects Teleported Back in Time
Throughout the ages, miners, stonecutters, engineers and even archaeologists have discovered impossible artifacts: alloy screws embedded in sixty million year old coal beds is a famous example that comes to mind. There are literally many thousands of cases of objects out of time that have been very well documented by experts, photographed and catalogued. Each one makes the case for a time vortex sweeping them from somewhere to somewhere else. The only other answers would be littering by ancient astronauts or time travelers.
Let's consider these seven excerpts, just a few examples out of thousands. These were compiled by About.com:
*The mystery 'spark plug' inside a geode.
In 1961, the owners of a gift shop in Olancha, Calif. found a fossil-encrusted geode in the Coso Mountains. When one of the owners cut the geode in half with a diamond saw, however, he found an object inside that was obviously artificial. The object had a metal core surrounded by layers of a ceramic-like material and a hexagonal wooden sleeve. When X-rayed, the object seemed to resemble a modern spark plug or some other electronic component. Yet it had been completely encased in a geode that was covered with fossils estimated to be 500,000 years old.
*The very, very old nail.
In 1851, The Illinois Springfield Republican reported that a businessman named Hiram de Witt found a fist-sized chunk of auriferous quartz while on a trip to California. When it accidentally slipped from his hands, it split open, and out fell a cut-iron nail. The quartz was about 1 million years old.
*Gold thread among the rock.
The Times of London reported in 1844 that workmen quarrying stone near the River Tweed in Scotland found a piece of gold thread embedded in the rock eight feet below ground level.
*The strand of gold chain in coal.
In 1891, Mrs. S. W. Culp, of Morrisonville, Ill. was fragmenting coal into smaller pieces for her kitchen stove when she noticed a chain stuck in the coal. The chain measured about 10 inches long and was later found to be made of eight-carat gold, and described as being 'of antique and quaint workmanship.' According to the Morrisonville Times of June 11, investigators concluded that the chain had not simply been accidentally dropped in with the coal, since some of the coal still clung to the chain, while the part that had separated from it still bore the impression of where the chain had been encased.
*The anomalous discovery of ancient-modern tools.
While quarrying limestone in 1786, workers came to a bed of sand about 50 feet below ground level. In the layer of sand, however, they found the stumps of stone pillars and fragments of half-worked rock. Digging further, they found coins, the petrified wooden handles of hammers, and pieces of other petrified wooden tools. The sand in which the discovery was made was beneath a layer of limestone dated at 300 million years old.
*The case of the very strange vase.
In June, 1851, Scientific American reprinted a report from the Boston Transcript about how a metallic vase, found in two parts, was dynamited out of solid rock 15 feet below the surface in Dorchester, Mass. The bell-shaped vase (photo), measuring 4-1/2 inches high and 6-1/2 inches at the base, was composed of a zinc and silver alloy. On the sides were figures of flowers in bouquet arrangements, inlaid with pure silver. The estimated age of the rock out of which it came: 100,000 years.
*The mystery of the too-old screw.
In 1865, a two-inch metal screw was discovered in a piece of feldspar unearthed from the Abbey Mine in Treasure City, Nev. The screw had long ago oxidized, but its form - particularly the shape of its threads - could be clearly seen in the feldspar. The stone was calculated to be 21 million years in age.
*Impossibly ancient nanotechnology.
In 1991-1993, gold prospectors on the Narada river on the eastern side of the Ural mountains in Russia found unusual, mostly spiral-shaped objects, the smallest measuring about 1/10,000th of an inch! The objects are composed of copper and the rare metals tungsten and molybdenum. Tests showed the objects to be between 20,000 and 318,000 years old. 
Baffling Disappearances: People Swallowed by Time
According to Stephen Wagner, Between 1920 and 1950, Bennington, Vermont was the site of several completely unexplained disappearances:
* On December 1, 1949, Mr. Tetford vanished from a crowded bus. Tetford was on his way home to Bennington from a trip to St. Albans, Vermont. Tetford, an ex-soldier who lived in the Soldier's Home in Bennington, was sitting on the bus with 14 other passengers. They all testified to seeing him there, sleeping in his seat. When the bus reached its destination, however, Tetford was gone, although his belongings were still on the luggage rack and a bus timetable lay open on his empty seat. Tetford has never returned or been found.
*On December 1, 1946, an 18-year-old student named Paula Welden vanished while taking a walk. Welden was walking along the Long Trail into Glastenbury Mountain. She was seen by a middle-aged couple that was strolling about 100 yards behind her. They lost sight of her when she followed the trail around a rocky outcropping, but when they rounded the outcropping themselves, she was nowhere to be seen. Welden has not been seen nor heard from since.
*In mid-October, 1950, 8-year old Paul Jepson disappeared from a farm. Paul's mother, who earned a living as an animal caretaker, left her small son happily playing near a pig sty while she tended to the animals. A short time later, she returned to find him missing. An extensive search of the area proved fruitless.
* Owen Parfitt had been paralyzed by a massive stroke. In June, 1763 in Shepton Mallet, England, Parfitt sat outside his sister's home, as was often his habit on warm evenings. Virtually unable to move, the 60-year-old man sat quietly is his nightshirt upon his folded greatcoat. Across the road was a farm where workers were finishing their workday by pooking the hay. At about 7 p.m., Parfitt's sister, Susannah, went outside with a neighbor to help Parfitt move back into the house, as a storm was approaching. But he was gone. Only his folded greatcoat upon which he sat remained. Investigations of this mysterious disappearance were carried out as late as 1933, but no trace or clues to Parfitt's fate were ever uncovered.
Perhaps the most spectacular incident of people swallowed up by time occurred during World War I in war torn Turkey.
Three soldiers claimed to be witnesses to the bizarre disappearance of an entire battalion in 1915. They finally came forward with the strange story 50 years after the infamous Gallipoli campaign of WWI. The three members of a New Zealand field company said they watched from a clear vantage point as a battalion of the Royal Norfolk Regiment marched up a hillside in Suvla Bay, Turkey. The hill was shrouded in a low-lying cloud that the English soldiers marched straight into without hesitation. They never came out. After the last of the battalion had entered the cloud, it slowly lifted off the hillside to join other clouds in the sky. When the war was over, figuring the battalion had been captured and held prisoner, the British government demanded that Turkey return them. The Turks insisted, however, that it had neither captured not made contact with these English soldiers. 
Extinct Animals Out of Time: Pteradons, Pterosaurs and Pterodactyls
Called by some Indonesian Islanders the Ropen, reports have trickled down through the centuries of living dinosaurs that resemble Pterosaurs thought extinct some sixty-five million years ago during the last great age of the dinosaurs.
Extensive interviews were conducted with eyewitnesses and are reported in the web article, Does a living pterodactyl fly over Papua New Guinea? 
Jonathan Whitcomb, an American author, reports that a psychologist saw a living Pterosaur soaring through the skies in Papua New Guinea:
"A psychologist at a university in Central China asserts that he saw, in 1971, a prehistoric-looking creature flying in Papua New Guinea. Brian Hennessy of the Chongqing University of Medical Sciences described the creature as black or dark brown with a "longish narrow tail" and a beak that was "indistinguishable from the head." 
The Umboi Island Eyewitnesses 
Testimony of David Moke
"Mesa, with his friends Gideon Koro and Wesley Koro, were terrified by the giant Ropen that flew, in daylight, over Lake Pung, Umboi Island. They were three of seven boys who hiked up to the Crater Lake (about 1994), but they all ran home after seeing the creature whose description suggests, to American investigators, a giant Rhamphorhynchoid pterosaur. Ten years later, during a videotaped interview, Mesa was still nervous talking about the encounter." 
Gary Bogue reports on sightings made over the years of pterosaur-like creatures that still roam the skies over the Southwest. 
Next, for your edification (or amusement you decide which) is a heavily visited video on YouTube that purports to be a Pterodactyl sighting in 2008 near Flathead Lake, Montana. The sighting took place on February 13, 2007. Please click here to watch the video.
The Hackensack Organization provides photographs from an eyewitness encounter of a Pterodactyl flying over the Hackensack River on during April 1, 2005. The date of April Fool's Day makes one a bit cautious to jump to conclusions with this evidence, although the photos do look impressive. The link to the photos is here and also available in the Footnotes. 
The Ropen (Flying Dinosaur) of Indonesia
YouTube is also hosting a video made by an individual claiming he was able to capture a Ropen with his video cam as it the creature flew past him. This interesting video is available for viewing here.
Did an aircraft nearly collide with a Pterodactyl?
A similar incident in South America was published in 1992 by the Australian weekly magazine People. In this encounter, a small commuter aircraft nearly crashed into a giant flying lizard over the mountain jungles of Brazil. A U.S. anthropologist named Dr. George Biles was supposedly aboard the plane of twenty-four passengers and was quoted as saying, 'This was a classic case of a white pterodactyl with a giant wingspan. Of course, I've heard the rumors for many years that these prehistoric creatures still roamed the Amazon. But I was skeptical like everybody else. But that wasn't an airplane or a UFO flying beside us. It was a pterodactyl.'
The People story says that the pterodactyl was flying alongside the plane as it was preparing to land and that the pilot veered away to avoid colliding with the 'giant bird.' A stewardess named Maya Cabon is quoted as saying, 'Here was this giant monster flying right next to the plane. He was only a few feet away from the window-and he looked right at me. I thought we were all going to die.'
No actual size is given in the story, and tales like this start becoming suspect when the pilot is quoted as saying '. . . he was coming straight at us and he was mighty big!' 
Modern Animals Teleported by Time
Big cat is making tracks for Moira ~ by Adrian Jenkins
Just when you thought it was safe to go back into the countryside, the big cat is back - and this time it is making its mark.
The evidence can be seen clearly in this striking paw print left in the soft earth in Moira. 
This news article is current. It just appeared on September 14, 2009. The writer is describing yet another case of the mysterious appearance of the black panthers in England. Sightings have taken place for many hundreds of years. The big cats appear suddenly, are spotted by dozens or hundreds of witnesses over a period of days or weeks, and then just as mysteriously disappear only to make an appearance again years later.
These big black cats, described by some as black leopards, are not constrained to roaming the British Isles. The mysterious felines have been spotted in North America as well. Some of the most famous cases have occurred in the Midwest, specifically southern Illinois.
Illinois, as well as many other unusual places, has also seen its fair share of rogue kangaroo spotting.
Out of Place Animals
The explanation of circus or zoo escapees is trotted out quite often to explain these creatures away, but only by newspapers and the uneducated, not by scientists. According to records, there have been very few of these escapees and they are usually captured within a few hours or days of getting out. Also, the time of these escapes do not generally correspond to periods when sightings are high.
Illegal or secretly kept exotic pets are a more likely explanation, but there is one problem with this. With many of these out-of-place cryptids, sightings have been happening with the same kinds of animals for decades or even for hundreds of years, long before the exotic pet problem was widespread. In a few cases, the sightings existed before any examples of the animal were kept in captivity, as with gorilla sightings in North America.
The exotic pet explanation also fails to explain why we don't see more variety. If lots of exotic pets are getting loose all the time, we would expect to see more different types of out-of-place cryptid in the same area, not just one or two types persisting over a long time period. For example, we might expect to see hyenas, alligators and leopards instead of just leopards. We would not expect one region to specialize in leopard sightings over a long time period unless a feral population had established itself or unless leopards had actually lived there from time immemorial. Scientists generally deny the possibility of an established feral population. Yet hard-to-explain patterns do persist, puzzling scientists and cryptozoologists alike.
Paranormal researchers sometimes explain such out-of-place animals as examples of teleportation. Supposedly, these animals are randomly teleported from their native environment into a foreign one, then teleported back, leaving nothing as proof except footprints and occasional hairs. Sometimes aliens are held to be responsible for this teleportation, though it is hard to think of a reason why such activity would have any purpose, and other times this teleportation is supposed to behave like some kind of purely natural phenomena, such as the weather, without any need for intelligent beings to operate it. There is seldom any explanation given for why these supposed teleportation vortexes seem to show a preference for big cats, kangaroos and apes. 
Other out of place animals popping in and out of existence on farmer's fields, city streets and shopping malls include: African peacocks, big cats American Lions, Black Panthers, Eastern Cougar, Mainland Orangutans, the Nandi Bear and Napes.
The Phantom Kangaroo Phenomenon 
As mentioned previously, Illinois is a nexus point for kangaroos. Why? No one knows.
Chicago, 1974: In the early morning hours of October 18, 1974, Officer Michael Byrne and Leonard Ciagi of the Chicago police were called to investigate a report that a kangaroo was standing in someone's porch. After a brief search, the officers located the animal in an alleyway, but were unable to capture it.
After the Chicago incident, kangaroo sightings were reported in Illinois and Wisconsin. The kangaroo was seen the next day by a paperboy, and again on the 23rd in Schiller Woods. Another police officer saw it on November 1 in Plano, just outside the city. He reported it jumping eight feet from a field into the road. Half an hour later it (or another one), was seen back in Chicago. It was then seen on the following three days in the surrounding countryside, and finally on the sixth, near Lansing. A few days later, there was a rash of sightings in Indiana.
Menomonee Falls, Wisconsin, 1978: two men photographed a large kangaroo beside the highway.
Like the UK's big black cat sightings, the kangaroo phenomenon erupts and multiple sightings occur. Then the phenomenon abruptly ends.
Theories abound in an attempt to explain, or explain away, all the various facets of time anomalies, glitches and oddities. No one theory has gained favor over another. A few are held in disrepute such as the gangs of rampaging demons manipulating time theory, the fairy theory and alien UFOnauts playing with time and space theory.
The actual answer may be a combination of some of the more reasonable theories. These theories, actually properly termed hypotheses, include aberrations of gravity affecting the forward progression of time; or loops, vortices or rifts in the space time continuum that can suck things in and spit them out (teleportation), transport objects or people to another era, or pick up things temporarily before returning them to their proper place (out of place animals).
I believe the phenomenon deserves much more investigation by qualified researchers with a strong background in theoretical physics, the string theory and basic quantum mechanics because all of these may come into play.
And what of the thousands of people that eyewitnesses have sworn disappeared right before their eyes never to return? Maybe someday if we can crack the secret of time shifts, we can rescue all those poor souls. They're probably drifting helplessly, ensnared within an eddy of time. Once freed, perhaps we could return them all to the land of the living.
Wouldn't they make quite a gathering, some foggy day in the future, if they all attended a time convention at the local Hyatt Regency?
1.Swartz, Tim. On the Edge of Time: The Mystery of Time Slips http://paranormal.about.com/gi/dynamic/offsite.htm?zi=1/XJ/Ya&sdn=paranormal&zu=http%3A%2F%2Fuforeview.tripod.com%2Ftimeslips.html
2.Randles, Jenny. Time Storms: Amazing Evidence for Time Warps, Space Rifts, and Time Travel.New York: Berkley Books, 2002, 2001
3.The Varsitarian, University of Santo Tomas, Espaa, Manila. http://www.varsitarian.net/editorial_opinion/opinion/the_teleported_man
4.He Got There Before He Arrived. ~ Wagner, Stephen, About.com http://paranormal.about.com/od/timeanddimensiontravel/a/aa012306_2.htm
5.Driving Into the Future. ~ About.com http://paranormal.about.com/od/timeanddimensiontravel/a/aa012306_3.htm
6.The Mysterious Cloud. ~ By Stephen Wagner, About.com http://paranormal.about.com/library/weekly/aa061101a.htm
7.Pieces out of Time. ~ Wagner, Stephen, About.com http://paranormal.about.com/library/weekly/aa072098.htm
8.Does a living pterodactyl fly over Papua New Guinea? http://www.laattorneyvideo.com/nonlegal/pterosaurs/DH/ and http://www.eworldwire.com/pressreleases/17135
9.Psychologist reports living Pterosaur http://www.laattorneyvideo.com/nonlegal/pterosaurs/umboi-eyewit/
10.Umboi Island Eyewitnesses ~ http://www.laattorneyvideo.com/nonlegal/pterosaurs/umboi-eyewit/
11.Eyewitness testimony of David Moke ~ http://www.laattorneyvideo.com/nonlegal/pterosaurs/wit-1/
12.Bogue, Gary.Prehistoric flying reptile sightings in New Mexico? http://www.ibabuzz.com/garybogue/2007/02/13/prehistoric-flying-reptile-sightings-in-new-mexico/
13.4/1/2005: Prehistoric Pterodactyl observed on Hackensack River http://www.hackensack.org/controls/eventview.aspx?MODE=SINGLE&ID=40
14.Near collision between an aircraft and a Pterodactyl? http://educate-yourself.org/cn/PterodactylsHauntSkies30mar05.shtml
15.Jenkins, Adrian. Big cat is making tracks for Moira September 14, 2009 http://www.burtonmail.co.uk/burtonmail-news/displayarticle.asp?id=447765
16.Out of Place Animals. ~ http://www.newanimal.org/out-placed.htm
17.The phantom kangaroo phenomena. http://en.wikipedia.org/wiki/Phantom_kangaroo