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A1 Beginner 英検3級
B1 Intermediate 英検2級
C1 Advanced 英検1級
Original article
A1 Level Beginner 英検3級
Why did T-rex have short arms?
Long ago, there was a big dinosaur named Tyrannosaurus rex, or T. rex for short. It was a very big meat-eater that lived a long, long time ago, about 83 to 66 million years ago. The T. rex is very famous and many children know about it. It was very large, about half as long as a basketball court and taller than a basketball hoop!
T. rex had very short arms, and people wonder why. Some think its arms were short because they used to be longer but changed over time. Others think the short arms were useful for holding onto food or helping the T. rex stand up. It’s also possible that having short arms kept them from being bitten off by other T. rexes!
Even though the T. rex had short arms, it was still a powerful hunter. It had strong legs but couldn’t run very fast because it was so big. Scientists think it could walk very quickly, but running too fast would hurt its legs.
The T. rex’s short arms might have had claws for slashing at close things or for holding onto food while eating. But, some people think the T. rex didn’t really need its arms for hunting because it had a strong neck and big teeth to catch and eat food.
Another interesting idea is that the short arms helped T. rex stand up from lying down. Imagine trying to get up without using your arms; it would be hard! T. rex might have used its little arms to help push itself up.
Lastly, since T. rexes might have lived and hunted together, having short arms could have stopped them from accidentally hurting each other when eating.
Even though the T. rex had tiny arms, it was still a very strong dinosaur. It didn’t need big arms because it had other ways to hunt and move around. So, the T. rex is remembered not just for its short arms, but for being one of the most amazing dinosaurs that ever lived. And that’s a little story about the famous T. rex and its short arms!
Questions
1. When did the Tyrannosaurus rex live?
– A. 100 to 85 million years ago
– B. 83 to 66 million years ago
– C. 90 to 70 million years ago
– D. 75 to 60 million years ago
2. Why do some people think T. rex had short arms?
– A. Because they were more attractive that way
– B. To make them faster runners
– C. They were just born that way and it never changed
– D. The arms were short for reasons like holding onto food or helping them stand up
3. How did the T. rex move around, according to scientists?
– A. It could fly short distances
– B. It swam in deep waters
– C. It jumped like a kangaroo
– D. It could walk very quickly
4. What might have been a use for the T. rex’s short arms?
– A. Helping it stand up from lying down
– B. Playing musical instruments
– C. Waving at other dinosaurs
– D. Making nests for its eggs
5. Why did the T. rex not need long arms for hunting?
– A. It used its feet instead of arms
– B. It was a vegetarian
– C. It had a strong neck and big teeth
– D. It scared its prey into surrendering
6. What is a theory about why T. rex’s arms were short to prevent injury during?
– A. Sleeping
– B. Eating together
– C. Running races
– D. Climbing trees
7. How big was the T. rex?
– A. About half as long as a basketball court and taller than a basketball hoop
– B. The size of a small car
– C. As long as a football field
– D. The height of a two-story building
8. What makes the T. rex famous and remembered?
– A. Its ability to swim
– B. The colors of its feathers
– C. Its long tail
– D. Being a powerful dinosaur with short arms
answers 1B 2D 3D 4A 5C 6B 7A 8D
B1 Level Intermediate 英検2級
Why did Tyrannosaurus rex have short arms?
The Tyrannosaurus rex, also known as T. rex, is a famous dinosaur that lived about 83.6 to 66 million years ago during the Cretaceous period. It was one of the biggest meat-eaters on land ever, with a length of about 12.5 meters and a height of nearly 4 meters. However, one of the most interesting things about T. rex is its very short arms, which have puzzled scientists and dinosaur enthusiasts for a long time.
There are several ideas about why T. rex had such short arms. Some think these arms might be leftovers from an evolutionary process where they shrank over time. Others suggest the arms could have been useful for holding prey, helping the dinosaur to stand up, or preventing their arms from being bitten off by other T. rexes.
Despite its small arms, T. rex was a powerful hunter. It had strong legs but couldn’t run very fast, likely not faster than 20 km/h, because running too quickly could hurt its legs. So, it’s believed T. rex could walk very fast instead.
The arms of T. rex, although short, were strong and had two long claws that could have been used for slashing at prey or holding it steady while eating. Some scientists think that T. rex might not have needed longer arms because it could use its strong neck and big teeth to catch and eat food.
Another interesting idea is that T. rex used its short arms to help it stand up after lying down. Since getting up without using arms is difficult, the short arms of T. rex might have been quite helpful.
Lastly, if T. rexes lived and hunted in groups, having short arms could have been a way to prevent accidentally hurting each other while eating.
Even though T. rex had tiny arms, it was still an incredible and powerful dinosaur. The short arms didn’t stop it from being an effective hunter because it had other ways to catch and eat its food. The T. rex is remembered not only for its size and strength but also for its unusual arms, which continue to interest people today. This shows us how much there is still to learn about dinosaurs and their way of life.
Questions
1. When did the Tyrannosaurus rex live?
– A. 90 to 70 million years ago
– B. 83.6 to 66 million years ago
– C. 100 to 85 million years ago
– D. 75 to 60 million years ago
2. Why are T. rex’s short arms interesting to scientists and enthusiasts?
– A. They are a puzzle that has many different explanations.
– B. They were the longest arms of any dinosaur.
– C. They show T. rex couldn’t hunt effectively.
– D. They prove T. rex was a peaceful dinosaur.
3. What was one potential use for T. rex’s short arms?
– A. For swimming
– B. For making nests
– C. For playing
– D. For holding prey steady while eating
4. How fast could the T. rex likely walk?
– A. 5 km/h
– B. 15 km/h
– C. No faster than 20 km/h
– D. 30 km/h
5. Why might T. rex not have needed longer arms?
– A. Its legs were long enough.
– B. It used its tail for hunting.
– C. It could use its strong neck and big teeth to catch and eat food.
– D. It was too heavy to move its arms.
6. How did the short arms potentially help T. rex?
– A. Helping it stand up after lying down
– B. Improving its balance while running
– C. Attracting mates
– D. Climbing trees
7. What could have been a reason for T. rex’s arms to remain short?
– A. They were more aerodynamic for running.
– B. To prevent injury while hunting in groups.
– C. They evolved into wings.
– D. They were used for fishing.
8. What does the T. rex’s unique feature of having short arms show us?
– A. That it was not a real dinosaur.
– B. That it lived in water.
– C. There is still a lot to learn about dinosaurs.
– D. It was the smallest dinosaur ever.
answers 1B 2A 3D 4C 5C 6A 7B 8C
C1 Level Advanced 英検1級
Why did Tyrannosaurus rex have short arms?
The enigmatic Tyrannosaurus rex, an emblematic figure within the annals of paleontology, continues to captivate the imagination with its distinctive anatomical feature: disproportionately short arms. This characteristic has been the subject of much speculation among scientists and enthusiasts alike, yielding a myriad of theories but no definitive answers. Could these vestigial limbs, reminiscent of our own wisdom teeth, be the remnants of an evolutionary trajectory that favored other physical adaptations? Or did they serve a purpose that has eluded our understanding thus far?
Living during the late Cretaceous period, approximately 83.6 to 66 million years ago, the Tyrannosaurus rex stood as a colossus among carnivores. Measuring up to 12.5 meters in length and reaching heights of nearly 4 meters, its sheer size is awe-inspiring. While popular culture often depicts this behemoth in an upright stance, scientific consensus asserts that a horizontal posture, counterbalanced by a robust tail, was necessary to distribute its massive weight and avoid joint damage. Furthermore, biomechanical analyses have debunked the myth of the T. rex as a swift predator, suggesting that its top speed did not surpass 20 km/h to prevent skeletal damage during locomotion.
The short arms of the T. rex, while puzzling, may have been more functional than previously assumed. Some hypotheses propose that these limbs, equipped with formidable claws, were used for slashing at prey in close quarters or grasping onto it during a struggle. Another possibility is that they facilitated the dinosaur’s ability to rise from a prone position, a task that would have required considerable effort without the aid of its arms. Additionally, the social behavior of these creatures might have influenced the evolution of their arms; living and hunting in packs could have led to shorter limbs to minimize the risk of accidental injury during feeding frenzies.
Despite the T. rex’s formidable jaw and neck muscles, which likely played a predominant role in its hunting strategy, the function of its diminutive arms remains a topic of debate. The juxtaposition of their limited reach against the backdrop of the T. rex’s overall strength and agility presents an evolutionary conundrum. Were these arms a mere evolutionary leftover, gradually diminishing as other physical attributes were favored? Or did they fulfill specific roles that contributed to the T. rex’s dominance as a predator?
As we delve deeper into the mysteries of the Tyrannosaurus rex, it becomes apparent that its short arms, far from being a trivial detail, offer a fascinating glimpse into the complexities of evolution and adaptation. These limbs may have been small, but they underscore the remarkable versatility and resilience of one of history’s most formidable predators. The ongoing exploration of the T. rex’s anatomy and behavior not only enriches our understanding of the past but also challenges us to rethink our assumptions about the natural world.
Questions
1. What has been the primary subject of speculation regarding the Tyrannosaurus rex?
– A. Its dietary habits
– B. The color of its skin
– C. Its hunting techniques
– D. Its disproportionately short arms
2. When did the Tyrannosaurus rex live?
– A. During the Jurassic period
– B. During the late Cretaceous period
– C. During the early Triassic period
– D. During the Ice Age
3. How tall could a Tyrannosaurus rex reach?
– A. 2 meters
– B. Nearly 4 meters
– C. 6 meters
– D. 10 meters
4. What is a widely accepted posture of T. rex according to scientific consensus?
– A. Horizontal posture with a robust tail for balance
– B. An upright stance on two legs
– C. A quadrupedal stance
– D. Sitting position when at rest
5. Why was the T. rex not considered a swift predator, according to biomechanical analyses?
– A. It preferred to ambush its prey
– B. It used its tail to propel itself forward
– C. Its top speed did not surpass 20 km/h to prevent skeletal damage
– D. It could fly short distances
6. What potential function could the T. rex’s short arms have served?
– A. As decoration to attract mates
– B. For climbing trees
– C. For swimming
– D. For slashing at prey or aiding in standing up
7. How might the social behavior of T. rexes have influenced their arm length?
– A. To minimize the risk of accidental injury during group feeding
– B. To improve their ability to communicate
– C. To enhance their speed when hunting in packs
– D. To make them look more intimidating to rivals
8. What does the exploration of the T. rex’s unique features reveal about evolution and adaptation?
– A. It confirms that the T. rex was not a real dinosaur
– B. It demonstrates the importance of size in predator dominance
– C. It offers insight into the complexities of evolutionary changes
– D. It proves that dinosaurs could regenerate lost limbs
answers 1D 2B 3B 4A 5C 6D 7A 8C
Original article
Why did Tyrannosaurus rex have short arms?
Why did Tyrannosaurus rex have short arms? No one really knows. They could have no reason and be left over from longer arms that evolved away. They could have been used for slashing, gripping prey, and longer arms might have been bitten off by other Tyrannosauruses. They may have been used to help the dinosaurs stand up, as well.
The Tyrannosaurus rex is probably the most famous of all dinosaurs and the one nearly all children will know. They lived in the Cretaceous period, from roughly 83.6 million years ago and they were wiped out by the asteroid 66 million years ago. Tyrannosaurus rex was the largest land carnivore that has ever lived, and they grew to be about 12.5 m long and 3.96 m tall. We can only know the heights of the fossils that have been found and there may very well have been much larger Tyrannosauruses. They are also often pictured as standing vertically, but they would have had to keep their bodies parallel with the ground, using their tails as a counterweight for balance. Standing upright would have damaged their hips and other joints. In fact, biomechanical models have shown that the Tyrannosaurus rex was not able to run as fast as was previously thought. Looking at its weight, length, and the strength of its bones, experts have calculated that it probably couldn’t exceed 20 km/h. That is still faster than most people on Earth, but it is not as fast as was thought. The reason is, if the Tyrannosaurus rex actually ran, it would have to have both legs off the ground at the same time and landing each time would shatter the bones in its legs. It could go no faster than a very fast walk.
So, why did Tyrannosaurus rex have short arms? One theory was that the short arms were left over from longer arms or legs that had evolved away over time, similar to our wisdom teeth. A vestigial feature, something that used to have a purpose, but not longer does. The Tyrannosaurus rex had massive neck muscles, which they used to power their jaws, and to rip and shake prey, tearing pieces off. Larger arms would have required larger muscles, which might have got in the way of the neck muscles. It is thought that the Tyrannosaurus rex didn’t need longer arms because it did everything with its neck muscles.
However, it seems that they did use their short arms for pose and if longer arms were an evolutionary advantage and shorter arms were a hindrance, it is most likely that the tyrannosaurus rex would have evolved longer arms over time. The fact that they didn’t shows that they either don’t need their arms much, or shorter arms are better. So, what did they use their arms for?
The first thing they used their short arms for was slashing. Each arm was about 1 m long and had two very long claws on the end of each one. Each claw was about 10 cm long. The bones of the arms were also incredibly thick and sturdy. Tyrannosaurus rex could have used these arms and claws to slash prey at close range while it held them with its jaws. Two 10 cm claws on a 1 m long arm could inflict long and deep cuts on a prey animal. The Tyrannosaurus would have been able to move them up and down very quickly as well.
The second reason could have been to grip prey. The Tyrannosaurus could have used its forearms and claws to hold onto the prey so it couldn’t move while it killed it. Once the prey was dead, the Tyrannosaurus would have used its teeth and strong neck muscles to rip flesh off it. However, there is some argument here because it is likely that the Tyrannosaurus rex hunted in the same way as Komodo dragons today, which is to use their powerful neck muscles to tear pieces off the prey until they died. In which case, they wouldn’t need their arms.
A third reason is possibly to help them stand up. Tyrannosauruses must have lain down to sleep or sat down at some point. They wouldn’t be able to sleep standing up, as four legged animals can. That means, they would have needed to get back up and fossils of footprints found in New Mexico appear to show that the Tyrannosaurus rex stood up by using the elbows of its tiny arms to balance and push off the ground.
A final reason is to avoid having them bitten off. Archaeological evidence suggests that Tyrannosauruses hunted in packs. If a number of Tyrannosauruses were using their powerful teeth and jaws to rip prey to shreds, it is safe to assume that they might have accidentally bitten each other’s arms off. Having short arms could have been protection against this.
It does seem that the tiny arms did have some uses but the arms weren’t tiny for these reasons, rather they were tiny and the Tyrannosaurus rex used them. They were really too small for slashing and the Tyrannosaurus would have to get too close to anything. It seems more likely that the Tyrannosaurus rex gradually evolved to get bigger and its arms didn’t. It sacrificed its arms for more muscle strength in the neck. And this is what I learned today.
Questions
1. What period did the Tyrannosaurus rex live in?
– A. Jurassic
– B. Cretaceous
– C. Triassic
– D. Permian
2. How fast could the Tyrannosaurus rex move according to biomechanical models?
– A. 10 km/h
– B. 15 km/h
– C. 25 km/h
– D. No faster than 20 km/h
3. What was a potential use for the T. rex’s short arms?
– A. Slashing at prey
– B. Flying short distances
– C. Swimming
– D. Running
4. How did the Tyrannosaurus rex stand to avoid damaging its joints?
– A. With its body parallel to the ground
– B. In an upright position
– C. On its hind legs only
– D. Leaning forward constantly
5. What is one theory about why T. rex had short arms?
– A. They were used for swimming.
– B. They evolved into wings.
– C. They were vestigial features, similar to human wisdom teeth.
– D. They grew shorter as T. rex grew larger.
6. How long were the T. rex’s arms?
– A. 2 m long
– B. 1.5 m long
– C. About 1 m long
– D. Less than 0.5 m long
7. What could have been a reason for the T. rex’s short arms not being a disadvantage?
– A. T. rex primarily used its legs for hunting.
– B. The arms were used for balance rather than for hunting.
– C. T. rex compensated with strong neck muscles and jaw power.
– D. T. rex was primarily a scavenger, not a hunter.
8. Which of the following is not mentioned as a possible use for T. rex’s short arms?
– A. To grip prey
– B. To help in standing up from a lying position
– C. To avoid having them bitten off by other T. rexes
– D. To build nests
answers 1B 2D 3A 4A 5D 6C 7B 8C.
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