Dinosaurs Displayed Fast Growth Rate Early
2024-04-18
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1Dinosaurs existed for 165 million years.
2The animals' evolutionary success was partly due to their fast growth rate.
3A new study finds that this pattern of fast growth appeared in the earliest dinosaurs.
4The researchers examined microscopic details in dinosaur bone fossils from Argentina.
5The details showed that the earliest dinosaurs had growth rates similar to animals found today like mammals and birds.
6Scientist Kristi Curry Rogers of Macalester College in Minnesota studies fossils.
7She is the lead writer of the research recently released in the publication PLOS ONE.
8She said, "Growing quickly allows organisms to escape the risky business of being small for a long part of their life history."
9And she added that it also allows them to reproduce more throughout their life.
10That means each following generation will be more successful.
11The researchers examined patterns fossilized within the bones of dinosaurs and some of their relatives.
12The dinosaurs they looked at lived in northwestern Argentina between 231 and 229 million years ago.
13Curry Rogers said cellular and chemical details in the fossils all show relative speed of growth.
14She added that the soft parts of the animal are no longer present,
15but the hard parts like the bones left a record of spaces where the soft parts once were.
16She said, "This allows us to reconstruct and compare growth patterns among animals."
17The researchers studied five early dinosaurs.
18They all walked on two feet, were quick on their feet, had clawed hands that could hold objects and had sharp teeth.
19Three were meat-eaters and the ancestors of large meat-eaters like T. rex and Giganotosaurus.
20The dinosaurs included Herrerasaurus and Sanjuansaurus which were around 3-4.5 meters long.
21The last meat-eater Eodromaeus was the size of a large bird.
22The two others, Eoraptor and Chromogisaurus, were also around the size of a large bird.
23They were the ancestors of long-necked, four-legged large dinosaurs like Argentinosaurus and Dreadnoughtus.
24All five showed signs of fast growth.
25But the researchers also surprisingly found that some non-dinosaur reptiles in the same area and time had their own fast growth rates.
26Quick growth was also found in four-legged Saurosuchus.
27It was a top-level meat-eater on land that was 7 meters long and similar to a reptile found today, the crocodile.
28Additionally, quick growth was found in crocodile relatives like Proterochampsa and Trialestes.
29Other animals like the planting-eating reptile Hyperodapedon and mammal-like reptile Exaeretodon also grew quickly.
30But they regularly paused their growth throughout their life.
31That is different than the continuous fast growth of dinosaurs.
32The first dinosaurs and these other animals evolved during a time on earth called the Triassic Period.
33It followed after Earth's worst mass extinction 252 million years ago at the end of the Permian Period.
34About 95 percent of different kinds of animals were lost after severe climate change.
35The climate change may have been caused by massive volcanic activity in an area found in today's Russia.
36Curry Rogers said that fast growth was good for them in a changing world.
37And she said that fast growth combined with dinosaur biology and behavior allowed dinosaurs to succeed early.
38Another mass extinction at the end of the Triassic about 201 million years ago killed off many early competitors to the dinosaurs.
39Curry Rogers said that as time continued, dinosaurs held onto these high growth rates.
40She said that lead to many different kinds of dinosaurs.
41But she said their competitors, like crocodile-cousins, had less differences in growth patterns and behavior.
42I'm Gregory Stachel.
1Dinosaurs existed for 165 million years. The animals' evolutionary success was partly due to their fast growth rate. 2A new study finds that this pattern of fast growth appeared in the earliest dinosaurs. The researchers examined microscopic details in dinosaur bone fossils from Argentina. 3The details showed that the earliest dinosaurs had growth rates similar to animals found today like mammals and birds. 4Scientist Kristi Curry Rogers of Macalester College in Minnesota studies fossils. She is the lead writer of the research recently released in the publication PLOS ONE. 5She said, "Growing quickly allows organisms to escape the risky business of being small for a long part of their life history." And she added that it also allows them to reproduce more throughout their life. That means each following generation will be more successful. 6The researchers examined patterns fossilized within the bones of dinosaurs and some of their relatives. The dinosaurs they looked at lived in northwestern Argentina between 231 and 229 million years ago. 7Curry Rogers said cellular and chemical details in the fossils all show relative speed of growth. She added that the soft parts of the animal are no longer present, but the hard parts like the bones left a record of spaces where the soft parts once were. 8She said, "This allows us to reconstruct and compare growth patterns among animals." 9The researchers studied five early dinosaurs. They all walked on two feet, were quick on their feet, had clawed hands that could hold objects and had sharp teeth. 10Three were meat-eaters and the ancestors of large meat-eaters like T. rex and Giganotosaurus. The dinosaurs included Herrerasaurus and Sanjuansaurus which were around 3-4.5 meters long. The last meat-eater Eodromaeus was the size of a large bird. 11The two others, Eoraptor and Chromogisaurus, were also around the size of a large bird. They were the ancestors of long-necked, four-legged large dinosaurs like Argentinosaurus and Dreadnoughtus. 12All five showed signs of fast growth. 13But the researchers also surprisingly found that some non-dinosaur reptiles in the same area and time had their own fast growth rates. 14Quick growth was also found in four-legged Saurosuchus. It was a top-level meat-eater on land that was 7 meters long and similar to a reptile found today, the crocodile. Additionally, quick growth was found in crocodile relatives like Proterochampsa and Trialestes. 15Other animals like the planting-eating reptile Hyperodapedon and mammal-like reptile Exaeretodon also grew quickly. But they regularly paused their growth throughout their life. That is different than the continuous fast growth of dinosaurs. 16The first dinosaurs and these other animals evolved during a time on earth called the Triassic Period. It followed after Earth's worst mass extinction 252 million years ago at the end of the Permian Period. 17About 95 percent of different kinds of animals were lost after severe climate change. The climate change may have been caused by massive volcanic activity in an area found in today's Russia. 18Curry Rogers said that fast growth was good for them in a changing world. And she said that fast growth combined with dinosaur biology and behavior allowed dinosaurs to succeed early. 19Another mass extinction at the end of the Triassic about 201 million years ago killed off many early competitors to the dinosaurs. 20Curry Rogers said that as time continued, dinosaurs held onto these high growth rates. She said that lead to many different kinds of dinosaurs. But she said their competitors, like crocodile-cousins, had less differences in growth patterns and behavior. 21I'm Gregory Stachel. 22Will Dunham reported this story for Reuters. Gregory Stachel adapted it for VOA Learning English. 23_____________________________________ 24Words in This Story 25evolve - v. to change or develop slowly often into a better, more complex, or more advanced state 26pattern - n. something that happens in a regular and repeated way 27fossil - n. something (such as a leaf, skeleton, or footprint) that is from a plant or animal which lived in ancient times and that you can see in some rocks 28allow - v. to permit (something) 29claw - n. a sharp curved part on the toe of an animal (such as a cat or bird) 30neck - n. the part of the body between the head and the shoulders 31extinction - n. the state or situation that results when something (such as a plant or animal species) has died out completely