Throughout the earlier part of the 20th century, it was widely (and perfectly reasonably) assumed that dinosaurs were a group of extinct reptiles. Admittedly, some were dramatically large or rather outlandish looking compared to modern reptiles, but they were crucially still reptiles. In the 19th century, Richard Owen (and Georges Cuvier before him) had confirmed that dinosaurs were anatomically most similar to living reptiles, creatures such as lizards and crocodiles. On this basis it was inferred, logically, that most of their biological attributes would have been similar, if not identical, to those of these living reptiles: they laid shelled eggs, had scaly skins and had a ‘cold-blooded’, or ectothermic, physiology.This combination of attributes created an entirely unexceptional view of dinosaurs: they were large, scaly, but crucially slow-witted and sluggish creatures. Their habits were assumed to be similar to those of lizards, snakes and crocodiles. The only puzzle was that dinosaurs were mostly built on a far grander scale compared to even the very biggest of known crocodiles.This view was challenged in 1964, when John Ostrom found the remains of a new and unusual predatory dinosaur. By 1969 Ostrom was able to describe the new dinosaur in sufficient detail and to christen it Deinonychus (‘terrible claw’) in recognition of a wickedly hooked, gaff-like claw on its hind foot. Ostrom noted a number of unexpected anatomical features in Deinonychus. It was a relatively large-brained, fast moving predator capable of sprinting on its hind legs and attacking its prey – common sense said that this was no ordinary reptile. These observations prepared the intellectual ground for a revolution that would shatter the then rather firmly held view of dinosaurs as archaic and outmoded creatures that plodded their way to extinction at the close of the Mesozoic Era.One of Ostrom’s students, Robert Bakker, took up this theme by aggressively challenging the view that dinosaurs were dull, stupid creatures. Bakker argued that there was compelling evidence that dinosaurs were more similar to today’s mammals and birds. Mammals and birds are regarded as ‘special’ because they can maintain high activity levels that are attributed to their ‘warm-blooded’, or endothermic, physiology. Living endotherms maintain a high and constant body temperature, have highly efficient lungs to maintain sustained aerobic activity levels, are capable of being highly active whatever the ambient temperature, and are able to maintain large and sophisticated brains; all these attributes distinguish birds and mammals from the other vertebrates on Earth.Bakker argued that far from being slow and dull, dinosaurs were intelligent, highly active creatures that had stolen the world from the traditionally superior mammals for 160 million years in the Mesozoic Era. Rather than being ousted from the world by the evolutionary rise of superior mammals, they had only given up their dominance because of some freakish climatic event 65 million years ago.Which of the following best represents the central idea of the passage?
Question
Throughout the earlier part of the 20th century, it was widely (and perfectly reasonably) assumed that dinosaurs were a group of extinct reptiles. Admittedly, some were dramatically large or rather outlandish looking compared to modern reptiles, but they were crucially still reptiles. In the 19th century, Richard Owen (and Georges Cuvier before him) had confirmed that dinosaurs were anatomically most similar to living reptiles, creatures such as lizards and crocodiles. On this basis it was inferred, logically, that most of their biological attributes would have been similar, if not identical, to those of these living reptiles: they laid shelled eggs, had scaly skins and had a ‘cold-blooded’, or ectothermic, physiology.This combination of attributes created an entirely unexceptional view of dinosaurs: they were large, scaly, but crucially slow-witted and sluggish creatures. Their habits were assumed to be similar to those of lizards, snakes and crocodiles. The only puzzle was that dinosaurs were mostly built on a far grander scale compared to even the very biggest of known crocodiles.This view was challenged in 1964, when John Ostrom found the remains of a new and unusual predatory dinosaur. By 1969 Ostrom was able to describe the new dinosaur in sufficient detail and to christen it Deinonychus (‘terrible claw’) in recognition of a wickedly hooked, gaff-like claw on its hind foot. Ostrom noted a number of unexpected anatomical features in Deinonychus. It was a relatively large-brained, fast moving predator capable of sprinting on its hind legs and attacking its prey – common sense said that this was no ordinary reptile. These observations prepared the intellectual ground for a revolution that would shatter the then rather firmly held view of dinosaurs as archaic and outmoded creatures that plodded their way to extinction at the close of the Mesozoic Era.One of Ostrom’s students, Robert Bakker, took up this theme by aggressively challenging the view that dinosaurs were dull, stupid creatures. Bakker argued that there was compelling evidence that dinosaurs were more similar to today’s mammals and birds. Mammals and birds are regarded as ‘special’ because they can maintain high activity levels that are attributed to their ‘warm-blooded’, or endothermic, physiology. Living endotherms maintain a high and constant body temperature, have highly efficient lungs to maintain sustained aerobic activity levels, are capable of being highly active whatever the ambient temperature, and are able to maintain large and sophisticated brains; all these attributes distinguish birds and mammals from the other vertebrates on Earth.Bakker argued that far from being slow and dull, dinosaurs were intelligent, highly active creatures that had stolen the world from the traditionally superior mammals for 160 million years in the Mesozoic Era. Rather than being ousted from the world by the evolutionary rise of superior mammals, they had only given up their dominance because of some freakish climatic event 65 million years ago.Which of the following best represents the central idea of the passage?
Solution 1
The central idea of the passage is the evolution of the understanding of dinosaurs. Initially, dinosaurs were viewed as large, slow, and unintelligent reptiles, similar to lizards and crocodiles. This perception was challenged in the mid-20th century, particularly by John Ostrom and his student Robert Bakker, who argued that dinosaurs were more similar to mammals and birds, being intelligent, highly active, and possibly warm-blooded. This shift in understanding reframed dinosaurs not as archaic and outmoded creatures, but as dominant beings that ruled the world for a significant period in the Mesozoic Era.
Solution 2
The central idea of the passage is the evolution of the perception of dinosaurs from being slow, dull reptiles to intelligent, highly active creatures similar to today's mammals and birds. This shift in understanding was largely due to the findings of John Ostrom and his student Robert Bakker, who challenged the traditional view of dinosaurs and argued that they were endothermic, like mammals and birds, rather than ectothermic like reptiles.
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