This preview shows page 1. Sign up to view the full content.
Unformatted text preview: y one of the modern groups. These unassignable animals include a large swimming predator called Anomalocaris and a softbodied animal called Wiwaxia, which ate detritus or algae. The Burgess Shale formation also has fossils of many extinct representatives of modern animal groups. For example, a wellknown Burgess Shale animal called Sidneyia is a representative of a previously unknown group of arthropods (a category of animals that includes insects, spiders, mites, and crabs). 10. Why does the author mention Anomalocans and Wiwaxia?
To contrast predators withanimals that eat plants such as algae
To question the effects of rapid mud slides on fossilization
To suggest that much is still unknown about animals found in the Burgess Shale
To provide examples of fossils that cannot be assigned to a modern animal group 11. idneyia is an example of S a relative of Anomalocaris and Wiwaxia
a previously unknown Burgess Shale animal
an extinct member of a currently existing category of animals
an animal that cannot be assigned to any modern animal group Paragraph7: Fossil formations like the Burgess Shale show that evolution cannot always be thought of as a slow progression. The Cambrian explosion involved rapid evolutionary diversification, followed by the extinction of many unique animals. Why was this evolution so rapid? No one really knows. Many zoologists believe that it was because so many ecological niches were available with virtually no competition from existing species. Will zoologists ever know the evolutionary sequences in the Cambrian explosion? Perhaps another ancient fossil bed of softbodied animals from 600millionyearold seas is awaiting discovery. 12. What can be inferred from Paragraph7 about why the Cambrian explosion is so unusual?
It generated new ecological niches through the extinction of many unique animals.
It was a period of rapid evolution, and evolution is often thought of as a slow process.
It is a period whose evolutionary sequences are clearly marked.
It generated a very large number of ancient fossil beds containing softbodied animals. Paragraph3: One interpretation regarding the absence of fossils during this important 100millionyear period is that early animals were soft bodied and simply did not fossilize. ■ Fossilization of softbodied animals is less likely 198
[email protected] 在在在在在在 www.liuwenyong.com 在在在在在在在在在在在在在在在,在在在在在在在在在在
than fossilization of hardbodied animals, but it does occur. ■ Conditions that promote fossilization of softbodied animals include very rapid covering by sediments that create an environment that discourages decomposition. ■ In fact, fossil beds containing softbodied animals have been known for many years. ■ 13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.
It is relatively rare because the fossilization of softbodied animals requires a special environment.
Where could the sentence best fit? 14. Directions...
View Full Document
This note was uploaded on 09/17/2013 for the course LANGUAGE 13DL208 taught by Professor Wang during the Fall '13 term at East China Normal University.
- Fall '13