Cambrian Radiation & Mass Extinctions I

The Cambrian Radiation is characterised by the evolution of....

• skin

• skeletons

• feathers

• lungs

In the deep divergence model for the Cambrian Radiation, animal body plans (phenotypes) evolved....

• rapidly after the genotype

• long after the genotype

• during the Cambrian

• none of the above

Why are deep divergence dates for basal animal groups hard to estimate?

• Rates of genetic change may be wrong

• We haven't got any fossil calibration points

• Both of the above

• None of the above

This is Cloudina, a member of the famous "smally shelly fossil" assemblage. It proves that....

• Animals evolved skeletons during the Cambrian Radiation

• Animals evolved skeletons after the Cambrian Radiation

• Animals evolved skeletons shortly before the Cambrian Radiation

• None of the above

Which of these groups probably arose around 700 Ma? 

• 
• 
• 
• 

What was the biggest impact of the evolution of the gut during the Cambrian radiation?

• change in ocean circulation

• microbial extinction

• decrease in atmospheric oxygen

• evolution of faecal pellets

Most of the coloured circles in the blue vertical bar on this phylogenetic tree occur in the late PreCambrian-Early Cambrian. This shows that most major animal groups originated....

• before the Cambrian

• during the Cambrian

• after the Cambrian

• none of the above

Why were the Late PreCambrian and Cambrian oceans so rich in phosphate?

• extinction of the Ediacarans

• changes in the Earth's orbit

• increased upwelling

• more skeletons

On a phylogenetic tree, what's a calibration point?

• A node where a new group originates

• A known fossil occurrence

• An extinction event

• A polytomy

The Cambrian Radiation may not be a typical adaptive radiation because the animal groups involved....

• may not have existed before the event

• all existed before the event

• aren't preserved

• got smaller