What is the End–Ordovician extinction event?
Q: What is the End–Ordovician extinction event?
A: The End–Ordovician extinction event is the third-largest extinction event of the Phanerozoic eon. It occurred during the Ordovician period, which followed the Cambrian and was followed by the Silurian.
Q: What type of organisms were affected by this extinction event?
A: The biota affected by this extinction event was almost entirely marine, with no living things on land except for bacteria and perhaps some single-celled algae. More than 100 invertebrate families became extinct in this event, including brachiopods, bryozoans, trilobites, conodonts and graptolites.
Q: How did this extinction occur?
A: This extinction occurred in two steps - firstly a climate change from very warm to very cold caused turnover of water in seas and rising anoxic water killed most plankton; secondly a warming ocean re-established glaciers melted and anoxic conditions reached continental shelves killing fauna again.
Q: What caused these climate changes?
A: The cause of these climate changes was likely due to the rise and erosion of the Appalachian Mountains which put much CO2 into the atmosphere then took it out again.
Q: How many genera were affected by this extinction event?
A: Almost half of all genera were affected by this extinction event.
Q: Were any land organisms impacted by this mass die off?
A: No land organisms were impacted as there were no living things on land at that time except for bacteria and perhaps some single-celled algae.
Q: Was there evidence of widespread glaciation during this time period? A: Yes, there was clear evidence of widespread glaciation during the cold stage when temperatures dropped significantly.
