Sunday, 13 March 2016

Ichthyosaurs – Ancient Victims of Climate Change

They ruled the oceans for more than 157 million years; dolphin-like marine reptiles called ichthyosaurs. Science learned of ichthyosaurs’ existence early in the nineteenth century with the discovery of the first complete skeleton in England. The order Ichthyosauria (Greek for fish-lizard) was named in 1834.
The mystery surrounding their extinction 66 million years ago towards the end of the Cretaceous period (30 million years prior to the global dinosaur extinction) has prompted many theories. Newly published research suggests the fate of ichthyosaurs was tied to climate change.
Strong fluctuations in temperatures and sea levels 100 million to 94 million years ago during the Cenomanian stage of the Cretaceous period coinciding with intense volcanic action, ice-free poles, rapidly shifting continents and periods of anoxia (a lack of oxygen) on the sea floor affected a large portion of the marine biosphere and significantly changed marine ecosystems.
Ichthyosaurs were unable to successfully evolve new species in response to their quickly changing world.