Twice hit by climate change
#GS3 #CLIMATE #GS1 #GEOGRAPHY
Global warming may have killed many dinosaurs 179 MYA
- Most people know that land-dwelling dinosaurs were wiped out some 66 million years ago when a huge asteroid crashed into Earth.
- If not this, the plunge in global temperature on a planet with little or no ice, caused by a blanket of heat-shielding debris in the atmosphere, would have killed them.
- New research says, more than 100 million years earlier, another climate change cataclysm – a global warming – devastated a different set of dinosaur species, with many going extinct.
- Scientists have found evidence of this traumatic event some 179 million years ago in plant fossils in Argentine Patagonia.
- They also discovered a previously unknown dinosaur, named Bagualia alba. This is in the family of massive, long-necked sauropods, the largest animals to walk the Earth.
- Before the global warming event, sauropods were only one branch of the Sauropodomorpha lineage.
- Other dinosaurs in the same group were smaller and lightly built, with some no bigger than a goat.
- But a series of volcanic eruptions over several million years released huge amounts of CO2 and methane in the atmosphere, warming the planet and transforming the vegetation dinosaurs fed on.
- The climate went from a temperate, warm and humid with diverse lush vegetation to a strongly seasonal, hot-and-dry regime.
- Smaller Sauropodomorpha dinosaurs were unable to cope with the change, but larger sauropods – like Bagualia alba – thrived.
- “Sauropods are massive, four-legged animals with long necks,” which meant they could reach the tops of trees.
- Their very robust mandibles and spoon-shaped teeth were adapted to feed on all kinds of plants such as conifer trees.
- Conifers in the early Jurassic had tough and leathery leaves that would be a challenge for any herbivore.
- But that gave Bagualia alba an advantage over other Sauropodomorpha dinosaurs.
- Sauropods’ new diet saw them expanded in size from 10 metres to 40 metres in length, as large digestion chambers were needed to cope.
- They became the dominant group of herbivores and eventually the largest animals to ever walk the Earth.