This idea was inspired by a recent BBC article on the rise of the dinosaurs and the extinction of the large non archosaur reptiles-the formally highly successful Therapsids and the Synapsids.
This mass extinction, which took place roughly 201.3 million years ago is, like the more famous K-T extinction, is very mysterious. Several conflicting theories exist over its cause, though evidence is very sparse for this period.
One theory suggests that given the comparative speed of the extinction, it was ( ironically) a meteorite, though currently no meteorite craters on the scale to cause such destruction dating from that period exists. Another theory suggests a series of volcanic eruptions in the flood basalt in the central Atlantic magnetic province released carbon, sulphur dioxide and aerosoles that caused either intense global warming or cooling. However, the most accepted theory is that it was caused by millions of years global warming, bought on by the acidification of the oceans and sea-level fluctuations that finally tipped over the edge. Of course, this itself poses more questions since such an extinction would be more gradual, then the rapid extinction geologists and paleontologists have observed.
http://en.wikipedia.org/wiki/Triassic–Jurassic_extinction_event
Whatever caused it though, its effects are more noticable, most notably, the mass extinction of around 70% of all species and 23% of all families were wiped out. Among st these casualties, were the long lasting Synapsids, most notable for the highly successful Lystrosaurus- arguably the most successful terrestrial animal ever.
http://en.wikipedia.org/wiki/Lystrosaurus
This extinction is important for us since it paved the way for a new line of bipedal reptiles to take over-the Archosaurs whose ancestors were the Dinosaurs. In the article, the author hypothesizes that without the extinction event Synpasids would continued to evolve into large mammal like reptiles, taking over the oceans and forcing the dinosaurs to inherit the niche that mammals occupied OTL as small scavengers and insectivorous. Then, when they are wiped out by the K-T event, dinosaurs and mammals will occupy the niches and compete against each other.
Is this hypothesis accurate? Firstly, it assumes ( wrongly) that dinosaurs couldn't simply out compete the synapsids, despite the fact that by the end of the Triassic dinosaurs had already diversified into both theropods, sauropods ( Plateosaurus.) The first dinosaur that we know of, Nyasasaurus parringtoni, lived around 250 million years ago, though their direct ancestor Asilisaurus kongwe had existed long before this.
http://www.bbc.co.uk/news/science-environment-20594147
http://news.bbc.co.uk/1/hi/sci/tech/8547735.stm
I think its fair to assume that dinosaurs would have out competed synapsids in the long term anyway, merely delaying their dominance, that is the extinction at the end of the Jurassic hadn't finished off the synapsids. But what do you think? And what other effects would no Triassic/Jurassic extinction have?
This mass extinction, which took place roughly 201.3 million years ago is, like the more famous K-T extinction, is very mysterious. Several conflicting theories exist over its cause, though evidence is very sparse for this period.
One theory suggests that given the comparative speed of the extinction, it was ( ironically) a meteorite, though currently no meteorite craters on the scale to cause such destruction dating from that period exists. Another theory suggests a series of volcanic eruptions in the flood basalt in the central Atlantic magnetic province released carbon, sulphur dioxide and aerosoles that caused either intense global warming or cooling. However, the most accepted theory is that it was caused by millions of years global warming, bought on by the acidification of the oceans and sea-level fluctuations that finally tipped over the edge. Of course, this itself poses more questions since such an extinction would be more gradual, then the rapid extinction geologists and paleontologists have observed.
http://en.wikipedia.org/wiki/Triassic–Jurassic_extinction_event
Whatever caused it though, its effects are more noticable, most notably, the mass extinction of around 70% of all species and 23% of all families were wiped out. Among st these casualties, were the long lasting Synapsids, most notable for the highly successful Lystrosaurus- arguably the most successful terrestrial animal ever.
http://en.wikipedia.org/wiki/Lystrosaurus
This extinction is important for us since it paved the way for a new line of bipedal reptiles to take over-the Archosaurs whose ancestors were the Dinosaurs. In the article, the author hypothesizes that without the extinction event Synpasids would continued to evolve into large mammal like reptiles, taking over the oceans and forcing the dinosaurs to inherit the niche that mammals occupied OTL as small scavengers and insectivorous. Then, when they are wiped out by the K-T event, dinosaurs and mammals will occupy the niches and compete against each other.
Is this hypothesis accurate? Firstly, it assumes ( wrongly) that dinosaurs couldn't simply out compete the synapsids, despite the fact that by the end of the Triassic dinosaurs had already diversified into both theropods, sauropods ( Plateosaurus.) The first dinosaur that we know of, Nyasasaurus parringtoni, lived around 250 million years ago, though their direct ancestor Asilisaurus kongwe had existed long before this.
http://www.bbc.co.uk/news/science-environment-20594147
http://news.bbc.co.uk/1/hi/sci/tech/8547735.stm
I think its fair to assume that dinosaurs would have out competed synapsids in the long term anyway, merely delaying their dominance, that is the extinction at the end of the Jurassic hadn't finished off the synapsids. But what do you think? And what other effects would no Triassic/Jurassic extinction have?
