Dino diversity had a long pedigree

PARIS (AFP) - The belief that dinosaurs underwent explosive species diversification just before they were wiped out is an illusion, for the beasts’ main evolutionary shifts took place millions of years before, a study says.
The strange demise of the dinosaurs at the end of the Cretaceous era some 65 million years ago has given rise to a popular view that almost has the tinge of Greek tragedy.
Just as the rulers of the Earth had reached their evolutionary zenith, a catastrophic event - possibly a space rock that slammed into Earth - brought the curtain down on their long reign.
Scientific support for this view comes the number of dinosaur fossils dating from a period called the Cretaceous Terrestrial Revolution, between 125m to 80m years ago, when Earth’s book of life was changed forever.
During this epoch of riotous biodiversity, flowering plants, social insects, butterflies, modern groups of lizards, mammals, and possibly birds, too, all emerged.
Some experts have suggested that dinosaurs were also part of the show, as so many weird fossils, such as duckbilled hadrosaurs, horned ceratopsians, pachycephalosaurs and other wonders, date from this time. But a new study, published on Wednesday in a British journal Proceedings of the Royal Society B, says that dinosaurs were less than a sideshow in the DNA spectacular.
Researchers led by Graeme Lloyd of the University of Bristol, western England, devised a “supertree” of dinosaur evolution, patiently analysing how more than 450 species - about 70pc of the known finds - developed.
They conclude that the big evolutionary splurge for dinosaurs occurred in the Late Triassic, some 225m to 200m years ago. This was about 15-40m years after dinosaurs first emerged.
A second, but smaller, diversification occurred in the Mid Jurassic, some 170 to 160m years ago.
By that time, all the main dinosaur lineages that were hoofing around in the Cretaceous Terrestrial Revolution had been established.