The dinosaur family tree may need a fundamental rethink, according to new research. The headlines have focused on this latest development, but there have been other important advances in our understanding of dinosaur evolution in recent months.
Dinosaurs have been divided into two families for more than a century. Stegosaurus, Triceratops and others with hip bones similar to modern birds are classified as Ornithischia. Meanwhile, those with hip bones closer to today’s reptiles – such as Brontosaurus and Brachiosaurus - fall under Saurischia. Tyrannosaurus Rex and Velociraptor are also classed as Saurischia, in the sub-family Theropodia. However, the new study suggests Theropodia are more closely related to Ornithischia than Saurischia, and calls for a new clade – Ornithoscelida – that combines Theropodia and Ornithischia. The paper also suggests that the definition of ‘dinosaurs’ may need to be revised, as species such as Diplodocus don’t fit the bill. And it convincingly argues that the first dinosaurs were omnivores; the prevailing theory is that they were a mix of carnivores, herbivores and omnivores.
Other discoveries have shaken up our understanding of dinosaur evolution, albeit to a lesser extent. Last year, palaeontologists unearthed hundreds of footprints and handprints made by Sauropods – a Saurischia sub-family - on the Isle of Skye, Scotland. The finding revealed the enormous creatures were distant relatives of Diplodocus and spent lots of time in coastal areas and shallow water. Researchers have also proposed that dinosaurs evolved to run on two legs in order to achieve faster speeds, rather than to free their forelimbs to serve as predatory weapons. And even the causes of dinosaurs' extinction are up in the air, after scientists found evidence that their eggs took several months to hatch, and snakes, birds and mammals evolved to more easily destroy the nests of ground-laying dinosaurs at the time of their mass extinction.
Dinosaur research rarely grabs headlines, largely because it concerns creatures that lived more than 65 million years ago. But the immense popularity of Jurassic Park – and, 22 years later, Jurassic World – point to enduring public fascination with these fantastical beasts. Yet despite widespread enthusiasm and ever-better investigative techniques and technologies, it’s evident there’s much more to learn about dinosaur ecology and evolution.