Dragon-like reptiles with huge heads and ‘steak knife’ teeth lived before the dinosaurs
Scientists have been studying the heads of ancient predators to find out more about life before the dinosaurs.
About 250 million years ago, reptiles called erythrosuchids - loosely translated as 'red crocodiles' - flourished. These reptiles had huge heads and powerful jaws, and included the largest land predators to have lived on Earth by that time.
One of these was an animal called Garjainia. About three metres long, the carnivores walked on four legs and looked like modern-day Komodo dragons. Their remains have been found in South Africa and Russia.
Not much is known about the Russian specimens, but scientists from the Museum and the University of Birmingham have collaborated with experts from Oxford, Moscow and Buenos Aires to study fossilised remains of skeletons from seven individuals, including a nearly complete skull.
It was thought that the skull fossils belonged to two distinct species of erythrosuchid called Garjainia prima and Vjushkovia triplicostata. On closer inspection, it was found the bones are all similar enough to be considered only a single species, Garjainia prima.
The team also confirmed that erythrosuchids like Garjainia had huge heads in comparison to their bodies.
The findings have been published in Royal Society Open Science.
Prof Richard Butler is a palaeontologist at the University of Birmingham and lead author of the study. He says, 'There are lots of animals from this period of time that were bizarre and interesting but we don’t know much about them at all.
'I am studying them because I want to know more about the evolutionary origins of a group of animals called archosaurs. That includes the dinosaurs, as well as birds and crocodiles.'
Although they never lived alongside the dinosaurs, erythrosuchids are distantly related to them. They would have dominated the ecosystem just like their dinosaur relatives.
Prof Butler worked on the specimens alongside Dr David Gower, a merit researcher at the Museum and a world expert on these animals. Museum palaeontologists Dr Susannah Maidment and Thomas Raven also worked on the study.
Dr Gower says, 'Our Moscow colleague Andrey Sennikov and I planned a reappraisal of this material this when we first worked together in the 1990s, but with additional experts involved we were able to be part of a much better study.
'Garjainia prima is now probably the best known erythrosuchid, and this will hopefully help to better understand the early history of the rise of the archosaurs during the Triassic.'
When Garjainia was around, the planet had recently (in geological terms) suffered the biggest extinction in its history. The Permian-Triassic extinction wiped out 90% of living things. There is evidence that the main driver of the extinction was a series of huge volcanic eruptions.
Life eventually bloomed again after the extinction period, and one of the new groups that emerged was the erythrosuchids.
The paper shows that relative to the overall size of the body, erythrosuchids had some of the largest heads of any reptiles.
That could have been because they were hypercarnivores - animals with diets almost exclusively composed of meat.
Richard says, 'These animals had an outlandishly large head, and we don't know for sure why this was the case. We think it might have been linked to their role as the top predators in a number of Triassic ecosystems. Having a big, powerful head and bite is likely to be useful in capturing prey.'
Massive heads were a common feature among predators of this time. Although species of Garjainia grew to about three metres, other erythrosuchids got much larger. Erythrosuchus africanus, from South Africa, was over five metres long, had a head that was over a metre in length and had teeth almost as large as those of T. rex.
Richard adds, 'These are bizarre animals, but much about their biology remains unstudied. They presumably must have had very powerful neck muscles to support such a massive head, but detailed studies of their muscles have not yet been done.'
Erythrosuchids were only around for a relatively short period of geological time, in the Triassic, from about 250–238 million years ago. They vanished before the first dinosaurs appeared.