New species of ancient reptile was an apex predator of the Middle Triassic

First unearthed some six decades ago in Tanzania, the remains of an ancient relative of modern crocodiles have now been formally described as a new species.

The large, formidable reptile lived at a time when the dinosaurs were only just appearing and would soon take over as the dominant animals on land. This active land predator would have been a fearsome sight, and probably the largest carnivore in its ecosystem.

The fossil remains consist of part of its skull, revealing a series of impressive looking curved and serrated teeth, as well as parts of its vertebrae and hand. It would have looked unlike any animal alive today, with a large powerful head, barrel-chested muscular body, upright stance and long tail allowing it to tackle any unfortunate prey it came across. 

The exact person who discovered the fossil was not recorded, but it was likely a local Tanzanian. The expedition was heavily reliant on the local people for their intimate knowledge of the land and the locations of where fossils had been found in the past, and for assistance in excavating the fossils.

The name of the new species, Mambawakale ruhuhu, is derived from the Kiswahili words for 'mamba', meaning crocodile, and 'wakale', which refers to its ancient age. Meanwhile, its specific name is a reference to the Ruhuhu Basin in southwestern Tanzania where the fossils were discovered.

The authors of the new study wanted to highlight the contributions of Tanzanians to the discovery and collection of the fossils as their critical roles were underplayed in previous reports of the 1963 expedition.

While the late Museum palaeontologist Dr Alan Charig, who is most well-known for his role in helping to describe the dinosaur Baryonyx, studied the fossils from the Manda Beds and recognised that Mambawakale was likely a new species, he never actually published this work.

By going back and looking at the fossils again, a team of researchers have finally been able to determine that Alan was right and have now officially named the new species and described its anatomy in detail in the journal Royal Society Open Science.

Dr David Gower, a researcher of amphibians and reptiles in the Museum an co-author of the paper, says, 'This is one of the last major archosaur fossils from the 1963 expedition that had remained unstudied. It’s fantastic to be able to finally share this wonderful fossil with the world, nearly 60 years after it was discovered.'

The study was a collaboration between three Museum scientists and colleagues at the University of Birmingham (UK) and Virginia Tech (USA).

A modern toolkit

The fossil skull remains of the new species were difficult to interpret because the condition of preservation meant that the connections between the bones, which can be used to better understand how an animal was related to other known species, were almost entirely invisible from the outside.

The team were able to solve this problem by undertaking computed tomography (CT) scanning of the skull in the Museum's Imaging and Analysis Centre. This technique makes use of X-rays to create 3D models of internal and external features. CT scanning of the Mambawakale ruhuhu skull allowed the team to identify the hidden sutures and describe each skull bone in detail.

A moment of change

The newly described fossils were found during an expedition to Tanzania in 1963 that included researchers from the South African Museum, the Uganda Museum, the University of London, the University of Edinburgh and the Museum, as well as the local people whose knowledge and efforts have previously gone largely unheralded.

The team were excavating a formation known as the Manda Beds. Dating to the Middle Triassic, some 247 to 242 million years ago, these rocks were formed during a key moment in the evolution of life on land. 

During this period of time, the dominant animals on land were shifting. At the start of the Triassic, a group of animals known as the synapsids, which included animals such as the sail-backed Dimetrodon and the ancestors to all mammals, were at the top of the food chain. But by the middle of the Triassic things were changing. 

At this point in time, the reign of the synapsids began to ebb and a group known as the archosaurs started to become more dominant. Archosaurs form a group that contains modern crocodiles and birds, but also included dinosaurs and pterosaurs. 

Top of the food chain

The Manda Beds is significant for recording this shift. Originally explored by professional scientists in the 1930s, it has already revealed notable specimens such as remains of Nyasasaurus parringtoni, which is believed by some to be one of the earliest dinosaurs to have been discovered.

But the formation also contains a wealth of other important archosaur remains that help to flesh out our understanding of the burst in diversity of this group at this moment in time. This includes animals such as Mambawakale ruhuhu, which was a type of pseudosuchian.

These were heavily built, fearsome animals that are more closely related to modern crocodiles and alligators than to birds, dinosaurs or pterosaurs. Unlike modern crocodiles they were probably not semiaquatic, had an upright gait, and had heads that were more flattened side-to-side than top-to-bottom.

They would have stalked the environment looking to predate on anything they could sink their long, steak knife-like teeth into, be it an early dinosaur, an early mammalian ancestor or any other creatures small enough to be prey.

But even among pseudosuchians, Mambawakale was an impressive animal. Its head was chunky even in comparison to other pseudosuchians from the Middle Triassic, meaning that it was likely the apex predator within its ecosystem.