100 million years fossil found in Tanzania

FOSSIL remains of an ancient crocodile with cat-like features that feasted on insects and other small animals have been recovered from a riverbank in south-western Tanzania.

The short, agile creature lived 105 million years ago, alongside dinosaurs, on a landscape dominated by a large river system and vast floodplains rich with vegetation.The unusual creature is changing the picture of animal life at 100 million years ago in what is now sub-Saharan Africa.

The animal had a small, broad skull, a robust lower jaw and bony protective plates on its back and tail.

Unlike modern crocodiles, it had fewer armoured plates on its body, making it more nimble.

Fossil hunters discovered a complete skeleton of the animal in red sandstone sediments while working along a riverbank in what is now the Rukwa Rift Basin in Tanzania.

Because the specimen was encased in rock with its jaws tightly clamped shut, the team used an X-ray scanner to reveal details of the skull and dentition.

The most curious feature of the animal was its teeth, which were more like those of a mammal than a reptile. While the teeth of modern crocodiles tend to be cone-shaped and pointed at the end to seize and tear prey, the ancient crocodile had a variety, including primitive canines, premolars and molars.

"Once we were able to get a close look at the teeth, we knew we had something new and very exciting," said Patrick O'Connor at Ohio University.

The new species has been named Pakasuchus kapilimai, where Paka means cat in Kiswahili, and suchus comes from the Greek for crocodile. The latter part of the name, kapilimai, honours a late researcher, Saidi Kapilimai, at the University of Dar es Salaam, who led the project.

The animal lived at a time when the southern supercontinent of Gondwana was breaking up into Africa, India, Australia, Madagascar and Antarctica.

Relatively few mammals of a similar age have been uncovered from this part of the world, and it is possible that Pakasuchus occupied a mammalian niche in the Gondwana ecosystem during the period.

The creature is not a close relative of modern crocodiles, but belonged to a successful sidebranch of the lineage, according to details published in the journal Nature. Previous fossil finds show that ancient crocodiles were once more varied in shape and size than those alive today.

Collaborators on the study include Jesuit Temba of the Tanzanian Antiquities Unit, Nancy Stevens and Ryan Ridgely of Ohio University; Joseph Sertich of Stony Brook University; Eric Roberts of James Cook University; Michael Gottfried of Michigan State University; Tobin Hieronymus of the Northeastern Ohio Universities College of Medicine; Zubair Jinnah of the University of the Witwatersrand, South Africa and Sifa Ngasala of Michigan State University and the University of Dar es Salaam.