A team of scientists has identified a new species of “pre-mammal” based on fossils unearthed in Zambia’s Luangwa Basin in 2009. The ancient, Dachshund-sized creature lived some 255 million years ago, in a time just before the largest mass extinction in Earth’s history.
Its discoverers include Christian Sidor, professor of biology at the University of Washington and curator of vertebrate paleontology at the Burke Museum of Natural History and Culture. Sidor and his colleagues, who announced their finding in July in the Journal of Vertebrate Paleontology, have named the creature Ichibengops munyamadziensis — or “Scarface of the Munyamadzi River.” This colorful designation combines the discovery location with the Bemba word for scar, “ichibenga,” since this long-extinct cousin of the mammalian lineage sported a unique groove on its upper jaw.
“Discoveries of new species of animals like Ichibengops are particularly exciting because they help us to better understand the group of animals that gave rise to mammals,” said senior author Kenneth Angielczyk of Chicago’s Field Museum of Natural History.
Ichibengops was a member of an extinct lineage of mammal-like reptiles called therocephalians or “beast-heads,” which refers to the mammal-like qualities of their skulls. Its closest known relative is a therocephalian that lived in Russia at about the same time. Therocephalians are a sister lineage to the reptilian ancestors of modern day mammals and may have independently evolved some mammal-like characteristics.Ichibengops, for example, had a hard, bony palate. But the diminutive carnivore also sported an unexpected feature.
“One interesting feature about this species in particular is the presence of grooves above its teeth, which may have been used to transmit venom,” said Angielczyk.
If so, this would be a rare finding among therocephalians, mammal-like reptiles and even mammals. Among mammals alive today, only the duck-billed platypus and several shrew species produce venom.
“There is only one other therocephalian that seems to show indications of being venomous,” said Sidor, referring to the extinct therocephalianEuchambersia. “However, it’s very difficult to assess function in fossils, so we can never be 100 percent certain.”
Therocephalians thrived during Earth’s Permian Period, which came to a cataclysmic end about 252 million years ago in the largest mass extinction in history. Some 90 percent of species went extinct, though some therocephalian species survived into the Triassic Period, the beginning of the so-called “age of dinosaurs.”
“In the grand scheme of things, therocephalians did quite well, considering that they didn’t go extinct at the Permian-Triassic mass extinction,” said Sidor. “However, their diversity was greatly decreased and the group never fully recovered. They went extinct about 8 million years later.”
Though nearly 250 million years have passed since Ichibengops and its relatives roamed underfoot, the curious case of therocephalians at such a turbulent time in Earth’s history still holds relevance today.
“By studying the effects of the Permian-Triassic mass extinction and the subsequent recovery, we can apply the lessons we learn to the mass extinction being caused by humans today,” said Angielczyk.
Source: University of Washington