Scientists have identified a new species of pre-mammal: an ancient Dachshund-sized creature that lived about 255 million years ago in a time just before the largest mass extinction in Earth’s history.
The creature has been named Ichibengops munyamadziensis—or “Scarface of the Munyamadzi River,” a colorful designation that combines the discovery location with the Bemba word for scar, “ichibenga,” since the long-extinct cousin of the mammalian lineage sports 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,” says 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.
Venom is a surprise
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,” Angielczyk says.
If so, this would be a rare find 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,” says Christian Sidor, professor of biology at the University of Washington and curator of vertebrate paleontology at the Burke Museum of Natural History and Culture, referring to the extinct therocephalian Euchambersia. “However, it’s very difficult to assess function in fossils, so we can never be 100 percent certain.”
Therocephalians ‘did quite well’
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,” Sidor says. “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,” Angielczyk says.
Adam Huttenlocker, who earned his doctoral degree in biology under Sidor, and is now a postdoctoral researcher at the University of Utah, is lead author of the paper that is published in the Journal of Vertebrate Paleontology.
The National Science Foundation, the National Geographic Society, the Granger Foundation, and the Field Museum/IDP Foundation, Inc. African Partners Program supported the work.
Source: University of Washington