A UT anthropologist and a team of international researchers have announced the discovery of a new, relatively massive fossil mammal that lived among the dinosaurs more than 66 million years ago.
Chris Kirk, associate professor of anthropology and an expert in the evolution of primate sensory systems, said Stony Brook University paleontologist David Krause led the research team that unexpectedly discovered a nearly complete cranium of the mammal, Vintana sertichi, which lived alongside Late Cretaceous dinosaurs in Madagascar.
The discovery helped researchers determine Vintana had a body mass of about 20 pounds, making it one of the largest mammals from the entire Mesozoic Era (252 to 66 million years ago). Vintana is part of an enigmatic group of mammals called the Gondwanatheria that is known only from southern continents. Researchers had previously discovered only isolated teeth and jaw fragments of gondwanatheres, so Vintana provides the first window into the cranial anatomy of this group. The findings were published in the science journal Nature.
Kirk worked with a team of researchers focused on the anatomy of the brain and sense organs of Vintana. “It was an opportunity that doesn’t come along very often – the chance to be one of the first scientists to study the cranial anatomy of a major group of fossil mammals,” Kirk said. The analyses of Kirk and his colleagues suggest that Vintana had large eyes, a sensitive nose, and good high-frequency hearing.
“Its eye sockets are enormous,” Kirk said. “Mesozoic mammals are typically reconstructed as having small eyes and poor vision, so Vintana really stands out in this respect.” Kirk also notes that Vintana is unusual in possessing a complex bony support network for the hearing organ of its inner ear – an arrangement otherwise found only in marsupials, placental mammals, and their close fossil relatives. “This feature is probably tied to an improved ability to hear high frequencies, so it’s a good bet that Vintana had better high-frequency hearing than modern egg-laying mammals like the platypus and echidna.”
Dr. Zhe-Xi Luo, a leading expert on early mammalian evolution from the University of Chicago who reviewed the manuscript for Nature, hailed the Vintana as “the discovery of the decade” for understanding the deep history of mammals, offering the best case of how plate tectonics and biogeography have impacted animal evolution.