Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey
Speaker 1: brain Stuff Lauren Bogebam here with a classic episode from
Speaker 1: our archives. This one deals with one of the weird
Speaker 1: quirks of evolution. Okay, so most of evolution is pretty weird,
Speaker 1: but this is about how turtles developed their shells. You'd
Speaker 1: think it was for protection, but it turns out that
Speaker 1: that was a side benefit of their original purpose. Hey
Speaker 1: brain stuff, Lauren Bogebam here. Many of us have seen
Speaker 1: a turtle tucking itself into its protective shell, pulling in
Speaker 1: not only it's four legs, but its head and tail
Speaker 1: as well. But while its shell shields a turtle's tender innards,
Speaker 1: it wasn't originally designed for that purpose, as an international
Speaker 1: group of scientists has found. Instead, they say the turtle
Speaker 1: shell most likely began as a digging tool. Tyler Lison,
Speaker 1: who is the lead author of the studying question and
Speaker 1: a paleontologist at the Denver Museum of Nature and Science,
Speaker 1: writes that when turtles first began to veloping shells, a
Speaker 1: major evolutionary transition. The process included a broadening of the ribs.
Speaker 1: Broadened ribs made the turtles thoraxic region or chest more rigid.
Speaker 1: But the puzzling thing is that a rigid chest means
Speaker 1: it's harder for the animal to breathe easily or move swiftly,
Speaker 1: hardly changes that appear to enhance protective capabilities, But that's
Speaker 1: because initially, turtle shells made of more than fifty fused
Speaker 1: bones and their broad ribs were developed not for protection,
Speaker 1: but to lend stability to the turtles so it could
Speaker 1: forcefully dig with its forelimbs. The researchers found being able
Speaker 1: to dig into the ground for food and shelter, they
Speaker 1: theorize allowed the turtles to move from the land into
Speaker 1: the water. This may have saved them in their early
Speaker 1: evolutionary history, specifically during the Permian Triassic extinction, the greatest
Speaker 1: mass extinction ever and one which was spurred by hot,
Speaker 1: dry weather. These insights came after two of the studies
Speaker 1: co authors discovered several specimens of a two hundred and
Speaker 1: sixty million year old turtle name you notice, Saurus africanus,
Speaker 1: the oldest known partially shelled proto turtle. These specimens, along
Speaker 1: with another partially shelled turtle found by a young boy
Speaker 1: in South Africa, indicate turtles developed shells for use as
Speaker 1: digging aids. The scientists found similarities between these turtles and
Speaker 1: gopher tortoises, which use their heads and next to brace
Speaker 1: themselves while they dig with their fore limbs. The authors
Speaker 1: believe that the turtle's shell as a protective enclosure is
Speaker 1: an ex adaption, meaning an evolutionary trait that originally served
Speaker 1: one function but winds up serving another. Scientists have been
Speaker 1: arguing for at least two hundred years over whether the
Speaker 1: turtle's shell evolved from bony scales like those on an
Speaker 1: armadillo or certain lizards, or as part of its ribs broadening.
Speaker 1: Thanks to recent discovery of partially shelled stem turtles, it
Speaker 1: now seems that the latter theory is more likely. Today's
Speaker 1: episode is based on the article the You'll reason turtles
Speaker 1: have shells and It's not for protection on how staff
Speaker 1: works dot com, written by Melanie red Seki McManus. Brain
Speaker 1: Stuff is production of i Heart Radio and partnership with
Speaker 1: how stuff works dot Com, and it is produced by
Speaker 1: Tyler Klang. Four more podcasts from my heart Radio, visit
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