Speaker 1: Welcome to brain Stuff, a production of iHeart Radio, Hey
Speaker 1: brain Stuff Lauren Bogle bomb here. Sue is the largest,
Speaker 1: most complete Tyrannosaurus Rex skeleton in the world. Sue is
Speaker 1: an impressive specimen, standing more than thirteen feet that's four
Speaker 1: meters tall and forty two ft or thirteen meters long.
Speaker 1: Many dinosaur fossils have missing or broken bones, but Sue
Speaker 1: is more than complete, so it was also often displayed
Speaker 1: as a real skeleton, not a cast. The bones that
Speaker 1: you can see are the real sixty seven million year
Speaker 1: old deal. Paleontologist Sue Hendrickson discovered the dinosaur's bones in
Speaker 1: South Dakota on August twelfth of nine. Since then, researchers
Speaker 1: have figured out a lot about Sue's life. In spite
Speaker 1: of breaking some ribs, Sue lived to a relatively old
Speaker 1: age for a dinosaur, at least according to signs of
Speaker 1: wear on the bones. A Researchers also estimate that the
Speaker 1: dinosaur weighed about seven tons, which is around as much
Speaker 1: as a male African elephant. But what scientists don't know
Speaker 1: is whether Sue was male or female. With just about
Speaker 1: all living animals that use sexual reproduction, it's pretty easy
Speaker 1: to figure out which sex is which, all you have
Speaker 1: to do is observe their behavior or take a look
Speaker 1: at their sex organs. Figuring out the sex of a
Speaker 1: dinosaur is a little trickier though there aren't any around today,
Speaker 1: so you can't observe their behavior, and since sex organs
Speaker 1: are made of soft tissue, they don't fossilize well. On
Speaker 1: top of that, most paleontologists believe that dinosaurs, like birds,
Speaker 1: used one opening called a cloaca for both reproduction and
Speaker 1: expulsion of liquid and solid waste, so even if researchers
Speaker 1: find a dinosaur fossil with well preserved skin, they still
Speaker 1: may not know it's sex for sure. DNA master reference
Speaker 1: for figuring out what's what isn't much help with dinosaurs either.
Speaker 1: While you can usually tell male and female mammals apart
Speaker 1: by their X and Y chromosomes, reptiles don't follow those rules.
Speaker 1: In many reptilian species, the temperature of the egg, not
Speaker 1: the chromosomes inside it, determines the sex. Plus DNA breaks
Speaker 1: down during fossilization, leaving little for researchers to analyze. But
Speaker 1: that doesn't mean figuring out the sex of a dinosaur
Speaker 1: fossil is impossible. Every once in an extremely long while,
Speaker 1: researchers might find a skeleton with eggs inside it a
Speaker 1: pretty good clue that one was female. One such find
Speaker 1: cropped up in China in two thousand five, but eggs
Speaker 1: aren't always the best indicator. It might seem likely that
Speaker 1: a skeleton perched to top a nest of eggs belonged
Speaker 1: to a female, but it's just as likely that male
Speaker 1: dinosaurs like male EMUs and ostriches were the ones that
Speaker 1: did the brooding. Another potential way of dividing males from
Speaker 1: females is through studying sexual dimorphism. To think of male
Speaker 1: peacocks that display huge ornate tails to attempt to impress
Speaker 1: relatively nondescript female p hens. It could be that differences
Speaker 1: in neck frills and head crests had to do with
Speaker 1: the dinosaurs need to attract a mate. The size and
Speaker 1: proportion of a dinosaur's body may have been sex related
Speaker 1: to Paleobiologist Phil Center hypothesizes that the ultralong necks of
Speaker 1: animals like a patosaurus may have evolved through sexual selection,
Speaker 1: with longer necked dinosaurs attracting more or better mates. The
Speaker 1: only trouble with this theory is that even if there
Speaker 1: are sex differences in dinosaurs, we still don't know which
Speaker 1: sexes which. Did a female triceratops use its neck frill
Speaker 1: to attract a mate or was it the other way around,
Speaker 1: where horns and tail spikes for defense against predators or
Speaker 1: for combat with rival males. Without preserved samples of sex
Speaker 1: organs or a time traveling look at dinosaur behavior, it's
Speaker 1: impossible to say. Aside from the serendipitous find of a
Speaker 1: dinosaur fossil filled with eggs or researchers have found and
Speaker 1: one way to figure out if a dinosaur is female,
Speaker 1: at least if she was pregnant at the time of
Speaker 1: her death. In two thousand five, in the journal Science,
Speaker 1: a team of researchers reported the discovery of what's called
Speaker 1: medillary or medillary bone and a Tyrannosaurs rex fossil. In
Speaker 1: birds which have hollow bones, medillary bone lines the interior
Speaker 1: cavity of females bones. Birds use this type of bone
Speaker 1: as a reservoir for the calcium they need to produce eggshells.
Speaker 1: In all likelihood, the t rex whose bones the team
Speaker 1: was studying was both female and pregnant. Unfortunately, Researchers can
Speaker 1: only determine the sex of dinosaurs this way by breaking
Speaker 1: into the interior of the bone. On top of that,
Speaker 1: it only works that the dinosaur was pregnant when she died.
Speaker 1: With groundbreaking discoveries like this and well preserved fossils still
Speaker 1: being unearthed, it may one day be possible to make
Speaker 1: a pretty good guess about a dinosaurs sex, but for
Speaker 1: right now, it's a shot in the darkness m Today's
Speaker 1: episode was written by Tracy V. Wilson and produced by
Speaker 1: Tyler Clang. For more on this and lots of other
Speaker 1: curious topics, visit how stuff works dot com. Brain Stuff
Speaker 1: is production of I Heart Radio. Or more podcasts. To
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