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  • ♩♩Intro♩♩

  • This week on SciShow News, we're talking about bugs and brains.

  • Exceptnot really true bugs, just some arachnids.

  • Butarachnids and brainsdidn't sound as catchy.

  • Anyway, in a paper published this week in Nature Communications, scientists found two

  • separate clues that teach us a little more about dinosaurs and their parasites.

  • For one, these researchers discovered an extinct tick entangled in a piece of a dinosaur feather.

  • This sample was trapped in a 99-million-year-old chunk of amber from Myanmar, and dates back

  • to the Cretaceous period.

  • The big news here isn't the feather itself, though.

  • It's the tick!

  • Because finding ticks preserved with direct evidence of what they fed on is really rare.

  • In fact, this is the oldest known example.

  • The bit of feather is about two centimeters long and includes more than 50 barbs along

  • a section of the central shaft.

  • It's pretty similar to modern-day bird feathers, but a whole range of dinosaurs from the Cretaceous

  • period had feathers like this, including ground-running dinos and more bird-like species.

  • So we don't know exactly what kind of dinosaur the tick was feeding on, but since this was

  • before modern birds existed, we can definitely rule them out.

  • And that one species wasn't alone in its taste for dinosaur blood.

  • This paper also looked at a separate piece of amber from the same period, with /indirect/

  • evidence that a different extinct tick was also a dinosaur parasite.

  • These ticks weren't all tangled up in feathers, which is why it's indirect evidence.

  • One was full of blood, and another pair of two ticks were preserved close together.

  • The pair had some other junk on them, toothese hair-like structures called setae

  • that came from larval dermestid beetles.

  • This family of beetles is still around today and some species like to hang out in bird

  • nests, eating stray bits of feathers and skin... all that delicious stuff.

  • We know some dinosaurs built nests too, so both the ticks and beetles were probably living

  • in one, hoping to score a meal.

  • The researchers also say that a drip of plant resin would be more likely to trap two unfed

  • ticks at once if they were hanging out in a nest together.

  • But, Jurassic Park aside, we won't be able to clone a feathered dinosaur from blood in

  • any of these old ticks.

  • No one's ever actually extracted DNA from insects preserved in amberthere are just

  • too many things that can go wrong or break down.

  • So for now, that's still the stuff of sci-fi.

  • But our second topic is something that happens to humans all the time.

  • Picture this: you're walking down the sidewalk when you realize that, right where your foot

  • is about to land, is a pile of dog poop.

  • You see it there, and you desperately try to adjust, but you know... plop.

  • You're weight is going down any way and... it's happened

  • But a group of researchers from Johns Hopkins University may have figured out why it's

  • so hard to stop doing something while your body is in motion.

  • Previously, scientists thought that only one region of the brainpart of the prefrontal

  • cortexwas involved in sending that last-minutestop!” signal after the brain directs

  • our muscles to move.

  • But now we know that getting this signal out actually requires super-fast coordination

  • between two different parts of the prefrontal cortex, plus part of the premotor cortex.

  • To figure this out, scientists gave 21 human subjects and one macaque monkey mostly similar

  • tasks while taking a peek at what their brains were doing.

  • The humans had their brain activity monitored with fMRI, which measures general blood flow

  • patterns.

  • And the monkey had electrodes implanted in its brain to monitor some individual neurons.

  • We didn't do that to the people... because we didn't want to cut their brains open.

  • In the main test, the subjects saw one of two shapes on a computer screen, which told

  • them whether blue was going to mean go and yellow was going to mean stop, or vice versa.

  • Then, a black circle would pop up, and the study participants would quickly move their

  • eyes to look at it.

  • But if a blue or yellow dot appeared, they would have to either stop or keep going with

  • their eye movement, depending on that initial shape and its meaning.

  • A previous version of this experiment used a simpler task.

  • But doing it this way let the researchers estimate signals related to different parts

  • of it, like watching for the shape on the screen versus sending the message to stop

  • motion.

  • The data suggest that one part of the prefrontal cortex identifies and interprets information

  • signals, and another part registers the intent to stop the motion.

  • Both regions seem to coordinate with another brain region in the premotor cortex, which

  • controls the eye movement.

  • And whether they successfully stopped or not or not depended on the timing.

  • The researchers calculated that if a subject's decision took more than about a quarter of

  • a second, then the originalmove!” signal was already on its way to the muscles and

  • couldn't be changed or stopped.

  • They even suggest that this could help explain why people might stumble more as they get

  • olderaging brains communicate more slowly, so they might not be able to put on the brakes

  • as easily when they need to.

  • But, as always, there's a lot more research left to do.

  • Thanks for watching this episode of SciShow News, and thanks especially to all of our

  • patrons on Patreon who make this show possible.

  • If you want to help us keep making videos like this for the whole world for free, you

  • can go to patreon.com/scishow­.

  • And don't forget to go to youtube.com/scishow and subscribe!

  • ♩♩Outro♩♩

♩♩Intro♩♩

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Dinosaurs Had a Bloodsucking Enemy

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    joey joey posted on 2021/05/13
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