Previous: What Happens After You Flush?
Next: How Do We Measure the Distance of Stars?



View count:321,524
Last sync:2022-12-31 09:30
SciShow News introduces you to the most massive land animal ever to walk the earth (pretty much) and tells you what’s going on with all of these earthquakes lately.

If you liked this video, check out more videos about natural history and paleontology on SciShow's sister channel, Eons:

Hosted by: Hank Green
Messages from our Subbable subscribers:
Like SciShow? Want to help support us, and also get things to put on your walls, cover your torso and hold your liquids? Check out our awesome products over at DFTBA Records:

Or help support us by subscribing to our page on Subbable:
Looking for SciShow elsewhere on the internet?

Thanks Tank Tumblr:

OK, what’s long, old, and kinda takes a while to explain?
The plot of Game of Thrones? No. I’m thinking here about the discovery, announced this week in the journal Scientific Reports, of the most massive dinosaur ever measured.
Paleontologists working in Argentina unearthed two giant fossils of a new type of titanosaur, the group of plant-eaters that hold the title as the heaviest animals that ever walked the Earth.
When it lived, some 77 million years ago, the newly found species was at least 26 meters long -- the size of an eight-story building -- and weighed 60 metric tons. That’s about as much as a dozen African elephants or more than seven T. rexes.
That’s how big the larger of the two specimens was, and its bones indicate that it wasn’t even fully grown by the time it had died.
Scientists named the new genus Dreadnoughtus, which means “nothing to fear,” which I imagine it didn’t have anything to fear, and they say it’s the most massive land animal known to science.
Technically, at least.
The way they actually put it is that the dreadnoughtus is “the largest land animal for which a body mass can be accurately calculated.”
Which is a polite and science-y way of saying that anyone who claims to have found a more massive dinosaur is basically guessing.
Because, to estimate the mass of any four-legged animal, paleontologists usually need two things: a femur, or thigh bone, and a humerus, the upper arm.
These tend to be two of a quadruped’s biggest bones, and dreadnoughtus is the first titanosaur to be found with both of them intact. 
In fact, it’s the most complete titanosaur ever recovered, with more than 45 percent of the entire animal having been found. 
By comparison, some dinosaur species, like Argentinosaurus, are thought to be just as large, but all we have of them are a few vertebrae, some ribs and a single leg bone.
And what may be the biggest dinosaur ever -- Amphicoelias, discovered in Colorado in the 1870s -- was described using only four bones, all of which have somehow been lost.
So with the discovery of dreadnoughtus, we not only have an awesome official superlative to add to the record books, we also have some more data than we ever had to help us figure out these creatures.
The team says that this new discovery will provide years of research into the anatomy, life histories, and biomechanics of these biggest land animals that ever lived.
And here’s another big topic that doesn’t lend itself to small answers: earthquakes.
On August 24th, a magnitude-6 earthquake struck Napa County, California, just north of San Francisco, the strongest quake to hit the area in 25 years.
The same day, a magnitude-7 earthquake struck southern Peru, and just a few hours before that, another with a magnitude of 6.4 hit the city of Valparaiso on the Chilean coast.
Not to be left out, Los Angeles then registered a 3.3-level earthquake.
Soon -- and true to form! -- the Internet began wondering: Are earthquakes … contagious?
Or maybe can one cause another? Do they always attack in groups, like the troops in Clash of Clans?
The answer is no.
At least, not really.
Earthquakes that happen around the same time, but in different places, are generally seen by seismologists as being unrelated.
And this is partly because earthquakes happen all the time. 
By which I mean, literally, there’s probably one happening right now, somewhere.
The U.S. Geological Survey says that it identifies an average of 20,000 earthquakes every year -- that’s like 55 a day. And the United States is actually a very small part of the Earth.
And about 90 percent of earthquakes occur around the Circum-Pacific Belt, also known as the Ring of Fire -- the string of ocean trenches and volcanic islands where many major plates of the Earth’s crust meet. 
So with all of these earthquakes going on all the time, it’s hard, if not impossible, to find connections among them.
Now, the USGS does say that there is some evidence that really major quakes can trigger some seismic activity a thousand kilometers away or more, but those secondary quakes tend to be faint and short.
But overall, the surface of the Earth is just a lot more fluid than we think -- it’s not rigid enough for physical stress to travel through it over long distances. 
So, while earthquakes can occur in clusters in the same place where stress builds up, ones that happen as far apart as California and South America are nothing to write home about. 
Or make a disaster movie about.
Thanks for watching this episode of SciShow News! If you want help us keep getting the world straight on its science, you can go to and become a contributing member. And don’t forget to and subscribe!