Why Were Dinosaurs So Large and Why Don't Animals of That Scale Exist Today?

iStock.com/Kirkikis
iStock.com/Kirkikis

Untorne Nislav:

Before we start, what you need to realize is that dinosaurs were definitely large, but not so large. You probably know the numbers: the largest land mammals ever are around 6–8 meters long (19-26 feet), while the largest dinosaurs were … is it 40 meters (131 feet)?

Damn, what a number!

However, numbers can be veeeery misleading. Look at the second-largest land mammal ever, Indricotherium, and one of the largest dinosaurs, Brachiosaurus, here.

The difference seems to be incomparable …

However …

Those are two entirely different body shapes: most of the brachiosaur's length is used up by its enormous neck and tail. To make it fair, I want you to use your two thumbs: place one over the dinosaur’s neck, and the other over the tail (hopefully, you are not reading this from a touchscreen).

And suddenly, enormous becomes quite … normous. Obviously, Brachiosaurus is still larger than Indricotherium, but it's not four times larger like the numbers would suggest. The real, fair difference between the two is roughly the same as the difference between an elephant and a hippo:

An elephant behind a number of hippos near the water.
iStock.com/JurgaR

Moral of the story: don't let the body shape mislead you.

So here's the answer to the "so large" part of your question: because they weren't.

However, there is still some "true" difference in size to account for. And at least two factors could've contributed to it:

1) Different rules of herbivory.

In the age of mammals, the most effective strategy of herbivory is grazing.

A large herd of wildebeests in a field.
iStock.com/WLDavies

Grasslands are super-effective. The two most productive mammal-dominated ecosystems ever are savannas and (now gone) mammoth steppes: both can feed enormous numbers of huge mammals. With grasses growing at insane rates everywhere, no other food source on Earth can provide for such high mammalian biomasses.

Moral of the story: if you want to grow up big and full, eat grasses.

However, it wasn't always so. In times of dinosaurs, grasses didn't exist. So, the largest animals then were forced to resort to the second-best herbivory strategy: browsing.

image of a brachiosaurus eating leaves from a tree
iStock.com/MR1805

Tree foliage doesn't grow like grasses, yet still there's usually a considerable amount of it per area unit, because it overlaps vertically many times.

Dinosaurs that fed from canopies could afford to grow large: for thermoregulation or defense from predators—usual reasons.

However …

Any animal that grows too big inevitably experiences difficulties with food. At present, any herbivore that became too large would likely just move onto grasses. But dinosaurs couldn't. Hence, the only solution that they had was to grow necks even longer to get even more foliage. But if you grow a larger neck, you also need a larger tail (for balance). Then, you also need broader and thicker bones for all those muscles to attach, stronger legs to support the extra tons of weight, and so on and so on.

Effectively, it was a dead loop: dinosaurs became large, then they grew longer necks to support the growing need for food, which in turn made them become even larger, which in turn further increased their need for food. Browsing herbivory was likely the driving force of sauropod size, and in the end, the only limiting factor was probably the height of the highest canopy.

2) Reproductive limitations

This one doesn't really answer the "why sauropods were large?," but the "why mammals aren't that large?".

A typical sauropod was, effectively, a reproductive frog. It laid dozens if not hundreds of small eggs that hatched into very small babies that had little to do with adults: they occupied very different niches and fed on different food. For sauropods, it killed two problems: firstly, it made pregnancies easy and unnoticeable (which is a factor when you weighed 60 metric tons), and secondly, it removed competition for food between adults and babies.

In other words, sauropods could afford to become as large as necessary without worrying much about how it would affect their pregnancy and reproduction.

On the contrary, being a pregnant 60-tonne (66-ton) mammal is a nightmare—of a real and deadly kind.

All (placental) mammals bear relatively large offspring. However, if you weighed 60 tonnes, that would be … what, 2 tonnes (4400 pounds) heavy offspring? Carrying extra 10 kilograms (22 pounds) of weight at the peak of pregnancy is difficult enough for humans, but having to carry 10 extra tonnes (22,000 pounds) is just impossible, unless you are a whale and swim.

Not to mention that it would be a very long pregnancy.

Not to mention that pregnant females require even more food.

Not to mention that the young must be fed, only to grow up to compete with you for the same food later.

Moral of the story: children are expensive … unless you are a frog or a sauropod.

Q: How about livebearing smaller babies?

There are two problems with this. Firstly, it just doesn't happen. There are relatively small newborns in some placental mammals, but nothing like the difference between sauropod adults and babies.

Secondly, if babies are too small, then they become unavailable for social interactions: in fact, they are better to stay away from parents immediately to avoid being stomped on. Social behavior and learning are the backbone of mammalian success. Trying to get rid of it just isn't worth it.

So in the end, dinosaurs that weren't so large were large because they bred like frogs and because their kitchen was … a little underrepresented.

This post originally appeared on Quora. Click here to view.

Where Did the Term Brownie Points Come From?

bhofack2/iStock via Getty Images
bhofack2/iStock via Getty Images

In a Los Angeles Times column published on March 15, 1951, writer Marvin Miles observed a peculiar phrase spreading throughout his circle of friends and the social scene at large. While standing in an elevator, he overheard the man next to him lamenting “lost brownie points.” Later, in a bar, a friend of Miles's who had stayed out too late said he would never “catch up” on his brownie points.

Miles was perplexed. “What esoteric cult was this that immersed men in pixie mathematics?” he wrote. It was, his colleagues explained, a way of keeping “score” with their spouses, of tallying the goodwill they had accrued with the “little woman.”

Over the decades, the phrase brownie points has become synonymous with currying favor, often with authority figures such as teachers or employers. So where exactly did the term come from, and what happens when you “earn” them?

The most pervasive explanation is that the phrase originated with the Brownies, a subsect of the Girl Scouts who were encouraged to perform good deeds in their communities. The Brownies were often too young to be official Girl Scouts and were sometimes the siblings of older members. Originally called Rosebuds in the UK, they were renamed Brownies when the first troops were being organized in 1916. Sir Robert Baden-Powell, who had formed the Boy Scouts and was asked to name this new Girl Scout division, dubbed them Brownies after the magical creatures of Scottish folklore that materialized to selflessly help with household chores.

But the Brownies are not the only potential source. In the 1930s, kids who signed up to deliver magazines like The Saturday Evening Post and Ladies' Home Journal from Curtis Publishing were eligible for vouchers labeled greenies and brownies that they could redeem for merchandise. They were not explicitly dubbed brownie points, but it’s not hard to imagine kids applying a points system to the brownies they earned.

The term could also have been the result of wartime rationing in the 1940s, where red and brown ration points could be redeemed for meats.

The phrase didn’t really seem to pick up steam until Miles's column was published. In this context, the married men speaking to Miles believed brownie points could be collected by husbands who remembered birthdays and anniversaries, stopped to pick up the dry cleaning, mailed letters, and didn’t spend long nights in pubs speaking to newspaper columnists. The goal, these husbands explained, was never to get ahead; they merely wanted to be considered somewhat respectable in the eyes of their wives.

Later, possibly as a result of its usage in print, grade school students took the phrase to mean an unnecessary devotion to teachers in order to win them over. At a family and faculty meeting at Leon High in Tallahassee, Florida, in 1956, earning brownie points was said to be a serious problem. Also called apple polishing, it prompted other students in class to shame their peers for being friendly to teachers. As a result, some were “reluctant to be civil” for fear they would be harassed for sucking up.

In the decades since that time, the idiom has become attached to any act where goodwill can be expected in return, particularly if it’s from someone in a position to reward the act with good grades or a promotion. As for Miles: the columnist declared his understanding of brownie points came only after a long night of investigation. Arriving home late, he said, rendered him “pointless.”

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Grocery Stores vs. Supermarkets: What’s the Difference?

gpointstudio/iStock via Getty Images
gpointstudio/iStock via Getty Images

These days, people across the country are constantly engaging in regional term debates like soda versus pop and fireflies versus lightning bugs. Since these inconsistencies are so common, you might have thought the only difference between a grocery store and a supermarket was whether the person who mentioned one was from Ohio or Texas. In reality, there are distinctions between the stores themselves.

To start, grocery stores have been around for much longer than supermarkets. Back when every town had a bakery, a butcher shop, a greengrocery, and more, the grocery store offered townspeople an efficient shopping experience with myriad food products in one place. John Stranger, vice president group supervisor of the food-related creative agency EvansHardy+Young, explained to Reader’s Digest that the grocer would usually collect the goods for the patron, too. This process might sound familiar if you’ve watched old films or television shows, in which characters often just hand over their shopping lists to the person behind the counter. While our grocery store runs may not be quite so personal today, the contents of grocery stores remain relatively similar: Food, drinks, and some household products.

Supermarkets, on the other hand, have taken the idea of a one-stop shop to another level, carrying a much more expansive array of foodstuffs as well as home goods, clothing, baby products, and even appliances. This is where it gets a little tricky—because supermarkets carry many of the same products as superstores, the next biggest fish in the food store chain, which are also sometimes referred to as hypermarkets.

According to The Houston Chronicle, supermarkets and superstores both order inventory in bulk and usually belong to large chains, whereas grocery stores order products on an as-needed basis and are often independently owned. Superstores, however, are significantly larger than either grocery stores or supermarkets, and they typically look more like warehouses. It’s not an exact science, and some people might have conflicting opinions about how to categorize specific stores. For example, Walmart has a line of Walmart Neighborhood Markets, which its website describes as “smaller-footprint option[s] for communities in need of a pharmacy, affordable groceries, and merchandise.” They’re not independently owned, but they do sound like grocery stores, especially compared to Walmart’s everything-under-the-sun superstore model.

Knowing the correct store terms might not always matter in casual conversation, but it could affect your credit card rewards earnings. American Express, for example, offers additional rewards on supermarket purchases, and it has a specific list of stores that qualify as supermarkets, including Gristedes, Shoprite, Stop & Shop, and Whole Foods. Target and Walmart, on the other hand, are both considered superstores, so you won’t earn bonuses on those purchases.

And, since grocery shopping at any type of store can sometimes seem like a competitive sport, here’s the ideal time to go.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER