The Truth Behind the "Truth" Behind Megalodon

Today, the great white shark rules the seas and haunts our imaginations.  After the release of the 1975 movie "Jaws," the great white shark and other sharks were feared and loathed more than they already were, although much of this fear was unbiased.  Ever since Jaws, hundreds of books, movies, television programs, and more have all capitalized on the shark craze, producing everything from the fantastic Steve Irwin Crocodile Hunter specials to the recent TV movie Sharknado.  One of the most popular shark-related features in the media is Discovery Channels "Shark Week," an annual event that features a week of shark-related programs.  Although many of these programs, as is to be expected for television programs nowadays, push the limits of reality, I think that the premiere of this year's Shark Week went too far, and I'm not the only one who thinks that, either.

First off, let's meet the star of this program: megalodon.  Estimates of the size of megalodon have varied widely and wildly, with some older estimates as high as about 100 feet long.  Today, however, most scientists agree that the largest megalodon could grow to around 60 feet long.  Which is still pretty massive, given that most great white sharks don't exceed lengths of around 20 feet, and look at how much people are afraid of them!  megalodon would have easily been able to swallow the average human in one bite: just take a look at those reconstructed jaws, below!  Also, below that picture, make sure to check out the size of just one megalodon tooth.  Suffice it to say, this shark was one massive bruiser.  This shark WAS one massive bruiser.  Notice how I emphasized the "was?"  Well, that's because megalodon went extinct about two million years ago.

Pyg encounters a mid-sized megalodon tooth, graciously donated to my collection of fossils and things that I take to local schools by local paleontologist Wayne Itano

Megalodon sounds pretty awesome, right?  I mean, to be honest, it's one of those extinct animals that just doesn't need to be "sci-fied up," because it's already cool enough as is, on par with other animals such as Tyrannosaurus, Spinosaurus, and Utahraptor.  Well, just because it didn't NEED to be sci-fied up doesn't mean that television networks didn't do it anyways.  And this years Shark Week premiere was the culprit.  Discovery Channel aired a two hour "documentary" showing "biologists" on the hunt for a megalodon.  Today.  In the present.

One of those extinct animals that just doesn't need to be "Hollywoodized!"  Meet Stan, the resident Tyrannosaurus rex at the Morrison Natural History Museum!  You can see Pig seated in the bottom jaw for scale!  Yeah, this guy was huge.

We have no evidence to indicate that megalodon is alive and with us today, and the "evidence" included in the "documentary" was very clearly doctored.  For example, below is a picture of a whale that has supposedly been bitten in half by a megalodon:

And here is a photo "uncovered from Nazi archives" of a giant shark fin surfacing behind a pair of U-Boats:

The first picture just screams CG.  And the second one....really?  Nazi's? Very Indiana Jones-esque.  OK then, Discovery.

The "documentary" starts off with "found footage" of a "boat capsizing off the coast of South Africa and several people being eaten, but whose bodies were never recovered."  Already, this reeks of a typical television plot.  Especially given the fact that a quick Google search of this supposed incident, as well as any of the "biologists" in the "documentary," yields diddly-squat.  Apparently the prospect of a giant shark brutally attacking and destroying a fishing boat just wasn't exciting enough to make it to the news, despite the fact that every news story relating to sharks and shark attacks spreads like wildfire.  Perhaps the South African press was just busy that day?

People refute our naysaying by pointing out that "we know more about the surface of the moon than the ocean," and "the coelacanth (which you can learn more about by clicking HERE) and the giant squid were only discovered recently!"  Yeah, that's true.  But megalodon is very different from a giant cephalopod or a five or six foot long fish.  We are talking about an active, 60 foot long predator that's feeding on much, much bigger prey than the giant squid or coelacanth would.  The giant squid and coelacanth eat a lot of fish, and are considered to be primarily piscivorous.  The giant squid, although very large, is by no means at the top of its food chain, and is fed upon by the largest of the toothed whales, the 60 to 70 foot long sperm whale.  And two million years ago, megalodon would have made up the final link in this food chain, feeding on the 60 to 70 foot long sperm whale.

Am I saying that there is no possibility that more giant animals exist in the deepest depths of the ocean, just waiting to be discovered?  No, I most definitely am not.  I do, however, encourage you to consider the ecological resources that would be needed by such a massive animal.  With no evidence of mutilated whale carcasses that could be attributed to such a massive animal, and an equal amount of evidence from first-hand accounts....I think that the conclusion should speak for itself.

The biggest issue that I have with all of this is not that a television program was made that packages myths, untruths, and exaggerations: it was with the fact that they packaged it as a documentary, no quotations this time.  Discovery tried to balance out the fact that they blatantly made stuff up to appease some of their viewers by pointing out that they included disclaimers in the show.  Yeah, true, there were disclaimers: but click HERE to see how short and hazy these disclaimers really were.  The disclaimers read:

None of the institutions or agencies that appear in the film are affiliated with it in any way, nor have approved its contents. Though certain events and characters in this film have been dramatized, sightings of "Submarine" continue to this day. Megalodon was a real shark. Legends of giant sharks persist all over the world. There is still debate about what they might be.

Notice how they never really say that none of it was true.  When he gave a press release, the executive producer of Shark Week, Michael Sorensen, said that “With a whole week of Shark Week programming ahead of us, we wanted to explore the possibilities of megalodon.  It’s one of the most debated shark discussions of all time, can megalodon exist today? It’s Ultimate Shark Week fantasy. The stories have been out there for years and with 95 percent of the ocean unexplored, who really knows?”  The part that bugs me the very, very most about that statement is the line "It's one of the most debated shark discussions of all time."  It isn't, I promise you.  It really, really isn't.  I have never heard of any paleontologist who seriously believes that megalodon swims the oceans today.  There might be some paleontologists who won't discount the possibility, which is fine.  Science changes all the time.  But with a complete and total lack of evidence, no serious scientist will really debate that sort of thing.

There's many more issues that people have had with this presentation, varying from thousands of people on social media voicing their complaints, all the way to actor Wil Wheaton, who wrote about the megalodon fiasco on his blog, which you can read HERE.  Others, such as popular paleo writer Brian Switek, went to Twitter:

I do hope that this backlash will cause the people at Discovery, as well as at other television stations, to reconsider what they make into a television program, and consider the possibility that, just maybe, there's a significant chunk of people out there who don't want to be fed this garbage.  I do hope that this causes some changes in any future programming, and if we are all really lucky, this event might spawn a South Park episode.  You have to admit, it'd be pretty perfect.  Let's just cross our fingers, shall we?

I Can't Decide (Whether I Should Swim or Fly) (to the tune of "I Can't Decide (Whether You Should Live or Die)")

Numero cinco (he said in flawless Spanish) of our song parody series!  "I Can't Decide (Whether I Should Swim or Fly)" to the tune of "I Can't Decide (Whether You Should Live or Die)" by Scissor Sisters!  This song is all about penguins!

Here are the lyrics to the song:


It's not easy having yourself a good time
Greasing up those penguin feathers
Waddling around, as clumsy as ever
Molt and feed my young at the same time
My feathers are fluffy and look like cotton
I smell like something dead and rotten

But I'm a penguin tonight
I live in sea and not the sky
I'm just a loner baby
But your dance led me astray

I can't decide
Whether I should swim or fly
Cause swimmings got its perks
But then with flight I just drop by
OK, goodbye
Blue sky, I will abide
Where its cold and hard and petrified
Jump on in, through the water we'll glide
At low or high tide

It's not a cinch getting other penguin to like you
Steal their rocks you make them bitter
Even though they're dull and not shiny like glitter
Doing all your moves at the right cue
Mating dance until I'm crippled
Scarf ten sardines, they're raw not pickled

I've got to flipper it to you
You've played by all the same rules
But now you stole my mate from me
Although I scream like a banshee

[CHORUS]

Oh I could throw you in a lake
But you can swim for goodness sake
I won't deny it's not too hard to egg me on
Oh I could try and make you dive
But in the water you still thrive
Which makes me see that maybe
That's why

I stay alive, underwater I can fly
Because flight has its perks
But underwater by and by
I will defy
Other birds who like to stay bone dried
The cold is where I will abide
The world has yet another side
It really must be tried

Are you diggin' the songs?  Well, then check out our playlist below!

CLICK HERE TO BE DIRECTED TO A FUN-FILLED PLAYLIST OF AMAZING SONGS.

Top 10 Favorite Dinosaurs by Zack Neher (Part 3)

Part three of my Top Ten Favorite Dinosaurs list.  Enjoy!

3. Masiakasaurus

A fairly small dinosaur at only around six feet, Masakisaurus knopfleri, as discussed IN A PREVIOUS POST, was named for the famous musician Mark Knopfler.  The animal, found in Madagascar, was named in 2001 by Matthew Carrano, Catherine A. Forster, and Scott Sampson, the author of Dinosaur Odyssey and the dude from Dinosaur Train.  Living on what was still an island, the little dinosaur lived about 70 MYA during the  Late Cretaceous Period, and was a contemoporary of the abelisaur Majungasaurus, the bird-like Rahonavis, and the sauropod Rapetosaurus.  Although Masiakasaurus sounds pretty unremarkable thus far, a quick glance at the picture below (which many of you have no doubt already done) says otherwise: Masiakasaurus definitely had some funky teeth!  These teeth are clearly not suited tearing into food like the teeth of Allosaurus or Velociraptor would be, and many paleontologists (including myself, even though I am not really a paleontologist.  I guess it would be better to say "many paleontologists, paleontologists-in-training, and myself."  There, much better.) believe that these weird, pointy teeth are an evolutionary adaptation to a piscivorous (fish-based) diet.  A look at various marine reptiles such as the plesiosaurs (like Elasmosaurus) and Liopleurodon show a similar pattern of interlocking teeth that point outside of the mouth.  Excellent when it comes to catching fish, and not so excellent when it comes to most, if not all, other diets, be they meat- or plant-based.  

TO BE CONTINUED IN PART 4

The Denver Gem and Mineral Show Part 2: The Piscivores (Excepting Penguins)

As we started talking about a few weeks ago, my friend Masaki Kleinkopf and I were able to visit the Denver Gem and Mineral Show at the Denver Merchandise Mart.  Last time, we talked about the giant ammonites, the baby eryops that Dr. Robert Bakker was working on, the gliding Indonesian lizards of the genus Draco and the pterosaurs that evolved from creatures purportedly much like this millions of years ago.  Today, we are going to talk about all of the piscivorous animals that we saw there, except for the fossil penguin that I saw there.  Knowing me, that would easily take up one whole post of its own there.  Keep in mind throughout this post that I'm not certain for all of these animals that they actually eat fish, I just know that the large groups that they belong to often eat fish.  Today, we are going to be looking at the mosasaurs, crocodilians, pterosaurs, sea lions, other fish, sharks, and the dreaded piscivorous dinosaur Spinosaurus.  

MESSAGE FROM ZACK FROM THE FUTURE:  Hello, everyone.  This is Zack Neher.  I have travelled to this post from the future.  I wanted to give you a link to the Homebase for these posts.  I am like Rose Tyler, leaving clues in the form of Bad Wolf.  Except this is not quite like that at all really.  Anyways.  The Homebase for the series is HERE.

Myself next to a gigantic mosasaur skull

I am pretty sure that this is the skull of a mosasaur , anyway.....it looks more like a mosasaur skull than the skull of a crocodilian, if you ask me

A mosasaur jaw, from Morocco by the looks of it

A mosasaur skull (Platecarpus, if memory serves, but it is entirely possible that I am wildly off) in front of a fossil ray

Another huge mosasaur skull

We also got to see the teeth of a piscivorous pterosaur.  The teeth of a piscivore are usually different from those of other carnivorous animals due to their conical shape.  The teeth of the fish eaters, like those of crocodilians and dolphins, are usually conical in shape, to prevent prey from struggling out of their grasp.

The teeth of a piscivorous pterosaurs

Below are the skulls of various crocodilians.

 

 

The skulls of these dudes seem like they should be out of a cartoon or something, they are so weird and comic looking!

Here are a pair of photos of fossilized sea lion teeth, both from the extinct sea lion Imagotaria sp., from the Miocene to Pliocene in the Atacama region of Chile.

Imagotaria sp., from the Miocene to Pliocene in the Atacama region of Chile

Imagotaria sp., from the Miocene to Pliocene in the Atacama region of Chile

Next, a picture of a pair of fossil jellyfish!

Fossil jellyfish!

Next are the teeth of the gigantic, fifty to sixty foot long carnivorous (or actually, piscivorous) dinosaur: Spinosaurus.  Also in the picture are the teeth of another enormous carnivorous dinosaur that lived in the same area of Northern Africa as Spinosaurus at this time of the Cretaceous Period: Carcharodontosaurus, who was not a piscivore, at least not primarily a piscivore, like a penguin, or as Spinosaurus is purported to
be.  (Did you see that alliteration?  My language arts teacher would be most impressed).  I discuss both Spinosaurus and Carcharodontosaurus in two previous posts, which you can look at HERE FOR SPINOSAURUS and HERE FOR SPINOSAURUS AND CARCHARODONTOSAURUS.

The teeth of Spinosaurus.  Actually in this shot, it looks as if most or all of these teeth belong to Spinosaurus.

And now for some pictures of the teeth of Megalodon, the largest shark that is ever known to have lived!  I have talked about Megalodon in the past, click HERE to learn more.

 

Now for some random ones.

It's a fish eat fish world out there

A pair of shark jaws.  I am not certain as I don't remember at all and they are unlabeled, but I believe them to be jaws of sand tiger sharks.  Again, I could be totally off on this!

Guards of the Fairy Penguin

In the summer of 2009, a number of brutal attacks in Sydney, Australia left nine victims dead.  According to BBC, “the mutilated bodies...were found in a national park near Sydney harbour.”  Autopsies performed on the bodies reveal that the murderers were most likely foxes, although dogs remain a definite suspect.

A picture of the red fox outside of the house in Breckenridge, Colorado, that our friends the Beckleys rented one summer.  It's an awesome place to stay, I tell you what!  Photo Credit: Julie Neher

There is more to this story than has been revealed thus far.  The nine victims were not humans; instead, they were korora, or little blue penguins, also often called fairy penguins. You would be excused for thinking that the victims were, in fact, humans, especially once you learned the whole story.

In an interview with BBC, Sally Barnes of the New South Wales Parks and Wildlife Service detailed what the group has been doing to protect the penguins from the dogs and foxes.  As well as raising public awareness, the NPWS has been baiting and trapping the predators, and “As a last resort, we’ve also had shooters out.” 

In this case, shooters means snipers.  That’s right; the Parks and Wildlife Service deployed two professional sharpshooters in order to ensure the safety of these penguins.  Armed with night-vision goggles, rifles, and orders to shoot to kill, these may be the most extreme methods used to protect penguins ever employed. 

The penguins are being further protected by vigilantes from the Manly Environment Centre, vowing that they will do “whatever it takes” to protect the penguins, and planning on assisting the snipers in keeping a sharp eye on the birds 24/7. 

Why is this colony such a big deal?  The kororaa is labeled as “Least Concern” by the IUCN.  Well that may be true for the total population of korora, but this colony is falling by the wayside.  As you can see in the map, the area where the colony is located is quite busy, and not ideal penguin habitat.  However, these penguins cannot be relocated; like many birds, they always return to where they themselves were raised to come ashore and raise their own chicks.  The people of Sydney also take pride in their colony of korora’s, as it is the sole population located in New South Wales.  The people at the Manly Environment Centre report that their efforts are, by and large, successful, and the korora’s numbers are on the rise.

Sydney on Dwellable

Top Ten: Extinct Sea Monsters (Part 5 of 5)

Our final edition of "Top Ten:  Extinct Sea Monsters!

9.  Tanystropheus - Living during the Middle Triassic Period, Tanystropheus is somewhat of a misfit amongst this group, as he is not really a sea-monster, and was, at most, a semi-aquatic animal (think otters).  Purportedly piscivorous, Tanystropheus fossils are usually found in semi-aquatic sites.  Its neck has been likened to that of the Plesiosaurs, like Elasmosaurus.  They would all use their necks to surprise a group of fish, long before the fish would be able to see the body of the reptile. Remains have been discovered throughout France, Germany, and Italy, amongst other places. 

10.  Tylosaurus - Interestingly enough, the closest living relative of the extinct mosasaurs, of which Tylosaurus is a member, are the monitor lizards, like the Komodo dragon.  Both the monitor lizards and the mosasaurs have a third eye on the top of their heads, although it just looks like a little white dot on the top of the head of the monitor lizard.  It doesn't work in the same fashion as their other eyes, however.  Look towards a light (not the sun, because apparently that can actually be harmful) and close your eyes.  You can still still some light, right?  Now, move your hand back and forth in front of your face, between your eyes and the light.  Can you see how the light changes?  You can't see anything more distinct than the fact that something moved between you and that light.  That is what the third eye of monitor lizards and mosasaurs would have been like.  Tylosaurus also inhabited the Western Interior Seaway during the Late Cretaceous.  Remains, amongst other places, have been discovered in Alabama and Kansas, amongst other places.

So that concludes our "Top Ten:  Extinct Sea Monsters" edition!  Unfortunate that we had to break it up into five parts, to be sure, but hey, that's life!

This post is part of the "Top Ten: Extinct Sea Monsters" series.  For the rest of the posts in this series, click HERE.  

What Is It? The Weekly Challenge #2 Answer

 Hello again!  Thank you to our guessers for this week: surprisingly, one of you got it exactly right!  Congratulations to Kristie C., who guessed this weeks mystery animal 100% correct!  The correct animal was Pakicetus, an ancient ancestor of the cetaceans, or the whales, dolphins and porpoises.  Around 53 MYA, Pakicetus lived in a world that was gradually becoming what we see today.  At this time, what we now know as India was its own special island continent, moving steadily northwards until, eventually, India crashed into Asia.  This crash resulted in the largest mountains we have today, the Himalayas. 

However, 53 MYA, during the Eocene Epoch, India hadn't quite reached Asia, a small sea separating the two, the remains of the vast Tethys Ocean.  The Tethys Sea was high in saline, which is incredibly good for life.  Microscopic organisms like plankton flourished, sending reverberations up the food chain, all of the way to the fish, which exploded in numbers as well.  And on the shore of this Tethys Sea, in what today is Pakistan, stood Pakicetus. 

As Pakicetus watched the gread abundnace of fish in the waters, he began to take short fishing trips into the water.  Over millennia, as Pakicetus took more and more fishing trips, of longer and longer duration, adaptations that proved beneficial for hunting fish in the water occurred, like a more streamlined shape, most likely webbed feet, and nostrils placed further back on the head.  Over a few million years, Pakicetus evolved into another ancient whale, called Ambulocetus.

Check back in a few hours for your next "What Is It?" challenge?  I promise you, after the last two, this one should seem like a piece of cake!  See you all then!

Convergent Evolution: Hesperornis and Penguins

Everyone who is reading this blog, and most people who aren't, have heard of penguins, and know, more or less, what they look like.  However, most people have no idea what a Hesperornis is, which is entirely forgivable.  What is especially interesting about Hesperornis is that it was really the "original penguin," in the loosest sense of the terms.

If not for the captions below each picture, these two animals would most likely be quite difficult to tell apart.  One major difference between the two birds is in the mouth: Hesperornis had teeth, a feature which no modern birds possesses.  Another major, but non-skeletal difference, between the two birds is that Hesperornis died out 78 MYA, during the Late Cretaceous.  Its remains have been found in the United States (Kansas), Canada, and Russia.

The similarities between Hesperornis and modern day penguins is called "Convergent Evolution," a fascinating topic which we will undoubtedly touch upon numerous times.  According to Science Daily, convergent evolution is, "In evolutionary biology, convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches."  In English, when two animals, not necessarily closely related at all, evolve similar features that serve the same purpose.

An (excellent) drawing of the skull of Thylacosmilus

 Another example which we have already talked about is the long, saber-like canines that evolved in both the saber-toothed cats, such as Smilodon, and the South American marsupial carnivore Thylacosmilus.

 This post is part of the "Convergent Evolution" series.  For the rest of the posts in this series, click HERE.

What Is It? The Weekly Challenge #1 Answer

Well, it's that time of the week again!  We only had a few guesses this week, and no one got it exactly right, but there were some close guesses!  The two closest were Kristie C., who guessed an Adélie Penguin, and Masaki K. who guessed Cormorant.  Well, the correct answer to last weeks challenge is Waimanu.  Waimanu is the scientific name of the oldest known fossil penguin.  Two species are known, and both of them were found on the South Island of New Zealand.  One of the species, Waimanu manneringi, lived during the Paleocene, around 61.6 MYA; that means that the oldest known penguin was swimming the oceans only a few million years after the death of the dinosaurs!  Although Waimanu manneringi is the oldest KNOWN fossil penguin, it by no means is the oldest penguin.  In fact, it is quite likely that, were scientists to uncover a fossil that shows when penguins split off from the other orders of birds, we would not even recognize it as a penguin.  Waimanu had undoubtedly already adapted to a fully non-aerial lifestyle, and almost certainly behaved much like modern penguins do when it comes to breeding on land, near the ocean.


Works Cited:

Waimanu, the first penguin. (2010, January 30). Retrieved July 11, 2012, from https://fossilpenguins.wordpress.com/2010/01/30/waimanu-the-first-penguin/

The Biggest Carnivorous Dinosaur Part 3: Spinosaurus, The World's Largest Penguin

Spinosaurus quickly smashed its way to the top (literally!) following the success of Jurassic Park III.  At up to 56 feet (17 meters) in length, Spinosaurus (found in Egypt and Morocco) is unquestionably the longest carnivorous dinosaur that has ever been discovered, and by a significant margin, too.  But how could Spinosaurus be so successful when another carnivorous monstrosity, Carcharodontosaurus, lived in such close proximity?  The answer lies in what it ate; in fact, Spinosaurus appears not to have been as carnivorous as we once thought, and seems to in fact have been more piscivorous.  Essentially, it is thought that Spinosaurus might have survived on a diet consisting a great deal upon fish.

There is a great wealth of information that indicates the staple diet of Spinosaurus was fish.  Here we will take a more in-depth look at this evidence.

A picture of Spinosaurus drawn by the talented young artist Sam Lippincott.

1.  POSITION OF THE NOSTRILS:  Spinosaurus, unlike most other theropod (meat-eating) dinosaurs had nostrils situated very high up on its skull.  By contrast, most other theropods, like Tyrannosaurus, had nostrils very close to the front of the skull.  The nostril placement in Spinosaurus would have allowed it to stick its nose into the water quite deep, enabling it to hunt fish more effectively.

2.  SENSORY ORGANS ON THE TIP OF THE SNOUT:  Along with the high placement of the nostrils, Spinosaurus also had a number of small sensory organs at the front of the snout, revealed by CT scans.  These greatly resemble those of the crocodile, who uses them to sense where prey is by "seeing" tiny movements in the water.  Thus, a crocodile can attack its prey without ever seeing them with their eyes.  Spinosaurus appears to have been able to do much the same thing, making its hunting method of choice quite obviously effective, given its immense size.

3.  ISOTOPIC EVIDENCE:  A study of the isotopes in the skull of a Spinosaurus specimen revealed something quite interesting.  Spinosaurus shares a great deal of isotopic overlap with crocodiles, fairly aquatic animals.  By contrast, other carnivorous dinosaurs like Tyrannosaurus have very different isotopic readings, indicating a terrestrial lifestyle.  Given the great deal of overlap possessed by Spinosaurus and crocodiles, it appears that Spinosaurus spent much of its life like a crocodile; semi-submerged in rivers and streams.

4.  THE TEETH TELL THE TALE:  Spinosaurus, unlike most other carnivorous dinosaurs like Tyrannosaurus, Allosaurus, or the famous Velociraptor, possess conical, round teeth.  These other carnivores possess thin, blade-like teeth, made for slicing, crushing or tearing into other animals.  Spinosaurus has teeth much like a crocodile; round and conical.  These teeth are made for gripping and making sure that an animal does not escape. 

5.  THE TEETH TELL THE TALE....AGAIN:  Yet again, we come to the issue of teeth, and this is one of the most damning pieces of evidence of all.  During the time that Spinosaurus lived in North Africa, another inhabitant of these streams and rivers was a saw-toothed fish called Onchopristis.  Two fossils involving Onchopristis have been discovered in conjunction with the remains of Spinosaurus.  One was the skull of a Spinosaurus; imbedded in one of the tooth sockets was a vertebrae from an Onchopristis.  The other discovery was the barb of an Onchopristis embedded in the jaw of the Spinosaurus.

6.  PLUS:  We only ever seem to find Spinosaurus in shallow aquatic environments, where fishy prey would be abundant.

All in all, it seems like an inevitable conclusion to draw that Spinosaurus was, in fact, a piscivore, at least much of the time.  A fascinating example of the crazy turns evolution can take.