Walkabout

I'm always amazed at the depth of information paleontologists can glean from fossils.

And I'm not even including the ones that show exceptional preservation, like the ichthyosaur fossils I mentioned in a post a couple of days ago, that were so well preserved that they could even determine features like countershading.  Ordinary fossils contain a wealth of information about the organisms they came from -- if you know where to look, and how to interpret it.

Take, for example, the paper by a team from the University of Bristol and the University of Uppsala that appeared last week in the journal Alcheringa: An Australasian Journal of Paleontology.  Conducted by Christine Janis, Adrian O'Driscoll, and Benjamin Kear, the study analyzed the bones of prehistoric kangaroos, and reached a rather startling conclusion: a good many ancient kangaroo species didn't have the group's signature hop.

The determination came from looking at the strength and articulation of the leg bones, as well as the animal's overall size.  In particular, the short-faced kangaroos, or sthenurines, may have preferred to walk on all fours -- or might even have had a bipedal stride like a human.

The skeleton of Simosthenurus occidentalis, which I find vaguely terrifying. [Image licensed under the Creative Commons Ghedoghedo, Simosthenurus occidentalis, CC BY-SA 3.0]

You can see why they're called short-faced kangaroos in the artist's recreation of Procoptodon goliah below, in which I notice two things:

1. These creatures looked like a cross between a bunny rabbit and Godzilla.
2. The woman posing next to it has a stance like a Glamour magazine model, which is an odd thing to do if you're confronted with an eight-foot-tall kangaroo with giant claws.  Me, I'd be running like hell, if I didn't just wet my pants and then faint.

[Image licensed under the Creative Commons Nobu Tamura, Procoptodon goliah NT, CC BY-SA 4.0]

The striding kangaroos seem to have split off from the hopping kind about fifteen million years ago, during the Miocene Epoch, when Australia was a lot wetter than it currently is.  The climate back then would have favored large herbivores like the sthenurines (thank heaven these things weren't carnivorous), and they simply became too heavy to jump efficiently.  Even smaller sthenurines, though, had a different leg articulation -- they all appear to have been walkers rather than hoppers.

The last of the striding kangaroos went extinct during the last Ice Age, when the climate took a turn toward more arid conditions.  Aridity meant fewer plants, and slower growth for the ones that survived, and the largest marsupials in Australia died out.

Just as well.  Even the kangaroos that are left can kick you into the middle of next week; every year people, mostly stupid tourists, are injured by kangaroos.  Australians also have to contend with the various venomous snakes, spiders, and jellyfish, a relative of the nettle (the gympie-gympie) whose spines inject a neurotoxin that causes intense pain for years, and a highly-aggressive bird called the cassowary that looks like the bastard child of a turkey and a velociraptor.  The last thing those poor people need is giant kangaroo-bunnies striding around like they own the place.

Because the kangaroo-bunnies probably were vicious.  Down there, it's kind of an inevitability.

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Trompe l'oeil

I have a fascination for optical illusions.

Not only are they cool, they often point out some profound information about how we process sensory input.  Take the famous two-and-a-half pronged fork:

The problem here is that we're trying to interpret a two-dimensional drawing as if it were a three-dimensional object, and the two parts of the drawing aren't compatible under that interpretation.  Worse, when you try to force your brain to make sense of it -- following the drawing from the bottom left to the top right, and trying to figure out when the object goes from three prongs to two -- you fail utterly.

Neil deGrasse Tyson used optical illusions as an example of why we should be slow to accept eyewitness testimony.  "We all love optical illusions," he said. "But that's not what they should call them.  They should call them 'brain failures.'  Because that's what they are.  A clever drawing, and your brain can't handle it."

(If you have some time, check out this cool compendium of optical illusions collected by Michael Bach, which is even more awesome because he took the time to explain why each one happens, at least where an explanation is known.)

It's even more disorienting when an illusion occurs because of two senses conflicting.  Which was the subject of a paper out of Caltech, "What You Saw Is What You Will Hear: Two New Illusions With Audiovisual Postdictive Effects," by Noelle R. B. Stiles, Monica Li, Carmel A. Levitan, Yukiyasu Kamitani, and Shinsuke Shimojo.  What they did is an elegant experiment to show two things -- how sound can interfere with visual processing, and how a stimulus can influence our perception of an event, even if the stimulus occurs after the event did!

Sounds like the future affecting the past, doesn't it?  It turns out the answer is both simpler and more humbling; it's another example of a brain failure.

Here's how they did the experiment.

In the first trial, they played a beep three times, 58 milliseconds apart.  The first and third beeps were accompanied by a flash of light.  Most people thought there were three flashes -- a middle one coincident with the second beep.

The second setup was, in a way, opposite to the first.  They showed three flashes of light, on the right, middle, and left of the computer screen.  Only the first and third were accompanied by a beep.  Almost everyone didn't see -- or, more accurately, didn't register -- the middle flash, and thought there were only two lights.

Sorry, I had to.

"The significance of this study is twofold," said study co-author Shinsuke Shimojo.  "First, it generalizes postdiction as a key process in perceptual processing for both a single sense and multiple senses.  Postdiction may sound mysterious, but it is not—one must consider how long it takes the brain to process earlier visual stimuli, during which time subsequent stimuli from a different sense can affect or modulate the first.  The second significance is that these illusions are among the very rare cases where sound affects vision, not vice versa, indicating dynamic aspects of neural processing that occur across space and time.  These new illusions will enable researchers to identify optimal parameters for multisensory integration, which is necessary for both the design of ideal sensory aids and optimal training for low-vision individuals."

All cool stuff, and more information about how the mysterious organ in our skull works.  Of course, this makes me wonder what we imagine we see because our brain anticipates that it will there, or perhaps miss because it anticipates that something out of of place shouldn't be there.  To end with another quote from Tyson: "Our brains are unreliable as signal-processing devices.  We're confident about what we see, hear, and remember, when in fact we should not be."

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Mysterious network

Back in 1850, Italian paleontologist Giuseppe Meneghini found a peculiar fossil in the early Cambrian rocks of Sardinia.  It had a very distinctive appearance -- a set of what appeared to be tubes arranged in a network of perfect hexagons, regular as a honeycomb -- and Meneghini named it Paleodictyon, which means "early net."

The problem was, no one could quite figure out what it was.  There was speculation that it was the skeleton of a sea sponge, that it was some kind of filter-feeding trap laid down by peculiar giant single-celled organisms called xenophyophores, or that it was the tunnel network of some burrowing creature like a tube worm.  None of these hypotheses had much in the way of direct evidence in their favor, and all had significant arguments against.

Then Paleodictyon was found in Devonian rocks.  Then Carboniferous rocks.  Then Triassic rocks.  Always in sedimentary strata associated with deep marine environments -- and never with the slightest evidence of who might have created it.

So it went into the catalogues as a "trace fossil" -- a remnant of some unidentified organism.  This didn't mean the paleontologists were giving up, however; the origins of other trace fossils have been solved, most notably the incredibly common conodonts, small, spiky fossils found in oceanic sedimentary rocks up through the Triassic Period, and which were finally determined to be the teeth of primitive fish a little like today's lampreys.

But Paleodictyon proved more difficult, despite the fact that pretty much everywhere -- and everywhen -- you look in deep-ocean sedimentary rocks, you find it.  Here's a specimen from the Miocene Epoch:

[Image licensed under the Creative Commons Hectonichus, Palaeodictyon, CC BY-SA 4.0]

Then a survey of the seafloor near volcanic vents on the Mid-Atlantic Ridge -- in very recent sediments -- came across a series of regularly-spaced holes.  Curious, the oceanographers studying the area devised what amounted to a giant water gun to blow away the sediment and see what was beneath the mud, and hopefully, what might be creating the holes.

And underneath...

... was Paleodictyon.

Here, though, there was an additional clue; at each of the nodes in the network was a small upward-facing tube.  It was the openings of the tubes, poking above the sediment, that had attracted the attention of the scientists.  Naturally, they took samples (not to mention a closer look) to see what was in there.

Nothing was.

Detailed DNA analysis was performed on the samples, looking for anything that might give a clue as to what had made the network.  All three of the most commonly-held hypotheses -- sponges, xenophyophores, and tube worms -- came up negative.  There were traces of DNA present, but all of it seemed to be from bacteria and protists living in the tubes, not the creature that made the tubes.

To cut to the punch line: we still have no idea what Paleodictyon is, or who made it.

But whatever it is has been around for a very, very long time -- at least 540 million years -- substantially unchanged.  It's true that there are lots of things in nature exhibiting hexagonal tiling; it's the simplest way to tile a two-dimensional surface, and is seen in everything from quartz crystals to the symmetrical cooling cracks in the Giant's Causeway in Ireland.  But the fact that this trace fossil is only found in deep-sea sedimentary rocks is certainly suggestive that its origin is biological.

In the end, we're left with a mystery, and are honestly no closer to figuring Paleodictyon out now than we were when Giuseppe Meneghini first discovered it over 170 years ago.  So we'll continue looking -- and trying to determine the origin of one of the most persistent and widespread fossils ever found.

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A new view of the "eye lizard"

I am forever astonished at the level of detail we can infer from fossils that are hundreds of millions of years old.

The most recent example of this came from analysis of a fossil of Stenopterygius, an ichthyosaur that lived during the Jurassic Period (this particular fossil has been dated to about 180 million years ago).  We usually think of fossils as preserving bones and teeth, and occasionally impressions of scales or skin or feathers -- but this one was so finely preserved that researchers have been able to make some shrewd inferences about color, metabolism, and the structure of soft tissues.

Artist's conception of Stenopterygius [Image licensed under the Creative Commons Nobu Tamura (http://spinops.blogspot.com), Stenopterygius BW, CC BY-SA 3.0]

We've known for a long time that ichthyosaurs are bizarre animals. They were streamlined predators that look remarkably like dolphins, although they are only distantly related (making the two groups a great example of convergent evolution).  A number of them had an even stranger feature, which is the largest eye-diameter-to-body-size ratio of any animal known -- the well-named Ophthalmosaurus (Greek for "eye lizard") was six meters long and had eyes the size of basketballs.

Stenopterygius was a bit smaller, with an average adult size of four meters.  But up until recently, all we've been able to do is speculate on what it might have looked like, and how it behaved.  A discovery in Germany, described in a paper in Nature called "Soft-Tissue Evidence for Homeothermy and Crypsis in a Jurassic Ichthyosaur" and authored by no fewer than 23 scientists, has given us incredibly detailed information on these oddball dinosaurs.

The authors write:

Ichthyosaurs are extinct marine reptiles that display a notable external similarity to modern toothed whales.  Here we show that this resemblance is more than skin deep.  We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius.  Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers.  These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy.  Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment.  Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation.  Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.

So from a 180-million-year-old fossil, we now know that Stenopterygius (1) was a homeotherm (colloquially called "warm-blooded"), (2) had a blubber layer much like modern dolphins and whales, and (3) were countershaded -- dark on top and light underneath, to aid camouflage -- similar to dozens of species of modern fish.

This level of preservation is extremely unusual.  "Both the contour of the body and the remains of internal organs are clearly visible," said paleontologist Johan Lindgren of the University of Lund, who co-authored the paper.  "Surprisingly, the fossil is so well preserved that it is possible to observe individual cell layers inside the skin."

"This is the first direct chemical evidence of warm blood in an ichthyosaur, because a subcutaneous fat layer is a characteristic of warm-blooded animals," said Mary Schweitzer of North Carolina State University, also a co-author.  "Ichthyosaurs are interesting because they have many features in common with dolphins, but they are not related at all to these mammals that inhabit the sea.  But the enigma does not stop there...  They have many characteristics in common with living marine reptiles, such as sea turtles; but we know from the fossil record that they gave live birth to their young...  This study reveals some of those biological mysteries."

Which is pretty astonishing.  I've always had a fascination for the prehistoric world, and have spent more time than I like to admit wondering what it might have been like to live in the Jurassic world. This research gives us one more piece of information -- about a fierce prehistoric predator that shared some amazing similarities to creatures that still swim in our oceans.

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A glimpse of a monster

Ever heard of TON 618?

I hadn't until a few days ago, which is surprising considering my dual fascination with (1) astronomy, and (2) things that are huge and violent and could kill you.  TON 618 is a quasar, a luminous active galactic nucleus common in the universe's distant past.  Thankfully the cosmos has settled down a bit, because these things are so energetic their light is still visible today from billions of light years away.

Even by quasarian (I just made that word up, you should find a way to incorporate it into your daily speech) standards, TON 618 is impressive.  It showed up in a 1957 survey of faint blue stars, but its intense red shift indicated it was extremely distant and therefore a lot brighter than it looked.  It was entry #618 in the Tonantzintla Catalogue, a list of stars described in the bulletin of the Tonantzintla and Tacubaya Observatories in Mexico, and that's what gave it its rather unassuming name.

Once you start looking into this thing, though, you find it's anything but unassuming.

First, it's huge.  The black hole at the center of TON 618 is forty billion times more massive than the Sun.  If you put it where the Sun is, the entire Solar System would be inside its event horizon -- in fact, its event horizon is estimated at forty times the orbit of the planet Neptune.

Because of this, it has an impossibly high gravitational field, and is the center of a turbulent infall of matter.  This unfortunate gas and dust, as it accelerates toward its inevitable doom, is compressed and heated, emitting enough light to make TON 618 one of the most luminous objects in the known universe.  If the above comparisons weren't enough to blow your mind, TON 618 is estimated to have a luminosity of 4 x 10^40 watts -- about 140 trillion times brighter than the Sun.

It's also what is known as a Lyman-alpha blob.  This is another astronomical creature I just learned about, only found in the early universe (and therefore at this point, very far away).  The name comes from its extremely high emission of the Lyman alpha emission line of hydrogen, which has only been used as a tool for astronomers in recent years; it is so strongly absorbed by the Earth's atmosphere that it is essentially invisible to ground-based telescopes.  With the advent of orbiting telescopes like the Hubble, Kepler, and James Webb Space Telescopes, astronomers are finding more and more Lyman-alpha emitters in the distant (i.e. early) universe, but the debate goes on about what those emissions mean -- and why they aren't seen in nearby objects.

[Image licensed under the Creative Commons J.Geach/D.Narayanan/R.Crain, Computer simulation of a Lyman-alpha Blob, CC BY 4.0]

The most fascinating question about all this is where -- and what -- are quasars now?  The surmise is that for the most part they've settled down to become quiet, ordinary galactic nuclei.  But what about monsters like TON 618?  It's on the order of ten thousand times more massive than Sagittarius A*, the black hole at the center of the Milky Way; so if this eventually evolved into a galactic center, it would have to be one big-ass galaxy.

To put it in quantitative scientific terms.

Of course, there's no way to find out for sure.  When you look into the distance, you're also looking into the past, because the light that reaches your eyes (or telescope) took a finite length of time to arrive.  So you're always seeing things as they were, not as they are, and the farther away something is, the further back in time you're looking.  We're seeing TON 618 as it was about 10.8 billion years ago -- there's no way to know what, or where, it is now.

But that doesn't stop it from being an astonishing object.  The more sophisticated our instruments get, and the more detailed our scientific knowledge, the more weird and wonderful and magnificent the universe becomes.  

Even so, I'm glad that TON 618 -- whatever it is -- is located at a safe distance.  As fascinating as it is, it wouldn't make a good neighbor.

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The backfire

From the Spectacular Backfire department, today we have: the guy who sponsored a bill to crack down on "pornographic and inappropriate" materials in public school classrooms in Utah has stated that he needs to "revisit" the wording of the law when a school district used it to remove Bibles from elementary and junior high school libraries.

Representative Ken Ivory (R-West Jordan) was alarmed at the unintended consequences of his bill, and held a rally of "faith and conservative" groups at the State Capitol this week, where protestors held signs saying "God cannot be cancelled" and "Remove porn, not the Bible."

"Is there any artistic value to the Bible?" Ivory asked the crowd.  "Has anyone been to Rome and visited the Sistine Chapel?  Has anyone also been to Paris and in the Louvre, seen The Last Supper?  Or have you been to Florence and seen the sculpture of the David?"

Which is an interesting example to choose, because it was people of precisely the same mindset who, just three months ago, got a school principal in Tallahassee fired for showing fifth graders a photograph of Michelangelo's David.

But hypocrisy, however blatant, never seems to register with these people.  Apparently, material is inappropriate whenever they say it is, and might well be appropriate tomorrow if the context changes.

[Image licensed under the Creative Commons Amandajm, Bible Johns Gospel 3 16, CC BY-SA 3.0]

The deeper problem is, it doesn't take much searching to find parts of the Bible that are inappropriate for children.  I mean, really inappropriate.  One of the best-known examples is Ezekiel 23:20-21: "There she lusted after her lovers, whose genitals were like those of donkeys and whose emission was like that of horses.  So you longed for the lewdness of your youth, when in Egypt your bosom was caressed and your young breasts fondled."

Then there's Genesis 19, which is not just about sex, but about drunken incest:

Lot and his two daughters left Zoar and settled in the mountains—for he was afraid to stay in Zoar—where they lived in a cave.  One day the older daughter said to the younger, “Our father is old, and there is no man in the land to sleep with us, as is the custom over all the earth.  Come, let us get our father drunk with wine so we can sleep with him and preserve his line.”

So that night they got their father drunk with wine, and the firstborn went in and slept with her father; he was not aware when she lay down or when she got up.

The next day the older daughter said to the younger, “Look, I slept with my father last night.  Let us get him drunk with wine again tonight so you can go in and sleep with him and we can preserve our father’s line.”

So again that night they got their father drunk with wine, and the younger daughter went in and slept with him; he was not aware when she lay down or when she got up.

Thus both of Lot’s daughters became pregnant by their father.  The older daughter gave birth to a son and named him Moab.  He is the father of the Moabites of today.  The younger daughter also gave birth to a son, and she named him Ben-ammi.  He is the father of the Ammonites of today.

And don't even get me started about the Song of Solomon.

The trouble is, people like Ken Ivory want one standard for Christian texts and a different standard for everything else.  A kids' story about a child with gay parents?  Oh, no, can't have that, it's inappropriate.  But a text that features lots of sex (consensual and not), violence, torture, and genocide -- that's just fine, because "God cannot be cancelled."

If he, and the others like him, want to have an honest conversation about what is and is not appropriate to have available to schoolchildren, that's just fine.  I don't know of a single person -- liberal or conservative, religious or not -- who wants to expose children to material that is unsuited to their personal and emotional development, and no one argues that young children should read explicitly sexual or violent books.

But you can't just set a standard, then when it's applied to your favorite book, say, "No, wait, not like that."

So as usual, it's not the idea behind the law that's the problem, here; it's the hypocrisy of its supporters.

Something I don't suppose Ken Ivory will understand.  People who specialize in performative virtue seldom do.  But maybe another biblical quote, from Matthew chapter 6, will strike home with him more clearly, something Jesus said about making a show of being holy: "When you pray, do not be like the hypocrites, for they love to pray standing in the synagogues and on the street corners to be seen by men… but when you pray, go into your room, close the door and pray in secret, to your Father who is unseen."

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The myth of the Golden Age

You hear it all the time, don't you?  There's no such thing as common decency any more.  Moral values are in freefall.  Simple politeness is a thing of the past.  Kids today don't understand the value of (choose all that apply): hard work, honesty, compassion, loyalty, friendship, culture, intellectual pursuits.  The whole world has gone seriously downhill.

Oh, and we mustn't forget "Make America Great Again."  Implying that there was a time in the past -- usually unspecified -- when America was great, but it's kind of gone down the tubes since then.  But it's not just the Republicans; a 2015 study found that 76% of respondents in the United States believed that "addressing the moral breakdown of the country should be a high priority for their government."

This whole deeply pessimistic attitude is widespread -- that compared to the past, we're a hopeless mess.  The first clue that this might not be accurate, though, comes from history, and not just the fact that the past -- regardless which part of it you choose -- had some seriously bad parts.  Consider in addition that just about every era has felt the same way about its own past.  Nineteenth century Europe, for example, had a nearly religious reverence for the societies of classical Rome and Greece -- which is ironic, because the Greeks and Romans at the height of their civilizations both looked back to their ancestors as living in a "Golden Age of Heroes" that had, sadly, devolved into chaos and highly unheroic ugliness.

The Golden Age by Pietro de Cortona (17th century) [Image is in the Public Domain]

So psychologists Adam Mastroianni (of Columbia University) and Daniel Gilbert (of Harvard University) decided to see if there was any truth to the claim that we really are in moral decline.

Their findings, which were published last week in Nature, drew on sixty years of surveys about moral values, with respondents from 59 different countries.  These surveys not only asked questions regarding whether morality had declined over the respondents' lifetimes (84% said it had), they asked them to rate their own values and their peers'.

Interestingly, although most people said things were worse now than they had been in the past, there was no decline over time in how people rated the values and morality of the people around them in the present.  The percentage of people respondents knew and described as kind, decent, honest, or hard-working has remained completely flat over the past sixty years.

So what's going on?

Mastroianni and Gilbert say it's simple.

People idealize the past because they have bad memories.

It's the same phenomenon as when we recall vacations where there have been mishaps.  After a couple of years have passed, we remember the positive parts -- the walks on the beach, the excellent food, the beautiful weather -- and the sunburn, mosquito bites, delayed flights, and uncomfortable hotel room beds have all faded from memory.  It has to be really bad before the unpleasant memories come to mind first, such as the trip I took with my wife to Belize where the guests and staff of the lodge where we were staying all simultaneously came down with the worst food poisoning I've ever experienced.

Okay, that I remember pretty vividly.  But most vacation mishaps?  Barely remembered -- or only recalled with a smile, a laugh, a "can you believe that happened?"

What Mastroianni and Gilbert found was that we put that same undeserved gloss on the past in general.  It's an encouraging finding, really; people aren't getting worse, morality isn't going downhill, the world isn't going to hell in a handbasket.  In reality, most people now -- just like in the past -- are honest and decent and kind.

The problem, of course, is that given how widespread this belief is, and how resistant it is to changing, how to get folks to stop looking at the past as some kind of Golden Age.  Because the fact is, we have made some significant strides in a great many areas; equality for women and minorities, LGBTQ rights and treatment, concern for the environment are all far ahead of where they were even forty years ago.  There are a lot of ways the past wasn't all that great.

Believe me, as a closeted queer kid who grew up in the Deep South of the 1960s and 1970s, I wouldn't want to go back there for any money.

So maybe we need to turn our focus away from the past and look instead toward the future -- instead of lamenting some mythical and almost certainly false lost paradise, working toward making what's to come even better for everyone. 

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