Cosmic Calendar: Mammals!

December 26th on the Cosmic Calendar:  Actual hairy, lactating, bug-eating mammals!  Not Synapsids anymore!  The earliest mammals lived in the Jurassic and Cretaceous, yes, in the shadow of dinosaurs.  The first group of no-doubt-about-it mammals were the Triconodonts (again, the earliest currently known).

Jeholodens jenkinsi, a triconodont mammal that lived about 120 to 140 million years ago

Not all of the tricodonts were small though.  Repenomamus was a meter long — about the size of a beaver!  Big enough to eat small dinosaurs!

Mmmm! Dinosaur tastes like chicken!

You may remember Cosmos, the 1980 PBS series by Carl Sagan. Maybe you also recall Sagan’s “Cosmic Calendar” from the series, where in order to put the immensely vast history of the universe into a comprehensible scale, he mapped it onto a calendar year. In other words, if the entire history of the universe were one year, with the big bang in the first second of midnight on January first, and the present day on the last second of December 31st, New Year’s Eve. A project of mine this year has been to note the major events in the Cosmic Calendar, on the real calendar, on this blog!

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Um, Santa?!?

That's "Merry Christmas" in Tyrannosaur...

That’s “Merry Christmas” in Tyrannosaur…

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Cosmic Calendar: Dinosaurs!

December 24th on the Cosmic Calendar:  Dinosaurs rule the Earth!  Finally!  Having scaled the entire 13.75 billion year history of the universe down to one year, the dinosaurs — who we usually think of as having lived in the inconcievably distant past — yes, they only show up in the last week of the cosmic year.  That is how long the 13.75 billion year history of the universe is.  251 million years is only one week on the cosmic calendar.

Tyrannosaurus Rex

Tyrannosaurus Rex

Diplodicus

Triceratops

Stegosaurus

So there are the classic four dinosaurs — Tyrannosaurus Rex, Diplodicus, Triceratops, and Stegosaurus.  But since this is an art blog, even though it’s been hijacked by the history of the universe for the last several posts, and for the next several too, I’ll close with my favorite dinosaur painting.  Animal Plumbing by Brian Filipowich.  At least I always thought the animal plumbed here was a Tyrannosaurus…  🙂

Animal plumbing, by Brian Filipowich

You may remember Cosmos, the 1980 PBS series by Carl Sagan. Maybe you also recall Sagan’s “Cosmic Calendar” from the series, where in order to put the immensely vast history of the universe into a comprehensible scale, he mapped it onto a calendar year. In other words, if the entire history of the universe were one year, with the big bang in the first second of midnight on January first, and the present day on the last second of December 31st, New Year’s Eve. A project of mine this year has been to note the major events in the Cosmic Calendar, on the real calendar, on this blog!

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Cosmic Calendar: The first reptiles and the first trees

December 23rd on the Cosmic Calendar: The first reptiles and trees, sort of.

In researching the first trees of the carboniferious period, I discovered new information about trees that grew as early as the devonian period.  Which means ideally I’d have posted about the first trees 2 days ago, on December 21st.  Oh well.  Figuring out exactly when these firsts were is a moving target as new discoveries are continually made.

The currently earliest known trees were Wattieza in the middle devonian period — December 21st on the Cosmic Calendar.    They’re related to modern ferns and reproduced with spores instead of the yet-to-evolve seeds.

Wattieza

Wattieza

Ok, back to the carboniferous and the first reptiles!  The earliest known reptile is Hylonomus.  Hylonomus was an 8 inch (20 cm) long lizard with tiny teeth, the better to eat bugs with.  The main differences between reptiles and the amphibians they evolved from are scales and egg shells.  Generally speaking even today amphibians cannot stray too far from the water’s edge because their skin dries out so quickly.   The development of scales which keep moisture in solved this problem and let reptiles roam farther to hunt.  Likewise egg shells did the same for their eggs.  Amphibians need to lay their eggs in water.  Like fish eggs they do not have shells, and would dry out long before hatching if left on land.  Egg shells solved this problem, again by holding in moisture.  As reptiles vertebrates were finally freed to really conquer the land!

Hylonomus

Hylonomus

By the Permian period our ancestors like Hylonomus had evolved into the mammal-like reptiles, the Synapsids and Therapsids.

Dimetrodon, everyone’s favorite synapsid!

These are not dinosaurs.  Dinosaurs are yet to come from a separate line of reptiles.  These are our ancestors, dinosaurs are not.  Synapsids have jaws and teeth like mammals.  Canine teeth, molars, and incisors — just like us.  Synapsids dominated the Permian, enjoying their moment in the sun before being overshadowed by the dinosaurs.  By then synapsids will have evolved fur and shrank to the mouse-like mammals we usually think of hiding in the shadows from dinosaurs.  But Dimetrodon here was 5 to 10 feet (2-3 meters) long and is more like modern mammals than modern reptiles.  In the same sense that birds can be considered dinosaurs, mammals, including ourselves, can be considered synapsids.

Therapsids are another group of synapsids from later in the Permian.  Therapsids are even more like mammals:

Biarmosuchus, a Therapsid. Nice doggie!

Therapsid Inostrancevia in the middle, flanked for scale by a person and smilodon, the famed “saber-tooth tiger”

Oligokyphus, a therapsid cynodont

You may remember Cosmos, the 1980 PBS series by Carl Sagan. Maybe you also recall Sagan’s “Cosmic Calendar” from the series, where in order to put the immensely vast history of the universe into a comprehensible scale, he mapped it onto a calendar year. In other words, if the entire history of the universe were one year, with the big bang in the first second of midnight on January first, and the present day on the last second of December 31st, New Year’s Eve. A project of mine this year has been to note the major events in the Cosmic Calendar, on the real calendar, on this blog!

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Cosmic Calendar: The first amphibians and winged insects

December 22nd on the Cosmic Calendar: The first amphibians and the first flyin’ bugs!  I feel safe using the term “bugs” because I don’t think there has ever been a flying arachnid (shudder).

It is thought  the first of our amphibian ancestors evolved from lobe-finned fish like coelacanths and lungfish in the carboniferous period.  Lobe-finned fish have thick, meaty ventral fins with muscle and bone structure.  These fins literally do double as legs for walking on the sea floor, which is an interesting adaptation in itself.  You may have heard of coelacanths — the “living fossils”.  Coelacanths were already well known to paleontologists from the fossil record, when to everyone’s shock and disbelief a fisherman in South Africa pulled one up in his nets in the 1930s.  They’re not extinct at all.

Lungfish are also lobe-finned, and as the name implies, developed primitive lungs.  It seems that like algae they found themselves living in shallow ponds that tended to evaporate.  They evolved lungs to breath air when necessary, and over time their lungs improved and their lobe-fins also evolved into land legs.  Enter the earliest known amphibian, Ichthyostega!

Reports of the extinction of Coelacanths are greatly exaggerated

Heeeyyyy…. Coelacanth!

Lungfish says “Derp”

Lungfish: “I’m bored. Lets get coffee.”

Ichthyostega: “Do do doot do dooo… Look at me!” Like a big, cute frog.

Ichthyostega: “Oooh! Land bugs! Yum!!”

Hynerpeton came along several million years later

Bugs took wing which eventually led in the carboniferous to this monster dragonfly, meganeura.  Meganeura had a 2 foot (65 cm) wingspan.  Yeah.  Forget that can of Raid — try a shotgun.

Meganeura!

Meganeura

Meganeura – like an eagle!

You may remember Cosmos, the 1980 PBS series by Carl Sagan. Maybe you also recall Sagan’s “Cosmic Calendar” from the series, where in order to put the immensely vast history of the universe into a comprehensible scale, he mapped it onto a calendar year. In other words, if the entire history of the universe were one year, with the big bang in the first second of midnight on January first, and the present day on the last second of December 31st, New Year’s Eve. A project of mine this year has been to note the major events in the Cosmic Calendar, on the real calendar, on this blog!

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Cosmic Calendar: The first plants on land!

December 20th on the Cosmic Calendar:  The first plants on land.  Yes, up until now there have been no plants on land.  Until now the land was just rock and sand, more like Mars than Earth today.  Trilobites and the first fish aside — and we haven’t even gotten to dinosaurs yet — I find this somehow even more mind-blowing.  Everything until now has been in the oceans.  No trees — no green at all upon the land — no oxygen to speak of in the air, just rock and sand.  Rock and sand.  Rivers cutting their way through rock to the sea.

The first land plants likely evolved from algae living in shallow pools of water.  That this water would evaporate was a problem for these algae.  They had to evolve to be able to do without water for a while.  Once they had done that, at some point water just from rain was enough and they were free to grow away from the pools.  The colonization of the land by plants had begun!

Algae scum

Rebel scum

Sorry, I couldn’t resist (the dark side).

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Cosmic Calendar: The first vertebrates and fish!

December 19th on the Cosmic Calendar:  The first vertebrates and actual fish appear!

Myllokunmingia is currently the oldest known vertebrate — a 28 x 6mm chordate.  It had a distinct head and body, dorsal and ventral fins.

Haikouichthys is considered the first actual fish.  Haikouichthys was a craniate, meaning it had an actual skull and backbone (myllokunmingia’s were probably made of cartilage).  Haikouichthys was about the same size at 25mm.  Fossils show it had between 6 and 9 gills.

Myllokunmingia

Haikouichthys

Haikouicthys

This is still the Cambrian explosion!

You may remember Cosmos, the 1980 PBS series by Carl Sagan. Maybe you also recall Sagan’s “Cosmic Calendar” from the series, where in order to put the immensely vast history of the universe into a comprehensible scale, he mapped it onto a calendar year. In other words, if the entire history of the universe were one year, with the big bang in the first second of midnight on January first, and the present day on the last second of December 31st, New Year’s Eve. A project of mine this year has been to note the major events in the Cosmic Calendar, on the real calendar, on this blog!

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