Now comes the thunder.
In the middle Jurassic,
When Conifera's forests grew tall and the rain
Fed the canopy to heights fantastic
That no creature's neck had yet been able to attain—
Sauropos answered the forest's invitation
By growing the longest neck in the history
Of vertebrate life—a slow-motion escalation
Over thirty million years, the mystery
Of how a body can become so vast
And still function, still breathe, still pump the blood
From heart to brain across an unsurpassed
And impossible distance—the body's flood
Of engineering solutions that allowed
The impossible to walk.
Brachio stood
Tallest—with his front legs longer, proud
And giraffe-like, his nostrils above the wood
Of the highest canopy, a living crane
That browsed the treetops like a grazing tower—
Fifty tons of gentle, vegetarian reign
Over the Jurassic forest's highest bower.
Diplodos was the longest—his whip-tail
Stretched behind him like a sonic weapon,
The crack of its tip breaking the air's veil
Like a bullwhip—twenty-seven meters, heaven
Alone knew how many vertebrae in the neck
And tail combined: more than a hundred, each
Articulated for the flex and check
Of the enormous body's sinuous reach.
And Argentinosauros would come later—
The largest of them all, a hundred tons,
The most massive land animal, the greater
And most extreme of Sauropos' sons—
But in the Jurassic's middle age, the first
Great sauropods were already shaking the earth
With every footfall—and the drumbeat burst
Of their walking was the Mesozoic's birth
Of thunder that was not from any cloud.
How did they breathe?—with lungs connected to
Air-sacs that permeated the bones—the proud
And hollow vertebrae that the X-ray flew
Through like a cathedral's buttressed vault—
The same bird-like respiratory system
That Archon had invented—the default
Of the archosaur body was the prism
That solved the oxygen problem: air flowed through
The lungs in one direction, not the tidal
In-and-out of mammal breathing—new
And efficient oxygen exchange, the bridal
Gift of Archon to his greatest children.
How did the heart pump blood so far?—
With a pressure that would kill a human, the buildin'
Of a cardiovascular star
That weighed as much as a small car and beat
With a force that the aorta had to channel
Through a body longer than a city street—
And the blood-pressure at the head was a panel
Of engineering that we still don't fully know.
They were warm—or warm enough—the mass
Of their bodies holding heat in the slow
And enormous thermal reservoir, the crass
And simple physics of being so large
That the surface-area-to-volume ratio meant
The body stayed warm without any charge
Of metabolic fire—gigantothermy lent
What endothermy gives to smaller things:
A stable, warm interior where the enzyme
Chemistry of life could spread its wings
Regardless of the night's cold or the daytime
Blaze of the Jurassic sun.
They walked in herds—
The footprints tell us this: great trackways of
A dozen or a hundred, and the words
Of the rock record say the giants above
Moved together, the young in the center
Protected by the adults' enormous flanks—
No predator but the boldest would enter
The moving fortress of a sauropod's ranks.
And they ate. They ate constantly. They stripped
The forests with the efficiency of machines,
Each day consuming more than a man has shipped
In a week of groceries—the Jurassic scenes
Of sauropod feeding must have sounded like
A continuous ripping of the world's green hide—
The crunch and tear of branch and bark and spike
Of conifer processed through the inside
Of a gut the length of a house, fermented
By bacteria that broke the cellulose
To energy—the forest demented
By the appetite that never found its close.
This was the age of giants. This was when
The earth trembled not from volcanism's fire
But from the footsteps of the greatest of all men—
If men is what we call the living spire
Of evolution's most ambitious reach:
To build the largest animal that walks
On four legs, each one massive as a beach-
Side pylon—and the thunder of their walks
Was the heartbeat of the Jurassic world.
Honor Sauropos—the thunder lizards,
The gentle giants whose banners were unfurled
In the conifer forests, who braved the blizzards
Of deep time and grew to the limit of what land
Can hold, what bone can bear, what heart can pump—
The largest things that ever walked on sand,
Whose every footstep was the drumbeat's thump
Of life saying: I am here, and I am vast,
And the earth itself remembers where I passed.