Analysis of A Moral Alphabet (excerpt)

D: The Dreadful Dinotherium he
Will have to do his best for D.
The early world observed with awe
His back, indented like a saw.
His look was gay, his voice was strong;
His tail was neither short nor long;
His trunk, or elongated nose,
Was not so large as some suppose;
His teeth, as all the world allows,
Were graminivorous, like a cow's.
He therefore should have wished to pass
Long peaceful nights upon the Grass,
But being mad the brute preferred
To roost in branches, like a bird.1
A creature heavier than a whale,
You see at once, could hardly fail
To suffer badly when he slid
And tumbled (as he always did).
His fossil, therefore, comes to light
All broken up: and serve him right.

MORAL
If you were born to walk the ground,
Remain there; do not fool around.

E stands for Egg.