On the far side of a wide, silver river, where ferns grew taller than a young dinosaur’s head and dragonflies shimmered like tiny blue jewels, there stood a hill called Warmback Ridge.

Warmback Ridge was not a very tall hill. It did not scrape the clouds like the jagged mountains in the north. It was not covered in snow, nor did it have a roaring waterfall. But deep inside its soft red stone were many round hollows, each one smooth and dry.

And one hollow was warmer than all the rest.

Even during the rainy season, when cold drops pattered on every leaf and the mud squelched between dinosaur toes, the warmest hollow stayed cozy. A gentle heat rose from the ground inside it. The air smelled of dry grass, sun-baked clay, and the faint, peppery scent of wildflowers.

For many generations, the warmest nesting hollow had been cared for by the oldest and wisest members of the Willowtail herd.

But this year, something surprising happened.

The keeper was chosen from the youngest dinosaurs.

Her name was Sanaa.

Sanaa was a young Maiasaura with a soft brown crest, bright amber eyes, and feet that always seemed to be stepping on something interesting. A shiny pebble. A fallen feather. A beetle carrying a crumb twice its size.

She was not the biggest young dinosaur. Her cousin Oren was bigger.

She was not the loudest. Her friend Tavi could call loudly enough to make sleeping birds flap out of trees.

And Sanaa was certainly not the bravest. When thunder rumbled, she liked to stand very close to her mother’s legs.

But Sanaa noticed things.

She noticed when the air turned cool before a rainstorm. She noticed when the river was rising. She noticed which grasses made the softest nest lining, and which dry leaves crackled too much beneath a sleeping egg.

So when Old Mother Nkem, the oldest Willowtail, pointed her long tail toward Sanaa and said, “This season, you will tend the warm hollow,” everyone grew quiet.

Sanaa’s mouth fell open.

“Me?” she squeaked.

“You,” said Mother Nkem.

“But what if I forget to turn the eggs?”

“You will make a turning song.”

“What if the rain comes in?”

“You will cover the entrance with fern fronds.”

“What if a night lizard sneaks close?”

“You will call for help.”

Sanaa’s mother lowered her gentle head beside hers. “A keeper does not have to do everything alone,” she said. “A keeper must remember what matters.”

So Sanaa began preparing the warmest nesting hollow.

She swept out old leaves with a branch of palm fern. She padded the floor with moss and soft seed fluff. She carried smooth river stones, warmed by the sun, and tucked them around the edges where the warmth was weakest.

Each morning, she pressed her cheek to the ground to feel the sleepy heat beneath the stone.

Each evening, she sat at the entrance and watched the sky become purple, then indigo, then dark as a berry.

Soon, the Willowtail mothers came one by one to lay their eggs.

Round eggs.

Speckled eggs.

Cream-colored eggs with pale green dots.

Sanaa arranged them carefully in wide circles, leaving room so each egg could breathe. She sang them her turning song as she worked.

“Round and warm, safe from harm,
Sleep beneath the fern.
Quiet feet, gentle heat,
Rest while seasons turn.”

The eggs seemed to glow softly in the hollow’s amber light.

Sanaa was proud.

Very proud.

Then, one afternoon, the birds stopped singing.

Sanaa was gathering dry grass near the river when she noticed it.

The little striped birds had vanished into the reeds.

The dragonflies hovered low.

Even the river seemed to hush.

Then came a sound from beyond the blackwood trees.

Thump.

Thump.

Thump.

Many heavy feet.

Sanaa hurried back to Warmback Ridge. At the top of the hill, she saw her herd gathered in a worried cluster. Their tails were low. Their crests tilted forward.

Across the open meadow stood another herd of dinosaurs.

They were Crestbacks, with darker hides and tall, curved crests striped in charcoal gray. The Willowtails and Crestbacks had never been friends. They drank from different bends of the river. They gathered fruit from different groves. When they met near the meadow, they usually turned away with stiff necks and suspicious eyes.

At the front of the Crestback herd stood a weary old dinosaur named Batiste.

His sides were muddy. A long scratch marked one shoulder. Behind him were mothers, fathers, and several little ones, all looking tired.

Batiste called out, “The Stonejaw flood has taken our nesting ground.”

Sanaa could hear the tremble in his voice.

“Our hollow caves have filled with water,” he continued. “Many of our eggs were saved, but they will grow cold before night. We ask for shelter.”

The Willowtails murmured.

Sanaa looked past the adults and saw the Crestback hatchlings. They were not yet hatched, of course, but their eggs were carried in woven grass cradles between the adults. Some had been splashed with mud. Some were shivering in the damp breeze.

There were so many.

Sanaa’s warm hollow was already full.

Her heart gave a hard little bump.

Mother Nkem stepped forward. “How many eggs?”

“Twenty-three,” said Batiste.

The Willowtail herd gasped.

Twenty-three more eggs would not fit. Not even close.

Oren whispered to Sanaa, “That is impossible.”

Sanaa did not answer. She was looking at the grass cradles.

One egg, pale blue with a gray stripe, rolled gently against another. It made the tiniest tap.

Tap.

Tap.

As if it were asking, Is there room for me?

Sanaa swallowed.

“The warm hollow has space for only six more eggs,” she said.

Batiste closed his eyes.

The Crestback mothers drew closer around their cradles.

A cold wind slipped over the meadow. Far away, thunder muttered.

“We can share the other hollows,” said one Willowtail adult.

“They are too cold,” said Sanaa quietly. “The eggs may not hatch.”

“But our own eggs are already inside,” said Oren. “We cannot move them.”

“No,” Sanaa said. “We cannot.”

Everyone looked at her.

Sanaa wished, very much, that she could hide behind her mother’s legs. But she was the keeper. She remembered what mattered.

She looked at Warmback Ridge.

At the ridges of red stone.

At the ferns growing thick around its base.

At the little stream that ran behind the hill and disappeared beneath a curtain of hanging vines.

Then she remembered something.

Last spring, she had followed a beetle under those vines. She had found a narrow crack in the stone. Warm air had puffed out onto her face, smelling of earth and minerals.

She had been too small to squeeze through then.

Maybe she was still too small.

But maybe not.

“I know of another place,” said Sanaa.

Oren blinked. “Another warm hollow?”

“I do not know if it is a hollow. But there is warm air behind the vines.”

Mother Nkem studied her. “You have seen this?”

“Yes.”

Batiste lifted his weary head. “Could it hold eggs?”

“I do not know,” said Sanaa honestly.

The thunder rumbled again, louder this time.

“We must look,” said Mother Nkem.

So Sanaa led them around the back of Warmback Ridge.

The rain began as a soft pattering, tapping the leaves. Sanaa pushed through curtains of vines dripping with clear drops. Behind them was the crack in the red stone.

Warm breath curled from it.

Oren squeezed his head close to the opening. “Too narrow,” he said.

“It is narrow at the front,” said Sanaa. “But I think it opens farther in.”

Nobody could fit except Sanaa.

Her knees wobbled.

Then she took a deep breath and slipped into the crack.

The stone pressed gently against her sides. It was dark, except for tiny green lights from glowworms resting on the walls. Sanaa moved slowly, one careful step at a time.

The passage bent.

Then widened.

Sanaa stopped.

Before her was a hidden chamber, round and high, with a ceiling dotted by shining stones. Warm steam rose from a little pool in the corner. Along the floor, the earth was dry and soft.

There was room.

Not for twenty-three eggs all in one place.

But there was room for many.

Sanaa hurried back out, muddy and breathless.

“There is a chamber,” she cried. “It is warm. It is dry. It is beautiful!”

The adults worked quickly.

The larger dinosaurs carefully widened the entrance by pushing away loose stone with their snouts and feet. They did not make it too wide, because a narrow entrance would help keep out cold wind.

The Willowtails brought dry reeds.

The Crestbacks brought thick bark strips from the blackwood trees.

Together they lined the hidden chamber.

Together they carried the eggs.

Six Crestback eggs went into the warmest nesting hollow beside the Willowtail eggs. Sanaa placed them in a new circle near the gentle heat in the center.

The other seventeen eggs were tucked inside the secret chamber.

For two days, rain fell over Warmback Ridge.

Water rushed in shining ribbons down the hillside. The meadow turned wet and silver. But inside the two nesting places, the eggs stayed warm.

At first, the Willowtails and Crestbacks kept to separate sides of the ridge.

They spoke only when necessary.

“More moss here.”

“Move that stone.”

“Your egg is rolling.”

But on the third day, Tavi found a bright orange snail and placed it on Oren’s tail. Oren yelped so loudly that three Crestback children began to laugh.

Then Oren laughed too.

After that, things became easier.

The two herds took turns gathering food. They shared stories while the rain drummed above them. Batiste told everyone about the time he had wandered into a field of purple berries and sneezed purple for three whole days.

Even Mother Nkem laughed at that.

Sanaa cared for both nests.

She sang the turning song in the warm hollow, then carried it into the secret chamber, where her voice echoed softly from the stone walls.

“Round and warm, safe from harm,
Sleep beneath the fern.
Quiet feet, gentle heat,
Rest while seasons turn.”

Soon, tiny cracks appeared on the first eggs.

Sanaa saw one in the secret chamber.

Crick.

A little piece of shell lifted.

Then came a small, squeaky sound.

Peep!

The first hatchling pushed out a damp, wrinkled nose.

Everyone gathered near, holding very still.

The hatchling blinked at the glowing stones above.

Then it peeped again, louder.

One by one, eggs began to crack in both nesting places.

Willowtail hatchlings.

Crestback hatchlings.

Some with soft brown fuzz along their heads. Some with gray-striped crests no bigger than curled leaves. They stumbled on wobbly legs, bumped into one another, and fell asleep in little warm heaps.

One pale blue Crestback hatchling with a gray stripe waddled straight toward Sanaa.

It was the egg she had seen tapping in the grass cradle.

The tiny hatchling pressed its nose against her foot.

Sanaa bent her long neck and smiled.

“You found room,” whispered Batiste, standing beside her.

Sanaa looked around.

The warmest hollow was full, but not too full. The secret chamber glowed with gentle light. The two herds stood together beneath the rainy sky, watching their hatchlings take their very first steps.

“There was room,” Sanaa said. “It was just hiding.”

When the rain finally ended, Warmback Ridge shone bright beneath the morning sun.

Water sparkled on every fern.

The river ran clear again.

And from that season onward, the warmest nesting hollow had not one keeper, but many helpers.

Still, whenever anyone asked who had first found the hidden chamber beneath the vines, the old dinosaurs would lower their heads respectfully toward Sanaa.

By then, she had grown a little taller.

She was still not the biggest dinosaur.

She was still not the loudest.

And thunder still made her want to stand close to her mother.

But Sanaa was the keeper who had remembered what mattered.

At night, when the hatchlings were tucked safely in their nests, the warm hollow breathed its soft, earthy warmth into the dark.

Outside, the moon rested over the silver river.

Inside, little dinosaur dreams curled gently beneath the ferns.