RAPTOR RED

THE TURTLE OF TRINITY LATE MAY

It’s midnight, but Raptor Red is wide awake because she’s curious. Something is going on in the pond, and she wants to know what it is. She’s been staring at a V-shaped series of tiny waves that means a living animal is moving just under the surface.

Flip! Up comes a little black scaly face, pushing its armored eyebrows just above the pond’s surface. The moonlight catches the crests of the delicate ripples widening as they pass outward from the disturbance. Pop! The eyes open, and a pair of orange-red pupils stare at the shore, where Raptor Red is hunched down, motionless but awake.

Pip! A bubble of air grows quickly at the tip of the back snout, pauses for a second, and bursts.

Raptor Red’s mind is on automatic-alert mode. She can’t sleep. Her sister is curled up in a temporary nest they made just before dusk. It’s two o’clock in the morning.

Sssnnnrrhht! Raptor Red flinches a tiny bit as her sister snores loudly, Tlssssshh.' The pair of eyes and bubble-blowing nose disappear under the pond water.

Raptor Red is disappointed - she’s still curious about that little dark head. She’s been watching it for an hour. Raptor Red is a late-night Utahmptor. She was born that way. She falls asleep at sundown but wakes up at midnight. It’s genetic, a trait she inherited from her father. Her sister is an early riser. She’s fully alert hours before dawn, but she falls asleep two hours after dusk and snores till dawn. Also genetic.

Siblings differ in their wake-sleep schedules, and evolutionary forces can work on this diversity. A diverse range of genetically fixed behaviors in a brood can ensure that at least some of the youngsters will survive to adulthood, no matter what sort of environmental challenges are thrown at them. A late-night gene may help survival when prey abundance shifts and the only vulnerable victims are herbivores who can be stalked after dusk. An early-riser gene could give just the opposite advantage -the ability to hunt before sunrise.

Raptor Red knows nothing about evolutionary theory. But she does know that her sister snores. She glares at her sister’s sleeping but noisiferous form. Just as her sister inhales in preparation for another snorting-wheezing-honk, Raptor Red reaches out with her left foot and pushes hard.

Fwwump - ooooph! Her sister rolls onto her side, exhales heavily, stays asleep, and then begins a new cycle of snores, far quieter this time.

Raptor Red goes back to watching for the head in the pond.

Just an inch below the water, the head is listening. A wide oval eardrum has been vibrating with each raptor snore. Each ssnnrrhht! has sent high-energy, low-frequency sound waves into the water. Some of the sound energy reflects off the water’s surface, but some penetrates, generating pulses of waterborne sound. The big eardrum is designed for just such low-frequency sound. It’s a turtle’s ear, and it belongs to a Trinitichelys, the Turtle of the Trinity River.

This Trinity Turtle is a female, only twelve years old and five pounds in weight. This year is the first year she has mated. Her biological clock went into alarm mode during the night. It’s time to try the most dangerous thing her genetically programmed lifestyle demands: It’s time to come ashore and lay eggs-

No two minds are more different than the raptor’s and the turtle’s. The raptor is a bundle of spunky inquisitiveness. She wants to find out about each and every animal in her world. She sniffs strange objects and pokes her snout down holes. She goes out of her way to investigate any strange and new sight. Her mind demands new stimuli, new mysteries to solve.

The turtle lives a life of comfortable monotony that would bore Raptor Red to death. Walking and swimming slowly over the pond bottom, picking up pieces of soft vegetation and an occasional hunk of dead fish. Crawling out onto a half-submerged log and letting the sun warm her turtle belly, assisting in digestion. For every ten degrees Celsius that the turtle guts warm up, the speed of the digestive process doubles. She crawls back into the pond late in the afternoon.

Every day the same routine, every day the exact same hundred square yards of pond bottom. Nothing unexpected, nothing exciting. The turtle’s body is undemanding. Her internal metabolic furnace needs only one-twentieth as much food per day as a dinosaur of the same size.

And so she is content to make do with a brain that is tiny and tubular, a brain that lacks the restless curiosity of raptors.

The Trinity Turtle would be scared into her shell and never come out if she had to deal with the range of stimuli Raptor Red experiences every day.

Pip. With a faint sound, the turtle pops her head above the surface again. The alarming sound of raptor snoring has stopped. Raptor Red creeps forward toward the water to get a better look. Her feet make a rustling noise against the dry ferns. Raptor Red freezes, but she doesn’t have to. Turtle ears can’t pick up soft, high frequency sounds. The heavy eardrum and the large ear bone attached to it can’t transmit such vibrations.

But it is perfectly adequate for the turtle’s needs. She doesn’t have to stalk soft-stepping prey across the forest floor. She doesn’t have to listen carefully for subtle variations in the calls of her mate and her siblings. Turtles live a noiseless life. They don’t communicate audibly with relatives, and the Trinity Turtle, like most of her sister species, finds food in water.

Sound is easy to detect underwater. When a crocodile snaps at a fish underwater, the sound waves pass quickly through the aqueous medium and go right through the turtle’s body with little impediment. Sound moves through the skin and then the muscle and then the brain tissue itself. So water-loving critters have an easy time hearing low-frequency sounds.

So there’s no need for the Trinity Turtle to be outfitted with the delicate ear bone and complex inner ear of a raptor. The only time she feels a deep-seated anxiety about sound is that one season of the year when she must climb out of her comfortable watery home and seek a suitable sandbank to lay her eggs. Raptor Red watches the turtle head disappear. A line of ripples shows that the turtle is swimming toward shore. Raptor Red crouches down even further, her calf muscles twitching with excitement. She’s not hunting now - she and her sister filled their bellies with iguanodon meat late that afternoon. What excites Raptor Red now is finding out something new.

Inside the turtle brain is the opposite emotion -fear of the unknown. The Trinity Turtle hasn’t been out onshore since she herself hatched twelve summers ago. That was the worst day of her life. Being tiny and helpless, cracking open her shell, and •smelling a thousand unknown things. Being one of fifty struggling turtle-ettes, all scrambling out of their nest, compelled by instinct to climb up through the sand that their mother piled on top of the eggs. Then instinct shifted gears, and the baby turtles were drawn irresistibly downslope to the smell of water.

Only two baby turtles made it to the water. The Trinity Turtle saw a brother three inches away get snatched upward in the toothy jaws of a dactyl. Then two sisters climbed over the Trinity Turtle. A second later, they too were pulled to their deaths. Just as the scent of the pond water was becoming sweet and strong, the Trinity Turtle herself was pulled four feet skyward, her left hindfoot pinioned by a set of sharp teeth. Pain, the first pain she had ever felt, paralyzed her left hindquarters. Then there was a flapping of huge, white wings and a snapping sound. Two dactyls were fighting over this turtle morsel.

She was dropped into the water. The instant she felt the warm summer water engulf her body, a third instinct cut in - to swim down. With three legs flailing madly, she made a crash dive at forty-five degrees, hitting a pond-weed clump at the bottom. She kept going, burying her bruised, half-hour-old turtle body into the mud.

The baby Trinity Turtle wasted no time grieving over her lost siblings. They meant nothing to her. In the turtle brain there is an almost complete void where the emotional bond between relatives would be in a raptor. The dead sisters and brothers were mere objects in the turtle’s environment. Their sudden deaths were useful as a warning that danger was near but had no other significance.

The Trinity Turtle, like nearly all turtle species, understands and appreciates only one individual -herself. She never saw or even smelled her mother, who scooped out a nest, laid the eggs, covered the nest, and crawled back into the water, never to interact in any way with her progeny afterward. A Lay 'em and leave 'em parent.

And the Trinity Turtle has never bonded with any brother or sister or any other turtle of her own species or any other species. Her courtship some weeks earlier did take six hours. The competing males had to swim around and around her, trying to impress her with their grace and coordination. She rejected the first five suitors. Mating with the sixth was quick and perfunctory. The male left immediately after the physiological act was completed, and now the Trinity Turtle ignores the male - even when they happen to pass each other in the pond.

To the turtle, the concept of loneliness is incomprehensible. She always has been alone, and any other social state is unthinkable.

The Trinity Turtle pushes her whole head and neck out of the water and swivels her face around, searching with eyes and nose. Like most turtles, Trinitichelys has only a mediocre sense of smell in the open air, compared to the olfactory powers of a long-snouted dinosaur or crocodile. The turtle snout is short, and the space for the smelling apparatus is squeezed between the front of the beak and the forwardly located eyeballs. This cramped olfactory chamber is perfectly okay for underwater work, where scent is carried by water currents. But out of the water smelling is much more difficult, because air currents carry only a tiny fraction of the scent-laden molecules that water can transport.

Raptor Red can smell the turtle now - she’s eaten rancid turtle meat before, scavenged from carcasses washed up on the shore.

But this is the first live turtle scent she’s experienced. It’s a dank, musky, slightly cool, and moist smell. It’s exciting, because it’s new to her brain.

The turtle drags her heavy shell up onto the shore with slow, jerky steps. Her long, straight claws dig into the earth.

Raptor Red can’t bear it any longer. She jumps on the turtle, coming down on the shell with both hands. The algae-coated shell slips between her fingers and goes squirting sideways.

Slapppp, slappp - slapslap. Raptor Red fumbles the slick turtle shell, picks it up, fumbles again.

Raptor Red sits down and tries to figure the turtle out. She attempts to nibble a hole in the shell, but her teeth slip off the sharp edges of the carapace. Then she picks up the whole shell in her mouth, blinks twice, and bites down really hard.

Ting! One of Raptor Red’s teeth breaks off at the base of the crown. The turtle is unscathed.

Inside the shell the turtle brain is not panicked. This has happened before. She has been picked up from the water by rambunctious dinosaurs who knock the shell about and gnaw ineffectively and finally give up.

Raptor Red’s teeth, which can cut through a two-ton iguanodon hide, are useless against the five-pound turtle. The turtle shell is triple-layered. The outermost armor is a thin but very tough layer of dead skin with the consistency of very hard fingernail. There are no nerves or blood vessels in the outer layer, no delicate tissue to be hurt. The shell constantly regenerates the fingernail layer from the inside as the outer surface gets worn and scratched. The scratches left by Raptor Red’s teeth do no permanent harm.

The next shell layer is made up of convex plates of bone on the top and flat plates on the bottom. Top and bottom shell bones meet on the left and right side at the bridge, a zone of especially thick, strong bone behind the armpit and in front of the hole for the hindlegs and tail. The smooth contour of the shell bones doesn’t give a predator any thin edges to bite off, and the arched cross section makes the shell nearly impossible to crack.

The innermost armor layer is a brilliant piece of evolutionary engineering and is the main reason that the turtle is safe from Raptor Red’s teeth and claws. On the inside surfaces of the bone plates of the upper shell are long, curved girders of bone that reinforce the shell dome and give it exceptional strength and rigidity. These girders are the turtle’s ribs. Unlike the ribs of any other backboned creature, turtle rib shafts are fused immovably to the backbone and to the shell plates.

And the backbone of the torso is fused to the underside of the upper shell too, so the entire torso is tremendously strong.

When she ate dead turtles, Raptor Red had no problem pulling the meaty hindlegs and tail out of the shell. But now the legs and tail have disappeared from this living specimen and are hidden inside the rib-braced armor. Raptor Red sniffs cautiously at the holes in the shell where the legs have withdrawn. She nudges the shell with her snout and tries to stick her front teeth into the holes. She picks up the turtle carefully in both hands and utters a growl of frustration. The turtle keeps her legs hacked safely inside.

The Utahraptor is completely foiled by yet another unprecedented and unparalleled triumph of turtle anatomy: the shoulder-swivel. The shoulder blade has a pivot joint with the top shell above and the bottom shell below. To swing the entire front leg into the safety of the bone-armored box, all the turtle has to do is rotate her elbow in toward her neck and - voila! The whole leg disappears within the capacious shell.

No other creature in the entire Early Cretaceous world has a disappearing shoulder.

Raptor Red slowly turns the shell around. A quick hsssssss comes from the front end, accompanied by bubbles. Raptor Red can see an eyeball staring back at her. Trinitichelys and all other turtles of the Early Cretaceous Age are primitive in one key area - they cannot retract their head all the way into the shell, the way modern-day turtles can.

Raptor Red cocks her head and looks very closely at the turtle head. She lifts the thin, outer finger of her left hand and gently probes the shell half covering the turtle head. She tries to dig into the top of the turtle head, but her claw just slips off. The turtle head is armored with thick bone and a fingernail layer. The Law of Darwinian Compensation is operating here. As long as turtles are in a state where they cannot retract their head entirely into the safety of the shell, the turtle skull wears a thick coat of bone armor and hard skin.

Raptor Red is experiencing the universal frustration of predators who try to crack a turtle. No animal before or since has had such an unbreakable cranial construction.

Right now the Trinity Turtle is just too much of a puzzle for Raptor Red. She sighs. Plop! She drops the turtle and yawns - she’s getting sleepy again. She trudges back to the temporary nest, flops down next to her sister, and closes her eyes.

Ten minutes later the Trinity Turtle peeks out from under her shell, sniffs, stares, sniffs again, and resumes her waddling march toward a very special piece of sandy shore. Despite being juggled and nibbled by the raptor, her dedication to her reproductive destiny remains unshaken. The sensors in her small olfactory chamber are dialed to one particular scent - the smell of the very same sandbar where she hatched twelve years ago.

Thirty minutes later her nose tells her brain to stop moving and start digging. Her short, sturdy hindpaws begin to shovel sand with alternating strokes, first left, then right. When the hole is as deep as her shell is tall, she stops and deposits eleven spherical eggs.

If Raptor Red were still awake and understood the process, she’d feel a pang of jealousy. The turtle’s instinct-driven, single-minded reproductive drive is simple compared with the social complexity of Raptor Red’s present life. The Trinity Turtle doesn’t have to balance the competing demands of sisters and mate. The turtle has no responsibilities other than to her own eggs, and even that duty is fully discharged as soon as she covers the nest with a layer of sand.

And so on this particular Early Cretaceous night, one turtle mother completes the life cycle of her species and returns to the comfortable monotony of her watery world. One female raptor must go to sleep with the vague hope that the entangling alliances of raptor society will someday give her another chance to reproduce.