Meanwhile the plesi fought on, inflicting scratches and bites on its assailants. One of the mesos was left whining, the tendons of its right hind leg badly ripped, blood leaking from torn flesh. But at last the plesi succumbed to their teeth and weight. The mesos formed a loose circle around their victim, their slim bodies and waving tails clustered around their meal like maggots around a wound. The rising stink of blood, and the fouler stench of panic shit and stomach contents, overwhelmed Noth’s sensitive nose.

Though some of the ancient plesiadapids had specialized, learning how to husk fruit like opossums or to live off the gum of trees, they remained primarily insect eaters. But now they faced competition from other insectivores, the ancestors of hedgehogs and shrews — and from their own descendant forms like the notharctus. Already the early-form plesis had become extinct across much of North America, surviving only in fringe areas like this marginally habitable polar forest, where the endless days did not suit bodies and habits shaped during the nights of the Cretaceous. Soon the last of them would be gone.

Noth, high in the cathedral calm of the trees, could see the family as they climbed up toward him, their lithe limbs working smoothly. But something disturbed him: a shift in the light, a sudden coldness. As clouds crowded past the sun, the great forest-spanning buttresses of light were dissolving. Noth felt cold, and his fur bristled. Rain began to fall: heavy misshapen drops that clattered against the trees’ broad leaves and pounded like artillery shells into the mud below.

It was because of the onset of the rain, and the overwhelming stink of the bloody deaths below, that Noth did not detect the approach of Solo.

Hidden in a patch of shadow, his scent blowing downwind, Solo saw the notharctus troop scurrying to safety.

And he saw Noth’s mother with her infant.

She was a fertile, healthy female: that was what the presence of the infant told him about her. But there was a mate with her, and since she already had a pup, she was unlikely to come into heat again this season. Neither of those factors were an obstacle to Solo. He waited until Noth’s family had settled on a branch, calming down, out of immediate danger.

Solo, at three years old, was a mature, powerful male notharctus. And he was something of a freak.

Most males roamed the forests in small bands, seeking out the larger, more sedentary troops of females where they might find a chance to mate. Not Solo. Solo preferred to travel alone. He was larger and more powerful than almost all the females he had encountered in his travels in this polar forest. Again, in this Solo was unusual; the average adult male was smaller than the average female.

And he had learned to use his strength to get what he wanted.

With a lithe swing Solo dropped down to the branch and stood upright before Noth’s mother. He looked unbalanced, for his hind legs were comparatively massive, his forearms short and slender, and he held his long tail up in the air so that it hooked over his head. But he was tall, and very still, and very intimidating.

Noth’s mother could smell this huge stranger: not kin. She immediately panicked. She hissed and pushed Left behind her.

Noth’s father came forward. He raised himself up on his hind legs and faced the intruder. Moving with fast jerky gestures he rubbed his genital glands against the foliage around him, and swept his tail over his forearms so that the horny spurs above his wrist glands combed through his tail fur and impregnated it with his scent. Then he waved the lustily stinking tail above his head at the intruder. In the scent-dominated world of the notharctus, it was an awesome display. Get away. This is my place. This is my troop, my young. Get away.

There was nothing sentimental in the father’s behavior. Producing healthy offspring that survived to breeding age was the only purpose of this father’s life; he was preparing to take on the intruder solely through a selfish drive to see his own heritage preserved.

Usually this game of malodorous bluff would have continued until one or the other of the males backed down, without physical contact. But again Solo was unusual. He did not respond with any form of display, save for a cold stare at the other’s feverish posturing.

Noth’s father was unnerved by the newcomer’s eerie stillness. He faltered, his scent glands drying, his tail drooping.

Then Solo struck.

With teeth bared he lunged at Noth’s father, slamming into his chest. Noth’s father fell back, squealing. Solo dropped to all fours and fell on him, biting into his chest through a layer of fur. Noth’s father screamed and scurried out of sight. He was only slightly injured, but his spirit was broken.

Now Solo turned on the females. The aunts could easily have resisted Solo, if they had combined their efforts. But they scrambled out of Solo’s way. Solo’s assault had disturbed them as much as its victim. They had never seen anything like it. All of them were mothers; all thought immediately of the infants they had left parked in the high branches.

Solo ignored them too. With a carnivore’s steely movements he advanced on Noth’s mother, his principal target.

She hissed, she showed her teeth, she even kicked at him with her powerful hind legs. But he resisted her blows easily, walked through her kicking — and took the unresisting, baffled infant from her grasp. He bit quickly into the pup’s throat, opening up the flesh, and rummaged there until he had ripped open the infant’s trachea. It was over in heartbeats. He dropped the quivering scrap into the forest below, where mesonychids, alerted by the scent of fresh blood, ran forward with their eerie uncaninelike barking. His mouth and hands bloodied, Solo turned to Noth’s mother. Of course she would not be fertile yet, perhaps not for some weeks, but he could mark her with his scent, make her his own, and repel the attentions of other males.

There was nothing truly cruel in Solo. If her pups were killed, it was possible Noth’s mother would come into heat again before the end of the summer — and if Solo covered her then, he could generate more offspring through her. So, for Solo, infanticide was a good tactic.

Solo’s brutal strategy wouldn’t have been sustainable for everybody. Notharctus males were not equipped to fight. They lacked the canine teeth that later primate species would use to inflict damage on rivals. And this polar forest was a marginal environment where true fights were literally a waste of energy, a squandering of scarce resources, which was why the ritual stink fights had evolved. But for Solo, the exception, it was a strategy that worked, over and over, and which had won him many mates — and which had generated many offspring, scattered through the forest, whose veins ran with Solo’s blood.

But it wasn’t going to work this time.

Noth’s mother, marked by the killer’s scent, gazed down into the green void below. She had lost her baby — just as Purga, her remote grandmother, had once endured. But, considerably more intelligent than Purga had been, she was much more acutely aware of her pain.

Blackness filled her. She lunged at Solo, her small limbs flailing, mouth gaping. Startled, he darted back.

She lunged past him. And she fell.

Noth saw his mother fall into the pit where his infant sister had fallen before. Immediately her twisting form was lost under the slick, writhing bodies of the mesos.

Noth had been weaned a few weeks after he had been born. Soon would have come a time when he would have wandered from the troop. His link to his mother was tenuous. And yet he felt a loss as powerful as if his mother’s breast had been ripped from his mouth.

And still the rain fell, harder all the time.