Sub-Zero Heroes

= Cenozoic era =

Paleogene age

 * Paleocene epoch
 * Paleocene America
 * Paleocene Dinosaurs (North America)
 * Lance Formation (Paleocene North America)
 * Nanotyrannus lancensis (Paleocene tyrannosaur)
 * Bison alticornis (Paleocene ceratopsian)
 * Brachychampsa perrugosus (Paleocene ankylosaur)
 * Tylosteus ornatus (Paleocene pachycephalosaur)
 * Paronychodon caperatus (Paleocene dromaeosaur)
 * Ugrunaaluk kuukpikensis (Paleocene hadrosaur)
 * Bugenasaura assinibolensis (Paleocene spinosaur)
 * Richardoestesia gilmorei (Paleocene raptor)
 * Paracimexomys propriscus (Paleocene stegosaur)
 * Trierarchuncus prairiensis (Paleocene sauropod)
 * Discoscaphites gulosus (Paleocene pterosaur)
 * Chamops segnis (Paleocene pterosaur)
 * Brodavis baileyi (Paleocene bird)
 * Ellesmere Island (Paleocene North America)
 * Coryphodon proterus
 * Plesiadapis walbeckensis
 * Cerrejón Formation (Paleocene South America)
 * Titanoboa cerrejonensis
 * Anthracosuchus balrogus
 * Notocaiman stromeri
 * Madtsoia camposi
 * Carbonemys cofrinii
 * Paleocene Oceania
 * Waipara Greensand (Paleocene New Zealand)
 * Waimanu manneringi
 * Paleocene Afro-Eurasia
 * Nile Basin (Paleocene Africa)
 * Otodus aksuaticus
 * Datong Basin (Paleocene Asia)
 * Anqingosaurus brevicephalus
 * Eocene epoch
 * Eocene Afro-Eurasia
 * Khutsin Formation (Eocene Asia)
 * Dinopanorpa megarche
 * Kuldana Formation (Eocene Asia)
 * Ambulocetus natans
 * Kutchicetus minimus
 * Kohat Formation (Eocene Asia)
 * Embolotherium grangeri
 * Pakicetus attocki
 * Puppigerus camperi
 * Andrewsarchus mongoliensis
 * Messel Pit (Eocene Europe)
 * Pristichampsus rollinatii
 * Diatryma gigantea
 * Propalaeotherium hassiacum
 * Godinotia neglecta
 * Europolemur klatti
 * Palaeolemur betillei
 * Formicium brodiei
 * Kentisuchus spenceri
 * Headon Hill Formation (Eocene Europe)
 * Anoplotherium commune
 * Leptictidium auderiense
 * Ameki Formation (Eocene Africa)
 * Gigantornis eaglesomei
 * Gigantophis garstini
 * Jebel Qatrani Formation (Eocene Africa)
 * Arsinoitherium zitteli
 * Dorudon atrox
 * Phiomia serridens
 * Apidium phiomense
 * Titanohyrax tantalus
 * Qasr el Sagha Formation (Eocene Africa)
 * Moeritherium lyonsi
 * Physogaleus secundus
 * Palaeomastodon beadnelli
 * Eocene Oceania
 * La Meseta Formation (Eocene Antarctica)
 * Colossus penguin (Palaeeudyptes klekowskii)
 * Eocene America
 * Itaboraí Formation (Eocene South America)
 * Eocaiman itaboraiensis
 * White River Formation (Eocene North America)
 * Archaeotherium mortoni
 * Brontotherium gigas
 * Dinictis felina
 * Eusmilus villebramarensis
 * Eohippus angustidens
 * Green River Formation (Eocene North America)
 * Uintatherium anceps
 * Basilosaurus cetoides
 * Eobasileus cornutus
 * Heliobatis radians
 * Icaronycteris index
 * Hoko River Formation (Eocene North America)
 * Nautilus praepompilius
 * Hesperocyon coloradensis
 * Brown Bed Member (Eocene North America)
 * Enchodus amicrodus
 * Oligocene epoch
 * Oligocene America
 * Ashley Formation (Oligocene North America)
 * Ankylorhiza tiedmani
 * Quercy Phosphorites Formation (Oligocene North America)
 * Nimravus intermedius
 * Cynodictis elegans
 * John Day Formation (Oligocene North America)
 * Daeodon shoshonensis
 * Puijila darwini
 * White River Formation (Oligocene North America)
 * Palaeolagus haydeni
 * Pelagornis sandersi
 * Sarmiento Formation (Oligocene South America)
 * Pyrotherium romeroi
 * Peltephilus undulatus
 * Oligocene Oceania
 * Riversleigh World Heritage Area (Oligocene Australia)
 * Obdurodon tharalkooschild
 * Kokoamu Greensand (Oligocene New Zealand)
 * Kairuku grebneffi
 * Seymour Island (Oligocene Antarctica)
 * Anthropornis nordenskjoeldi
 * Oligocene Afro-Eurasia
 * Nsungwe Formation (Oligocene Africa)
 * Chalicotherium goldfussi
 * Hyaenodon horridus
 * Rupel Formation (Oligocene Europe)
 * Entelodon magnus
 * Squalodon antverpiensis
 * Chitarwata Formation (Oligocene Asia)
 * Indricotherium transouralicum

Neogene age

 * Miocene epoch
 * Miocene Afro-Eurasia
 * Shanxi Province (Miocene Asia)
 * Amphimachairodus kabir
 * Kubanochoerus minheensis
 * Bessho Formation (Miocene Asia)
 * Brygmophyseter shigensis
 * Baikong Cave (Miocene Asia)
 * Gigantopithecus blacki
 * Ninjadelphis ujiharai
 * Liushu Formation (Miocene Asia)
 * Iranotherium morgani
 * Palaeopatragus microdon
 * Linxia Basin (Miocene Asia)
 * Tetralophodon xialongtanensis
 * Sivalik Hills (Miocene Asia)
 * Colossochelys atlas
 * Bugti Hills (Miocene Asia)
 * Amphicyon giganteus
 * Apis lithohermaea
 * Pietra Leccese Formation (Miocene Europe)
 * Zygophyseter varolai
 * Chlamydoselachus garmani
 * Middle Awash (Miocene Africa)
 * Agriotherium africanum
 * Machairodus aphanistus
 * Muruyur Formation (Miocene Africa)
 * Megistotherium osteothlastes
 * Platybelodon holyokensis
 * Carcharocles chubutensis
 * Ngorora Formation (Miocene Africa)
 * Simbakubwa kutokaafrika
 * Zygolophodon aegyptensis
 * Miocene Oceania
 * Bullock Creek (Miocene Australia)
 * Bullockornis planei
 * Miocene America
 * Albuquerque Basin (Miocene North America)
 * Pterolophosoma otiliae
 * Stegodon trigonocephalus
 * Great Plains (Miocene North America)
 * Amebelodon floridanus
 * Megalictis ferox
 * Coffee Ranch (Miocene North America)
 * Epicyon aelurodontoides
 * Sucker Creak Formation (Miocene North America)
 * Moropus oregonensis
 * Aepycamelus major
 * Chamita Formation (Miocene North America)
 * Chamitataxus avitus
 * Synthetoceras tricornatus
 * Monterey Formation (Miocene North America)
 * Balaenoptera ryani
 * White River Formation (Miocene North America)
 * Gomphotherium angustidens
 * Haynes Cave (Miocene North America)
 * Megalonyx jeffersoni
 * American mastodon (Mammut americanum)
 * Pebas Formation (Miocene South America)
 * Telicomys amazonensis
 * Hapalops brachycephalus
 * Thylacosmilus atrox
 * Xotodon catamarcensis
 * Collón Curá Formation (Miocene South America)
 * Kelenken guillermoi
 * Neotamandua borealis
 * Santa Cruz Formation (Miocene South America)
 * Phorusrhacos longissimus
 * Andalhualá Formation (Miocene South America)
 * Argentavis magnificens
 * Pisco Formation (Miocene South America)
 * Acrophoca longirostris
 * Livyatan melvillei
 * Carcharodon megalodon
 * Thalassocnus carolomartini
 * Odobenocetops leptodon
 * Pliocene epoch
 * Pliocene America
 * Ituzaingó Formation (Pliocene South America)
 * Devincenzia pozzi
 * Megapiranha paranensis
 * Tarija Formation (Pliocene South America)
 * Cuvieronius tropicus
 * Monte Hermoso Formation (Pliocene South America)
 * Toxodon chapalmalensis
 * American Ornithological Society (Pliocene North America)
 * Great auk (Pinguinus impennis)
 * Tarkio Valley (Pliocene North America)
 * Paramylodon harlani
 * Epigaulus minor
 * Santa Fe River (Pliocene North America)
 * Titanis walleri
 * Glenns Ferry Formation (Pliocene North America)
 * Camelops kansanus
 * Hagerman Horse Quarry (Pliocene North America)
 * Hagerman horse (Equus simplicidens)
 * Oncorhynchus rastrosus
 * Friesenhahn Cave (Pliocene North America)
 * Homotherium serum
 * Cetotherium furlongi
 * Pliocene Afro-Eurasia
 * Great Rift Valley (Pliocene Africa)
 * African mammoth (Mammuthus africanavus)
 * Amphiorycteropus mauritanicus
 * Swartkrans (Pliocene Africa)
 * Dinopithecus ingens
 * Hippopotamus gorgops
 * Site 333 (Pliocene Africa)
 * Australopithecus africanus
 * Deinotherium giganteum
 * Ancylotherium hennigi
 * Dinofelis cristata
 * Swiss Alps (Pliocene Europe)
 * Anancus ultimus
 * Macrocephalochelys pontica
 * Mesopithecus pentelici
 * Yangzte River (Pliocene Asia)
 * Sivatherium hendeyi
 * Bramatherium magnum
 * Gavialis browni
 * Pliocene Oceania
 * Shire of Peak Downs (Pliocene Australia)
 * Dromornis australis
 * Thylacoleo carnifex
 * Camfield Beds (Pliocene Australia)
 * Meiolania platyceps

Quaternary period

 * Pleistocene epoch
 * Pleistocene Oceania
 * Nawarla Gabarnmung (Pleistocene Australia)
 * Genyornis newtoni
 * Lake Tarkarooloo (Pleistocene Australia)
 * Giant koala (Phascolarctos stirtoni)
 * Willandra Lakes Region (Pleistocene Australia)
 * Procoptodon goliah
 * Mammoth Cave (Pleistocene Australia)
 * Zaglossus hacketti
 * Tasmanian tiger (Thylacinus cynocephalus)
 * Darling Downs (Pleistocene Australia)
 * Megalania prisca (Varanus priscus)
 * Diprotodon optatum
 * Quinkana fortirostrum
 * Giant crab
 * Pleistocene America
 * La Brea Tar Pits (Pleistocene North America)
 * Columbian mammoth (Mammuthus columbi)
 * Castoroides ohioensis
 * Armbruster's wolf (Canis armbrusteri)
 * Neocnus comes
 * Eremotherium eomigrans
 * Harrington's mountain goat (Oreamnos harringtoni)
 * Bootherium bombifrons
 * Arctodus simus
 * Pleistocene coyote (Canis orcutti)
 * American lion (Panthera atrox)
 * Miracinonyx inexpectatus
 * Long-horned bison (Bison latifrons)
 * Ornimegalonyx gigas
 * Californian turkey (Meleagris californica)
 * Cueva del Milodón Natural Monument (Pleistocene South America)
 * Megatherium americanum
 * Smilodon fatalis
 * Macrauchenia patachonica
 * Doedicurus clavicaudatus
 * Glyptodon clavicpes
 * Hemiauchenia guanajuatensis
 * Arctotherium bonariense
 * Protopithecus brasiliensis
 * Panthera augusta
 * Dire wolf (Canis dirus)
 * Drakensberg Mountains (Pleistocene Africa)
 * Metridiochoerus jacksoni
 * Giraffa jumae
 * Rusingoryx atopocranion
 * Anthropopithecus erectus
 * Pithecanthropus rudolfensis
 * Pleistocene Park (Pleistocene Asia)
 * Elasmotherium sibiricum
 * Palaeoloxodon namadicus
 * Javan elephant (Elephas sondaicus)
 * Ngandong tiger (Panthera soloensis)
 * Indian aurochs (Bos namadicus)
 * Acinonyx pardinensis
 * Stephanorhinus kirchbergensis
 * Giant tapir (Megatapirus augustus)
 * Vietnamese orangutan (Pongo hooijeri)
 * Peking man (Sinanthropus pekingensis)
 * Mammoth Steppe (Pleistocene Europe)
 * Steppe mammoth (Mammuthus trogontherii)
 * Holarctic Realm (Pleistocene Europe)
 * Woolly mammoth (Mammuthus primigenius)
 * Woolly rhinoceros (Coelodonta antiquitatis)
 * Irish elk (Megaloceros giganteus)
 * Cave bear (Ursus spelaeus)
 * Hipparion forcei
 * Ancient bison (Bison antiquus)
 * Aurochs (Bos primigenius)
 * Pygmy elephant (Elephas falconeri)
 * Cave hyena (Crocuta spelaea)
 * European cave lion (Panthera spelaea)
 * Straight-tusked elephant (Elephas antiquus)
 * Neanderthal (Homo neanderthalensis)
 * Holocene epoch
 * Holocene Afro-Eurasia
 * Holocene Europe
 * Cave wolf (Canis spelaeus)
 * St. Kilda house mouse (Mus musculus muralis)
 * Cumberland pig (Sus scrofa domesticus)
 * Neapolitan horse (Equus ferus caballus)
 * Holocene Asia
 * Japanese wolf (Canis hodophilax)
 * Black softshell turtle (Nilssonia nigricans)
 * Père David's deer (Elaphurus davidianus)
 * Arabian ostrich (Struthio syriacus)
 * Syrian elephant (Elephas asurus)
 * Elephants in ancient China (Elephas rubridens)
 * Littoraria flammea
 * Junzi imperialis
 * Leptoptilos lüi
 * Rhinoceroses in ancient China
 * Steppe wisent (Bison priscus)
 * Bali tiger (Panthera sondaica)
 * Caspian tiger (Panthera tigris)
 * Japanese river otter (Lutra whiteleyi)
 * Japanese sea lion (Zalophus japonicus)
 * Javan tiger (Panthera sondaica)
 * Steller's sea cow (Hydrodamalis gigas)
 * Holocene Africa
 * Western black rhinoceros (Diceros longipes)
 * North African elephant (Loxodonta pharaohensis)
 * Atlas bear (Ursus crowtheri)
 * Bluebuck (Hippotragus leucocphaeus)
 * Dodo bird (Raphus cucullatus)
 * Giant fossa (Cryptoprocta spelea)
 * Aepyornis maximus
 * Scimitar oryx (Oryx dammah)
 * Somali wild dog (Lycaon somalicus)
 * Kihansi spray toad (Nectophrynoides asperginis)
 * Ptychochromis insolitus
 * Cape lion (Panthera capensis)
 * Holocene America
 * Holocene South America
 * Xenorhinotherium bahiensis
 * Mylodon darwini
 * Pinta Island tortoise (Chelonoidis abingdonii)
 * Alagoas curassow (Mitu mitu)
 * Spix's macaw (Cyanopsitta spixii)
 * Biotocus turbinatus
 * Holocene North America
 * Passenger pigeon (Ectopistes migratorius)
 * Carolina parakeet (Conuropsis carolinensis)
 * Bison occidentalis
 * Tremarctos floridanus
 * Holmesina septentrionalis
 * Euceratherium collinum
 * Equus occidentalis
 * Megalomys desmarestii
 * Barbados raccoon (Procyon lotor gloveralleni)
 * Caribbean monk seal (Neomonachus tropicalis)
 * Eastern cougar (Panthera couguar)
 * Stenodus leucichthys
 * Aiolornis incredibilis
 * Cyprinodon longidorsalis
 * Heath hen (Tympanuchus cupido cupido)
 * Eastern cougar (Puma concolor couguar)
 * Golden skiffia (Skiffia francesae)
 * Guam kingfisher (Todiramphus cinnamominus)
 * Golden toad (Incilius periglenes)
 * Leptogryllus deceptor
 * Socorro dove (Zenaida graysoni)
 * Thermosphaeroma thermophilum
 * Holocene Oceania
 * Holocene New Zealand
 * Giant moa (Dinornis giganteus)
 * Haast's eagle (Harpagornis moorei)
 * New Zealand grayling (Prototroctes oxyrhynchus)
 * Holocene Australia
 * Lepidodactylus listeri
 * Holocene Hawaii
 * Hawaiian crow (Corvus hawaiiensis)
 * King Kong grosbeak (Chloridops regiskongi)

= Cenozoic =

Paleogene

 * Paleocene
 * Eocene
 * Oligocene

Neogene

 * Miocene
 * Pliocene

Quaternary

 * Pleistocene
 * Holocene

= Seasons =

Episode 1

 * Bring on the Beasts

Episode 2

 * Killer Whale's Tale

Episode 3

 * Mega-Mammal

Episode 1

 * First Came the Apes

Episode 2

 * Saber-Tooth

Episode 1

 * Ice Age Survivor

= Plot = The episode starts by showing how the dinosaurs were dominating the land and that mammals were small. Then it shows how "an asteroid the size of Mount Everest" struck the Earth and demolished the dinosaurs, and how mammals evolved into new forms thereafter. The first episode depicts the warm tropical world of the early Eocene, sixteen million years after the extinction of the non-avian dinosaurs. Birds, the surviving lineage of the dinosaurs, including the giant carnivorous Diatryma, rule this world, while mammals are still very small. The setting is near the Messel pit in Germany. Due to volcanic activity, sudden bulk escapes of carbon dioxide trapped underneath lakes pose a significant hazard to the local wildlife. The episode centers around a Leptictidium family, a leaping, shrew-like mammal, which has emerged in the dawn hours to forage for food. As the mother Leptictidium forages, first in solidarity, and then with her pups, she wanders near a large predatory mammal, identified as an Ambulocetus, a "walking whale". Despite its crocodilian similarity, the Ambulocetus is shown swimming by caudal undulation like a modern cetacean. A female Diatryma, who has been taking care of the single egg in her nest, makes two attempts to hunt a small herd of Propalaeotherium, early horses. The first attempt fails when sounds among the vegetation betray her presence. The second attack proves successful when the Propalaeotherium consume fermenting grapes and are unable to evade her attack. The Diatryma also defends her territory from another Diatryma. Unfortunately, while the mother hunts, a horde of Formicium, giant carnivorous ants, encounter the egg when it was just starting to hatch, and successfully kill and eat the chick. When the female discovers her dead offspring at dusk she leaves the forest to try and start another family.

With the arrival of night, a band of lemur-like Godinotia, socialize and copulate in the dark. Ambulocetus finally manages to catch a creodont near the lake edge. As the night wears on, an earth tremor unleashes trapped carbon dioxide out from underneath the lake and the gas suffocates most of the surrounding life. The Leptictidium survive because the nest was upwind of the gas, and Diatryma also survived because she left that area in the forest.

It is mentioned that although the Leptictidium survived the gas, they would ultimately leave no descendants, while the Ambulocetus, who was killed by the lethal gases, would evolve into the whales, hereby setting the scene for the next episode.

The second episode is set in late Eocene, when the polar caps froze over and drastically changed the Earth's ocean currents and climate. The first part of the episode explains how an early whale, Basilosaurus mates and how the world is changing into an ocean famine. On land there is an Andrewsarchus driven to the beach to feed on sea turtles. The narrator explains that Andrewsarchus, the largest land mammal predator ever to walk the earth, has hooves and is related to sheep, so it is, in a sense, a "sheep in wolf's clothing". Back in the ocean, a starving mother Basilosaurus is forced to hunt in the mangrove swamps of Africa, which will later become the Sahara Desert. Unable to catch a primate called Apidium due to a shark killing one of the primates and spooking the others, she is then hunting a lone Moeritherium. The Moeritherium crawls on to land, but in the mangroves, land does not last long. However the Moeritherium escapes and the Basilosaurus returns to the sea. The cast moves on to land where a herd of Embolotherium struggle to survive: one of their calves dies after birth and two Andrewsarchus feast on it, but the mother Embolotherium drives them away because she has a strong bond with her offspring, even if it is dead. Back in the sea, the mother Basilosaurus preys on a group of dolphin-like Dorudon and their young, and is successful. The episode ends with the mother Basilosaurus swimming with her newborn calf.

It is acknowledged in the end that soon Africa will be pulled closer to Europe, causing the Tethys Sea to disappear. While whales as a whole will survive the ensuing extinction, Basilosaurus, unfortunately, will disappear with the Tethys as well.

The third episode takes place during the late Oligocene, in Mongolia, where there were seasonal rains followed by a long drought. It focuses on a mother Indricotherium, a massive hornless rhinoceros, the largest land mammal to ever live as one night, she gives birth to a healthy male calf, while trying to fend off the predatory Hyaenodon. By morning, the calf slowly learns how to walk and after a week, his mother takes him out to the open plain where he will spend the rest of his life. The inquisitive calf runs into a mother Cynodictis, who drives him out of her family burrow to protect her pups. The calf then learns to survive on his own, by copying his mother's actions. Not long after, his mother's previous calf arrives, but the mother violently repels him. A Hyaenodon is then seen stalking a herd of Chalicotherium, successfully killing one, but a trio of Entelodon drive it off the carcass. During the dry season, there is a huge shortage of food and water, putting even the hardiest to their greatest stress. The mother, dehydrated, has not been able to produce enough milk for the calf, who has been getting weaker and weaker as time progresses. At night, the pair are joined by an older female, who leads them to a small, muddy lake, where they drink their fill and recover their strength. The wet season returns and the water levels rise, flooding the Cynodictis family burrow, and drowning the sleeping pups. The mother and calf cross a river, the mother doing so with ease, while the calf struggles to make it up a muddy bank, but finally succeeding. 3 years pass, and the calf is furiously chased away by his mother in anticipation of her upcoming birth. He then goes unseen for days, but when he is seen, he is limping and has a leg injury, possibly caused by another young male Indricotherium. When he returns to his mother, she aggressively chases him away, her maternal instincts having transferred to her new calf. After 3 months, the calf learns how to stand on his own two feet and successfully drives away an Entelodon.

The fourth episode takes place in the Great Rift Valley in northeastern Africa of the late Pliocene. The climate has changed, and now great grasslands have replaced trees, with many modern-day animals appearing with them. The episode focuses around a tribe of small hominids known as Australopithecus, one of the first apes able to walk upright and a close ancestor to humans. The Australopithecus has evolved to walk upright so as to better manoeuvre the plains as well as the climb the trees. However, it notes that although the Australopithecus looks human, it still only has a brain the size of a chimpanzee's. Some of the topics explored in the episode are the close social bonds among the tribe, how they use grooming as a means of communication, and how they work together to forage for food and to defend one another from attacks from such animals as an angry male Deinotherium, an ancestor of the modern elephant which they have to run from to avoid being crushed, and the feline predator Dinofelis. It touches upon how competing tribes of Australopithecus war among one another, although most of the fighting is for show. It also explains the hierarchy in the tribe among the males, who are much larger than the females, and tells a story of how the dominating male nicknamed Grey is eventually overcome by another male nicknamed Hercules, who wins the right to feed first at a carrion and to mate with the females. The main story tells of a young Australopithecus nicknamed Blue whose mother has been killed by malaria. He and his tribe are later forced to flee their homeland during a fight over a waterhole with a rival tribe. After a long journey in search of a new home, Blue fits into his tribe by rallying them into scaring off a hungry Dinofelis.

The fifth episode shows the strange fauna of the isolated continent of South America and explores the effects of the Great American Interchange, which had happened 1.5 million years earlier. Since South America had drifted apart from Antarctica 30 million years ago, many unique mammals had evolved, including the Doedicurus, an armoured armadillo-like mammal with a cannon ball-sized spiked club on its tail; the Macrauchenia, a camel-like mammal with a long trunk; and the Megatherium, a giant ground sloth. Before the continents of South America and North America collided, a 10-foot-tall predatory terror bird called Phorusrhacos, had reigned as top predator. However, the great cats migrating from the north, soon displaced them as top predators. The episode focuses on a male Smilodon, a sabre-toothed cat, called Half Tooth, whose leadership of a pride is threatened by two rival males who are brothers and work together against him. Half Tooth wisely backs off without any serious injuries, feeling that the rival males would be too strong for him. The rival males kill Half Tooth's cubs, and take over his pride. Next, the episode shows the Smilodon hunting down Macrauchenia and trying to protect the remaining two young from the two males. In the background, Phorusrhacos wait to scavenge the Macrauchenia, which the pride of Smilodon have killed. However, a Megatherium charges the Smilodon, in order to eat some of the carrion as a diet supplement. In the process, the Megatherium kills the dominant rival male, enabling Half Tooth to return, kill the other male and reclaim his territory. A year later, his mate has another litter of cubs.

The sixth episode takes place during the last Ice Age of the late Pleistocene. It starts in the peak of the summer. The North Sea has become a grassy plain because the ice at the polar caps has caused the sea levels to drop significantly. Grazing on the plain are herds of woolly mammoths, saiga antelopes, and bison. A clan of Cro-Magnon is also there spending the summer. The central focus of the episode is the migration of the herd of mammoths as they travel 400 kilometres from the North Sea to the Swiss Alps for the winter and then back again in the spring. As the mammoth herd migrates south, the episode shows two large deer, the elk-like Megaloceros, fighting for rights to a harem of females. As the male elk fight, a group of Cro-Magnons ambushes them and kills one. A mother mammoth and her baby are separated from the herd, but survive an encounter with a European cave lion. When the herd of mammoths reaches the Swiss Alps, the mother and baby mammoth reunite with their herd. The episode also depicts a clan of Neanderthals, who have especially evolved to survive in the cold climate. One is charged by a woolly rhinoceros, but escapes, in part because of his stocky constitution. The climax of the episode is when the clan of Neanderthals attack the herd of mammoth as they turn back to the north. The Neanderthals are gifted hunters who are able to chase two mammoths off a cliff by using fire and spears, one of them being the matriarch of the herd. The episode ends in the Oxford University Museum of Natural History with people looking at various skeletons of some descendants of the animals featured in the series. The camera then pulls back through the roof of the museum until the whole world is visible. The narrator states that, "We have since built museums to celebrate the past, and spent decades studying prehistoric lives. And if all this has taught us anything, it is this: no species lasts forever."

Alternative titles

 * Prehistoric Park: Sub-Zero Heroes
 * Prehistoric Park 3: Sub-Zero Heroes
 * Sub-Zero Heroes (Prehistoric Park 3)
 * Prehistoric Park III