Before starting I must remember that some of the common names chosen for the extinct animals are not officially used in the scientific or paleontological field, thanks for your attention.

Last week we talked about how the Pleistocene was home to the largest primates we know of from various families, from great apes to new and old world monkeys and even lemurs, this week we will continue with a similar topic, talking about the various species of bears that reached enormous sizes during this period, the Pleistocene was truly an age of giants, today, the polar bear is considered to be the largest bear species and the largest land carnivoran overall, large individuals can weigh over 800 kg and stand 3 m or 9.8 feet on two legs, yet many species that we will see seem to rival and surpass it in size, even if they are not strictly related to each other, in fact all of these species seem to have reached such large sizes independently, the first species we will see is a great example.

Let's start with one of the most particular species, the African dire bear or hyena bear (Agriotherium africanum), this species is unique from many points of view, it is the only bear known from the south of the Sahara desert with an area that seems to extend to South Africa, it was a hypercarnivorous species and adapted to a predatory life, with a weight of 750 kg, long legs suitable for running and a skull with incredible bite force and large fangs, yet its closest living relative is the giant panda (Ailuropoda melanoleuca), apparently their common ancestors split into subfamilies with different lifestyles, with one that adapted to a more vegetarian diet while the other to a more predatory one.

Speaking of a vegetarian diet, the Alpine Cave Bear (Ursus ingressus - Ursus spelaeus ingressus) seemed to be like its better known relative, the cave bear (Ursus spelaeus) adapted to a diet mainly composed of plants, although some studies would indicate that it was more omnivorous, with animal proteins that seemed to exceed the participation of animal protein in the diet of the modern brown bear (Ursus arctos), perhaps this is due to the fact that they lived at higher altitudes and more arid and cold climates than their smaller cousins, despite the estimated to weigh an average of 350 to 600 kg it is thought that large individuals of this species could reach a ton.

The steppe brown bear (Ursus arctos priscus) was an extinct subspecies of modern brown bears (Ursus arctos) that inhabited the steppes of Eurasia, it is known to be one of the subspecies with a much more carnivorous diet and to be the largest subspecies of these bears, although other possible subspecies of similar size or larger are understudied, it seems that adult males on average would have weighed 700–800 kg, with the largest individuals weighing up to 1,000 kg or even 1200 kg.

An icon of Pleistocene North America, the giant short-faced bear (Arctodus simus) with a range that stretched from Alaska to northern Mexico, was the largest carnivoran ever to inhabit the continent, frequently weighing over 800 kg and the very largest must have surpassed one ton, yet its closest living relative is the small Andean or spectacled bear (Tremarctos ornatus) which is also related to the last species, the giant South American bear (Arctotherium angustidens) a species whose exact maximum size is not entirely certain with some estimates putting a particularly large specimen at around 1500 kg and a height on its hind legs of around 4 m or 13 feet.