1999 Walking with... 25 Sabre Tooth

Smilodon living in social groups is a controversial theory at best, but all experts agree that the lion pride idea is extremely unlikely, since male and female Smilodon are not known to have had sexual dimorphism, in sharp contrast to lions, where the two sexes are very differently built and also because both sexes appear to have been active hunters. It is possible that their social structure was more like that of modern-day wolves, with males and females providing a similar role in the pack order, if they were indeed social. Macrauchenia probably had a shorter trunk than what is shown in the film. It would most likely either have had a trunk like those of Saiga antelope or not have had a trunk at all, but rather a moose-like snout. Smilodon was a bulky predator that was built to ambush and wrestle its prey to the ground, and was ill-equipped for high-speed chases and quick, sharp turns like modern big cats, so the Macrauchenia chase scene is inaccurate. Phorusrhacos probably did not have wing claws, just like the seriema, its closest living relative. Phorusrhacos was probably stockier and had a shorter neck than is shown in the series, and the most currently accepted estimates give it a height of just 1.6 meters tall. Phorusrhacos lived in the Miocene, from 20,000,000 BCE to 13,000,000 BCE, not the Pleistocene a mere 1,000,000 BCE. Psilopterus material has been attributed to the Pleistocene, but the validity of this dating is dubious and hard to ascertain. Psilopterus was also too small to be a feasible replacement to the Phorusrhacos in the episode. Titanis was also attributed to Pleistocene strata and was big enough to fit a similar role to the terror birds from the episode, however the exact dating of the known material is inconclusive on whether or not it would have been found in the Pleistocene, and if so, would probably only live in the earliest stages of the epoch. Titanis would have also lived in North America, instead of South America. There is no evidence that Megatherium ate carrion to supplement its diet, but it is far from impossible as some herbivores today have been recorded eating meat, and some paleontologists do believe Megatherium was partly carnivorous, though that carnivory claim has little fundament to it, given carbon isotope analysis strongly suggest Megatherium was a obligate herbivore. [1]That said, its not impossible meat-eating was a very occasional behaviour, to gain extra nutrients in their diet, as observed in other herbivores, including in modern day sloths. To corroborate this idea, a study from 2021 has found evidence for omnivory in Mylodon, another type of ground sloth, so it's possible that Megatherium ate meat on occasion too.