A recent paper analyzing megafauna specialization among hunting cultures in the Americas indicated that the Clovis culture in mid-latitude North America lasted roughly 250–600 years, while the Fishtail Projectile Point (FPP) culture in South America persisted for about 1,300 years. Both disappeared following the megafaunal extinctions in their respective continents, suggesting that the extinction process took notably longer in South America than in North America-something thats been pointed out before-even though South America ultimately lost a larger proportion of its megafauna (over 80% versus roughly 72%).

One possible explanation is this had to with trophic cascades. When a new predator rapidly depletes prey populations, established predators often switch to alternative prey, placing additional pressure on those species and causing them to decline or go extinct. This effect can be especially pronounced in ecosystems with many large predators for obvious reasons. It's been argued that this is why N. American ecosystems were less stable than S. American ones.

Terminal Pleistocene North America supported an impressive predator guild that included American lions, Smilodon fatalis, Arctodus simus, Miracinonyx, Panthera onca augusta, cougars, dire wolves, gray wolves, brown bears, and black bears. South America by contrast had Smilodon populator, Arctotherium wingei, cougars, dire wolves in the northern half, and Panthera onca mesembrina in Patagonia. Obviously, North America had more species.

If humans quickly depleted important herbivore populations in North America, native predators might've shifted to remaining prey instead of immediately dying off. Competition between humans and predators could then have accelerated declines among surviving herbivores, creating a snowball effect that led to rapid ecosystem collapse. In South America, a smaller predator guild might've reduced that cascading dynamic, letting extinctions unfold more gradually. It is even possible that many S. American predators disappeared well before the last herbivores, reducing non-human pressure on herbivores for a while.

However, this still leaves the question of why South America experienced more severe extinctions despite the slower pace. There's two non-mutually exclusive possibilities in my opinion. First, human population density during the FPP period in S. America may have been lower than during the Clovis period in N. America, resulting in weaker hunting pressure and a longer extinction process. Second, many South American megaherbivores, especially glyptodonts and giant ground sloths, would have been inherently vulnerable to sustained human predation because of their large size, slow reproduction, and other traits such that they would have gone extinct regardless of a trophic cascade or not.

In that way, trophic cascades may have influenced the speed of extinction more than its magnitude. Greater ecological stability in South America could have only delayed the extinctions of many of its species rather than preventing them from occurring altogether.

I know this was long but what thoughts do you guys have?

Abstract

The timing and causes of the extinction of Pleistocene megafauna are unresolved issues in the natural history of Australia and New Guinea (Sahul). In Australia, megafauna are believed to have become extinct by c. 41ka, but in the Highlands of New Guinea some species persisted until the Last Glacial Maximum (LGM), as late as c. 22ka. Here, we present the first evidence that one of these taxa survived beyond even this timeframe. We describe a manual phalanx from a megafaunal macropodid, probably referable to a quadrupedal, forest-dwelling member of the genus Protemnodon recovered from the Middle Holocene (6.8 - 5.3ka) archaeological deposit of Taora, a coastal rockshelter located west of Vanimo, Papua New Guinea. This late local persistence is likely a consequence of low human populations and a relatively small body size. Its disappearance from the region is coincident with broader decline in local mammalian diversity following post-glacial environmental change. Taora provides the first indication that any of Sahul’s megafauna survived beyond the end of the LGM and highlights geographic and chronological variability in this diverse group’s extinction history.

LINK: https://www.nature.com/articles/s44185-026-00146-5

Abstract

The worldwide extinction of megafauna during the Late Pleistocene and Early Holocene is evident from the fossil record, with dominant theories suggesting a climate, human or combined impact cause. Consequently, two disparate scenarios are possible for the surviving megafauna during this time period - they could have declined due to similar pressures, or increased in population size due to reductions in competition or other biotic pressures. We therefore infer population histories of 139 extant megafauna species using genomic data which reveal population declines in 91% of species throughout the Quaternary period, with larger species experiencing the strongest decreases. Declines become ubiquitous 32–76 kya across all landmasses, a pattern better explained by worldwide Homo sapiens expansion than by changes in climate. We estimate that, in consequence, total megafauna abundance, biomass, and energy turnover decreased by 92–95% over the past 50,000 years, implying major human-driven ecosystem restructuring at a global scale.

Link: https://www.nature.com/articles/s41467-023-43426-5?fromPaywallRec=false

a Each step line represents changes in Ne with respect to time for a single megafauna species, coloured by a gradient based on average adult mass. The dashed line represents the fit of the piecewise linear model, as determined by breakpoint analysis. The grey-shaded area represents the 95% confidence interval of the linear model prediction. The blue rectangle represents the timespan of realm-specific breakpoints (Supplementary Fig. 2). Both axes are log10-transformed. Credit information for photographs of Antilocapra americana, Elephas maximus, Ursus arctos, Macropus giganteus and Giraffa tippelskirschi are available in Supplementary Table 2. All photographs are under CC-BY copyright (https://creativecommons.org/licenses/by/4.0/) and adapted for the purpose of the figure. b Relationship between species’ adult mass and the rate of population size change (slope). The x-axis is log10-transformed. Points are median slope values with 95% HPDI ranges indicated by bars (each distribution is derived using n = 1000 posterior samples). c Distribution of species’ decline severity. Source Data for this figure are in Source Data 1–4.

I would like to argue more about this topic but I'm kind of lazy to write all I want to say.I don't think that's how bringing back dinosaurs would be, those primal genes that composed dinosaurs morphed and/or adapted to fulfill birds needs and also to be able to survive, at most, we are creating a new chicken species or a chicken dinosaur looking, but we are not resurrecting and extinct animal, it's kind of the same with the wolves they tried to revive. For the question "do we need dinosaurs back" I would say we definitely don't, since they become extinct for a reason, but some of them might be beneficial on today's world. Not long time ago, I saw an article which basically said that scientists are trying to bring back Mammoths to terraform arid places with their wastes (I that's not all the reasons but it's like the most important one). with that, I want to say that maybe bringing back big herbivores such as sauropods (long necked dinos such as brachiosaurus and amargasaurus) might be beneficial for terraforming arid land. One downside of that would be that it would definitively affect and change the whole food chain of said places.

Abstract

1. The global decline of apex predator populations risks the loss of their crucial ecological functions. This raises a pressing yet contentious question: can human hunters, often termed ‘super-predators’, functionally substitute for the complex regulation once provided by their natural counterparts?
2. To investigate this question, we analysed 30,778 camera-trap records from 400 sites in southwestern China (2017–2021). Using propensity score matching (PSM) to control for environmental heterogeneity, we compared wildlife communities across hunter-dominated, apex predator-dominated, and predator-absent sites.
3. Our results showed that hunters fail to replicate the collective and individual ecological functions of natural apex predators (dhole, Asian golden cat, and clouded leopard). Apex predator sites supported the highest species richness and abundance, with 33.0% and 32.5% more species and 49.8% and 44.8% greater abundance than hunter-dominated and predator-absent sites, respectively. The prey species–site network was the most robust at apex predator sites and the weakest at hunter-dominated sites, indicating that hunting increases prey vulnerability to cascading extirpations following habitat loss.
4. Compared with hunter-dominated sites, sites dominated by single-apex predators had distinct species compositions and dominant prey. Prey exhibited prolonged avoidance (up to 2.6 times longer) of hunters compared with any apex predator, coinciding with the weakest network robustness at hunter-dominated sites.
5. Collectively, our findings provide compelling evidence that human hunters cannot replace apex predators in sustaining biodiversity and promoting stable spatial patterns. Our work therefore strongly supports the conservation of natural apex predators and offers crucial insights for regulating human hunting in ecosystem management.

LINK: https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.70306