Giant tunnels known as "paleoburrows" in South America, some exceeding a meter in diameter and tens of meters long, were likely dug by giant extinct ground sloths (specifically, scelidotheriines and mylodontines). Researchers used a variety of evidence, including claw marks, sediment analysis, and the burrows' size and shape, to rule out other potential excavators such as armadillos or humans. These immense burrows, which represent the largest ichnofossils (trace fossils) on the continent, provide insight into the behavior and ecology of these megafauna and demonstrate a unique adaptation not seen in extant sloths.
A newly published study in the scientific journal Palaeontology meticulously examines a network of enigmatic, large-diameter tunnels crisscrossing various regions of South America, specifically Brazil and Argentina. These extensive subterranean passages, often referred to as "paleoburrows," have long puzzled researchers due to their impressive scale and the uncertainty surrounding their origin. The prevailing hypothesis, until recently, attributed their construction to extinct megafauna, specifically giant ground sloths. This assumption stemmed from the observation that the dimensions of some tunnels seemed consistent with the size of these massive, now-vanished creatures.
However, this recent research challenges that long-held belief. Through a comprehensive analysis encompassing the architecture of the tunnels, the claw marks discovered within them, and a comparative study with known burrows of extant animals, the authors propose a compelling alternative explanation. They posit that these colossal burrows are not the handiwork of giant sloths, but rather the product of another group of ancient South American denizens: large armadillos belonging to the extinct genera Pampatherium and Holmesina.
The study meticulously documents several key lines of evidence to support this claim. Firstly, the researchers highlight the unique morphology of the tunnels, noting distinct features such as elliptical or circular cross-sections, smooth walls and ceilings, and frequent branching patterns. These characteristics, they argue, are more consistent with the burrowing habits of armadillos, which are known to excavate complex subterranean networks, than with the comparatively simpler burrows expected from sloths.
Secondly, the study emphasizes the significance of the claw marks etched into the walls of the paleoburrows. Detailed examination of these markings reveals a recurring pattern of parallel grooves. The researchers meticulously compare these traces to the claw morphology of both giant sloths and large armadillos. Their analysis concludes that the observed grooves bear a striking resemblance to the claw structure of armadillos, particularly the arrangement and number of claws used in digging, rather than the claw marks expected from sloths.
Finally, the researchers draw parallels between the paleoburrows and the documented burrowing behavior of modern armadillos. They highlight the propensity of extant armadillos to create extensive burrow systems with similar architectural features, lending further credence to their hypothesis.
The study ultimately concludes that these intricate networks of tunnels, a testament to the impressive engineering capabilities of ancient fauna, are likely the result of the labors of large, now-extinct armadillos. This revised understanding of the paleoburrows' origin significantly alters our perception of the paleoecological dynamics of prehistoric South America and offers valuable insights into the behavior and habitat utilization of these fascinating extinct creatures. While the mystery surrounding these tunnels is not entirely resolved, this study represents a substantial advancement in our understanding of their creation and provides a strong argument for the role of large armadillos in shaping the subterranean landscape of ancient South America.
Summary of Comments ( 2 )
https://news.ycombinator.com/item?id=43082287
HN commenters discuss the likelihood of the giant paleoburrows being created by giant ground sloths, expressing skepticism due to the sheer size and complexity of some tunnels. Several suggest the possibility of multiple generations of sloths expanding the burrows over time, while others question the practicality of such large burrows for creatures needing to escape predators. The lack of claw marks in some sections is noted, prompting speculation about other unknown extinct creatures or even geological processes. Some commenters focus on the implications for understanding megafauna and past ecosystems, highlighting the surprising scale of these ancient burrows and the need for further investigation. One commenter humorously links the lack of clear answers to the enduring mysteries of Göbekli Tepe.
The Hacker News post titled "Who carved South America's mysterious ancient tunnels? [pdf]" has generated several comments discussing the linked study about paleoburrows in South America. The discussion primarily revolves around the creatures responsible for these extensive tunnel systems and the evidence presented in the research.
Several commenters express fascination with the size and extent of the burrows, pointing out the sheer scale of the digging involved. Some question whether extinct giant ground sloths could be the sole creators, considering the enormous amount of earth that had to be moved. The possibility of multiple generations of sloths contributing to the tunnel systems over long periods is raised as a potential explanation.
There's debate regarding the proposed function of these tunnels. While the researchers suggest protection from predators and climate extremes, some commenters speculate about other possibilities, such as social behavior, food storage, or even territorial marking. The idea of interconnected burrow networks forming extensive underground "cities" is a recurring theme, sparking imaginative discussions.
Some commenters focus on the geological aspects, questioning the methodology used to date the burrows and the processes that led to their preservation. The composition of the surrounding sediment and its impact on the burrow's structural integrity over millennia are also discussed.
A few users share personal anecdotes about encountering similar, albeit smaller, animal burrows, offering real-world context to the scale and complexity of the paleoburrows described in the study.
Some skepticism about the definitive attribution to sloths is expressed. Commenters point out the lack of direct fossil evidence within the burrows themselves and propose alternative or contributing excavators, like giant armadillos. The possibility of the burrows serving as habitats for multiple species over time is also considered.
Overall, the comments demonstrate a high level of engagement with the topic, showcasing a mix of scientific curiosity, skepticism, and imaginative speculation regarding the origins and purpose of these ancient tunnels. The discussion reflects the inherent mystery surrounding these paleoburrows and the challenges in reconstructing the behaviors of extinct megafauna.