Panochthus tuberculatus was a large glyptodont – a group of giant heavily-armored armadillos – that lived in central and southern South America during the late Pleistocene, about 800,000-12,000 years ago.
Around 3.5m long (~11.5′) and 1.5m tall (~5′), it was similar in size to a modern rhino (or a small car), and its large domed “shell” made up of numerous small bony osteoderms made it resemble a mammalian tortoise. Its skull was short and deep, with ever-growing grinding teeth and downwards-flaring cheekbones that anchored powerful jaw muscles. A preserved hyoid apparatus indicates that Panochthus also had a more flexible tongue than some other glyptodonts.
The base of its tail was segmented into rings that allowed it to flex, while the end of the tail was fused into a solid bony tube that was probably studded with large keratinous knobs or spikes.
While these sort of tail weapons in glyptodonts have been proposed as being anti-predator defenses, biomechanical studies suggest they required precise aiming to be most effective and weren’t well-suited to fending off fast-moving attackers. Instead they may have been more specialized for fighting each other in ritualized forms of combat – an idea supported by injuries in fossil carapaces that appear to have been caused by blows from opponents’ tail clubs.
References:
- Blanco, R. Ernesto, Washington W. Jones, and Andrés Rinderknecht. “The sweet spot of a biological hammer: the centre of percussion of glyptodont (Mammalia: Xenarthra) tail clubs” Proc. R. Soc. B. 276 (2009): 3971–3978. https://www.academia.edu/download/71293979/The_sweet_spot_of_a_biological_hammer_th20211004-20926-1xg5uwp.pdf
- Luna, Carlos A., et al. “Memories of the blows: severe soft-tissue injuries in caudal vertebrae of Panochthus Burmeister (Xenarthra, Glyptodontidae).” Journal of Mammalian Evolution 31.3 (2024): 29. https://doi.org/10.1007/s10914-024-09729-0
- Lima, F.C.G., Porpino, K. & Ribeiro, A.M. “Trauma-induced alterations in the exoskeleton of glyptodonts (Cingulata, Xenarthra) associated with fighting behavior.” Journal of Mammalian Evolution 32, 9 (2025). https://doi.org/10.1007/s10914-025-09750-x
- Wikipedia contributors. “Glyptodont” Wikipedia, 25 May 2025, https://en.wikipedia.org/wiki/Glyptodont
- Wikipedia contributors. “Panochthus” Wikipedia, 02 Jun. 2025, https://en.wikipedia.org/wiki/Panochthus
- Zamorano, Martín, and Richard A. Fariña. “Changes in form and function of the caudal tubes in Panochthus (Xenarthra; Glyptodontidae) along the Pleistocene.” Historical Biology 34.12 (2022): 2265-2272. https://www.researchgate.net/publication/357020158_Changes_in_form_and_function_of_the_caudal_tubes_in_Panochthus_Xenarthra_Glyptodontidae_along_the_Pleistocene
- Zamorano, Martín, et al. “Hyoid apparatus of Panochthus sp. (Xenarthra; Glyptodontidae) from the Late Pleistocene of the Pampean Region (Argentina). Comparative description and muscle reconstruction.” (2018). Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen 288.2 (2018): 205–219. https://ri.conicet.gov.ar/bitstream/handle/11336/97007/CONICET_Digital_Nro.bcac99f6-b327-435a-bca7-137dfd6af700_D.pdf?sequence=5