Doedicurus

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Doedicurus
Temporal range:
Ma
↓
Illustration of a skeleton
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cingulata
Family: Chlamyphoridae
Subfamily: †Glyptodontinae
Genus: †Doedicurus
Burmeister, 1874
Species:
†D. clavicaudatus
Binomial name
†Doedicurus clavicaudatus
Owen, 1847
Synonyms[1]
List
    • Glyptodon clavicaudatus
      Owen, 1847
    • Hoplophorus clavicaudatus
      Nodot, 1857
    • Glyptodon giganteus
      Serres, 1866
    • Panochthus giganteus
      Burmeister, 1874
    • Doedicurus giganteus
      Burmeister, 1874
    • Doedicurus uruguayanesis
      Gervais and Ameghino, 1847
    • Doedicurus gigas
      Ameghino, 1847

Doedicurus (

quadrupeds
, large ones like Doedicurus may have been able to stand on two legs like other xenarthrans. It notably sported a spiked tail club, which may have weighed 40 or 65 kg (88 or 143 lb) in life, and it may have swung this in defense against predators or in fights with other Doedicurus at speeds of perhaps 11 m/s (40 km/h; 25 mph).

Doedicurus was likely a grazer, but its teeth and mouth, like those of other glyptodonts, seem unable to have chewed grass effectively, which may indicate a slow metabolism. Doedicurus existed during the Pleistocene. Before this, South America had been isolated from the rest of the world, but the formation of the Isthmus of Panama allowed North American fauna to invade South America in the Great American Interchange, including big cats, bears, proboscideans, camelids, and horses. Doedicurus seems to have inhabited the relatively cold and humid Chaco-Pampean plains of northeastern Patagonia. It may have been the latest-surviving glyptodont, with remains suggested to date to 8,000–7,000 years ago during the middle Holocene, though these dates have been questioned. It may have gone extinct due to some combination of human hunting and climate change.

Taxonomy and evolution

Doedicurus fossil in Brazil

The animal was first described by British paleontologist

pestle" and oυρά "tail".[2]

Doedicurus was a

Castellanosia, Xiphuroides, Daedicuroides, and Plaxhaplous.[5]

In 2016,

extant Chlamyphoridae.[7] Based on this and the fossil record, glyptodonts would have evolved their characteristic shape and large size (gigantism) quite rapidly, possibly in response to the cooling, drying climate and expansion of open savannas.[6]

Cladogram of glyptodonts after Barasoain et al. 2022[8]:

Glyptodonts

Description

Skull of Doedicurus from the front and right

Teeth

Glyptodonts have

dentine and cementum eventually protruding through the enamel of horse and cattle teeth.[9]

Glyptodonts have eight

bovines, completely lack canines and incisors. Nonetheless, Doedicurus and other large glyptodonts appear to have had a markedly reduced gape, and the teeth have relatively small grinding surfaces, which indicate they were incapable of thoroughly chewing food. This may have been caused by the increasing size of the muscles to support the head and neck as the armor in this region became heavier and heavier, displacing the chewing muscles to less mechanically efficient positions. This is odd as thoroughly grinding grass is very important in maximizing nutrient absorption, and such inefficiency could indicate a slow metabolism. The apparently strong tongue may have partially reworked and pushed incompletely chewed food into the stomach or possibly a cecum.[9]

Body

1913 reconstruction of Doedicurus and Glyptodon by Robert Bruce Horsfall

Doedicurus, on average, had a height of 1.5 m (4 ft 11 in), an overall length of around 3.6 m (12 ft),

scutes, somewhat similar to that of its modern-day relative, the armadillos. The carapace was firmly anchored to the pelvis but loose around the shoulder. The carapace featured a dome, which may have been a fat-filled space, similar to a camel's hump.[12]

Tail

Its tail was surrounded by a flexible sheath of bone, and features shallow depressions along the edges, which may have been spikes in life.[12] The tail club could reach up to 1 m (3 ft 3 in) in length. Assuming a maximum strain of 0.25 (typical for vertebrates), stress exertion of 3x105 N m−2 (based on what is measured in the muscles of recently dead animals), and a volume of 100 L (22 imp gal; 26 US gal) for the tail muscle, Doedicurus may have been capable of delivering a blow of about 2.5 kJ (1,800 ft⋅lbf), though this may be an underestimate. Assuming a total mass of 40 kg (88 lb) in life for the club, this would equate to a maximum velocity of 11 m/s (40 km/h; 25 mph).[a][13] The tip of the tail may have reached 15 m/s (54 km/h; 34 mph). Assuming the club was 65 kg (143 lb) in life, the center of percussion (the point of impact on the club which would have exerted maximum force and minimized damage done to itself) would have been about 77 cm (2.5 ft) from the tip.[14]

Limbs

As with other glyptodonts and xenarthrans, the center of mass appears to have been closer to the hind limbs than the forelimbs, indicating the vast majority and in some instance nearly all of the weight was borne on the hind limbs. This might show that glyptodonts, when their weight was displaced farther tailwards, could stand on two legs, though not necessarily maintaining an erect posture.[15][16] Modern xenarthrans commonly stand up in this fashion for defense, to observe, or to feed. Strong hind limbs would also have been important while accelerating the tail club and maintaining posture after getting hit.[16]

Nonetheless, glyptodonts also had powerful forearms. Because the forelimbs did not need to bear weight, it is possible that they dug much like modern armadillos, but the carapace and spine were much more rigid than those of armadillos. Alternatively, the forelimbs may have been engaged while rotating the body to swing the tail club.[16] Because earlier, smaller glyptodonts do not share similar weight distribution, the adoption of a bipedal stance may be related to increasing body size.[15][16]

Paleobiology

The depressions on the tail club may have supported spikes

Doedicurus is thought to have been a

bulk feeder.[17]

Glyptodont species notably increased in size after the Great American Interchange and immigration of new mammals into the previously isolated continent, with some of the largest glyptodonts, including Doedicurus, being known from the Pleistocene following this event. This may indicate increasing gigantism was an anti-predator adaptation in response to new mammalian carnivores.[6][11] There is evidence that Smilodon preyed upon Doedicurus.[18] In the Late Pleistocene and Holocene, size dramatically increased, perhaps in response to a cooling climate (which would have reduced its metabolism, causing an increase in size) or to defend against recently immigrating human hunters.[11]

However, the increase in armor and body mass might instead have been driven primarily by intraspecific competition in fights between Doedicurus individuals. If so, males would probably have been much more heavily built than females. Evidence of carapace fractures consistent with the force calculated for a tail club impact has been noted. The eyesight of Doedicurus may have been too poor for use of the tail club in predator defense.[12] The accuracy needed to strike a target with the club may only have been attainable with a stationary adversary, further supporting use in ritualistic combat rather than predator defense.[14]

Paleoecology

glyptodonts Glyptodon, Doedicurus, and Panochthus

Following the formation of the

toxodonts; and native rodents such as New World porcupines.[20]

Doedicurus is among the most commonly identified glyptodont genera of the Pleistocene, alongside Glyptodon, Neosclerocalyptus, Hoplophorus, Neuryurus, and Panochthus.[21] Glyptodonts generally inhabited open grassland with temperate to cool climate.[11] It appears to have been restricted to the cold, humid Chaco-Pampean plains of northeastern Patagonia.[17] Fossils have been found in Argentina, Brazil, and Uruguay.[22] The Pleistocene was characterized by frequent cold/warm cycles (glacials and interglacials), and sequences in Patagonia record over 15 glacial cycles, indicated by the switch from loess (deposited during glacials) to paleosol (during interglacials).[23] Glacials may have seen an increase in savanna, whereas interglacials (including modern day) are characterized by an expansion of rainforests.[20]

Extinction

Doedicurus may be the most recent-surviving glyptodont species, with the latest fossils suggested to date to about 8,000–7,000 years ago in the Pampas, though a G. claviceps specimen was contentiously dated to about 4,300 years ago.[11][24] A 2019 study suggested that these Holocene ages at Pampean sites are underestimates due to contamination by humic acids, more likely dating to the Late Pleistocene.[25]

Doedicurus, like many other

first human settlers of South America and coexisted with them for several thousand years. Because many other South American megafauna also seem to have persisted for some time following the close of the Pleistocene in this region—such as the armadillo Eutatus, the giant ground sloth Megatherium, and the dog Dusicyon avus—the Pampas may have been a refuge zone provided the dating is correct, providing productive grassland which was likely in decline elsewhere on the continent.[26] Their final demise may have been brought on or simply accelerated by human hunting.[27] However, a later study suggested that the late date for Doedicurus at La Moderna as well as other supposedly Holocene dated megafauna at other Pampas sites was likely due to contamination or other errors, casting doubt on their Holocene survival.[28]

See also

Wikimedia Commons has media related to Doedicurus.

Notes

  1. point mass—the entire mass was effectively summed down to a single point—which is an inaccurate representation.[13]

References

  1. ^ Lydekker, R. (1887). Catalogue of the Fossil Mammalia in the British Museum, (Natural History): The group Tillodontia, the orders Sirenia, Cetacea, Edentata, Marsupialia, Monotremata, and Supplement. Natural History Museum, London. pp. 122–123.
  2. JSTOR j.ctt16gzd2q
    .
  3. hdl:11336/43130
    .
  4. PMID 26906483
    .
  5. ISBN 978-0-231-52853-5
    .
  6. ^
    S2CID 3720645
    .
  7. ^
    PMID 26906483
    .
  8. S2CID 245945029
    .
  9. ^ a b Fariña, R. A.; Vizcaíno, S. F. (2001). "Carved teeth and strange jaws: How glyptodonts masticated" (PDF). Acta Palaeontologica Polonica. 46 (2): 219–234.
  10. S2CID 92413294
    .
  11. ^ a b c d e f Soibelzon, L. H.; Zamorano, M.; Scillato-Yané, G. J.; Piazza, D.; Rodriguez, S.; Soibelzon, E. &; Beilinson, E. (2012). "Un Glyptodontidae de gran tamaño en el Holoceno temprano de la Región Pampeana, Argentina" [A glyptodont of great size in the early Holocene of the Pampas, Argentina] (PDF). Revista Brasileira de Paleontología, Sociedade Brasileira de Paleontología, Rio de Janeiro, Brazil (in Spanish). 15 (1): 105–112. Archived from the original (PDF) on 24 September 2015.
  12. ^
    doi:10.1006/zjls.1997.0179
    .
  13. ^
    S2CID 250808555
    .
  14. ^
    PMID 19710060
    .
  15. ^
    doi:10.1111/j.1502-3931.1995.tb01422.x
    .
  16. ^
    doi:10.1111/j.1502-3931.2010.00228.x
    .
  17. ^
    S2CID 25974749
    .
  18. hdl:11336/4334
    .
  19. S2CID 15751319
    .
  20. ^
    PMID 21125025
    .
  21. doi:10.1016/j.annpal.2010.01.001
    .
  22. ^ "Doedicurus in the Paleobiology Database". Fossilworks. Retrieved 17 December 2021.
  23. ^ Soibelzon, E.; Tonni, E. P. (2009). "Early-Pleistocene Glaciations in Argentina (South America) and the Response of Mammals: The Case of the Pampean Region". Paleoenvironments: Vertebrates and Invertebrates.
  24. doi:10.1016/j.palaeo.2015.02.026
    .
  25. PMID 30854426
    .
  26. S2CID 163958695
    .
  27. doi:10.1016/S1040-6182(97)00063-3
    .
  28. doi:10.1016/j.quaint.2021.01.007
    .
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