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Two-toed sloths (genus Choloepus) are almost exclusively arboreal. However, they often descend to the ground in places known as mineral licks or “saladeros” and feed from soil, which presumably enhances their digestion of toxins and helps them obtain minerals not readily available in their diet. Mineral licks are risky areas which may increase their visitors’ vulnerability to predators. Here, we report a predation attempt on an adult Linnaeus two- toed sloth (Choloepus didactylus) by an adult ocelot (Leopardus pardalis) at a mineral lick at the Tiputini Biodi- versity Station in the Ecuadorian Amazon. Predation events are rarely recorded in camera traps, and this particular predation event can be considered unusual, given that sloths usually come down to mineral licks during the night. Also, it is not clear how ocelots are able to capture sloths, and other arboreal animals and this record evidence that predation of arboreal vertebrates by ocelots may also take place in the ground. Finally, the anti-predatory behavior displayed by the two-toed sloth demonstrates that there are intrinsic risks for predators while attempting to capture prey.
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Ossification pattern of the unusual pisiform in two‐toed ( Choloepus ) and three‐toed sloths ( Bradypus )
Abstract Two‐toed (Choloepus sp.) and three‐toed (Bradypus sp.) sloths possess short, rounded pisiforms that are rare among mammals and differ from other members of Xenarthra like the giant anteater (Myrmecophaga tridactyla) which retain elongated, rod‐like pisiforms in common with most mammals. Using photographs, radiographs, and μCT, we assessed ossification patterns in the pisiform and the paralogous tarsal, the calcaneus, for two‐toed sloths, three‐toed sloths, and giant anteaters to determine the process by which pisiform reduction occurs in sloths and compare it to other previously studied examples of pisiform reduction in humans and orangutans. Both extant sloth genera achieve pisiform reduction through the loss of a secondary ossification center and the likely disruption of the associated growth plate based on an unusually porous subchondral surface. This represents a third unique mechanism of pisiform reduction among mammals, along with primary ossification center loss in humans and retention of two ossification centers with likely reduced growth periods in orangutans. Given the remarkable similarities between two‐toed and three‐toed sloth pisiform ossification patterns and the presence of pisiform reduction in fossil sloths, extant sloth pisiform morphology does not appear to represent a recent convergent adaptation to suspensory locomotion, but instead is likely to be an ancestral trait of Folivora that emerged early in the radiation of extant and fossil sloths.
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- PAR ID:
- 10445449
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- The Anatomical Record
- Volume:
- 305
- Issue:
- 7
- ISSN:
- 1932-8486
- Format(s):
- Medium: X Size: p. 1804-1819
- Size(s):
- p. 1804-1819
- Sponsoring Org:
- National Science Foundation
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