Megalocnidae is an extinct family (alternatively considered to be a superfamily as Megalocnoidea) of sloths, native to the islands of the Greater Antilles from the Early Oligocene to the Mid-Holocene. They are known from Cuba, Hispaniola and Puerto Rico, but are absent from Jamaica. While they were formerly placed in the Megalonychidae alongside two-toed sloths and ground sloths like Megalonyx, recent mitochondrial DNA and collagen sequencing studies place them as the earliest diverging group basal to all other sloths. or as an outgroup to Megatherioidea. They displayed significant diversity i
Megalocnidae is an extinct family (alternatively considered to be a superfamily as Megalocnoidea) of sloths, native to the islands of the Greater Antilles from the Early Oligocene to the Mid-Holocene. They are known from Cuba, Hispaniola and Puerto Rico, but are absent from Jamaica. While they were formerly placed in the Megalonychidae alongside two-toed sloths and ground sloths like Megalonyx, recent mitochondrial DNA and collagen sequencing studies place them as the earliest diverging group basal to all other sloths. or as an outgroup to Megatherioidea. They displayed significant diversity in body size and lifestyle, with Megalocnus being terrestrial and probably weighing several hundred kilograms, while Neocnus was likely arboreal and similar in weight to extant tree sloths, at less than 10 kilograms.
== Origin == It is thought that sloths arrived in the Caribbean from South America (where they arose) around the Eocene-Oligocene boundary about 33 million years ago, when there was a significant sea level drop caused by a glaciation episode. This has been associated with the GAARlandia (Greater Aves Antilles Ridge) hypothesis, where the Aves Ridge is suggested to have formed a land bridge during the interval, allowing overland migration into the Greater Antilles. The existence of such a land bridge has been questioned because of the lack of geological evidence for the Aves Ridge having been subaerially exposed as well as the fact that many other South American animals (such as marsupials and ungulates) are absent from the Greater Antilles, making a complete land bridge unlikely. The earliest evidence suggesting the presence of sloths in the Caribbean is a partial femur from the Early Oligocene of Puerto Rico. Other pre-Pleistocene fossil remains include Imagocnus from the Early Miocene of Cuba, and an indeterminate species from the Late Miocene of the Dominican Republic.
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