Researchers reconstructing sloth evolution found that extinct sloths developed large body sizes at an amazing rate. The study showed that some sloth lineages increased in size by over 100 kilos every million years -- some of the fastest rates of body size evolution known for mammals.

Our analysis support trended walks as the predominant model of sloth body size evolution, with driven trends and random walks receiving some support as well. For more on sloth evolution and locomotion, see this WIRED Science article I wrote about Nyakatura's previous work in 2010.

Speculative Evolution (also called Speculative Biology and Speculative Zoology) is the envisioning of fictional, but scientifically possible creatures that could have existed on an alternate Earth, or might actually exist somewhere on another planet or in the deep sea. 1. Evolution. All four sloth subgroups were separately parameterized in 6 of the 8 best-supported models, reflecting … Using a data set of all 57 species of known living and fossil sloths, a trio of researchers led by John Finarelli of University College Dublin examined changes in body mass through sloth evolution.

However new research, published today in BMC Evolutionary Biology, suggests this makes them the black sheep of the sloth family; instead most species in this group have been more like the giant ground sloths, now long extinct. Evolution of a Sloth By: Kileigh Devlin and Sydney Kidd Period 6 Megatherium Americanum Timeline of the Sloth They tested different statistical models of body size evolution against data for 57 species of living and extinct sloth. Sometimes, it helps to look at the evolution of science at a sloth’s pace.

Research published last year in BMC Evolutionary Biology indicates that sloths have changed dramatically during their evolution, showing extremely fast evolution in body size over the last … years. Christopher Foote 10 Sep 2014. Rapid Evolution in the Sloth Lineage. Today, sloths are all small tree-climbing animals. Most research on sloth evolution has previously focussed only on extant sloths, but the authors point out this gives a distorted view of sloth evolution. There are 6 species of sloth split between two very different families: the three-fingered (Bradypodidae, genus: Bradypus) and the two-fingered (Megalonychidae, genus: Choloepus). Most research on sloth evolution has previously focussed only on extant sloths, but the authors point out this gives a distorted view of sloth evolution. Slothful trends in evolution: from walking giants to tiny tree-dwellers. evolution of sloth body size through time using a “fam-ily”-level phylogeny and a general time-variable model [8,22,23] for analyzing continuous character evolution in clades lacking fully-resolved phylogenies. Our model structure estimates ancestral average body mass and the The diversification of B. variegatus lineages was estimated to have started 4 to 5 million years ago..

For more on sloth evolution and locomotion, see this WIRED Science article I wrote about Nyakatura’s previous work in 2010. A study of mitochondrial cytochrome b and 16S rRNA sequences suggests that B. torquatus diverged from B. variegatus and B. tridactylus about 12 million years ago, while the latter two split 5 to 6 million years ago.

Sloth Evolution Timeline By: Emily Thavenet-the giant ground sloth-existed 35 million years ago-6 meters tall-they weighed more than an elephant. Where evolution meets science fiction and art. Share -called the marine sloth-they lived about 4 million years ago-they have long snorts unlike modern day sloths-their longs claws helped them dig for food in the water . In order to accurately reconstruct sloth evolution, it is critical to incorporate their extinct diversity in analyses.