User:Boor.17

Topic: Evolution of tree sloths; particularly the relationship between two- and three-toed sloths

Nyakatura, J. A., A. Petrovitch, and M. S. Fischer. "Limb Kinematics during Locomotion in the Two-toed Sloth (Choloepus Didactylus, Xenarthra) and Its Implications for the Evolution of the Sloth Locomotor Apparatus." (2010): n. pag. PubMed. Web. 13 Sept. 2014.

This study was conducted in order to analyze the locomotion of the two-toed sloth. They examined gait, limb coordination and kinematics. It was determined that in order to move faster sloths would decrease contact time and increase the step length. They also analyzed the structure of the hands and feet and their effect on locomotion. They determined that the hands and feet were utilized to maintain grip and stability and not used to alter step length or speed. The implications of the study are that we know more about suspensory posture and movement in sloths.

Pujos, Francois, Timothy J. Gaudin, Gerardo De Iuliis, and Castor Cartelle. "Recent Advances on Variability, Morpho-Functional Adaptations, Dental Terminology, and Evolution of Sloths." Journal of Mammalian Evolution 19.3 (2012): 159-69. Web.

This article studies evidence of sloths in typically underexamined locations like the Andes and Pacific desert coast. Fossils of sloths were found that exhibit varying traits from the modern tree sloths such as bipedality, aquatic/semiaquatic lifestyle and semiarboreality. The use of a phylogenetic tree was utilized in order plot functional traits and determine/track evolutionary change in sloths. DNA analysis was also utilized.

Pant, Sara Raj, Anjali Goswami, and John A. Finarelli. "Complex Body Size Trends in the Evolution of Sloths (Xenarthra: Pilosa)." BMC Evolutionary Biology 14.2 (2014): n. pag. CrossRef. Web. 13 Sept. 2014.

This study consisted of analyzing 57 different species of living and fossil sloths focusing on changes in body mass and evolutionary variance. They resulted in 8 models which could potentially explain the extreme variance between sloth species. Species of sloths that exist today are believed to be separated by 30 million years of evolution. This study is useful in its stress of the use of fossil sloths since evolution is something that can only be accurately analyzed over an extensive period of time.

Billet, G., D. Germain, I. Ruf, and L. Hautier. "The Inner Ear of Megatherium and the Evolution of the Vestibular System in Sloths."Journal of Anatomy 223.6 (2013): 557-67. Elsevier B.V. Web. 13 Sept. 2014.

Like the “Complex body size in the evolution of sloths” article, this article also uses fossil sloths to gather information about the evolution of sloths, but instead of focusing on body mass it focuses on the structure of the inner ear in the fossil sloth, Megatherium americanum. The study found that the inner ear structure of Megatherium americanum suggests proximity to armadillos and anteaters.

Gaudin, Timothy J. "Phylogenetic Relationships among Sloths (Mammalia, Xenarthra, Tardigrada): The Craniodental Evidence." Zoological Journal of the Linnean Society 140.2 (2004): 255-305. Wiley Online Library. Web. 13 Sept. 2014.

This article evaluates relationships between extant and extinct sloths by analyzing bone structures such as that of the skull, jaw, and hyoid arch. The results suggest that the extant species of sloths, the two-toed sloths and three-toed sloths, split up to 40 million years ago. The author asserts that many of their adaptations such as suspensory locomotor habits are due to dramatic convergent evolution. By analyzing 286 characteristics in the bones the authors sought to create a phylogenetic tree with 33 different sloth species. Many of the relationships between clades are still unknown.