A joint research group from Kyoto University, Juntendo University, and Saitama Medical University conducted macroscopic dissection of the muscles of the koala's buttocks and lower limbs (rear thighs). By updating the koala anatomy, which had not been updated for about 100 years, it became possible to compare anatomical findings with those of us placentals.
Mammals are divided into placental mammals, including humans, and marsupials, including koalas. Despite being phylogenetically distant, these two organisms acquired similar morphology during the evolutionary process. is allowed.This evolution is called convergence.In order to understand the convergent evolution of mammals, it is important to compare placentals and marsupials based on anatomical observations to determine whether there are similarities not only in appearance but also in function.
However, prior research on marsupial anatomy has been uniformly old (19th and early 20th centuries) and classically inadequate so far to make comparisons with placentals.For example, different names are used for muscles that are considered to be equivalent to those of placentals, and the same muscles of marsupials are described differently depending on the literature. It needed re-evaluation and updating.
Therefore, in cooperation with the University of Adelaide, Australia, our group performed gross dissection of the hips and posterior thigh muscles of adult koala specimens.At this time, by adopting a method based on the developmental origin of muscles, by carefully observing the course of nerves and identifying muscles by their innervating nerves, dissection of placental animals, which was previously difficult, has become possible. It made it possible to compare findings.
This study has clarified the inconsistent findings on koala muscle morphology in previous studies, and made the first step toward comparative anatomy of marsupials.They say that they were able to clarify common characteristics of marsupials and arboreal primates, as well as muscle morphological characteristics unique to koalas.The group plans to apply this research method to other muscles in marsupials.
Paper information:[PLOS ONE] Gross anatomy of the gluteal and posterior thigh muscles in koalas based on their innervations
