THE YOUNGEST SPECIES OF THE AQUATIC SLOTH THALASSOCNUS AND A REASSESSMENT OF THE RELATIONSHIPS OF THE NOTHROTHERE SLOTHS (MAMMALIA: XENARTHRA)
THE YOUNGEST SPECIES OF THE AQUATIC SLOTH THALASSOCNUS AND A REASSESSMENT OF THE RELATIONSHIPS OF THE NOTHROTHERE SLOTHS (MAMMALIA: XENARTHRA)
复制标题
水生树懒最年轻的物种以及对其他树懒（哺乳动物：Xenarthra）关系的重新评估
作者：
C. Muizon;H. Gregory McDonald;R. Salas;M. Urbina
描述了产于秘鲁上新世的两种新的水栖树懒Thalassocnus标本，其中一种为T. carolomartini McDonald and Muizon，2002;与模式种Thalassocnus，T. natans，证明T. carolomartini和T. yaucensis在形态上彼此比该属的其他物种更相似，并且更衍生。例如，两者都有更长的喙（前颌骨和下颌喷口）和更坚固的方形至圆形臼齿。水栖树懒Thalassocnus在形态上足够独特，因此被归入一个新的亚科，Thalassocninae，而Nothrotheriinae被提升到家庭等级。形态特征与T. carolomartini和T. yaucensis表明这些物种比早期的Thalassocnus物种更适合放牧海洋植被。
Abstract Two new specimens of the aquatic sloth Thalassocnus from the Pliocene of Peru are described, one of T. carolomartini McDonald and Muizon, 2002 and the other T. yaucensis, sp. nov. Comparisons with the type species of Thalassocnus, T. natans, demonstrates that T. carolomartini and T. yaucensis are more similar morphologically to each other than to other species of the genus and are more derived. For example, both have a more elongated rostrum (premaxillae and mandibular spout) and more robust, quadrate to circular molariform teeth. The aquatic sloth Thalassocnus is sufficiently distinct morphologically that it is placed in a new subfamily, the Thalassocninae, and the Nothrotheriinae is raised to family rank. The morphological features shared by T. carolomartini and T. yaucensis indicate these species were better adapted to grazing on marine vegetation than earlier species of Thalassocnus.