Transitional vertebrae in sloths and manatees showing incomplete and asymmetric transformations. A) Ventral view of a transitional thoraco-lumbar vertebra of a Bradypus tridactylus (ZMA.331) with a short rudimentary rib on the left (white arrow). B)Dorsal view of a transitional lumbo-sacral vertebra of a Choloepus didactylus (ZMA.334) with bilaterally incomplete fusion with the sacrum (arrows). C) Ventral view of a transitional sacro-coccygeal vertebra in a Bradypus tridactylus (ZMA.331) with on the right incomplete fusion with the sacrum (arrow). D) ventral view of a transitional thoraco-caudal vertebra in a Trichechus manatus (RMNH.MAM.22392),with a rudimentary rib on the right side and a transitional transverse process without rib on the left side (arrows).