Tethytheria

Tethytheria is a clade of paenungulate mammals that includes the sirenians, proboscideans, and the extinct order Embrithopoda.

Sobrarbesiren (meaning "siren from Sobrarbe") is a genus of extinct sirenian that lived in the Eocene, about 47 million years ago. The type and only species is S. cardieli, known from a multitude of specimens from the Spanish Pyrenees. Sobrarbesiren was a medium-sized animal, long and still retaining both pairs of limbs. Although initially thought to be amphibious, later studies instead suggest that they would have been fully aquatic and been selective sea grass browsers. Unlike modern dugongs and manatees, they likely lacked a tail fluke, although it would have appeared horizontally flattened