Dusisiren, Sobrarbesiren and Prorastomus

Prorastomus sirenoides (Owen 1855; Middle Eocene, 40 mya; 1.5m in length) is a basal sirenian with four legs of even length, a short tail and more teeth.

Sobrarbesiren cariedli (Díaz-Berenguer 2018; Eocene, 47mya) is a basal sirenian with four legs, a short tail and teeth. The anterior dorsals are taller and the pelvis is longer. The caudal vertebrae have ventral processes. The cervicals are shorter. The forelimbs are larger than the hind limbs.

Dusisiren reinharti (Donning 1978) is a recely extinct dugong adapted to cold waters. Related most closely to Elephas among tested taxa, both were derived from a sister to Stylinodon, Moeritherium and Ectocion. Tusks and hind limbs are absent here. This was a slow-swimming herbivore.

Díaz-Berenguer E et al. 2018. First adequately-known quadrupedal sirenian from Eurasia (Eocene, Bay of Biscay, Huesca, northeastern Spain. Scientific Reports. 8 (1): 5127.

Domning DP 1978. Sirenian evolution in the North Pacific Ocean. University of California Publications in Geological Sciences 118:1-176

Owen R 1855. On the fossil skull of a mammal (Prorastomus sirenoïdes, Owen) from the island of Jamaica. The Quarterly Journal of the Geological Society of London 11:541-543.

Self-Sullivan C. Evolution of the Sirenia.

wiki/Dusisiren
wiki/Prorastomus
wiki/Evolution_of_sirenians
wiki/Sobrarbesiren