1. Sirenian Evolution & Systematics MARE 390 Dr. Turner

2. Order Sirenia Only herbivorous marine mammals 2 Families of Sirenians Trichechidae – manatee (3 species) Dugongidae – dugong (1 species)

3. Order Sirenia Fossil record from early Eocene (50 mya)

4. Sirenian Biogeography Sirenians first evolved in the Caribbean (Jamaica) By end of the Eocene – occupied tropical Atlantic & Pacific Dugongids – most diverse & successful sirenians; appeared in Mediterranean “No, mon, let's go home to Jamaica. I and I been in Babylon too long. I want to pass the dutchie on the left-hand side!” – Homer Simpson

5. Sirenian Biogeography Dugongids – most diverse & successful sirenians; appeared in Mediterranean Manatees – diverged from Dugongids in late Eocene; occupied coastal estuaries of South America

6. Order Sirenia Earliest partially aquatic quadrupeds Morphology consistent – aquatic existence

7. Order Sirenia Sirenians, proboscideans (elephants), & desmostylians (extinct) termed Tethytheria

8. Order Sirenia ManateeDugong

9. Hydrostatic Adaptions Sirenian skeleton – thick compact bone Heavy bones & horizontal lungs – neutral buoyancy Muscular diaphragm

10. Whatever Sea Cow! Sea Elephants? “This is the greatest case of false advertising I've seen since I sued the movie ‘The Never Ending Story’.” - Lionel Hutz Attorney at Law

11. Family Trichechidae Trichechus senegalensis - West African manatee Trichechus inunguis - Amazonian manatee Trichechus manatus - West Indian manatee 2 subspecies: Trichechus m. latirostris - Florida manatee Trichechus m. manatus Antillean manatee

12. Family Dugongidae Dugong dugong - Dugong Hydrodamalis gigas - Steller’s sea cow

13. Family Dugongidae More diverse in the past than manatee 19 extinct genera; some cold adapted Many had tusks

14. Steller’s Sea Cow Known for 27 yrs (1741-1768) Large sized sirenian (7.5-7.9 m) Cold-temperate waters of Bering Sea Fed in water column – Kelp Small in number & range when described Quickly wiped out by sailors, sealers, & fur traders Hunted for food, skins, & blubber

15. Order Desmostylia Only extinct order of marine mammals At least 6 genera; 10 species Hippo-sized amphibious quadrapeds Estuarine/coastal – subtropical/temperate

16. Order Desmostylia Similar locomotion to polar bears Herbivore – marine algae & seagrasses