The animal was also monogamous and social, living in small family groups and raising its young, similar to extant sirenians
She covers setting the stage: rocks, fossils, and evolution; the oldest marine mammals: whales and sea cows; later-diverging whales: neoceti; aquatic carnivorans: pinnipeds and a bear-like carnivoran; crown sirenians
and their desmostylian relatives; aquatic sloths and recent occupants of the seas, sea otters and polar bears; and diversity changes through time: the influence of climate change and humans.
Globally, the macroalgal grazer clade includes marine mammals (sirenians
) reptiles (chelonids and squamates), a variety of herbivorous fish (kyphosids, scarids, acanthurids, pomacentrids, siganids, among some others), and a vast array of invertebrates (gastropods, amphipods, decapods, polyplacophorans, echinoderms, among others).
These were the famous fossil whales but also turtles, sirenians
-- represented in modern Egypt by the Dugong -- and even whole mangrove swamps cast in rock.
The relation between the size of the ribs and the vertebrae exclude most of the cetaceans and sirenians
such as Trichechidae and some Dugongidae (e.g.
Sea cows, also known as sirenians
, are aquatic plant-eating mammals.
Age determination of toothed whales and sirenians
: Report of the Workshop.
Gardner) in 1986followed by volume 2 (primates, carnivorans, sirenians
, ungulates, cetaceans, and lagomorphs: editor S.
The Sierra Club handbook of seals and sirenians
, 359 p.
(The only exceptions among mammals are sloths and aquatic mammals known as sirenians
, such as manatees.)
In marine mammals, anomalously white individuals have been reported for 25 cetacean species and eight species of pinnipeds (otariids and phocids), with no known record for otters and sirenians
(Acevedo et al., 2009).
All the sirenians
are at some risk of extinction (IBAMA, 2001).