Showing posts tagged dugong


Walking With Sea Cows, Closing the Gap

by Brian Switek

Sea cows once walked on land. Pezosiren leaves no doubt of that.

This roughly 48 million year old mammal once trod over prehistoric Jamaica, and looked akin to a hippo with the skull of a manatee. Much like Pakicetus in the history of early whales, Pezosiren embodies a critical transitional period in the evolution of manatees and dugongs, yet the place where this amphibious sea cow was found did not match what paleontologists expected.

In the big picture of mammalian evolution, sea cows are paenungulates – members of a group that also encompasses hyraxes, elephants, and extinct branches such as the double-horned Arsinoitherium and the aquatic desmostylians.

The earliest members of these lineages first appear in Africa shortly after the end-Cretaceous extinction of 66 million years ago, with the perplexing exception of the sea cows. The earliest, most archaic progenitors of today’s manatees and dugongs, such as Pezosiren, have been found in Jamaica. Anatomical and genetic evidence is clear that sea cows must have shared an African origin with the other paenungulates, but, until now, no one has picked up the fossil trail of the earliest sirenians.

Today, in PLoS One, paleontologist Julien Benoit and colleagues describe a bone from the Eocene of Tunisia that closes the geographical gap in the sea cow backstory…

(read more: National Geo)

(images: T -uncredited; BL -by TheSuperMat | Wikipedia ; BR - Benoit et al., PLoS ONE)

explosionsoflife asked: Could you possibly inform me of the main differences between manatees and dugongs? =)

Sure thing Kumquat :3

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MANATEES AND DUGONGS:

Manatees are in the family Trichechidae. They have large rounded, paddle like tails, and shorter muzzles. Manatees are coastal Atlantic, with 3 species found in the Americas and Africa. Manatees are the only mammals who constantly grow new adult teeth (through horizontal tooth displacement) as old teeth are lost or damaged.

Dugongs are in the family Dugongidae. The have fluked tails (like whales), and have longer snouts. Dugongs are found in coastal areas of the Indian and Pacific Oceans. Dugongs do not experience horizontal tooth displacement.

Afrotheria  … a (probable) clade of mammals, the living members of which belong to groups from Africa or of African origin: golden moles, sengis (also known as elephant shrews), tenrecs, aardvarks, hyraxes, elephants and sea cows. The common ancestry of these animals was not recognized until the late 1990s. Historically, the Paenungulata had been linked to other ungulates; the golden mole, tenrecs, and elephant shrews with the traditional (and polyphyletic) Insectivora; and the aardvarks with the pangolins and the xenarthrans within the invalid taxon, the Edentata. Continuing work on the molecular and morphological diversity of afrotherian mammals has provided ever increasing support for their common ancestry… (read more: Wikipedia)      (image: Esculapio) View high resolution

Afrotheria 

… a (probable) clade of mammals, the living members of which belong to groups from Africa or of African origin: golden moles, sengis (also known as elephant shrews), tenrecs, aardvarks, hyraxes, elephants and sea cows. The common ancestry of these animals was not recognized until the late 1990s. Historically, the Paenungulata had been linked to other ungulates; the golden mole, tenrecs, and elephant shrews with the traditional (and polyphyletic) Insectivora; and the aardvarks with the pangolins and the xenarthrans within the invalid taxon, the Edentata. Continuing work on the molecular and morphological diversity of afrotherian mammals has provided ever increasing support for their common ancestry…

(read more: Wikipedia)      (image: Esculapio)

Lumbering Sea Cows Were Once Plentiful and Diverse

by Jennifer Welsh

Today’s sea cows are lonely: They share their habitat only with others of their species. This wasn’t always the case, new research suggests. In the past multiple species of sea cow lived together in harmony.

Sea cows, also known as Sirenians, are defined by four species, the best known in the United States being our Florida resident, the manatee. There are two other species of manatee in the Atlantic Ocean, as well as the dugong, from the Indo-Pacific.

The researchers found multiple examples of Sirenians in the same fossil bed at the same depth — evidence the two species would have lived in the same area at the same time. Before modern times, up to three species of these big herbivores (they eat mainly sea grasses) could be found together in the same area. This suggests that the environment and food sources for ancient sea cows were different in the past, but researchers weren’t sure how…

(read more: Live Science)

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(top image: Dugong, by Julien Willem)

(bttom image: Three sets of sea cows lived in three different times and locations: the late Oligocene (23 million to 28 million years ago) in Florida, the early Miocene (16 million to 23 million years ago) in India and the early Pliocene (3 million to 5 million years ago) in Mexico; illustration by Carl Buell)

Dugong (Dugong dugon) by National Geo staff These enormous vegetarians can be found in warm coastal waters from East Africa to Australia, including the Red Sea, Indian Ocean, and Pacific. Dugongs are related to manatees and are similar in appearance and behavior— though the dugong’s tail is fluked like a whale’s. Both are related to the elephant, although the giant land animal is not at all similar in appearance or behavior. Dugongs graze on underwater grasses day and night, rooting for them with their bristled, sensitive snouts and chomping them with their rough lips. These mammals can stay underwater for six minutes before surfacing. They sometimes breathe by “standing” on their tail with their heads above water. Dugongs spend much of their time alone or in pairs, though they are sometimes seen gathered in large herds of a hundred animals. Female dugongs have one calf after a yearlong pregnancy, and the mother helps her young reach the surface and take its first breath. A young dugong remains close to its mother for about 18 months, sometimes catching a ride on her broad back… (read more: National Geo)     (photo: OSF/D. Fleetham/Animals Animals—Earth Scenes) View high resolution

Dugong (Dugong dugon)

by National Geo staff

These enormous vegetarians can be found in warm coastal waters from East Africa to Australia, including the Red Sea, Indian Ocean, and Pacific. Dugongs are related to manatees and are similar in appearance and behavior— though the dugong’s tail is fluked like a whale’s. Both are related to the elephant, although the giant land animal is not at all similar in appearance or behavior.

Dugongs graze on underwater grasses day and night, rooting for them with their bristled, sensitive snouts and chomping them with their rough lips. These mammals can stay underwater for six minutes before surfacing. They sometimes breathe by “standing” on their tail with their heads above water.

Dugongs spend much of their time alone or in pairs, though they are sometimes seen gathered in large herds of a hundred animals. Female dugongs have one calf after a yearlong pregnancy, and the mother helps her young reach the surface and take its first breath. A young dugong remains close to its mother for about 18 months, sometimes catching a ride on her broad back…

(read more: National Geo)    

(photo: OSF/D. Fleetham/Animals Animals—Earth Scenes)

scientificillustration: superorder Afrotheria “Representatives of the six orders of mammals comprising the Superorder Afrotheria: (Upper Left) African forest elephant (Loxodonta africana); (Upper Right) Golden-rumped elephant shrew (Rhynchocyon chrysopygus); (Middle Left) Aardvark (Orycteropus afer); (Middle Right) Streaked tenrec (Hemicentetes nigriceps); (Lower Left) Eastern tree hyrax (Dendrohyrax validus); and (Lower Right) Dugong (Dugong dugon). [Images of tenrec and dugong reproduced with permission from Andromeda Oxford Limited (18); other images reproduced with permission from Jonathan Kingdon.].” View high resolution

scientificillustration: superorder Afrotheria

“Representatives of the six orders of mammals comprising the Superorder Afrotheria: (Upper Left) African forest elephant (Loxodonta africana); (Upper Right) Golden-rumped elephant shrew (Rhynchocyon chrysopygus); (Middle Left) Aardvark (Orycteropus afer); (Middle Right) Streaked tenrec (Hemicentetes nigriceps); (Lower Left) Eastern tree hyrax (Dendrohyrax validus); and (Lower Right) Dugong (Dugong dugon).

[Images of tenrec and dugong reproduced with permission from Andromeda Oxford Limited (18); other images reproduced with permission from Jonathan Kingdon.].”

(Reblogged from scientificillustration)
The Discovery of Multispecies Communities of Seacows by Jorge Velez-Juarbe Sirenians, or seacows, are a group of marine mammals that include manatees and dugongs. In the modern world, only one species of seacow is found in each world region, however, the fossil record tells a different story. According to the fossil record of these marine mammals, which dates back 50 million years ago, it was more common to find three, maybe more, different species living together at one time. This oddity hinted that seacows’ environment and food sources were different than what we see today. Inspired by this finding, a group of paleontologists including Drs. Daryl Domning, Nick Pyenson and myself conducted research on extinct seacows from different ocean basins, in different geological times, to learn more about the paleoecology and evolution of these marine mammals. Presently, there are only four species of living seacows. These include three species of manatees, which are found in different coastal waters of the Atlantic Ocean, and one species of dugong, found around coasts of the Indo-Pacific Ocean. All seacows are consumers of marine vegetation, and they generally concentrate on seagrasses.  The geographic distribution of living seacows shows no overlap.  However, the fossil record of seacows shows several instances where different species co-existed… (read more: Smithsonian Ocean Portal)     (image: Carl Buell) View high resolution

The Discovery of Multispecies Communities of Seacows

by Jorge Velez-Juarbe

Sirenians, or seacows, are a group of marine mammals that include manatees and dugongs. In the modern world, only one species of seacow is found in each world region, however, the fossil record tells a different story. According to the fossil record of these marine mammals, which dates back 50 million years ago, it was more common to find three, maybe more, different species living together at one time. This oddity hinted that seacows’ environment and food sources were different than what we see today.

Inspired by this finding, a group of paleontologists including Drs. Daryl Domning, Nick Pyenson and myself conducted research on extinct seacows from different ocean basins, in different geological times, to learn more about the paleoecology and evolution of these marine mammals.

Presently, there are only four species of living seacows. These include three species of manatees, which are found in different coastal waters of the Atlantic Ocean, and one species of dugong, found around coasts of the Indo-Pacific Ocean. All seacows are consumers of marine vegetation, and they generally concentrate on seagrasses.  The geographic distribution of living seacows shows no overlap.  However, the fossil record of seacows shows several instances where different species co-existed…

(read more: Smithsonian Ocean Portal)     (image: Carl Buell)

 The Dugong (Dugong dugon) is a large marine mammal which, together with the manatees, is one of four living species of the order Sirenia. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller’s Sea Cow (Hydrodamalis gigas), was hunted to extinction in the 18th century. It is also the only sirenian in its range, which spans the waters of at least 37 countries throughout the Indo-Pacific.The dugong is the only strictly-marine herbivorous mammal, as all species of manatee utilize fresh water to some degree.[3] The dugong is heavily dependent on seagrasses for subsistence and is thus restricted to the coastal habitats where they grow, with the largest dugong concentrations typically occurring in wide, shallow, protected areas such as bays, mangrove channels and the lee sides of large inshore islands.[3] (read more: Wikipedia) View high resolution

 The Dugong (Dugong dugon) is a large marine mammal which, together with the manatees, is one of four living species of the order Sirenia. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller’s Sea Cow (Hydrodamalis gigas), was hunted to extinction in the 18th century. It is also the only sirenian in its range, which spans the waters of at least 37 countries throughout the Indo-Pacific.The dugong is the only strictly-marine herbivorous mammal, as all species of manatee utilize fresh water to some degree.[3] The dugong is heavily dependent on seagrasses for subsistence and is thus restricted to the coastal habitats where they grow, with the largest dugong concentrations typically occurring in wide, shallow, protected areas such as bays, mangrove channels and the lee sides of large inshore islands.[3]

(read more: Wikipedia)

one green planet: Save the Sea Cow (Dugongs)!

onegreenplanet:

The sea mammal that is believed to be responsible for the origin of the mermaid legends is at serious risk of becoming extinct within the next 40 years. The dugong (Manatee-like mammals also known as sea cows) is the largest marine herbivorous mammal that feeds on sea grasses and other…

(Reblogged from onegreenplanet)