A fossil discovered in 2008 belongs to an extinct sea cow ancestor, demonstrating their freshwater African origins.
The evolution of the Sirenia order, which is comprised of manatees and
dugongs, has long been shrouded in mystery. Though their closest living
relatives are elephants, no evidence of an African ancestry had ever
been found. The oldest fossils (such as the terrestrial Pezosiren) had been found in Jamaica. It's only now, with this single fossil, that the history of sea cows in Africa is beginning to emerge.
The fossil itself is a petrosal bone, part of the skull. That may not
seem a lot, but petrosal bones on their own can tell us a lot about the
animal they belonged to. Because the bone molds to the structures
surrounding it (the brain, carotid artery, cranial nerves and others),
it has a unique shape for each species. Its shape told the team (of the
University of Science and Technology in Montpellier, France) that it
belonged to a sirenian creature, while its density showed it was from an
aquatic species. Rather than give it a proper name based on limited
information, the team just call it "the Chambi sea cow".
Found
in what used to a freshwater lake in Tunisia, the fossil has been dated
to around 50 million years ago. This puts it at the same age as
Prorastomus (the oldest discovered Sirenian fossil until now, but found
in Jamaica), meaning there must have been an earlier dispersal event
when prehistoric (and legged) Sirenians crossed the Atlantic. The team
suspect that this sea cow had legs too, but spent a great deal of time
in water and was a successful swimmer.
To read the paper, click here: http://bit.ly/Wd4oZ8
Photo credit: Luciano Candisani/Minden Pictures.
http://
http://www.livescience.com/
A fossil discovered in 2008 belongs to an extinct sea cow ancestor, demonstrating their freshwater African origins.
The evolution of the Sirenia order, which is comprised of manatees and dugongs, has long been shrouded in mystery. Though their closest living relatives are elephants, no evidence of an African ancestry had ever been found. The oldest fossils (such as the terrestrial Pezosiren) had been found in Jamaica. It's only now, with this single fossil, that the history of sea cows in Africa is beginning to emerge.
The fossil itself is a petrosal bone, part of the skull. That may not seem a lot, but petrosal bones on their own can tell us a lot about the animal they belonged to. Because the bone molds to the structures surrounding it (the brain, carotid artery, cranial nerves and others), it has a unique shape for each species. Its shape told the team (of the University of Science and Technology in Montpellier, France) that it belonged to a sirenian creature, while its density showed it was from an aquatic species. Rather than give it a proper name based on limited information, the team just call it "the Chambi sea cow".
Found in what used to a freshwater lake in Tunisia, the fossil has been dated to around 50 million years ago. This puts it at the same age as Prorastomus (the oldest discovered Sirenian fossil until now, but found in Jamaica), meaning there must have been an earlier dispersal event when prehistoric (and legged) Sirenians crossed the Atlantic. The team suspect that this sea cow had legs too, but spent a great deal of time in water and was a successful swimmer.
To read the paper, click here: http://bit.ly/Wd4oZ8
Photo credit: Luciano Candisani/Minden Pictures.
http://
http://www.livescience.com/
The evolution of the Sirenia order, which is comprised of manatees and dugongs, has long been shrouded in mystery. Though their closest living relatives are elephants, no evidence of an African ancestry had ever been found. The oldest fossils (such as the terrestrial Pezosiren) had been found in Jamaica. It's only now, with this single fossil, that the history of sea cows in Africa is beginning to emerge.
The fossil itself is a petrosal bone, part of the skull. That may not seem a lot, but petrosal bones on their own can tell us a lot about the animal they belonged to. Because the bone molds to the structures surrounding it (the brain, carotid artery, cranial nerves and others), it has a unique shape for each species. Its shape told the team (of the University of Science and Technology in Montpellier, France) that it belonged to a sirenian creature, while its density showed it was from an aquatic species. Rather than give it a proper name based on limited information, the team just call it "the Chambi sea cow".
Found in what used to a freshwater lake in Tunisia, the fossil has been dated to around 50 million years ago. This puts it at the same age as Prorastomus (the oldest discovered Sirenian fossil until now, but found in Jamaica), meaning there must have been an earlier dispersal event when prehistoric (and legged) Sirenians crossed the Atlantic. The team suspect that this sea cow had legs too, but spent a great deal of time in water and was a successful swimmer.
To read the paper, click here: http://bit.ly/Wd4oZ8
Photo credit: Luciano Candisani/Minden Pictures.
http://
http://www.livescience.com/
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